UCS Blog - All Things Nuclear (text only)

Xi’s China

What’s happening in China? The US consensus seems to be that President Xi Jinping is upending the place. Yet, midway through an expected ten-year term China’s communist party general secretary delivered a report to the 19th Party Congress that reiterated all the language, ideas and policies that the Chinese communists have used to govern the country since the mid-1980s. The most remarkable thing about Xi’s China is that it hasn’t changed at all.

Chinese Communist Party General Secretary Xi Jinping addresses the 19th Party Congress

China remains a socialist country. Xi’s not only proud of that, he’s confident that continuing to follow the socialist road will put China on the right side of history. What makes his tenure at the top seem different is that he’s unapologetically elevated ideology over policy. In Chairman Mao’s parlance, Xi is a little more red than expert.

But that doesn’t mean he’s changed Chinese policy. Internationally, Xi reported China remains open to the outside world. Domestically, his government remains committed to economic and political reform. It may not be the kind of openness or the type of reform US officials hoped for, but US expectations for China have always been based on a different view of history. Even after the Chinese leadership used lethal military force to suppress nationwide public demonstrations in June of 1989, most US observers still believed that international engagement, market economics and the rise of the Chinese middle class would eventually lead to the fall of the Chinese Communist Party (CCP) and the emergence of a multi-party Chinese democracy. Instead, if Xi’s report is to be believed, Chinese socialism has emerged from the crucible of Tiananmen Square stronger than it was before.

Continuity and Change in Communist China

The last time China really changed was when Mao died. Mao believed that global revolution was right around the corner and that China was ready for a rapid transformation to communism. The leaders who inherited the party in Mao’s wake, especially Deng Xiaoping, saw the world and China’s place within it very differently. At home, China was only in the beginning stages of a transformation to socialism that would take a very long time. And as the party set about engineering that incremental transformation, China would need to engage the world as it was rather than imagining they would change it. Deng told his comrades they needed to be humble as they worked to fulfill their Chinese socialist dream to modernize the country and restore Chinese influence in the world.

Xi Jinping’s report does not stray too far from that advice. China’s made a lot of progress since Deng died twenty years ago, but it is still, according to Xi, in the early stages of a long-term transformation to socialism. China’s progress may have elevated its position in the world, and given China a greater say in international governance, but there is nothing in Xi’s report about China leading a movement to upend the global status quo.

Xi does believe that Chinese socialism can set an example for the rest of the world to follow, and that more active Chinese participation can help transform the international order. As a committed Marxist, Xi should believe an eventual transition to a socialist global order is inevitable. But in the short term, Xi’s China appears squarely focused on the fifth of humanity that lives within its borders, where good governance is at a crossroads, crippled by endemic corruption rooted in the attitudes and behavior of party cadres who’ve lost the faith. Xi’s project, if you take his party congress report at face value, seems to be to save Chinese socialism and consolidate its gains, not to change it.

Implications for the United States

Is a consolidated and internationally persuasive Chinese socialism a threat to the United States? Unfortunately, that’s a question many US analysts and officials are no longer inclined to address. During the Maoist era, when China was “more red than expert,” there was greater US interest in the content of Chinese socialism. Today, US observers tend to view the CCP leadership’s repeated recitations of its socialist principles and practices as propaganda masking personal or national ambitions.

US commentaries on Xi’s speech reflect this. Most of them interpret Xi’s campaign against corruption as a personal quest to consolidate power rather than a campaign to save Chinese socialism. Instead of taking Xi and his recent predecessors at their word and seeing the principal aim of their post-1980s efforts as the achievement of a “moderate level of prosperity” for China‘s 1.4 billion, many US observers see this as an attempt to hide the CCP’s real aim, which they believe is kicking the United States out of Asia and supplanting US dominance of the region. For Americans, the contest between the United States and China is perceived as an historic struggle between rising and falling national powers rather than competing ideologies.

If Xi is a budding dictator leading a nationalist political organization focused on replacing the United States at the top of a global hierarchy then US policy makers should be concerned. But what if the Chinese dream articulated in Xi’s report to the 19th Party Congress is a fair representation of the CCP’s ambitions? Should the United States be alarmed? The answer is not obvious and the question seems to deserve greater consideration.

Why NRC Nuclear Safety Inspections are Necessary: Columbia Generating Station

The Nuclear Regulatory Commission (NRC) adopted its Reactor Oversight Process (ROP) in 2000. The ROP is far superior to the oversight processes previously employed by the NRC. Among its many virtues, the NRC treats the ROP as a work in progress, meaning that agency routinely re-assesses the ROP and makes necessary adjustments.

Earlier this year, the NRC initiated a formal review of its engineering inspections with the goal of making them more efficient and more effective. During a public meeting on October 11, 2017, the NRC working group conducting the review outlined some changes to the engineering inspections that would essentially cover the same ground but with an estimated 8 to 15 percent reduction in person-hours (the engineering inspections and suggested revisions are listed on slide 7 of the NRC’s presentation). Basically, the NRC working group suggested repackaging the inspections so as to be able to examine the same number of items, but in fewer inspection trips.

The nuclear industry sees a different way to accomplish the efficiency and effectiveness gains sought by the NRC’s review effort—they propose to eliminate the NRC’s engineering inspections and replace them with self-assessments. The industry would mail the results from the self-assessments to the NRC for their reading pleasure.

UCS is wary of self-assessments by industry in lieu of NRC inspections. On one hand, statistics might show that self-assessments increase safety just as a community firing all its law enforcement officers would see a statistical decrease in arrests, suggesting a lower crime rate. I have been researching the records publicly available in ADAMS to compare the industry’s track record for finding latent safety problems with the NRC’s track record to see whether replacing NRC’s inspections with industry self-assessments could cause nuclear safety to go off-track.

This commentary is the first in a series that convinces us that the NRC’s engineering inspections are necessary for nuclear safety and that public health and safety will be compromised by replacing them with self-assessments by industry.

Columbia Generating Station: Not so Cool Safety Moves

The Columbia Generating Station is a boiling water reactor owned by Energy Northwest and located 12 miles northwest of Richland, Washington. The Washington Public Power Supply System (the original name of the plant’s owner) submitted a Preliminary Safety Analysis Report (PSAR) for the Washington Nuclear Project Unit 2 (the original name for the reactor) to the Atomic Energy Commission (AEC, the original name of the nuclear regulator) in February 1973.

The PSAR described the proposed design of the plant and associated safety studies that demonstrated compliance with regulatory requirements. The PSAR described the two systems intended to cool the control room during normal operation and during postulated accidents. The control room heating, ventilation, and air conditioning (HVAC) would use chillers within the Radwaste Building HVAC system during normal operation. Because the Radwaste Building HVAC system is not designed to withstand earthquake forces or remain running when offsite power is unavailable, it cannot be credited with performing this role during accident conditions. So, the Standby Service Water system was proposed to cool the control room during accidents. The Standby Service Water system features pumps, pipes, and valves that recirculate water between a large cooling pond and safety equipment within the plant. Two independent sets, called divisions in the figure, are used to enhance reliability of this safety function (Fig. 1).

Fig. 1 (Source: Energy Northwest modified by UCS)

The PSAR indicated that for worst-case design conditions of 77°F cooling pond water temperature and 105°F outside air temperature, the Standby Service Water system would prevent the air temperature within the control room from exceeding 104°F. The AEC/NRC expressed concern that such warm control room temperatures could impair both human and equipment performance.

The owner resolved the regulator’s concerns by committing to installing two Seismic Category I emergency chillers for the control room HVAC system (Fig. 2). The emergency chillers were fully redundant such that one emergency chiller alone could maintain the air temperature inside the control room from exceeding 78°F during an accident. The NRC issued an operating license for the Columbia Generating Station on April 13, 1984, with License Condition 2.C.(21) that required the two emergency chillers to be operable by May 31, 1984. In November 1984, the owner revised the PSAR (now called the Final Safety Analysis Report or FSAR) to describe the emergency chillers and their role in keeping the control room air temperature from exceeding 78°F.

Fig. 2 (Source: Energy Northwest)

In September 1989, the owner revised the FSAR to change the control room air temperature limit to 85°F. The owner determined that this change did not require prior NRC review and approval. The NRC later disagreed with this self-imposed temperature relaxation.

In May 1998, the owner revised the FSAR to change the control room air temperature limit from 85°F to 85°F effective (see below). Once again, the owner determined that this change did not require prior NRC review and approval. And again, the NRC later disagreed with this self-imposed temperature limit relaxation.

“Effective temperature” is based on a combination of wet-bulb and dry-bulb temperatures. The original 75°F and initial 85°F limits were based solely on dry-bulb temperatures. The 85°F effective temperature allowed dry-bulb temperatures of up to 105°F—higher than the control room air temperature expressly rejected by the regulator. The owner made this change without seeking NRC’s approval because it was considered an editorial change. The NRC later determined that this temperature limit relaxation was not an editorial change.

Because the Standby Service Water system alone could maintain the dry-bulb temperature inside the control room at or below 104°F and the revised limit was now 105°F, the owner implemented another change—also unreviewed and unapproved by the NRC—eliminating the need for the emergency chillers to perform any safety role during postulated accidents. The NRC issued a Severity Level IV non-cited violation on April 23, 103, for the owner relaxing the control room air temperature limit without prior NRC approval.

The following month, the owner notified the NRC about deficiencies in the test periodically conducted to demonstrate the adequacy of the Standby Service Water system to cool the control room during accident conditions. When the test deficiencies were remedied and the corrected test performed, one of the two Standby Service Water system trains failed. Workers determined that the tubes within the control room cooler units had become degraded due to the buildup of scale on the inside tube surfaces and the collection of sediment in the lower region of the units. Routine testing of the control room cooler units had been discontinued 16 years earlier.

So, around the same time that the owner improperly decided that the emergency chillers were no longer needed to cool the control room during accidents, it discontinued proper testing of the Standby Service Water system that it thought would perform this role during accidents. Maybe it was another editorial change that discontinued the tests.

On November 12, 2015, the NRC issued a Green finding for a violation of Criterion III, “Design Control,” of Appendix B to 10 CFR Part 50. The NRC inspectors found that the emergency chillers, as designed and governed by operating procedures, would not maintain the air temperature inside the control room below 85°F under accident conditions. The vendor manual for the emergency chillers stated that the STOP-RESET pushbutton had to be depressed after a power interruption because the chillers would not automatically restart. But the operating procedures failed to have the operators perform this necessary step.

On December 22, 2015, Energy Northwest contested the NRC’s finding. The owner stated, in writing, that “There are no design basis requirements to maintain the control room temperature at less than or equal to 85°F at all times for all accident scenarios” [boldfacing in original]. The owner further requested that the NRC conduct a backfit analysis per 10 CFR 50.109 before imposing these “new” regulatory requirements.

By letter dated June 10, 2016, the NRC responded to the owner’s appeal. The NRC carefully considered the owner’s arguments and delineated why it was rejecting each one. The NRC concluded “…it cannot be concluded that the system function as described in the current design basis can be achieved.”

On May 3, 2016 (perhaps sensing that its appeal would not be successful), the owner met with the NRC to discuss a pending license amendment request that would resolve the concerns about the emergency chillers. As shown in the figure, the two emergency chillers sit side-by-side in the same room vulnerable to a common mode, like a fire, disabling them both (Fig. 3). But the chillers are seismically qualified and redundant, consistent with the original commitment to install them. The pending license amendment request would reconcile departures from two NRC General Design Criteria and justify the use of manual vice automatic actions to place the chillers in service.

Fig. 3 (Source: Energy Northwest)

UCS Perspective

Under the Atomic Energy Act as amended, the NRC is tasked with establishing and enforcing regulations to protect workers and the public from the inherent hazards from nuclear power reactor operation.

Owners are responsible for conforming with applicable regulatory requirements. In this case, the owner made a series of changes that resulted in the plant not conforming with applicable regulatory requirements for the air temperature within the control room. But there’s no evidence suggesting that the owner knew that the changes were illegal yet made them anyway hoping not to get caught. Nevertheless, ignorance of the law is still not a valid excuse. The public is not adequately protected when safety regulations are not met, regardless of whether the violations are intentional or inadvertent.

This case study illustrates the vital role that NRC’s enforcement efforts plays in nuclear safety. The soundest safety regulation in the world serves little use unless owners abide by it. The NRCs inspection efforts either verify that owners are abiding by safety regulations or identify shortfalls. Self-assessments by owners are more likely to sustain mis-interpretations and misunderstandings than to flush out safety problems.

The NRC’s ROP is the public’s best protection against hazards caused by aging nuclear power reactors, shrinking maintenance budgets, and emerging sabotage threats. Replacing the NRC’s engineering inspections with self-assessments by the owners would lessen the effectiveness of that protective shield.

The NRC must continue to protect the public to the best of its ability. Delegating safety checks to owners is inconsistent with that important mission.

No, Missile Defense Will Not Work 97% of the Time

In an October 11 interview on Fox News, President Trump claimed:

We have missiles that can knock out a missile in the air 97 percent of the time. If you send two of them, they are going to get knocked down.

This is not true. At least not in any relevant way.

The only homeland missile defense system is the Ground-based Midcourse Defense (GMD) system, which I’ve written plenty about here in these pages, and have co-authored a recent report about. If you’ve been following along, you’ll know the president’s statement was clearly untrue.  I’ll explain why.

What does the actual test record show?

The GMD interceptors have succeeded in destroying the target in nine out of 18 tests since 1999 (50%).  They have destroyed their target in four out of 10 tries (40%) since the GMD system was nominally deployed in 2004. They have destroyed their target in two of the last five tests (40%).

So there is no basis to expect it to work any better than 40 to 50% of the time even under the most generous and easiest conditions—former Pentagon testing agency director Phil Coyle calls the test conditions so far as “scripted for success.”

While the test record says something about the GMD’s capabilities under scripted conditions, the real world will be more complex and challenging. The Pentagon’s highest testing official assessed in 2014 that the test program was “insufficient to demonstrate that an operationally useful capability exists.” More on this later.

But for sake of argument, say the “single shot kill probability” has been determined via tests to be 40 to 50% in those optimistic conditions. Because reliability is low, the US would fire multiple interceptors at the missile to try to boost the system’s effectiveness. Using four-on-one targeting, and a 40 to 50% chance that a given interceptor would work, this leads to a 6 to 13% chance that the warhead gets through.

Real-world conditions

But this isn’t the right question. If it came down to a nuclear attack, would North Korea send just a single missile, and choose the most convenient conditions? That seems unlikely. Let’s say the salvo is five incoming missiles. In that case, with an interceptor kill probability of 40 to 50%, using four interceptors on each missile, the probability that one warhead gets through is 28 to 50%. Uncomfortably high.

I could not stress more that this is a best-case scenario. It assumes that:

1) Failures are uncorrelated and not, e.g., a design flaw common to all interceptors, such as the guidance system issues that took nearly a decade to diagnose and fix,

2) The intercept attempts take place under simplified conditions and that the system is not being stressed as it would in a real-world situation, and

3) The system successfully identified the five real targets from among decoys. If the system cannot distinguish decoys from the real targets, it will have to engage them all, quickly depleting the interceptor inventory. These do not need to be the Ferraris of decoys to be an issue. Some of the GMD intercept tests have included decoys, but all of those have been designed to be easily distinguished from the target warhead.

In short, one can construct situations under which missile defense might destroy missiles: a small salvo of missiles sent without countermeasures and under the limited range of conditions under which the system has been tested. The problem is that these are not by any stretch the most *likely* situations. A potential adversary has every incentive to make the attack as difficult as possible to intercept if he is going to initiate World War Three.

Note that even if the president were instead talking about one of the missile defense systems that has a better and more complete test record, such as THAAD, the issues with not having been tested in operationally realistic conditions is the same. And because THAAD defends against shorter-range missiles from North Korea, which are cheaper and more plentiful, it has the additional issue that it may be overwhelmed even if it is able to discriminate between decoys and real targets. There just may be too many targets.

Why is this dangerous?

The best-case scenario is that President Trump is trying to avoid a confrontation by allowing himself to save face: he has declared that North Korea must not be able to threaten the US mainland with nuclear-armed missiles. Or that he hopes such statements would help dissuade North Korea from considering an attack.

Certainly worse than this is the possibility that Trump actually believes that strategic missile defense provides credible protection and he has not been advised correctly. One hopes he is provided accurate information by stewards of these programs, although at least in public, government official often describe the GMD system as much more capable than it has been demonstrated to be.

This is dangerous, because common sense would say that if we have spent $40 billion on a missile defense system that the US has claimed has been “operational” for going on fifteen years, it must “work.” But it doesn’t. Look at the test record.

The problem is that believing missile defense works when it doesn’t can lead you to take actions that make you need it, and then it can’t help you.

Don’t Make the Same Mistake on Iran that Bush Made on North Korea

Press reports say President Trump will likely not certify Iranian compliance with the Iran nuclear deal in the near future, setting up a situation in which Congress can reimpose sanctions and effectively end US compliance with the deal.

(Source: US State Dept.)

Since the agreement includes several other countries, that would significantly weaken the deal but would not end it.

Still, that the United States would undermine the agreement—which administration officials acknowledge Iran is abiding by—is incredibly short-sighted. It goes against the advice of President Trump’s senior advisors and essentially the whole US security policy community. It erodes US credibility as a treaty partner in future negotiations.

Killing the deal would throw out meaningful, verified limits on Iran’s ability to make nuclear weapons because the president doesn’t think the agreement goes far enough.

The US did this with North Korea, and it was a disaster

The US did this before—with North Korea—and that led to the crisis we are in today.

In 2001, when the Bush administration took office, there was an agreement in place (the Agreed Framework) that verifiably stopped North Korea’s production of plutonium for weapons and put international inspectors on the ground to make sure it was not cheating. This stopped Pyongyang from making fissile material that could be used for dozens of nuclear weapons, and provided the world valuable information about an intensely opaque country.

Also by 2001 North Korea had agreed to stop ballistic missile tests—which was readily verified by US satellites—as long as negotiations continued. This was also meaningful since it would cap Pyongyang’s missile capability at a range of only 800 miles.

Former Secretary of Defense William Perry, who was closely involved in the negotiations with Pyongyang, has said he believes at that point the United States was a couple months from reaching an agreement that would have ended the North’s nuclear and missile programs. This was years before North Korea had done any nuclear tests or long-range missile tests.

Instead of capturing these important restrictions and building on them, the Bush administration—like Trump today—argued these limits were flawed because they did not go far enough to reign in the whole range of activities the United States was concerned about. Bush stopped the talks and eventually let the constraints on North Korea’s nuclear and missile programs fall apart, bringing us to where we are today: facing a North Korea with hydrogen bombs and long-range missiles.

One reason the Bush administration gave for stopping implementation of the Agreed Framework was that Pyongyang had a fledgling uranium enrichment program that was not captured by the agreement. US negotiators knew about that program in the 1990s, and were watching it, but decided that ending Korea’s operating plutonium-production capabilities and getting inspectors on the ground was the crucial first step, and with that in place the uranium program could be addressed as a next step. The Agreed Framework was not meant to be all-encompassing—it was an important, logical step toward solving the bigger problem that was too complex to be solved all at once.

The Iran deal was similarly seen by those negotiating it as a meaningful, achievable step toward solving the bigger issues that could not be addressed all at once. And it has been successful at doing that.

Drifting toward disaster

In the case of Iran, as well as North Korea, President Trump is taking provocative steps that go against the advice of his senior advisors—and in many cases simply defy common sense. The stakes are extremely high in both cases. Dealing with them requires an understanding of the issues and potential consequences, and a long-term strategy built on realistic steps and not magical thinking.

If Trump de-certifies the Iran agreement, he will be tossing the fate of the deal to Congress. Congress needs to heed the advice the president is not taking. That means it should listen to Secretary of Defense James Mattis; Gen. Joseph Dunford, chair of the Joint Chiefs of Staff; Secretary of State Rex Tillerson; and others who believe it is in the best interests of the United States to continue to support the agreement.

We find ourselves in a situation in which the whims of the president are escalating conflicts that potentially put millions of lives at risk and create long-term security risks for the United States, and no one appears to have the ability to reign him in and stabilize things. That situation should be unacceptable to Congress and the US public. If this situation continues, it could go down as one of the darkest periods of US history.

Well-Deserved Recognition: ICAN Wins Nobel Peace Prize

For most of my professional life going back to the late 1980’s, I have been a nuclear weapons organizer/campaigner.  It’s my life’s work.  Over all these years, no group of campaigners has impressed me more than the good folks with the International Campaign to Abolish Nuclear Weapons (ICAN).  Their skill, passion, energy, professionalism and unrelenting doggedness is truly inspiring in our mutual pursuit of a safer world free of nuclear weapons.

I am not the only one who feels this way and today I am so pleased to join a global chorus of folks honoring and congratulating ICAN for being awarded the Nobel Peace Prize for their “work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its ground-breaking efforts to achieve a treaty-based prohibition of such weapons.”

It is hard to overstate how significant an achievement it was to get 122 nations to join together and adopt this treaty –one vigorously opposed by all of the nuclear weapons states and those under their nuclear protection.

To this day, the many supporters of the US nuclear status quo—both within and outside of the government—are full of excuses for not acting and not aggressively pursuing disarmament.  Even worse, the United States seems to be going in the wrong direction with all of the talk of, and plans for, new more usable nuclear weapons and the rebuilding of the entire US nuclear arsenal at a cost that is sure to exceed $1 trillion of our tax dollars. The international discussion that ICAN has been leading about nuclear weapons and humanitarian consequences is even more important in that context.

Similarly, it’s well past time for a debate on the morality of threatening millions of innocent civilians in the name of national security.  And who thinks it’s OK that one person has the power and authority to effectively end humanity?

What ICAN and many of us are saying is: let’s get serious folks (we are looking at you. nuclear weapons states) about nuclear disarmament before our luck runs out.

But for now, let’s raise our glasses and congratulate and honor everyone at ICAN and elsewhere who wake up every day and work so hard—against such incredible odds—to prevent nuclear war and make the world a safer, better place.  I thank you.  My children thank you.

Nuclear Plant Risk Studies: Then and Now

Nuclear plant risk studies (also called probabilistic risk assessments) examine postulated events like earthquakes, pipe ruptures, power losses, fires, etc. and the array of safety components installed to prevent reactor core damage. Results from nuclear plant risk studies are used to prioritize inspection and testing resources–components with greater risk significance get more attention.

Nuclear plant risk studies are veritable forests of event trees and fault trees. Figure 1 illustrates a simple event tree. The initiating event (A) in this case could be something that reduces the amount of reactor cooling water like the rupture of a pipe connected to the reactor vessel. The reactor protection system (B) is designed to detect this situation and immediately shut down the reactor.

Fig. 1. (Source: Nuclear Regulatory Commission)

The event tree branches upward based on the odds of the reactor protection system successfully performing this action and downward for its failure to do so. Two emergency coolant pumps (C and D) can each provide makeup cooling water to the reactor vessel to replenish the lost inventory. Again, the event tree branches upward for the chances of the pumps successfully fulfilling this function and downward for failure.

Finally, post-accident heat removal examines the chances that reactor core cooling can be sustained following the initial response. The column on the right describes the various paths that could be taken for the initiating event. It is assumed that the initiating event happens, so each path starts with A. Paths AE, ACE, and ACD result in reactor core damage. The letters added to the initiating event letter define what additional failure(s) led to reactor core damage. Path AB leads to another event tree – the Anticipated Transient Without Scram (ATWS) event tree because the reactor protection system failed to cause the immediate shut down of the reactor and additional mitigating systems are involved.

The overall risk is determined by the sum of the odds of pathways leading to core damage. The overall risk is typically expressed something like 3.8×10-5 per reactor-year (3.8E-05 per reactor-year in scientific notation). I tend to take the reciprocal of these risk values. The 3.8E-05 per reactor-year risk, for example, becomes one reactor accident every 26,316 years—the bigger the number, the lower the risk.

Fault trees examine reasons for components like the emergency coolant pumps failing to function. The reasons might include a faulty control switch, inadequate power supply, failure of a valve in the pump’s suction pipe to open, and so on. The fault trees establish the chances of safety components successfully fulfilling their needed functions. Fault trees enable event trees to determine the likelihoods of paths moving upward for success or downward for failure.

Nuclear plant risk studies have been around a long time. For example, the Atomic Energy Commission (forerunner to today’s Nuclear Regulatory Commission and Department of Energy) completed WASH-740 in March 1957 (Fig. 2). I get a kick out of the “Theoretically Possible but Highly Improbable” phrase in its subtitle. Despite major accidents being labeled “Highly Improbable,” the AEC did not release this report publicly until after it was leaked to UCS in 1973 who then made it available. One of the first acts by the newly created Nuclear Regulatory Commission (NRC) in January 1975 was to publicly issue an update to WASH-740. WASH-1400, also called NUREG-75/014 and the Rasmussen Report, was benignly titled “Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants.”

Fig. 2. (Source: Atomic Energy Commission)

Nuclear plant risk studies can also be used to evaluate the significance of actual events and conditions. For example, if emergency coolant pump A were discovered to have been broken for six months, analysts can change the chances of this pump successfully fulfilling its safety function to zero and calculating how much the broken component increased the risk of reactor core damage. The risk studies would determine the chances of initiating events occurring during the six months emergency coolant pump A was disabled and the chances that backups or alternates to emergency coolant pump A stepped in to perform that safety function. The NRC uses nuclear plant risk studies to determine when to send a special inspection team to a site following an event or discovery and to characterize the severity level (i.e., green, white, yellow, or red) of violations identified by its inspectors.

Nuclear Plant Risk Studies: Then

In June 1982, the NRC released NUREG/CR-2497, “Precursors to Potential Severe Core Damage Accidents: 1969-1979, A Status Report,” that reported on the core damage risk from 52 significant events during that 11-year period. The events included the March 1979 meltdown of Three Mile Island Unit 2 (TMI-2), which had a core damage risk of 100%. The effort screened 19,400 licensee event reports submitted to the AEC/NRC over that period, culled out 529 event for detailed review, identified 169 accident precursors, and found 52 of them to be significant from a risk perspective. The TMI-2 event topped the list, with the March 1975 fire at Browns Ferry placing second.

The nuclear industry independently evaluated the 52 significant events reported in NUREG/CR-2497. The industry’s analyses also found the TMI-2 meltdown to have a 100% risk of meltdown, but disagreed with all the other NRC risk calculations. Of the top ten significant events, the industry’s calculated risk averaged only 11.8% of the risk calculated by the NRC. In fact, if the TMI-2 meltdown is excluded, the “closest” match was for the 1974 loss of offsite power event at Haddam Neck (CT). The industry’s calculated risk for this event was less than 7% of the NRC’s calculated risk. It goes without saying (but not without typing) that the industry never, ever calculated a risk to be greater than the NRC’s calculation. The industry calculated the risk from the Browns Ferry fire to be less than 1 percent of the risk determined by the NRC—in other words, the NRC’s risk was “only” about 100 times higher than the industry’s risk for this event.

Fig. 3. Based on figures from June 1982 NRC report. (Source: Union of Concerned Scientists)

Bridging the Risk Gap?

The risk gap from that era can be readily attributed to the immaturity of the risk models and the paucity of data. In the decades since these early risk studies, the risk models have become more sophisticated and the volume of operating experience has grown exponentially.

For example, the NRC issued Generic Letter 88-20, “Individual Plant Examination for Severe Accident Vulnerabilities.” In response, owners developed plant-specific risk studies. The NRC issued documents like NUREG/CR-2815, “Probabilistic Safety Analysis Procedures Guide,” to convey its expectations for risk models. And the NRC issued a suite of guidance documents like Regulatory Guide 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decision on Plant-Specific Changes to the Licensing Basis.” This is but a tiny sampling of the many documents issued by the NRC about how to conduct nuclear plant risk studies—guidance that simply was not available when the early risk studies were performed.

Complementing the maturation of nuclear plant risk studies is the massive expansion of available data on component performance and human reliability. Event trees begin with initiating events—the NRC has extensively sliced and diced initiating event frequencies. Fault trees focus on performance on the component and system level, so the NRC has collected and published extensive operating experience on component performance and system reliability. And the NRC compiled data on reactor operating times to be able to develop failure rates from the component and system data.

Given the sophistication of current risk models compared to the first generation risk studies and the fuller libraries of operating reactor information, you would probably think that the gap between risks calculated by industry and NRC has narrowed significantly.

Except for being absolutely wrong, you would be entirely right.

Nuclear Plant Risk Studies: Now

Since 2000, the NRC has used nuclear plant risk studies to establish the significance of violations of regulatory requirements, with the results determining whether a green, white, yellow, or red finding gets issued. UCS examined ten of the yellow and red findings determined by the NRC since 2000. The “closest” match between NRC and industry risk assessment was for the 2005 violation at Palo Verde (AZ) where workers routinely emptied water from the suction pipes for emergency core cooling pumps. The industry’s calculated risk for that event was 50% (half) of the NRC’s calculated risk, meaning that the NRC viewed this risk as double that of the industry’s view. And that was the closest that the risk viewpoints came. Of these ten significant violations, the industry’s calculated risk averaged only 12.7% of the risk calculated by the NRC. In other words, the risk gap narrowed only a smidgen over the decades.

Fig. 4. Ratios for events after 2000. (Source: Union of Concerned Scientists)

Risk-Deformed Regulation?

For decades, the NRC has consistently calculated nuclear plant risks to be about 10 time greater than the risks calculated by industry. Nuclear plant risk studies are analytical tools whose results inform safety decision-making. Speedometers, thermometers, and scales are also analytical tools whose results inform safety decision-making. But a speedometer reading one-tenth of the speed recorded by a traffic cop’s radar gun, or a thermometer showing a child to have a temperature one-tenth of her actual temperature, or a scale measuring one-tenth of the actual amount of chemical to be mixed into a prescription pill are unreliable tools that could not continue to be used to make responsible safety decisions.

Yet the NRC and the nuclear industry continue to use risk studies that clearly have significantly different scales.

On May 6, 1975, NRC Technical Advisor Stephen H. Hanauer wrote a memo to Guy A. Arlotto, the NRC’s Assistant Director for Safety and Materials Protection Standards. The second paragraph of this two-paragraph memo expressed Dr. Hanauer’s candid view of nuclear plant risk studies: “You can make probabilistic numbers prove anything, by which I mean that probabilistic numbers ‘prove’ nothing.”

Oddly enough, the chronic risk gap has proven the late Dr. Hanauer totally correct in his assessment of the value of nuclear plant risk studies. When risk models permit users to derive results that don’t reside in the same zip code yet alone the same ball park, the results prove nothing.

The NRC must close the risk gap, or jettison the process that proves nothing about risks.

START from the Beginning: 25 Years of US-Russian Nuclear Weapons Reductions

For the past 25 years, a series of treaties have allowed the US and Russia to greatly reduce their nuclear arsenals—from well over 10,000 each to fewer than 2,000 deployed long-range weapons each.  These Strategic Arms Reduction Treaties (START) have enhanced US security by reducing the nuclear threat, providing valuable information about Russia’s nuclear arsenal, and improving predictability and stability in the US-Russia strategic relationship.

US and Russian team members shake hands before a Strategic Arms Reduction Treaty inspection visit in 2009. START established an in-depth verification regime, including boots-on-the-ground inspections that provided unprecedented levels of data exchange and transparency. Photo: U.S. Air Force/Christopher Hubenthal

Twenty-five years ago, US policy-makers of both parties recognized the benefits of the first START agreement: on October 1, 1992, the Senate voted overwhelmingly—93 to 6—in favor of ratifying START I.

The end of START?

With increased tensions between the US and Russia and an expanded range of security threats for the US to worry about, this longstanding foundation is now more valuable than ever.

The most recent agreement—New START—will expire in early February 2021, but can be extended for another five years if the US and Russian presidents agree to do so. In a January 28 phone call with President Trump, Russian President Putin reportedly raised the possibility of extending the treaty. But instead of being extended, or even maintained, the START framework is now in danger of being abandoned.

President Trump has called New START “one-sided” and “a bad deal,” and has even suggested the US might withdraw from the treaty. His advisors are clearly opposed to doing so. Secretary of State Rex Tillerson expressed support for New START in his confirmation hearing. Secretary of Defense James Mattis, while recently stating that the administration is currently reviewing the treaty “to determine whether it’s a good idea,” has previously also expressed support, as have the head of US Strategic Command and other military officials.

Withdrawal seems unlikely, but unless Mattis and other military officials push the president hard, so does an extension. Worse, even if Trump is not re-elected, and the incoming president is more supportive of the treaty, there will be little time for a new administration, taking office in late January 2021, to do an assessment and sign on to an extension before the deadline. While UCS and other treaty supporters will urge the incoming administration to act quickly, if the Trump administration does not extend the treaty, it is quite possible that New START—and the security benefits it provides—will lapse.

The Beginning: The Basics and Benefits of START I

The overwhelming bipartisan support for a treaty cutting US nuclear weapons demonstrated by the START I ratification vote today seems unbelievable. At the time, however, both Democrats and Republicans in Congress, as well as the first President Bush, recognized the importance of the historic agreement, the first to require an actual reduction, rather than simply a limitation, in the number of US and Russian strategic nuclear weapons.

By the end of the Cold War, the US had about 23,000 nuclear warheads in its arsenal, and the Soviet Union had roughly 40,000. These numbers included about 12,000 US and 11,000 Soviet deployed strategic warheads—those mounted on long-range missiles and bombers. The treaty limited each country to 1,600 strategic missiles and bombers and 6,000 warheads, and established procedures for verifying these limits.

The limits on missiles and bombers, in addition to limits on the warheads themselves, were significant because START required the verifiable destruction of any excess delivery vehicles, which gave each side confidence that the reductions could not be quickly or easily reversed. To do this, the treaty established a robust verification regime with an unprecedented level of intrusiveness, including on-site inspections and exchanges of data about missile telemetry.

Though the groundwork for START I was laid during the Reagan administration, ratification and implementation took place during the first President Bush’s term. The treaty was one among several measures taken by the elder Bush that reduced the US nuclear stockpile by nearly 50 percent during his time in office.

START I entered into force in 1994 and had a 15-year lifetime; it required the US and Russia to complete reductions by 2001, and maintain those reductions until 2009. However, both countries actually continued reductions after reaching the START I limits. By the end of the Bush I administration, the US had already reduced its arsenal to just over 7,000 deployed strategic warheads. By the time the treaty expired, this number had fallen to roughly 3,900.

The Legacy of START I

Building on the success of START I, the US and Russia negotiated a follow-on treaty—START II—that required further cuts in deployed strategic weapons. These reductions were to be carried out in two steps, but when fully implemented would limit each country to 3,500 deployed strategic warheads, with no more than 1,750 of these on submarine-launched ballistic missiles.

Phase II also required the complete elimination of independently targetable re-entry vehicles (MIRVs) on intercontinental ballistic missiles. This marked a major step forward, because MIRVs were a particularly destabilizing configuration. Since just one incoming warhead could destroy all the warheads on a MIRVed land-based missile, MIRVs create pressure to “use them or lose them”—an incentive to strike first in a crisis. Otherwise, a country risked losing its ability to use those missiles to retaliate in the case of a first strike against it.

While both sides ratified START II, it was a long and contentious process, and entry into force was complicated by provisions attached by both the US Senate and Russian Duma. The US withdrawal from the Anti-Ballistic Missile (ABM) treaty in 2002 was the kiss of death for START II. The ABM treaty had strictly limited missile defenses. Removing this limit created a situation in which either side might feel it had to deploy more and more weapons to be sure it could overcome the other’s defense. But the George W. Bush administration was now committed to building a larger-scale defense, regardless of Russia’s vocal opposition and clear statements that doing so would undermine arms control progress.

Russia responded by announcing its withdrawal from START II, finally ending efforts to bring the treaty into force. A proposed START III treaty, which would have called for further reductions to 2,000 to 2,500 warheads on each side, never materialized; negotiations had been planned to begin after entry into force of START II.

After the failure of START II, the US and Russia negotiated the Strategic Offensive Reductions Treaty (SORT, often called the “Moscow Treaty”). SORT required each party to reduce to 1,700 to 2,200 deployed strategic warheads, but was a much less formal treaty than START. It did not include the same kind of extensive verification regime and, in fact, did not even define what was considered a “strategic warhead,” instead leaving each party to decide for itself what it would count. This meant that although SORT did encourage further progress to lower numbers of weapons, overall it did not provide the same kind of benefits for the US as START had.

New START

Recognizing the deficiencies of the minimal SORT agreement, the Obama administration made negotiation of New START an early priority, and the treaty was ratified in 2010.

New START limits each party to 1,550 deployed strategic nuclear warheads by February 2018. The treaty also limits the number of deployed intercontinental ballistic missiles, submarine-launched ballistic missiles, and long-range bombers equipped to carry nuclear weapons to no more than 700 on each side. Altogether, no more than 800 deployed and non-deployed missiles and bombers are allowed for each side.

In reality, each country will deploy somewhat more than 1,550 warheads—probably around 1,800 each—because of a change in the way New START counts warheads carried by long-range bombers. START I assigned a number of warheads to each bomber based on its capabilities. New START simply counts each long-range bomber as a single warhead, regardless of the actual number it does or could carry. The less stringent limits on bombers are possible because bombers are considered less destabilizing than missiles. The bombers’ detectability and long flight times—measured in hours vs. the roughly thirty minutes it takes for a missile to fly between the United States and Russia—mean that neither side is likely to use them to launch a first strike.

Both the United States and Russia have been moving toward compliance with the New START limits, and as of July 1, 2017—when the most recent official exchange of data took place—both are under the limit for deployed strategic delivery vehicles and close to meeting the limit for deployed and non-deployed strategic delivery vehicles. The data show that the United States is currently slightly under the limit for deployed strategic warheads, at 1,411, while Russia, with 1,765, still has some cuts to make to reach this limit.

Even in the increasingly partisan atmosphere of the 2000s, New START gained support from a wide range of senators, as well as military leaders and national security experts. The treaty passed in the Senate with a vote of 71 to 26; thirteen Republicans joined all Democratic senators in voting in favor. While this is significantly closer than the START I vote, as then-Senator John F. Kerry noted at the time, “in today’s Senate, 70 votes is yesterday’s 95.”

And the treaty continues to have strong support—including from Air Force General John Hyten, commander of US Strategic Command, which is responsible for all US nuclear forces. In Congressional testimony earlier this year, Hyten called himself “a big supporter” of New START and said that “when it comes to nuclear weapons and nuclear capabilities, that bilateral, verifiable arms control agreements are essential to our ability to provide an effective deterrent.” Another Air Force general, Paul Selva, vice chair of the Joint Chiefs of Staff, agreed, saying in the same hearing that when New START was ratified in 2010, “the Joint Chiefs reviewed the components of the treaty—and endorsed it. It is a bilateral, verifiable agreement that gives us some degree of predictability on what our potential adversaries look like.”

The military understands the benefits of New START. That President Trump has the power to withdraw from the treaty despite support from those who are most directly affected by it is, as he would say, “SAD.”

That the US president fails to understand the value of US-Russian nuclear weapon treaties that have helped to maintain stability for more than two decades is a travesty.

North Korea’s Next Test?

North Korean Foreign Minister Ri Yong Ho warned reporters in New York that his country may place a live nuclear warhead on one of its missiles, launch it, and then detonate the bomb in the open air.

It would not be the first time a country conducted such a test. The Soviet Union tried and failed in 1956. The United States was successful in 1962. But perhaps the most relevant historical precedent is the Chinese test in 1966.

 

An excerpt from 东方巨响 : a documentary film on the history of China’s nuclear weapons program produced by China’s People’s Liberation Army and released in 1999.

 

China’s Choice

At the time China was nearly as isolated as North Korea is today. The Soviet Union was no longer an ally but an adversary, massing military forces along China’s northern border. The United States kept the People’s Republic out of the United Nations and encircled its eastern coast with military bases in Japan, South Korea, the Republic of China on Taiwan, the Philippines, Australia and New Zealand. Despite relentless Chinese propaganda proclaiming invincible revolutionary strength, China’s leaders felt extraordinarily insecure in the face of mounting Soviet and US pressure.

China set off its first nuclear explosion in October of 1964 and proved it could deliver a militarily useful nuclear weapon with a bomber less than a year later. But the Chinese leadership still felt a need to demonstrate it could launch a nuclear-armed missile and detonate it near a target hundreds of kilometers away. Only then could Chinese leaders feel confident they introduced the possibility of nuclear retaliation into the minds of US and Soviet officials considering a first strike. Chinese Marshall Nie Rongzhen, who led China’s nuclear weapons program and directed the test, summed up Chinese thinking in his memoir.

Mating an atomic bomb to a missile and conducting a real swords and spears test required facing very great risks. If the missile exploded at the launch site, if it fell in the middle of its flight or if it strayed out of the target area there would be unthinkable consequences. But I was deeply confident in our scientists, in our engineers and in our comrades working at the bases, who all possessed a spirit of high responsibility. Our research and design work was thorough and the medium-range missile we developed was reliable, with a highly successful launch rate. But more than that, in order to show our missiles were genuinely a weapon of great power that could be used in war we had to conduct this test of them together.

North Korea’s Choice

It is impossible to know if the individuals leading North Korea’s nuclear weapons program have the same degree of confidence in their technology and their personnel.  But it is not hard to believe they feel the same urgent need to prove North Korea has a useable nuclear weapon, especially in the face of continuing US doubts. China’s expansive land mass allowed its leaders to conduct their test in a way that only put their own people at risk. But tiny North Korea must send its nuclear-armed missile out into the Pacific Ocean on a trajectory that would fly over Japan. If a failed North Korean test were to impact Japan it could precipitate a large-scale war in North-East Asia that could kill a million people on the first day.

Hopefully, avoiding that horrible outcome is the top priority of the North Koreans contemplating the test and the Americans considering responses. Kim and his cadres might feel less inclined to risk the test if it they were convinced President Trump and his national security team were already genuinely worried about the possibility of North Korean nuclear retaliation. Unfortunately, that’s an assurance Washington is unlikely to give Pyongyang. It still hasn’t given it to Beijing. US unwillingness to take the option of a first strike off the table, combined with demonstrations of resolve like the provocative flight of B1 bombers out of Guam and F15 fighters out of Okinawa, could tip North Korean scales in favor of conducting the test.

Critical Differences

Chairman Mao didn’t worship nuclear weapons. He famously disparaged the atomic bomb as a paper tiger. Mao believed nuclear weapons were too destructive to use in a war. Their only value was in vitiating nuclear threats against China with the fear of potential retaliation. Does Kim Jong-un think about nuclear weapons the same way? We don’t know, because we don’t talk to the North Koreans enough to understand their point of view or trust anything they say.

China went on to develop a very limited nuclear force calibrated to maintain a credible possibility of nuclear retaliation. The United States government not only never panicked, it found a way to develop a viable relationship with the nuclear-armed communist giant. By the time China first tested an ICBM capable of reaching the United States, reforms within China made it appear even less threatening. Profound US discomfort with China’s nuclear force remains, but the two sides have managed to not only avoid a war but to develop robust and mutually beneficial ties.

North Korea may seem too small, its culture too parochial to make dialog and cooperation as appealing to the United States as Nixon’s opening to China in 1972—just six years after China’s daring nuclear-armed missile test. It is hard for the nation of 24 million with a GDP the size of Jackson, Mississippi’s to command the same respect as China’s 1.3 billion. Perhaps the North Korean leadership sees nuclear weapons as a great equalizer: a viable means to force the United States to sign a peace treaty, and, as one North Korean student recently told a US reporter, “leave us alone.

The US Choice

Ri told the United Nations that the “ultimate goal” of his country’s nuclear weapons program was to “establish a balance of power with the United States.” It is worth exploring what that means, and bilateral dialog is the only way to do that.

There is no indication North Korea will agree to denuclearize unless the United States agrees to join them. The US must decide whether the risks of continuing to rely solely on pressuring North Korea, at the cost of Pyongyang’s ever more provocative demonstrations of its capability to harm the United States, are more likely to yield an acceptable outcome than the risks of engaging the North Koreans in a discussion of what might be required to make their nuclear weapons program less threatening to the United States and its allies. The most immediate choice is whether continuing to introduce ambiguity about pre-emptive US military action is worth provoking the test flight of a nuclear-armed missile over Japan.

In the Chinese case the United States came to tolerate its nuclear weapons program in the context of broader shifts in the international security environment that encouraged a bilateral rapprochement, even though the fundamental security problem – Chinese reunification and the status of the Republic of China on Taiwan – remained unresolved. The initial impetus for reestablishing relations was a shared concern about a mutual adversary, the Soviet Union. But the relationship managed to outlive the Soviet Union’s collapse. Tensions within the US-China security relationship have slowly intensified in the post-Cold War period and the United States is still unwilling to accept its vulnerability to Chinese nuclear retaliation. Yet both sides, for the time being, do not seem overly concerned about the risk of a nuclear confrontation.

Despite their volatility, Donald Trump and Kim Jong-un could find the basis for a US-North Korean rapprochement in their shared concern about an accidental nuclear war, or the outbreak of a conventional confrontation that would cause great harm to both nations. Talking about stopping a risky test of a nuclear-armed missile that would fly over Japan is a good place to start.

China is urging both sides to come to the table.

 

North Korea’s Sept. 15 Missile Launch over Japan

North Korea conducted another missile test at 6:30 am September 15 Korean time (early evening on September 14 in the US). Like the August 28 test, this test appears to have been a Hwasong-12 missile launched from a site near the Pyongyang airport. The missile followed a standard trajectory—rather than the highly lofted trajectories North Korea used earlier this year—and it flew over part of the northern Japanese island of Hokkaido (Fig. 1).

Fig. 1. Approximate path of the launch.

The missile reportedly flew 3,700 kilometers (km) (2,300 miles) and reached a maximum altitude of 770 km (480 miles). It was at an altitude of 650 to 700 km (400 to 430 miles) when it passed over Hokkaido (Fig. 2).

Fig. 2. The parts of Hokkaido the missile flew over lie about 1,250 to 1,500 km (780-930 miles) from the missile launch point.

The range of this test was significant since North Korea demonstrated that it could reach Guam with this missile, although the payload the missile was carrying is not known. Guam lies 3,400 km from North Korea, and Pyongyang has talked about it as a target because of the presence of US forces at Anderson Air Force Base.

This missile very likely has low enough accuracy that it could be difficult for North Korea to use it to destroy this base, even if the missile was carrying a high-yield warhead. Two significant sources of inaccuracy of an early generation missile like the Hwasong-12 are guidance and control errors early in flight during boost phase, and reentry errors due to the warhead passing through the atmosphere late in flight. I estimate the inaccuracy of the Hwasong-12 flown to this range to be likely 5 to 10 km, although possibly larger.

Even assuming the missile carried a 150 kiloton warhead, which may be the yield of North Korea’s recent nuclear test, a missile of this inaccuracy would still have well under a 10% chance of destroying the air base. (For experts: This estimate assumes the air base would have to fall within the warhead’s 5 psi air blast radius, which is 3.7 km, and that the CEP is 5 to 10 km.)

Heating of the reentry vehicle

As I’ve done with some previous tests, I looked at how the heating experienced by the reentry vehicle (RV) on this test compares to what would be experienced by the same RV on a 10,000 km-range missile on a standard trajectory (MET). My previous calculations were done on North Korea’s highly lofted trajectories, which tended to give high heating rates but relatively short heating times.

Table 1 shows that in this case the duration of heating (τ) would be roughly the same in the two cases. However, not surprisingly because of the difference in ranges and therefore of reentry speeds, the maximum heating rate (q) and the total heat absorbed (Q) by the RV on this trajectory is only about half that of the 10,000 km trajectory.

Table 1. A comparison of RV heating on the September 15 missile test and on a 10,000 km-range trajectory, assuming both missiles have the same RV and payload. A discussion of these quantities can be found in the earlier post.

So while it seems likely that North Korea can develop a heat shield that would be sufficient for a 10,000 km range missile, this test does not demonstrate that.

Tennessee Valley Authority’s Nuclear Safety Culture Déjà vu

The Nuclear Regulatory Commission (NRC) issued a Confirmatory Order to the Tennessee Valley Authority (TVA) on July 27, 2017.  An NRC team inspecting the Watts Bar Nuclear Plant in fall 2016 determined that TVA failed to comply with elements of another Confirmatory Order that NRC had issued to TVA on December 22, 2009. Specifically, the 2009 Confirmatory Action required TVA to implement measures at all its nuclear plant sites (i.e., Watts Bar and Sequoyah in Tennessee and Browns Ferry in Alabama) to ensure that adverse employment actions against workers conformed to the NRC’s employee protection regulations and whether the actions could negatively impact the safety conscious work environment. The NRC inspection team determined that TVA was not implementing several of the ordered measures at Watts Bar.

To be fair to TVA, the agency did indeed develop the procedures to ensure adverse employee actions did not violate NRC’s employee protection regulations.

To be fair to NRC, its inspectors found that TVA senior management simply did not use those procedures when taking adverse employee action against several TVA employees and contractors.

To say that TVA has a nuclear safety culture problem is like saying the sun is hot.

After determining that TVA failed to implement mandated in its December 2009 Confirmatory Order, the NRC issued another Confirmatory Order to TVA in July 2017.

How many Confirmatory Orders it will take to get TVA to establish and sustain proper nuclear safety cultures at its nuclear power plants?

I don’t know. But at least we are now one Confirmatory Order closer to that magic number. Perhaps before too many more years roll by, workers at Watts Bar, Sequoyah, and Browns Ferry will actually be protected the way they are supposed to be by NRC’s regulations.

Broken Valve in Emergency System at LaSalle Nuclear Plant

An NRC Special Inspection Team (SIT) conducted an inspection at the LaSalle Nuclear Plant this spring to investigate the cause of a valve’s failure and assess the effectiveness of the corrective actions taken.

The two units at Exelon Generation Company’s LaSalle County nuclear plant about 11 miles southeast of Ottawa, Illinois are boiling water reactors (BWRs) that began operating in the early 1980s. While most of the BWRs operating in the U.S. are BWR/4’s with Mark I containment designs, the “newer” LaSalle Units feature BWR/5’s with Mark II containment designs. The key distinction for this commentary is that while BWR/4’s employ steam-driven high pressure coolant injection (HPCI) systems to provide makeup cooling water to the reactor core in event that a small pipe connected to the reactor vessel breaks, the BWR/5’s use a motor-driven high pressure core spray (HPCS) system for this safety role.

The Event

Workers attempted to refill the Unit 2 high pressure core spray (HPCS) system with water on February 11, 2017, following maintenance and testing of the system. The Unit 2 reactor was shut down for a refueling outage at the time and this downtime was used to inspect emergency systems, like the HPCS system.

The HPCS system is normally in standby mode during reactor operation. The system features one motor-driven pump that supplies a design makeup flow rate of 7,000 gallons per minute to the reactor vessel. The HPCS pump draws water from the suppression pool inside containment. In event that a small-diameter pipe connected to the reactor vessel broke, cooling water would leak out but the pressure inside the reactor vessel would remain too high for the array of low-pressure emergency systems (i.e., the residual heat removal and low pressure core spray pumps) to function. Water pouring from the broken pipe ends drains to the suppression pool for re-use. The motor-driven HPCS pump can be powered from the offsite electrical grid when it is available or from an onsite emergency diesel generator when the grid is unavailable.

Fig. 1(Source: Nuclear Regulatory Commission)

Workers were unable to fill the piping between the HPCS injection valve (1E22-F004) and the reactor vessel. They discovered that the disc had separated from the stem of this double disc gate valve manufactured by Anchor Darling and blocked the flow path for filling the piping. The HPCS injection valve is a normally closed motor-operated valve that opens when the HPCS system is actuated to provide a pathway for makeup water to reach the reactor vessel. The motor applies torque that rotates a screw-like stem to raise (open) or lower (close) the disc in the valve. When fully lowered, the disc blocks flow through the valve. When the disc is fully raised, flow through the valve is unobstructed. Because the disc became separated from the stem in the fully lowered position, the motor might rotate the stem as if to raise the disc, but the disc would not budge.

Fig. 2 (click to enlarge) (Source: Nuclear Regulatory Commission)

Workers took a picture of the separated double disc after the valve’s bonnet (casing) was removed (Fig. 3). The bottom edge of the stem appears at the top center of the picture. The two discs and the guides they travel along (when connected to the stem) can be seen.

Fig. 3 (Source: Nuclear Regulatory Commission)

Workers replaced the internals of the HPCS injection valve with parts redesigned by the vendor and restated Unit 2.

Background

The Tennessee Valley Authority submitted a report under 10 CFR Part 21 to the NRC in January 2013 about a defect in an Anchor Darling double disc gate valve in the high pressure coolant injection system at their Browns Ferry nuclear plant. The following month, the valve’s vendor submitted a 10 CFR Part 21 report to the NRC about a design issue with Anchor Darling double disc gate valves that could result in the stem separating from the discs.

In April 2013, the Boiling Water Reactor Owners’ Group issued a report to its members about the Part 21 reports and recommended methods for monitoring the affected valves for operability. The recommendations included diagnostic testing and monitoring the rotation of the stems. Workers performed the recommended diagnostic testing of HPCS injection valve 2E22-F004 at LaSalle during 2015 without identifying any performance issues. Workers performed maintenance and testing of HPCS injection valve 2E22-F004 on February 8, 2017, using the stem rotation monitoring guidance.

In April 2016, the Boiling Water Reactor Owners’ Group revised their report based on information received from one plant owner. Workers had disassembled 26 potentially susceptible Anchor Darling double disc gate valves and found problems with 24 of them.

In April 2017, Exelon notified the NRC about the failure of HPCS injection valve 2E22-F004 due to separation of the stem from the discs. Within two weeks, a Special Inspection Team (SIT) chartered by the NRC arrived at LaSalle to investigate the cause of the valve’s failure and assess the effectiveness of the corrective actions taken.

SIT Findings and Observations

The SIT reviewed Exelon’s evaluation of the failure mode for the Unit 2 HPCS injection valve. The SIT agreed that a part within the valve had broken due to excessive force. The broken part allowed the stem-to-disc connection to become steadily more misaligned until eventually the discs separated from the stem. The vender redesigned the valve’s internals to correct the problem.

Exelon notified the NRC on June 2, 2017, of its plan to correct 16 other safety-related and important to safety Anchor Darling double disc gate valves that may be susceptible to this failure mechanism during the next refueling outages of the two LaSalle units.

The SIT reviewed Exelon’s justifications for waiting to fix these 16 valves. The SIT found the justifications to be reasonable with one exception—the HCPS injection valve on Unit 1. Exelon had estimated the number of times that the Unit 1 and the Unit 2 HPCS injection valves had been cycled. The Unit 2 valve was original equipment installed in the early 1980s while the Unit 1 valve had been replaced in 1987 following damage due to another cause. Exelon contended that the greater number of strokes by the Unit 2 valve explained its failure and justified waiting until the next refueling outage to address the Unit 1 valve.

Citing factors like unknown pre-operational testing differences between the units, slight design differences of unknown consequence, uncertain material strength properties, and uncertain differences in stem-to-wedge thread wear, the SIT concluded “that it was a matter of “when” and not “if” the 1E22-F004 valve would fail in the future if it had not already failed.” In other words, the SIT did not buy the delayed look at the Unit 1 valve.

Exelon shut down LaSalle Unit 1 on June 22, 2017, to replace the internals of HPCS injection valve 1E22-F004.

NRC Sanctions

The SIT identified a violation of Criterion III, Design Control, of Appendix B to 10 CFR Part 50 associated with the torque values developed by Exelon for the motors of HPCS injection valves 1E22-F004 and 2E22-F004. Exelon assumed the valves’ stem to be the weak link and established motor torque values that would not over-stress the stem. But the weak link turned out to be another internal part. The motor torque values applied by Exelon over-stressed this part, causing it to break and the discs to separate from the stem.

The NRC determined that the violation to be a Severity Level III Violation (out of a four-level system with Level I being most serious) based on the failure of the valves preventing the HPCS system from performing its safety function.

But the NRC exercised enforcement discretion per its Enforcement Policy and did not issue the violation. The NRC determined that the valve design defect was too subtle for Exelon to have reasonably foreseen and corrected before the Unit 2 valve’s failure.

UCS Perspective

Exelon looked pretty good in this event. The NRC’s SIT documented that Exelon was aware of the Part 21 reports made by the Tennessee Valley Authority and the valve’s vendor in 2013. That they were unable to use this awareness to identify and correct the problems with the Unit 2 HPCS injection valve is really not a poor reflection on their performance. After all, they performed the measures recommended by the Boiling Water Reactor Owners’ Group for the two Part 21 reports. The shortcoming was in that guidance, not in Exelon’s application of it.

The only blemish on Exelon’s handling of the matter was its weak justification for operating Unit 1 until its next scheduled refueling outage before checking whether its HPCS injection valve was damaged or broken. But the NRC’s SIT helped Exelon decide to hasten that plan with the result that Unit 1 was shut down in June 2017 to replace the susceptible Unit 1 valve.

The NRC looked really good in this event. Not only did the NRC steer Exelon to a safer place regarding LaSalle Unit 1, but the NRC also prodded the entire industry to get this matter resolved without undue delay. The NRC issued Information Notice 2017-03 to plant owners on June 15, 2017, about the Anchor Darling double disc gate valve design defects and the limitations in the guidance for monitoring valve performance. The NRC conducted a series of public meetings with industry and valve vendor representatives regarding the problem and its solution. Among the outcomes from these interactions is a resolution plan by the industry enumerating a number of steps with target deadlines no later than December 31, 2017, and a survey of where Anchor Darling double disc gate valves are used in U.S. nuclear power plants. The survey revealed about 700 Anchor Darling double disc gate valves (AD DDGVs) used in U.S. nuclear power plants, but only 9 valves characterized as High/Medium risk, multi-stoke valves. (Many valves are single stroke in that their safety function is to close, if open, or open, if closed. Multi-stroke valves may be called open to open and close, perhaps several times, in fulfilling their safety function.)

Fig. 4 (Source: Nuclear Energy Institute)

There’s still time for the industry to snatch defeat from the jaws of victory, but the NRC seems poised to see this matter to a timely and effective outcome.

Florida’s Nuclear Plants and Hurricane Irma

Will Florida’s two nuclear plants, Turkey Point and St. Lucie, be able to withstand Hurricane Irma?

Florida governor Rick Scott, the utility Florida Power & Light (FP&L), and the US Nuclear Regulatory Commission (NRC) have all provided assurances that they will. But we are about to witness a giant experiment in the effectiveness of the NRC’s strategy for protecting nuclear plants from natural disasters.

A review of the plans that the two plants have developed to protect against extreme natural disasters leaves plenty of room for concern. These plans were developed in response to new requirements that the NRC imposed in the years following the March 2011 Fukushima nuclear plant disaster in Japan. A prolonged loss of all electrical power—caused by an earthquake and subsequent tsunami that flooded the Fukushima site—resulted in three nuclear reactor meltdowns and a large release of radioactivity to the environment. (Even when reactors are shut down, they normally rely on electrical power to provide cooling water to the fuel in the cores and the spent fuel in storage pools, which remain hot.)

Fukushima made it clear that nuclear plants around the world were not sufficiently protected against natural disasters. Subsequently, the NRC imposed new requirements on US nuclear plants to develop strategies to cope with prolonged electric blackouts.

However, these new requirements were heavily influenced by pressure from a cost-conscious nuclear industry. As a result, they were limited in scope.

Moreover, these requirements are based on numerous assumptions that may not prove valid in the face of massive and powerful storms. In effect, the NRC is betting that no nuclear plant will experience conditions that don’t conform to these assumptions. Soon, the nation will find out whether the NRC wins or loses the next round with Mother Nature: Hurricane Irma.

The Plan for Turkey Point

Turkey Point Nuclear Plant (Source: NARA)

FP&L’s plan for Turkey Point, 25 miles south of Miami, contains many questionable assumptions.

To give just one example, its strategy to keep the two reactors cool if there is a total loss of electrical power (both offsite and on-site back-up power) includes initially drawing water from two water supply tanks (so-called condensate storage tanks), running the water through the reactors’ steam generators, and dumping the steam that is produced by the heat of the nuclear fuel in the reactor cores into the atmosphere (when the plant is operating, the steam is used to generate electricity).

But here’s the rub: These tanks were not designed to withstand objects thrown about by the high winds occurring during tornadoes or hurricanes.

Nevertheless, FP&L assumed—and the NRC accepted—that at least one of the two tanks on site would withstand any hurricane. They argued that this was a reasonable assumption because the two tanks are separated by a few hundred feet and there are structures between them. There seems to be a degree of wishful thinking at work here. If both tanks were damaged, the challenges in keeping the cores cool would be far greater.

Also, to deal with prolonged station blackouts—when both offsite and onsite back-up power is lost—the Turkey Point plan assumes that offsite assistance would be available after five days. The nuclear industry has set up two “National SAFER Response Centers,” one in Memphis, Tennessee and the other in Phoenix, Arizona. Each one contains additional emergency equipment and supplies to supplement those that each reactor owner is required to have on site. The NRC requires that every plant in the country have an agreement with one of the SAFER centers to provide equipment and assistance should it be needed.

But the functioning of this system depends on the ability of the SAFER centers to deliver the equipment in a timely manner, which might not be possible if there were a widespread and prolonged natural disaster.

Turkey Point’s plan requires that deliveries from the Memphis SAFER center be shipped to Miami International Airport and then hauled (if the roads are clear) to the site or to the Homestead Air Reserve Base and taken to the site via helicopter. But it doesn’t take too great a stretch of the imagination, given the potential impact of a massive storm like Irma, to see where this plan could go badly wrong. And looking at the current track of the storm, the Memphis SAFER center itself could well be in its path, causing problems at the shipping end as well as the receiving end.

Even if the Turkey Point plan were effective, it is not clear how much of it has been put into place on the ground yet. At the end of June, the plant reported to the NRC that it needed to make ten modifications to address the risk of storm surges that could exceed the flood level that the plant was originally designed to withstand.

But it isn’t clear how many of those modifications have been completed yet. And the NRC’s first inspection of the post-Fukushima measures at Turkey Point is not even scheduled until March 2018. So at this time all the public has to rely on is an assumption that FP&L has implemented the plan completely and correctly.

With one assumption piled upon another, it is very hard for observers to assess how prepared Turkey Point really is to deal with superstorms. Hopefully, the plant will pass the Irma test, but the NRC will need to reevaluate whether its new requirements can adequately address the potential for more severe storms in the future.

Strategic missile defense failures: who’s to blame?

In Wednesday’s Washington Post, columnist Marc Thiessen blames Democrats’ historic skepticism about missile defense for the poor state of these systems today, but that’s a misrepresentation of its history.

What is the poor state of the Ground-based Midcourse System (GMD) due to?

In our 2016 report, we looked back at the history of the development of the GMD system since its origins in 2002.

The Bush administration exempted the missile defense development program from the normal oversight and accountability processes required of other major military systems, with the goal of quickly fielding the GMD system. These exemptions allowed the Pentagon to cut engineering cycles short and to field poorly tested equipment; the haste with which the system was fielded ensured this would be the case.

Today this poorly tested equipment makes up key parts of the fielded GMD system. Nearly all of the GMD interceptors—the core of the GMD system’s defensive capability today—were fielded before their design had been successfully intercept-tested even once.

This flawed approach—not a lack of money– is responsible for most of the problems with the system. The GMD system’s test record has been notably poor, with just nine successful intercepts out of 18 tries, despite the fact that the tests are heavily scripted for success. Identifying the cause of these failures and fixing the already-fielded interceptors has cost considerable time and money. The GMD system continues to have major schedule and cost overruns.

Yet, it is not just the execution of the program that has been problematic, it is the approach to the task of hitting a missile with a missile. A scathing 2012 National Academy of Sciences study called the GMD system “deficient” with respect to all of the study’s fundamental principles for a cost-effective missile defense, and recommended a complete overhaul of the interceptors, sensors, and concept of operations.

Insufficient oversight has not only exacerbated the GMD system’s problems, but has obscured their full extent. Obama administration attempts to improve oversight and accountability without bringing missile defense under the normal processes have led to ongoing problems. These include projects that have been started without sufficient vetting and later canceled, and components that are being fielded based on imposed deadlines rather than technical maturity—in some cases with known flaws.

Build more or fix the system?

Is following the Bush plan the right idea? The full complement of 44 interceptors envisioned by the Bush plan will be fielded by the end of this year. Yet Pentagon testing officials assess that the GMD system has not yet demonstrated an operationally useful capability.

The Missile Defense Agency’s (MDA) decision to build and field additional untested interceptors rather than systematically fix all known flaws also ignores specific advice on how best to balance a sense of urgency with the responsibility to build a cost-effective and high-quality system. A top-level recommendation of the 2008 “Welch report” (produced by a panel headed by retired Air Force Chief of Staff General Larry Welch) on missile defense concerned this balance:

For mid-course intercept systems, the balance between qualitative improvements and deploying more of existing capabilities should be strongly in favor of qualitative improvements. Without such a focus, the current system capabilities will become obsolete regardless of the numbers of interceptors deployed.

For the GMD system, however, the balance has been strongly in favor of building more of the existing capabilities, presumably to provide reassurance domestically and to allies. Rushing minimally tested hardware into the field may give the appearance of a defense, but it does not reliably protect US cities.

Did the US abandon promising programs prematurely?

Thiessen suggests that missile defense programs have been abandoned prematurely. In reality, this was the overdue discarding of wasteful, unworkable programs.

Regarding the three programs Thiessen mentions: Airborne Laser, the Kinetic Energy Interceptor, the Multiple Kill Vehicle, Secretary of Defense Robert Gates strongly criticized these (and their supporters) in the New York Times in 2009:

I have found since taking this post that when it comes to missile defense, some hold a view bordering on theology that regards any change of plans or any cancellation of a program as abandonment or even breaking faith. I encountered this in the debate over the Defense Department’s budget for the fiscal year 2010 when I ended three programs: the airborne laser, the multiple-kill vehicle, and the kinetic energy interceptor. All were plainly unworkable, prohibitively expensive and could never be practically deployed—but had nonetheless acquired a devoted following.

In fact, Congress contributes to going down the rabbit hole of wasteful programs in two ways. First, Congress is not providing strict enough oversight of Pentagon proposals, being neither skeptical enough nor requiring robust analyses of alternatives up front, with in-depth analysis of feasibility, costs, and risks.

Second, the weakened oversight system and the politicized nature of missile defense leave strategic missile defense vulnerable to missile defense advocates in Congress adding their own unnecessary or unvetted projects to the missile defense budget. Indeed, several times Congress has generated new and unasked-for efforts, such as a proposal for a third continental interceptor site on the US East Coast. Despite having no validated requirement for such a site, and in spite of testimony from the MDA director that other priorities for improving strategic missile defense are more pressing, congressional advocates of an East Coast site have included mandates in budget legislation intended to fast-track the process for building a third site and have added unasked-for money to the budget for it each year since 2012.

Congress has also pressed for a return to discarded ideas, such as the Bush plan for land-based Ground Based Interceptors in Eastern Europe and space-based boost-phase interceptors. Congress added money to the fiscal year 2016 budget to study the feasibility of a space-based boost-phase missile defense layer—despite having several years ago received the advice it solicited from the National Academy of Sciences on this very question. The NAS recommendation on space-based boost phase missile defense, which it estimated would cost at least $300 billion for a limited capability, was unequivocal:

The total life-cycle cost of placing and sustaining the [space-based boost-phase] constellation in orbit is at least an order of magnitude greater than that of any other alternative and impractical for that reason alone.

North Korea’s Missile Test over Japan

Yesterday’s missile launch by North Korea is reported to have been launched from a site near the capitol city of Pyongyang (Sunan) and landed 2,700 kilometers (km) (1,700 miles) to the east after flying over part of the Japanese island of Hokkaido. The missile reportedly flew to a maximum altitude of about 550 km (340 miles), reaching Hokkaido after about eight minutes of flight and splashing down after 14 to 15 minutes.

Fig. 1 shows a possible trajectory for the flight, although it is possible the missile flew somewhat further north and passed over more of Hokkaido.

Fig. 1 (Source: Google Earth)

The launch appears to have been of a Hwasong-12 missile, since it is the only known missile able to reach this distance. The range of this test, however, was much shorter than that of the May 14 test of the Hwasong-12, which would have had a range on a standard trajectory of about 4,800 km (3,000 miles).

What accounts for the shorter range?

One possibility is that the missile was flown with a much larger payload on this flight than on the May 14 test. However, even assuming the May 14 test only carried a payload of 150 kg (corresponding to an empty RV), this launch would have required a payload of about 1,300 kg to give the reported trajectory. That seems unlikely.

A second possibility is that it was flown on a depressed trajectory to reduce the range from 4,800 to 2,700 km. However, that would require a severely depressed trajectory with a burnout angle below nine degrees and a maximum altitude of only 150 km (95 miles). That would also give flight times that were much shorter than those reported.

A more likely reason for a shorter range is a shorter burn time for the engines, either due to North Korea terminating the thrust early to reduce the range, or possibly due to a mechanical problem. In particular, I find if the burn time of the engine is reduced by about eight seconds from the time of about 151 second for the May 14 launch, the missile will fly on the reported trajectory (Fig. 2).

If flown on a standard trajectory (a “minimum-energy trajectory”), a missile with this range would reach a maximum altitude of about 630 km (390 miles) with a burnout angle of 38.1 degrees. The reported altitude of 550 km on yesterday’s launch would mean it was slightly depressed from normal, with a burnout angle of 33.6 degrees. This amount of depression does not seem particularly significant, and may not have been intended.

Fig. 2. The apparent trajectory of yesterday’s launch. Cape Erimo on Hokkaido is at a range of about 1525 km.

A missile on this trajectory would reach the closest part of Hokkaido after eight minutes, which seems to agree with reports. It would pass over Cape Erimo after 9 minutes, and would splash down at 15.5 minutes

Flying over Japan

Yesterday’s launch was the first time North Korea flew a ballistic missile over Japanese territory, although in 1998 and 2009 it launched rockets that overflew Japan on failed attempts to put satellites into orbit. It has gone to some lengths to avoid flying over Japan, by launching its missile tests on highly lofted trajectories so they will land in the Sea of Japan. In addition, it has directed its more recent satellite launches to the south, even though it is preferable to launch to the east—over Japan—since it allows the rocket to gain speed from the rotation of the earth.

After its threats of firing Hwasong-12 missiles near Guam, it is interesting that North Korea fired this missile to the east rather than in the direction of Guam, which might have been interpreted as an attack despite the short range. The missile also appears to have flown in a direction that did not pass over highly populated parts of Japan.

It is not clear what new North Korea would have learned from this launch that is relevant to a long-range missile. It would not have been useful in simulating the reentry forces and heating of a long range missile; in particular, the heating would have been only about half of that on a 10,000 km range missile.

The launch could be useful in getting information about reentry on a standard, non-lofted trajectory with a missile that could reach Guam, although that would require a missile with about 3,400 km range rather than the 2,700 km of this flight.

US Talks to China about North Korea, But Does Not Listen

The United States and China both want North Korea to abandon its nuclear weapons program. The North Korean leadership continues to defy them both. The United States says it is willing to risk a war to stop them. China is not.

Marine Corps Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, signs the Joint Staff Dialogue Mechanism with his Chinese counterpart Gen. Fang Fenghui following a roundtable discussion in Beijing, Aug. 15, 2017. (DOD photo by U.S. Navy Petty Officer 1st Class Dominique A. Pineiro)

China’s top priority is preserving the peace, however uneasy that peace might be. A credible North Korean capability to launch a nuclear-armed ICBM may make US officials psychologically uncomfortable. But the Chinese leadership does not feel that increased US anxiety is a sufficient justification for starting a war that could conceivably kill hundreds of thousands of people and collapse Asia’s economy, even if no nuclear weapons were used.

China has made its priorities clear to both the United States and North Korea. An August 10 editorial published in China’s Global Times warned both sides against striking first. The editorial was not an official statement of Chinese government policy but it almost certainly was reviewed and approved at the highest level. It suggested to the leadership in Pyongyang that, “If North Korea launches missiles that threaten US soil first and the US retaliates, China will stay neutral”. It also suggested to Washington that, “If the US and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so.”

China has also made it clear that it will not agree to sanctions that strangle North Korea’s economy. China supports economic penalties that punish North Korea for defying the United Nations and continuing its testing programs. And China is willing to work with the United States and the international community to deny North Korea access to critical technologies. But on August 5th, in an official statement made at the time of the vote on the latest round of UN sanctions, China emphasized, as it has many times in the past, that China “did not intend to negatively impact such non-military goods as food and humanitarian aid.”

US Refusal to Listen

Though China’s position on North Korea is clear and consistent, US policy is based on the assumption that China’s position will change. On August 13th, US Secretary of Defense James Mattis and Secretary of State Rex Tillerson penned an editorial in which they repeated the claim, believed by most US policy makers and analysts,  that China has “decisive diplomatic and economic leverage over North Korea.” The implication is that China can force the North Korean leadership to abandon its nuclear weapons program. The joint editorial reiterated a US policy announced earlier this year by Secretary Tillerson, who said the Trump administration was engaged in an unprecedented effort to “lean hard into China” in order to pressure its leaders to change their policy.

Presumably this means trying to compel China to take steps to strangle the North Korean economy. The United States reportedly attempted to include a crude oil embargo in the latest round of UN sanctions. But China refused, as it has in the past, to agree to sanctions that would have the kind of suffocating economic impact the United States believes would force North Korea to surrender its nuclear ambitions. In their editorial Tillerson and Mattis told their Chinese counterparts they expect China to “do more” than enforce the current round of UN sanctions. They want China to cut off North Korea’s “economic lifelines.”

US policy experts imagine there are several factors that might prompt the Chinese leadership to bend to US demands. Henry Kissinger raised the specter of nuclear proliferation in Asia, including a nuclear-armed Japan. Others believe the Chinese are worried about increased US economic and diplomatic pressure, especially President Trump’s statements linking Chinese cooperation on North Korea to punitive US trade policies. US observers of Chinese domestic politics speculated that Chinese President Xi Jinping may need to alter China’s longstanding policies on North Korea to mollify domestic critics as he makes his case for a second five-year term at the upcoming Party Congress in November.

China Remains Calm

Despite these imagined pressures, there is no indication that President Xi is about change China’s position on North Korea. Throughout the month of July there was very little Chinese coverage or commentary on the North Korean missile tests. Official statements repeated past calls for calm, mutual restraint and a resumption of negotiations. It wasn’t until President Trump’s threat to unleash “fire and fury” on August 8th, followed by North Korea’s threat to fire missiles towards Guam on August 9th, that the Chinese leadership had the Global Times publish the August 10th editorial containing more emphatic and explicit language.

Not long afterwards, North Korea walked back its threat to fire missiles at Guam. The United States then made a series of high level statements intended to diffuse tensions.  In their editorial, Tillerson and Mattis questioned whether China was willing or able to “show the world how a great power should act.” History may well record that in this particular moment of high tension, China’s president acted with greater patience, skill and prudence than the president of the United States.

On August 14th, as tensions began to subside, an editorial in the overseas edition of China’s People’s Daily chastised both the United States and North Korea for “playing a game of chicken on the Korean peninsula.” That’s not the language of a country that lacks confidence in its current position or is overly concerned about upsetting the United States.

The Pyroprocessing Files

The article by Ralph Vartabedian in the Los Angeles Times highlights the failure of the Department of Energy’s decades-long effort to chemically process a stockpile of spent nuclear fuel at Idaho National Laboratory, ostensibly to convert the waste to forms that would be safer for disposal in a geologic repository. A secondary goal was to demonstrate the viability of a new type of processing spent fuel—so-called pyroprocessing. Instead, it has demonstrated the numerous shortcomings of this technology.

(Source: Idaho National Lab)

It is particularly important to disseminate accurate information about the failure of this DOE program to dispel some of the myths about pyroprocessing. The concept of the “Integral Fast Reactor”—a metal-fueled fast neutron reactor with co-located pyroprocessing and fuel fabrication facilities—has attracted numerous staunch advocates.

In addition to Argonne National Laboratory, which first developed the technology, the concept has been promoted in the popular media (most notably in the 2013 documentary Pandora’s Promise) and by GE-Hitachi, which seeks to commercialize a similar system. South Korea has long sought to be able to implement the technology, and countries such as China, Japan and Russia all have expressed interest in pursuing it. But this interest has been driven largely by idealized studies on paper and not by facts derived from actual experience.

DOE internal documents reveal problems

The LA Times article refers to a June 2017 Union of Concerned Scientists (UCS) report that draws on documents that UCS received in response to a Freedom of Information Act (FOIA) request. UCS initiated the request in 2015 to seek information that could shed light on DOE’s troubled program for pyroprocessing 26 metric tons of “sodium-bonded” metallic spent fuel from the shutdown Experimental Breeder Reactor-II (EBR-II).

Pyroprocessing is a form of spent fuel reprocessing that dissolves metal-based spent fuel in a molten salt bath (as distinguished from conventional reprocessing, which dissolves spent fuel in water-based acid solutions). Understandably, given all its problems, DOE has been reluctant to release public information on this program, which has largely operated under the radar since 2000.

The FOIA documents we obtained have revealed yet another DOE tale of vast sums of public money being wasted on an unproven technology that has fallen far short of the unrealistic projections that DOE used to sell the project to Congress, the state of Idaho and the public. However, it is not too late to pull the plug on this program, and potentially save taxpayers hundreds of millions of dollars.

History of the pyroprocessing program

DOE originally initiated the pyroprocessing program for EBR-II spent fuel in the mid-1990s as a consolation prize to Argonne-West National Laboratory (now part of present-day Idaho National Laboratory) after it cancelled the Integral Fast Reactor (IFR) program. The idea was that the metal-based spent fuel from the reactor could be pyroprocessed in a facility connected to the reactor, which would extract plutonium, uranium and other elements to be fabricated into new reactor fuel. In theory, this could be a system that could convert its nuclear waste into usable fuel on site and thus could be largely self-contained. Pyroprocessing was billed as a simpler, cheaper and more compact alternative to the conventional aqueous reprocessing plants that have been operated in France, the United Kingdom, Japan and other countries.

Although DOE shut down the EBR-II in 1994 (the reactor part of the IFR program), it allowed work at the pyroprocessing facility to proceed. It justified this by asserting that the leftover spent fuel from the EBR-II could not be directly disposed of in the planned Yucca Mountain repository because of the potential safety issues associated with presence of metallic sodium in the spent fuel elements, which was used to “bond” the fuel to the metallic cladding that encased it. (Metallic sodium reacts violently with water and air.)

Pyroprocessing would separate the sodium from other spent fuel constituents and neutralize it. DOE decided in 2000 to use pyroprocessing for the entire inventory of leftover EBR-II spent fuel – both “driver” and “blanket” fuel – even though it acknowledged that there were simpler methods to remove the sodium from the lightly irradiated blanket fuel, which constituted nearly 90% of the inventory.

Little progress, big cost overruns

However, as the FOIA documents reveal in detail, the pyroprocessing technology simply has not worked well and has fallen far short of initial predictions (Figure 1) (Refs. 1-3). Although DOE initially claimed that the entire inventory would be processed by 2007, as of the end of Fiscal Year 2016, only about 15% of the roughly 26 metric tons of spent fuel had been processed. Over $210 million has been spent, at an average cost of over $60,000 per kilogram of fuel treated. At this rate, it will take until the end of the century to complete pyroprocessing of the entire inventory, at an additional cost of over $1 billion.

But even that assumes, unrealistically, that the equipment will continue to be usable for this extended time period. Moreover, there is a significant fraction of spent fuel in storage that has degraded and may not be a candidate for pyroprocessing in any event (Ref. 4). The long time to completion is problematic because DOE has an agreement with the state of Idaho to remove all spent fuel from the state by the year 2035. The FOIA documents reveal that DOE is well aware that it is not on track to comply with this obligation (Ref 5). Yet DOE has not made any public statements to that effect and continues to insist that it can meet the deadline.

More waste, not less

An impure uranium waste product is deposited on a cathode in a  pyroprocessing cell (Source: Idaho National Lab)

What exactly is the pyroprocessing of this fuel accomplishing? Instead of making management and disposal of the spent fuel simpler and safer, it has created an even bigger mess. Pyroprocessing separates the spent fuel into three principal waste streams. The first is an enriched uranium metal material called the “spent fuel treatment product.” Because this material contains unacceptably high levels of plutonium and other contaminants, the uranium cannot be used to make new nuclear fuel unless it is further purified; thus it is a waste product. Meanwhile, the material is accumulating and taking up precious space at INL storage facilities, causing its own safety issues.

The second waste stream is the molten salt bath that is used to dissolve the spent fuel. Fission products and plutonium have accumulated in this salt for 20 years. Eventually it will have to be removed and safely disposed of. But for various reasons—including cost and a lack of available space for the necessary equipment—INL is reconsidering the original plan to convert this waste into a stable ceramic waste form. Instead, it may just allow it to cool until it hardens and then directly dispose of it in the Waste Isolation Pilot Plant (WIPP) in New Mexico (Ref. 6).

The third waste stream consists of the leftover metal cladding tubes that encased the nuclear fuel, and the metal plenums that extended above the fuel region, which are contaminated with fission products and sodium. The original plan was to convert these scraps into a stable, homogeneous waste form. But the FOIA documents reveal that DOE is also reconsidering this plan, and considering redefining this material as transuranic or low-level waste so it could be disposed of without further processing in WIPP or a low-level radioactive waste disposal facility. Storage of the accumulating metal scrap material is also becoming an increasing burden at INL (Ref. 7).

In other words, pyroprocessing has taken one potentially difficult form of nuclear waste and converted it into multiple challenging forms of nuclear waste. DOE has spent hundreds of millions of dollars only to magnify, rather than simplify, the waste problem. This is especially outrageous in light of other FOIA documents that indicate that DOE never definitively concluded that the sodium-bonded spent fuel was unsafe to directly dispose of in the first place. But it insisted on pursuing pyroprocessing rather than conducting studies that might have shown it was unnecessary.

Everyone with an interest in pyroprocessing should reassess their views given the real-world problems experienced in implementing the technology over the last 20 years at INL. They should also note that the variant of the process being used to treat the EBR-II spent fuel is less complex than the process that would be needed to extract plutonium and other actinides to produce fresh fuel for fast reactors. In other words, the technology is a long way from being demonstrated as a practical approach for electricity production. It makes much more sense to pursue improvements in once-through nuclear power systems than to waste any more time and money on reprocessing technologies that pose proliferation, security and safety risks. DOE continues to consider alternatives to pyroprocessing for the blanket fuel (Ref. 8). It should give serious thought to the possibility of direct disposal of the remaining inventory without processing.

Links to FOIA documents

Below are links to some of the documents that UCS obtained from its FOIA request. We will provide more documents and analyses of them soon.

  1. Argonne National Laboratory Spent Fuel Treatment Implementation Plan (2000)
  2. INL Preferred Disposition Plan for Sodium-Bonded Spent Nuclear Fuel (2007)
  3. History of Processing (through 2013)
  4. Technical Evaluation of Disposition of Non-Candidate Fuels (2014)
  5. 2014 INL Environmental Liabilities Spreadsheet
  6. Technical Evaluation of Alternatives for Salt Waste Disposition (2014)
  7. Disposal Solutions for Metal Scraps Derived from Treatment of Irradiated Sodium Bonded Fuel (2014)
  8. Technical Evaluation of EBR-II Blanket Disposition Alternatives (2014)

NRC’s Decision Making: 18 Reasons Why You Are Right, but Wrong

As described in a prior blog post, the Unit 3 reactor at the Palo Verde Generating Station had one of two emergency diesel generators (EDGs) explode during a test run. The license issued by the Nuclear Regulatory Commission (NRC) allowed the reactor to remain running for up to 10 days with one EDG unavailable. Fixing the heavily damaged EDG would require far longer than 10 days, so the plant’s owner submitted requests to the NRC for its permission to run the reactor for up to 21 days and then up to 62 days with only one EDG available.

As described in a followup blog post, NRC staffer(s) filed formal opposition to the agency’s approval of the owner’s requests by initiating Differing Professional Opinions (DPOs). Under the NRC’s DPO process, a DPO panel is formed to review the issue and to document its findings and conclusions in a report to the NRC senior manager who makes the final decisions. In this matter, that individual was the Director of the Office of Nuclear Reactor Regulation (NRR). The DPO originator(s) can nominate one individual to serve on the DPO panel. (The DPO process requires a minimum of three persons on the DPO panel, ensuring that the panel won’t have a majority of members sympathetic to the originator(s)’s concerns.)

The DPO panel issued its report on June 5, 2017, and the NRR Director issued his decision on June 28, 2017.  The NRC made the DPOs, the DPO panel report, and the NRR Director’s decision publicly available on July 21, 2017.

The DPO Originator

Troy Pruett originated both of the DPOs in the Palo Verde EDG case. Mr. Pruett is the Director of the Division of Reactor Projects in NRC Region IV. Among other things, Mr. Pruett oversees the NRC’s resident inspectors at all of the nuclear power plants operating in Region IV, including Palo Verde. Mr. Pruett has worked for the NRC for nearly a quarter century—long enough to know the agency’s regulations and procedures intended to protect nuclear plant workers and the American public inside and out (Fig. 1).

Fig. 1 (Source: Nuclear Regulatory Commission)

The DPO Originator’s Position

In his DPOs, Mr. Pruett contended that the owner’s requests to operate Palo Verde Unit 3 for up to 21 and later up to 62 days with one emergency diesel generator unavailable should not have been approved because they departed from the agency’s regulations, procedures, and practices.

The DPO Panel’s Conclusion

Quoting from their report: “The DPO Panel was not unanimous in concluding that Palo Verde License Amendments 199 and 200 should have been approved by the staff.”

One of Mr. Pruett’s candidates was appointed to the DPO Panel. NRC management selected three other members, assuring they’d have a majority. And sure enough, a majority of the NRC management-appointed panel sided with NRC management.

The DPO Panel’s 18 Observations

The DPO Panel’s report contained 18 Observations about the processes used (and not used) en route to the Palo Verde EDG approvals:

(1) The owner submitted two licensing requests to the NRC: one to operate for up to 21 days and the second to operate for up to 62 days with one EDG unavailable. The overwhelming majority of the hundreds of licensing requests submitted to the NRC each year are not bifurcated in this way and the agency’s procedures for reviewing licensing requests do not address such “split” requests. The DPO panel recommended that additional guidance be provided in LIC-101, the NRC’s procedure for handling such reviews, if the practice becomes more frequent.

(2) The DPO Panel noted that the staff’s reasoning for the two-step approach could have been made clearer in the first approval in the interest of transparently providing a complete record of the staff’s decision basis to the public.

(3) The DPO Panel observed that there may be opportunities to more effectively communicate with the public, including the use of less formal communications tools, during emergency requests, and suggests that guidance and training be considered in this area.

 (4) The second approval issued by the NRC staff contained an explicit requirement to shut down Unit 3 if workers found the cause of the EDG’s failure could also disable the surviving EDG. The DPO Panel noted that no formal regulatory commitment existed in the first approval. During interviews, the NRC staff was not able to provide a sufficient basis as to why a similar condition was not included.

(5) The DPO Panel observed that the Safety Evaluation issued by the NRC staff in support of the first approval lacked sufficient documentation to objectively identify the staff’s decision basis in several key areas, including how the potential for common cause failure of the surviving EDG was evaluated and the basis for a 21 day EDG outage time. In other words, the NRC staff failed to ask and answer all the relevant safety questions.

(6) The DPO Panel concluded that the use of a zero test and maintenance assumption (i.e., no other safety equipment would fail or be unavailable while the EDG was broken) in the owner’s probabilistic risk assessment (PRA) model was not consistent with Regulatory Guide 1.177 guidance and the regulatory commitment put in place for the second approval for the conduct of routine maintenance and surveillance was not consistent with PRA assumptions.

In other words, when the EDG was unbroken, the owner’s risk assessment assumed that there was a small, but non-zero, chance that the highly reliable emergency equipment would not perform needed safety functions during an accident. But when evaluating the risk during the 62 days the reactor would operate with a broken EDG, the owner’s risk assessment assumed that all emergency equipment would function perfectly. The DPO Panel found this assumption unrealistic, non-conservative, and contrary to longstanding NRC expectations.

(7) Additional guidance should be evaluated with respect to defense-in-depth, the adequacy of long duration equipment outage periods, and whether there should be a backstop (i.e., maximum outage period).

(8) The DPO Panel concluded that the Branch Technical Position 8-8 guidance was not strictly adhered to for the two approvals. The DPO Panel recommended that deviations from established guidance should be documented and justified. The Branch Technical Position explicitly stated that the NRC staff should not even review a request to operate for longer than 14 days with one EDG unavailable; in this case, the NRC staff not only reviewed such a request, they approved it without explaining why they dismissed the 14-day maximum duration.

(9) The DPO Panel confirmed that the NRC’s safety evaluation supporting the first approval did not include an independent verification of the owner’s risk evaluations.

(10) The DPO Panel identified that the second approval used the three risk-informed tiered review approach outlined in Regulatory Guide 1.177. The DPO Panel pointed out this approach was inconsistent with Standard Review Plan 16.1 guidance, which states that Regulatory Guide 1.177 only applied to permanent (as opposed to temporary or “one-time”) changes. In other words, the NRC staff used an approach not allowed by the agency’s procedures.

(11) The DPO Panel found no discernible differences between the DC Cook request for a 65-day EDG outage in June 2015 and the Palo Verde request. However, the staff appears to have arrived at entirely different conclusions, based upon different interpretations of the deterministic guidance of Branch Technical Position 8-8. Cook’s owner sought the NRC’s permission to operate Unit 1 for up to 65 days with one of two EDGs unavailable. The NRC said no to Cook’s owner and yes to Palo Verde’s owner, citing Branch Technical Position 8-8 for each of the entirely opposite decisions.

(12) In the DPO Panel’s opinion, the Palo Verde risk evaluation warranted closer scrutiny. However, interviews of the NRC staff identified that there is no guidance for when to use the agency’s SPAR models for independent verification and it appears to be at the discretion of the reviewer(s).

(13) Section 4.2 of the NRC’s procedure for reviewing licensing requests, LIC-101, states that, “Decisions to not apply specific precedents, especially precedents cited by a licensee, should be clearly explained in the SE [NRC’s Safety Evaluation] (to avoid the appearance of being arbitrary and/or inconsistent).” The DPO Panel observed that neither of the Safety Evaluations prepared by the NRC staff for the two approvals addressed the licensee’s referenced precedents. In other words, the NRC staff did not follow the procedure they purportedly used to make the approvals.

(14) The DPO Panel found that both of the Safety Evaluations prepared by the NRC staff for its approvals included Branch Technical Position 8.8 in the list of regulatory guidance documents reviewed. The Safety Evaluations stated that Branch Technical Position 8.8 required more defense-in-depth for station blackout scenarios than for loss of coolant accident scenarios because of a higher likelihood of occurrence. But the DPO Panel found no such statement or implication about design basis accident likelihoods in the Branch Technical Position. In other words, the NRC staff departed from the regulatory guidance document it purportedly used to justify the approvals.

(15) The DPO Panel determined that there is no established guidance for how NRC staff should judge the adequacy of risk evaluations provided by plant owners. The good news is that the NRC staff cannot depart from non-existent guidance; the bad news is that the NRC staff can, and has, wandered all over the map since it lacks proper directions.

(16) The DPO Panel identified a lack of clarity in the existing review guidance and related inconsistencies in the understanding between the NRC departments regarding who is responsible for reviewing what in licensing requests.

(17) The DPO Panel recommended additional guidance be developed for the NRC staff when reviewing requests for extended periods of safety equipment unavailability.

(18) The DPO Panel recommended that a lessons learned review be conducted after significant or first of a kind licensing actions to determine if the action should be used as future precedent and/or whether there should be specific attributes identified that future staff should evaluate before using the precedent.

Grading on a (Mobius) Curve

If you read these observations, and the more voluminous supporting text in the report, before reading the conclusion, you’d likely think that the entire panel agreed with Mr. Pruett.

After all, Mr. Pruett contended that the requests departed from regulations and the DPO Panel’s Observations 5, 6, and 14 confirm that contention and several others support it.

Mr. Pruett contended that the requests departed from the agency’s procedures. The DPO Panel’s Observations 1, 8, and 13 confirm that contention and several others support it.

Mr. Pruett contended that the requests departed from the agency’s practices. The DPO Panel’s Observations 9, 10, and 11 confirm that contention and several others support it.

But nooooo. The DPO Panel disagreed with Mr. Pruett.

You might ask why the DPO Panel could possibly have disagreed with Mr. Pruett.

If you do ask and someone gives you a straight answer, please forward it to me. I’ve monitored the NRC for nearly two decades and I cannot fathom how the DPO Panel could assemble so many reasons why Mr. Pruett was right, and yet conclude he was wrong.

It’s like a 19 chapter mystery novel with the first 18 chapters describing how the upstairs maid committed crime after crime only to have the butler—mentioned for the first time—arrested for the crimes.

Perhaps that explains it: the DPO Panel report is an intriguing work of fiction. Or maybe it only needed a non-fictional final chapter.

Simorgh Launch: Iran’s Bigger Ride to Space Gets off the Ground

Iranian press has announced a successful launch of the Simorgh space launch vehicle.

A couple days later, there’s no sign of an orbital object being tracked from the launch. It’s not like the US space surveillance to take so long to catalog a low-earth orbiting object, so I don’t think one is forthcoming.

That nothing got to orbit may be either by design or failure. Iran tends not to announce its space program failures, and the video showed at least the early part of the launch went off without catastrophe. In any case, this would be the first successful launch of the Simorgh. We wrote a few pieces on Simorgh last year, in anticipation of its launch then: first, second, third.

What’s interesting about the Simorgh?

So far, all Iran’s satellites have been launched with the Safir rocket, which is significantly less capable than the Simorgh. The Simorgh is closer to North Korea’s Unha, but with two stages instead of three.

Simorgh was meant to be launched in 2010; its conspicuous absence could mean that its development has been harder than anticipated, or that sanctions on ballistic missile and space technology have limited Iran’s ability to get materials it needs, or that there have been test launches that have failed and not been reported. Last year’s test may have been one such failure, or it may have been a suborbital test.

Why would Iran want satellites?

A new satellite would be the fifth for Iran, following Omid (2009), Rasad (2011), Navid (2012), and Fajr (2015). These satellites were all launched by the Safir rocket.

These were all small satellites, 50 kg or lighter, lofted into such low-altitude orbits that atmospheric drag brought them down within weeks. I’ve not seen any data published from these satellites. Perhaps they didn’t work as anticipated or perhaps the results were not impressive enough to burnish program’s reputation.

The Simorgh is larger and more capable than Safir, and can put heavier satellites at higher orbits. Larger satellites mean more capability, and higher orbits mean they will stay up for longer. Iran is a large country with tough geography–big deserts & mountains. It’s prone to natural disasters such as earthquakes, and has adversarial neighbors.  It could benefit from satellites for national security purposes as well as for economic & social development.

North Korean ICBM Appears Able to Reach Major US Cities

Based on current information, today’s missile test by North Korea could easily reach the US West Coast, and a number of major US cities.

Reports say that North Korea again launched its missile on a very highly lofted trajectory, which allowed the missile to fall in the Sea of Japan rather than overflying Japan. It appears the ground range of the test was around 1,000 km (600 miles), which put it in or close to Japanese territorial waters. Reports also say the maximum altitude of the launch was 3,700 km (2,300 miles) with a flight time of about 47 minutes.

If those numbers are correct, the missile flown on a standard trajectory the missile would have a range 10,400 km (6,500 miles), not taking into account the Earth’s rotation.

However, the rotation of the Earth increases the range of missiles fired eastward, depending on their direction. Calculating the range of the missile in the direction of some major US cities gives the approximate results in Table 1.

Table 1.

Table 1 shows that Los Angeles, Denver, and Chicago appear to be well within range of this missile, and that Boston and New York may be just within range. Washington, D.C. may be just out of range.

It is important to keep in mind that we do not know the mass of the payload the missile carried on this test. If it was lighter than the actual warhead the missile would carry, the ranges would be shorter than those estimated above.

 

Marijuana and Nuclear Power Plants

The Nuclear Regulatory Commission (NRC) adopted regulations in the mid-1980s seeking to ensure that nuclear power plant workers are fit for duty. The NRC’s regulations contained provisions seeking to verify that workers were trustworthy and reliable as well as measures intended to prevent workers from being impaired on duty. The former measures included background checks before workers could gain access to the plant while the latter components included drug and alcohol testing.

The regulations require that nuclear plant owners test workers for marijuana and alcohol use at the time of hiring, randomly thereafter, and for cause when circumstances warrant it. In 2014, marijuana use was the #1 reason for positive drug and alcohol tests by contractors and vendors and was the #2 reasons for positive tests by nuclear plant employees. Positive tests for alcohol are the #1 reason for positive tests by employees and the #2 reason for positive tests by contractors and vendors. A positive test may not be a career killer, but it is often a career crimper.

Fig. 1 (Source: Nuclear Regulatory Commission)

Alcohol can be legally purchased and consumed in all 50 states. So, mere detection of having used alcohol will not result in a positive test. But detection of a blood alcohol concentration of 0.04 percent or higher yields a positive test. People have different metabolisms and alcoholic beverages come in different sizes, but that threshold is often equated to having consumed one alcoholic beverage within five hours of the test. Similar to the reason that states require motorists to not drive under the influence of alcohol (i.e., don’t drink and drive), the NRC’s regulations seek to control alcohol consumption by workers (i.e, don’t drink and operate nuclear plants.)

Unlike the reason for the alcohol controls, the NRC’s ban on marijuana use is not because it might make them more likely to make mistakes or otherwise impair their performance, thus reducing nuclear safety levels. The NRC banned marijuana use because at the time marijuana was an illegal substance in all 50 states and its criminal use meant that workers fell short of the trustworthiness and reliability standards in the fitness for duty regulation. Since the NRC adopted its regulation, 8 states have legalized recreational use of marijuana and another 12 states have decriminalized its use.

Fig. 2 (Source: NORML)

The NRC recognized that marijuana’s legalization creates potential problems with its fitness for duty regulation. If an individual uses marijuana in a state that has legalized or decriminalized its use but tests positive at a nuclear plant in a state where its use is not legal, is the individual sufficiently trustworthy and reliable? In the eyes of the NRC, the answer remains yes.

Fig. 3 (Source: Nuclear Regulatory Commission)

The NRC conceded that no comparable scientific basis links marijuana use to performance impairment as existed when the alcohol limits were established. But the NRC continues to consider marijuana use as indicating one lacks the trustworthiness needed to work in a nuclear power plant.

The NRC is in a hard spot on this one. Revising its regulations to eliminate marijuana as a disqualifier for working in a nuclear power plant would likely spawn news reports about the agency permitting Reefer Madness at nuclear plants. But the country’s evolving mores are undermining the basis for the NRC’s regulation.

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