UCS Blog - All Things Nuclear (text only)

UCS to Nuclear Regulatory Commission: Big THANKS!

This spring, I ran into Mike Weber, Director of the Office of Nuclear Regulatory Research for the Nuclear Regulatory Commission (NRC), at a break during a Commission briefing. The Office of Research hosts a series of seminars which sometimes include presentations by external stakeholders. I asked Mike if it would be possible for me to make a presentation as part of that series.

I explained that I’d made presentations during annual inspector conferences in NRC’s Regions I, II, and III in recent years and would appreciate the opportunity to reach out to the seminars’ audience. Mike commented that he’d heard positive feedback from my regional presentations and would welcome my presentation as part of their seminars. Mike tasked Mark Henry Salley and Felix Gonzalez from the Research staff to work out arrangements with me. The seminar was scheduled for September 19, 2017, in the auditorium of the Two White Flint North offices at NRC headquarters. I appreciate Mike, Mark, and Felix providing me the opportunity I sought to convey a message I truly wanted to deliver.

Fig. 1 (Source: Union of Concerned Scientists)

The title of my presentation at the seminar was “The Other Sides of the Coins.” The NRC subsequently made my presentation slides publicly available in ADAMS, their online digital library.

As I pointed out during my opening remarks, the NRC staff most often hears or reads my statements critical of how the agency did this or didn’t do that. My presentation that day focused on representative positive outcomes achieved by the NRC. For that presentation that day, my whine list was blank by design. Instead, I talked about the other sides of my usual two cents’ worth.

Fig. 2 (Source: Union of Concerned Scientists)

I summarized eight positive outcomes achieved by the NRC and listed five other positive outcomes. I emphasized that these were representative positive outcomes and far from an unabridged accounting. I told the audience members that I fully expected they would be reminded of other positive outcomes they were involved in as I covered the few during my presentation. Rather than feeling slighted, I hoped they would feel acknowledged and appreciated by extension.

One of the eight positive outcomes I summarized was the inadequate flooding protection identified by NRC inspectors at the Fort Calhoun nuclear plant in Nebraska. The NRC issued a preliminary Yellow finding—the second highest severity in its Green, White, Yellow, and Red classification system—in July 2010 for the flood protection deficiencies. To help put that Yellow finding in context, the NRC issued 827 findings during 2010: 816 Green, 9 White, and 2 Yellow. It was hardly a routine, run of the mill issuance.

The plant’s owner formally contested the preliminary Yellow finding, contending among other things that Fort Calhoun had operated for nearly 30 years with its flood protective measures, so they must be sufficient. The owner admitted that some upgrades might be appropriate, but contended that the finding should be Green, not Yellow.

The NRC seriously considered the owner’s appeal and revisited its finding and its severity determination. The NRC reached the same conclusion and issued the final Yellow finding in October 2010. The NRC then monitored the owner’s efforts to remedy the flood protection deficiencies.

The NRC’s findings and, more importantly, the owner’s fixes certainly came in handy when Fort Calhoun (the sandbagged dry spot in the lower right corner of Figure 3) literally became an island in the Missouri River in June 2011.

Recall that the NRC inspectors identified flood protection deficiencies nearly 8 months before the Fukushima nuclear plant in Japan experienced three reactor meltdowns due to flooding. Rather than waiting for the horses to trot away before closing the barn door, the NRC acted to close an open door to protect the horses before they faced harm. Kudos!

Fig. 3 (Source: Union of Concerned Scientists)

The real reason for my presentation in September and my commentary now is to acknowledge the efforts of the NRC staff. My concluding slide pointed out that tens of millions of Americans live within 50 miles of operating nuclear power plants and tens of thousands of Americans work at these operating plants. The efforts of the NRC staff make these Americans safer and more secure. I observed that the NRC staff deserved big thanks for their efforts and my final slide attempted to symbolically convey our appreciation. (The thanks were way bigger on the large projection screen in the auditorium. To replicate that experience, lean forward until your face is mere inches away from your screen.)

Fig. 4 (Source: Union of Concerned Scientists)

Whose Finger Is on the Button? Nuclear Launch Authority in the United States and Other Nations

Throughout the 2016 presidential campaign, and perhaps even more since Trump’s election, the media discovered a newfound interest in the minutiae of US nuclear policy. One question in particular has been asked over and over—can the president, with no one else to concur or even advise, order the use of US nuclear weapons? Most people have been shocked and somewhat horrified to find that there is a simple answer—yes.

Starting a nuclear war shouldn’t be easy

The president has the sole authority to order a nuclear strike—either a first strike or one in response to an attack. Although there are people involved in the process of transmitting and executing this order who could physically delay or refuse to carry it out, they have no legal basis for doing so, and it is far from clear what would happen if they tried.

This belated realization (the system has been in place since the early Cold War) has prompted some ideas for ways to change things, including legislation restricting the president’s ability to order a nuclear first strike without a declaration of war by Congress. But more often it has prompted concern—and sometimes outrage—without a clear idea of how to fix the problem.

It may be useful to ask how other nuclear-armed states approach the problem of making a decision about the use of their nuclear weapons. How does the US compare to Russia, China, and other nuclear-armed states? Are there existing systems that rely on multiple people to order the use of nuclear weapons that the US might learn from?

To try to answer these questions, our new issue brief compiles information on the systems that other nuclear-armed states have in place to order the use of their weapons. While information is necessarily limited, and some of these systems may not completely correspond to what would happen in a true crisis, they still provide useful information about what these countries think is important when making a decision about the use of nuclear weapons. And, in most cases, that includes some form of check on the power of any single individual to order the use of these weapons by him or herself.

The current US process for deciding to use nuclear weapons is unnecessarily risky in its reliance on the judgment of a single individual. There are viable alternatives to sole presidential authority, and it is past time for the US to establish a new process that requires the involvement of multiple decision-makers to authorize the use of nuclear weapons. An investigation of how this decision works in other nuclear-armed states provides a good place to start.

 

Grand Gulf: Three Nuclear Safety Miscues in Mississippi Warranting NRC’s Attention

The Nuclear Regulatory Commission (NRC) reacted to a trio of miscues at the Grand Gulf nuclear plant in Mississippi by sending a special inspection team to investigate. While none of the events had adverse nuclear safety consequences, the NRC team identified significantly poor performance by the operators in all three. The recurring performance shortfalls instill little confidence that the operators would perform successfully in event of a design basis or beyond design basis accident.

The Events

Three events prompted the NRC to dispatch a special inspection team to Grand Gulf:

(1) failure to recognize that reactor power fluctuating up and down by more than 10% during troubleshooting of a control system malfunction in June 2016 exceeded a longstanding safety criterion calling for immediate shutdown,

(2) failure to recognize in September 2016 that the backup reactor cooling system relied upon when the primary cooling system broke was unable to function if needed, and

(3) failure to understand how a control system worked on September 27, 2016, resulting in the uncontrolled and undesired addition of nearly 24,000 gallons of water to the reactor vessel.

(1) June 2016 Reactor Power Oscillation Miscue

Figure 1 shows the main steam system for a typical boiling water reactor like Grand Gulf. The reactor vessel is not shown but is located off its left side. Heat produced by the reactor core boils water. Four pipes transport the steam from the reactor vessel to the turbine. The steam spins the turbine which is connected to a generator (off the right side of Figure 1) to make electricity.

Fig. 1 (Source: Nuclear Regulatory Commission)

Periodically, operators reduce the reactor power level to about 65% power and test the turbine stop valves (labeled SV in Figure 1). The stop valves are fully open when the turbine is in service, but are designed to rapidly close automatically if a turbine problem is detected. When the reactor is operating above about 30 percent power, closure of the stop valves triggers the automatic shutdown of the reactor. Below about 30 percent power, the main steam bypass valves (shown in the lower left of Figure 1) open to allow the steam flow to the main condenser should the stop valves close.

Downstream of the turbine stop valves are the turbine control valves (labeled CV in Figure 1.) The control valves are partially open when the turbine is in service. The control valves are automatically re-positioned by the electro-hydraulic control (labeled EHC) system as the operators increase or decrease the reactor power level. Additionally, the EHC system automatically opens the three control valves in the other steam pipes more fully when the stop valve in one steam pipe closes. The EHC system and the control valve response time is designed to minimize the pressure transient experienced in the reactor vessel when the steam flow pathways change.

The test involves the operators closing each stop valve to verify these safety features function properly. During testing on June 17, 2016, however, unexpected outcomes were encountered. The EHC system failed to properly reposition the control valves in the other lines when a stop valve was closed, and later when it was re-opened. The control system glitch caused the reactor power level to increase and decrease between 63% and 76%.

Water flowing through the core of a boiling water reactor is heated to the boiling point. By design, the formation of steam bubbles during boiling acts like a brake on the reactor’s power level. Atoms splitting within the reactor core release heat. The splitting atoms also release neutrons, subcomponents of the atoms. The neutrons can interact with other atoms to cause them to split in what is termed a nuclear chain reaction. The neutrons emitted by splitting atoms have high energy and high speed. The neutrons get slowed down by colliding with water molecules. While fast neutrons can cause atoms to split, slower neutrons perform this role significantly better.

The EHC system problems caused the turbine control valves to open wider and close more than was necessary to handle the steam flow. Turbine control valves opened wider than necessary lowered the pressure inside the reactor vessel, allowing more steam bubbles to form. With fewer water molecules around to slow down the fast neutrons, more neutrons went places other than interacting with atoms to cause more fissions. The reactor power level dropped as the neutron chain reaction rate slowed.

When turbine control valves closed more than necessary, the pressure inside the reactor vessel increased. The higher pressure collapsed steam bubbles and made it harder for new bubbles to form. With more water molecules around, more neutrons interacted with atoms to cause more fissions. The reactor power level increased as the neutron chain reaction rate quickened.

Workers performed troubleshooting of the EHC system problems for 40 minutes. The reactor power level fluctuated between 63% and 76% as the turbine control valves closed too much and then opened too much. Finally, a monitoring system detected the undesired power fluctuations and automatically tripped the reactor, causing all the control rods to rapidly insert into the reactor core and stop the nuclear chain reaction.

The NRC’s special inspection team reported that the control room operators failed to realize that the 10% power swings exceeded a safety criterion that called for the immediate shut down of the reactor. Following a reactor power level instability event at the LaSalle nuclear plant in Illinois in March 1988, Grand Gulf and other boiling water reactors revised operating procedures in response to an NRC mandate to require reactors to be promptly shut down when the reactor power level oscillated by 10% or more.

EHC system problems causing unwanted and uncontrolled turbine control valve movements had been experienced eight times in the prior three years. Operators wrote condition reports about the problems, but no steps had been taken to identify the cause and correct it.

Consequences

Due to the intervention by the system triggering the automatic reactor scram, this event did not result in fuel damage or release of radioactive materials exceeding normal, routine releases. But that outcome was achieved despite the operators’ efforts but because of them. The operators’ training and procedures should have caused them to manually shut down the reactor when its power level swung up and down by more than 10%. Fortunately, the plant’s protective features intervened to remedy their poor judgement.

(2) September 2016 Backup Reactor Cooling System Miscue

On September 4, 2016, the operators declared residual heat removal (RHR) pump A (circled in red in the lower middle portion of Figure 2) to be inoperable after it failed a periodic test. The pump was one of three RHR pumps that can provide makeup cooling water to the reactor vessel in case of an accident. RHR pumps A and B can also be used to cool the water within the reactor vessel during non-accident conditions. Grand Gulf’s operating license only permitted the unit to continue running for a handful of days with RHR pump A inoperable. So, the operators shut down the reactor on September 8 to repair the pump.

Fig. 2 (Source: Nuclear Regulatory Commission)

The operating license required two methods of cooling the water within the reactor vessel during shut down conditions. RHR pump B functioned as one of the methods. The operators took credit for the alternate decay heat removal (ADHR) system as the second method. The ADHR system is shown towards the upper right of Figure 2. It features two pumps that can take water from the reactor vessel, route it through heat exchangers, and return the cooled water to the reactor vessel. The ADHR system’s heat exchangers are supplied with cooling water from the plant service water (PSW) system. Warmed water from the reactor vessel flows through hundreds of metal tubes within the ADHR heat exchangers. Heat conducted through the tube walls gets carried away by the PSW system.

By September 22, workers had replaced RHR pump A and successfully tested the replacement. The following day, operators attempted to place the ADHR system in service prior to removing RHR pump B from service. They discovered that all the PSW valves (circle in red in the upper right portion of Figure 2) to the ADHR heat exchangers were closed. With these valves closed, the ADHR pumps would only take warm water from the reactor vessel, route it through the ADHR heat exchangers, and return the warm water back to the reactor vessel without being cooled.

The operating license required workers to check each day that both reactor water cooling systems were available during shut down. Each day between September 9 and 22, workers performed this check via a paperwork exercise. No one ever walked out into the plant to verify that the ADHR pumps were still there and that the PSW valves were still open.

The NRC team determined that workers closed the PSW valves to the ADHR heat exchangers on August 10 to perform maintenance on the ADHR system. The maintenance work was completed on August 15, but the valves were mistakenly not re-opened until September 23 after being belatedly discovered to be mis-positioned.

Consequences

Improperly relying on the ADHR system in this event had no adverse nuclear safety consequences. It was relied upon was a backup to the primary reactor cooling system which successfully performed that safety function. Had the primary system failed, the ADHR system would not have been able to take over that function as quickly as intended. Fortunately, the ADHR system’s vulnerability was not exploited.

(3) September 2016 Reactor Vessel Overfilling Miscue

On September 24, Grand Gulf was in what is called long cycle cleanup mode. Water within the condenser hotwell (upper right portion of Figure 3) was being sent by the condensate pumps through filter demineralizers and downstream feedwater heaters before recycling back to the condenser via the startup recirculation line. A closed valve prevented this water from flowing into the reactor vessel. Long cycle cleanup mode allows the filter demineralizers to remove particles and dissolved ions from the water. Water purity is important in boiling water reactors because any impurities tend to collect within the reactor vessel rather than being carried away with the steam leaving the vessel. The water in the condenser hotwell is the water used over and over again in boiling water reactors to make the steam that spins the turbine-generator.

Fig. 3 (Source: Nuclear Regulatory Commission)

Workers were restoring RHR pump B to its standby alignment following testing. The procedure they used directed them to open the closed feedwater valve. This valve was controlled by three pushbuttons in the control room: OPEN, CLOSE, and STOP. As soon as this valve began opening, water started flowing into the reactor vessel rather than being returned to the condenser.

The operator twice depressed the CLOSE pushbutton wanting very much for the valve to re-close. But this valve was designed to travel to the fully opened position after the OPEN pushbutton was depressed and travel to the fully closed position after the CLOSE pushbutton was depressed. By design, the valve would not change direction until after it had completed its full travel.

Unless the STOP pushbutton was depressed. The STOP pushbutton, as implied by its label, caused the valve’s movement to stop. Once stopped, depressing the CLOSE pushbutton would close the valve and depressing the OPEN pushbutton would open it.

According to the NRC’s special inspection team, “operations personnel did not understand the full function of the operating modes of [the] valve.” No operating procedure directed the operators to use the STOP button. Training in the control room simulator never covered the role of the STOP button because it was not mentioned in any operating procedures.

Not able to use the installed control system to its advantage, the operator waited until the valve traveled fully open before getting it to fully re-close. But the valve is among the largest and slowest valves in the plant—more like an elephant than a cheetah in its speed.

During the time the valve was open, an estimated 24,000 gallons of water overfilled the reactor vessel. As shown in Figure 4, the vessel’s normal level is about 33 inches above instrument zero, or about 201 inches above the top of the reactor core. The 24,000 gallons filled the reactor vessel to 151 inches above instrument zero.

Fig. 4 (Source: Nuclear Regulatory Commission)

Consequences

The overfilling event had no adverse nuclear safety consequences (unless revealing procedure inadequacies, insufficient training, and performance shortcomings count.)

NRC Sanctions

The NRC’s special inspection team identified three violations of regulatory requirements. One violation involved inadequate procedures for the condensate and feedwater systems that resulted in the reactor vessel overfilling event on September 24.

Another violation involved crediting the ADHR system for complying with an operating license requirement between September 9 and 22 despite its being unable to perform the necessary reactor water cooling role due to closed valves in the plant service water supply to the ADHR heat exchangers.

The third violation involved inadequate verification of the ADHR system availability between September 9 and 22. Workers failed to properly verify the system’s availability and had merely assumed it was a ready backup.

UCS Perspective

Th trilogy of miscues, goofs, and mistakes that prompted the NRC to dispatch a special inspection team have a common thread. Okay, two common threads since all three happened at Grand Gulf. All three miscues reflected very badly on the operations department.

During the June power fluctuations miscue, the operators should have manually scrammed the reactor, but failed to do so. In addition, operators had experienced turbine control system problems eight times in the prior three years and initiated reports intended to identify the causes of the problems and remedy them. The maintenance department could have, and should have, reacted to these reports earlier. But the operations department could have, and should have, insisted on the recurring problems getting fixed rather than meekly adding to the list of unresolved problem reports.

During the September backup cooling system miscue, many operators over nearly two weeks had many opportunities to notice that the ADHR system would not perform as needed due to mispositioned valves. The maintenance department could have, and should have, not set a trap for the operators by leaving the valves closed when maintenance work was completed. But the operators are the only workers at the plant licensed by the NRC to ensure regulatory requirements intended to protect the public are met. They failed that legal obligation again and again between September 9 and 22.

During the September reactor vessel overfilling event, the operators failed to recognize that opening the feedwater valve while in long cycle cleanup mode would send water into the reactor vessel. That’s a fundamental mistake that’s nearly impossible to justify. The operators then compounded that mistake by failing to properly use the installed control system to mitigate the event. They simply did not understand how the three pushbutton controls worked and thus were unable to use them properly.

The poor operator performance that is the common thread among the trio of problems examined by the NRC’s special inspection team inspire little to no confidence that their performance will be any better during a design basis or beyond design basis event.

Scientists to Congress: The Iran Deal is a Keeper

The July 2015 Iran Deal, which places strict, verified restrictions on Iran’s nuclear activities, is again under attack by President Trump. This time he’s kicked responsibility over to Congress to “fix” the agreement and promised that if Congress fails to do so, he will withdraw from it.

As the New York Times reported, in response to this development over 90 prominent scientists sent a letter to leading members of Congress yesterday urging them to support the Iran Deal—making the case that continued US participation will enhance US security.

Many of these scientists also signed a letter strongly supporting the Iran Deal to President Obama in August 2015, as well as a letter to President-elect Trump in January. In all three cases, the first signatory is Richard L. Garwin, a long-standing UCS board member who helped develop the H-bomb as a young man and has since advised the government on all matters of security issues. Last year, he was awarded a Presidential Medal of Freedom.

What’s the Deal?

Diplomats announcing the framework of the JCPOA in 2015 (Source: US Dept. of State)

If President Trump did pull out of the agreement, what would that mean? First, the Joint Comprehensive Plan of Action (JCPoA) (as it is formally named) is not an agreement between just Iran and the US—but also includes China, France, Germany, Russia, the UK, and the European Union. So the agreement will continue—unless Iran responds by quitting as well. (More on that later.)

The Iran Deal is not a treaty, and did not require Senate ratification. Instead, the United States participates in the JCPoA by presidential action. However, Congress wanted to get into the act and passed The Iran Agreement Review Act of 2015, which requires the president to certify every 90 days that Iran remains in compliance.

President Trump has done so twice, but declined to do so this month and instead called for Congress—and US allies—to work with the administration “to address the deal’s many serious flaws.” Among those supposed flaws is that the deal covering Iran’s nuclear activities does not also cover its missile activities!

According to President Trump’s October 13 remarks:

Key House and Senate leaders are drafting legislation that would amend the Iran Nuclear Agreement Review Act to strengthen enforcement, prevent Iran from developing an inter– —this is so totally important—an intercontinental ballistic missile, and make all restrictions on Iran’s nuclear activity permanent under US law.

The Reality

First, according to the International Atomic Energy Agency, which verifies the agreement, Iran remains in compliance. This was echoed by Norman Roule, who retired this month after working at the CIA for three decades. He served as the point person for US intelligence on Iran under multiple administrations. He told an NPR interviewer, “I believe we can have confidence in the International Atomic Energy Agency’s efforts.”

Second, the Iran Deal was the product of several years of negotiations. Not surprisingly, recent statements by the United Kingdom, France, Germany, the European Union, and Iran make clear that they will not agree to renegotiate the agreement. It just won’t happen. US allies are highly supportive of the Iran Deal.

Third, Congress can change US law by amending the Iran Nuclear Agreement Review Act, but this will have no effect on the terms of the Iran Deal. This may be a face-saving way for President Trump to stay with the agreement—for now. However, such amendments will lay the groundwork for a future withdrawal and give credence to President Trump’s claims that the agreement is a “bad deal.” That’s why the scientists urged Congress to support the Iran Deal as it is.

The End of a Good Deal?

If President Trump pulls out of the Iran Deal and reimposes sanctions against Iran, our allies will urge Iran to stay with the deal. But Iran has its own hardliners who want to leave the deal—and a US withdrawal is exactly what they are hoping for.

If Iran leaves the agreement, President Trump will have a lot to answer for. Here is an agreement that significantly extends the time it would take for Iran to produce enough material for a nuclear weapon, and that would give the world an alarm if they started to do so. For the United States to throw that out the window would be deeply irresponsible. It would not just undermine its own security, but that of Iran’s neighbors and the rest of the world.

Congress should do all it can to prevent this outcome. The scientists sent their letter to Senators Corker and Cardin, who are the Chairman and Ranking Member of the Senate Foreign Relations Committee, and to Representatives Royce and Engel, who are the Chairman and Ranking Member of the House Foreign Affairs Committee, because these men have a special responsibility on issues like these.

Let’s hope these four men will do what’s needed to prevent the end of a good deal—a very good deal.

Grand Gulf: Emergency Pump’s Broken Record and Missing Record

The Grand Gulf Nuclear Station located about 20 miles south of Vicksburg, Mississippi is a boiling water reactor with a Mark III containment that was licensed to operate by the Nuclear Regulatory Commission (NRC) in November 1984. It recently set a dubious record.

The Mark III containment is a pressure-suppression containment type. It features a large amount of water in its pressure suppression pool and upper containment pool. In case of an accident, energy released into containment gets absorbed by this water, thus lessening the pressurization of the atmosphere within containment. The “energy sponge” role allows the Mark III containment to be smaller, and less expensive, than the non-pressure suppression containment structure that would be needed to handle an accident.

Fig. 1 (Source: Nuclear Regulatory Commission)

The emergency core cooling systems (ECCS) reside in a structure adjacent to the containment building. The ECCS for Grand Gulf consist of the high pressure core spray (HPCS) pump, the low pressure core spray (LPCS) pump, and three residual heat removal (RHR). The preferred source of water for the HPCS pump is the condensate storage tank (CST), although it can also draw water from the suppression pool within containment. The other ECCS pumps get their water from the suppression pool.

One of the RHR pumps (RHR Pump C) serves a single function, albeit an important one called the low pressure coolant injection (LPCI) function. When a large pipe connected to the reactor vessel breaks and drains cooling water rapidly from the vessel, RHR Pump C quickly provides a lot of water to replace the lost water and cool the reactor core.

The other two RHR pumps (RHR Pumps A and B) can perform safety functions in addition to the LPCI role. Each of these RHR pumps can be aligned to route water through a pair of heat exchangers. When in use, the heat exchangers cool down the RHR water.

RHR Pumps A and B can be used to cool the water within the reactor vessel. In what is called the shutdown cooling (SDC) mode, RHR Pump A or B takes water from the reactor vessel, routes this water through the pair of heat exchangers, and returns the cooled water to the reactor vessel.

Similarly, RHR Pumps A and B can use used to cool the water within the suppression pool. RHR Pump A or B draws water from the suppression pool, routes this water through the heat exchangers, and returns the cooled water to the suppression pool.

Finally, RHR Pumps A and B can be used to cool the atmosphere within the containment structure. RHR Pump A or B can take water from the suppression pool and discharge it through carwash styled sprinkler nozzles mounted to the inside surfaces of the containment’s upper walls and roof.

Fig. 2 (Source: Nuclear Regulatory Commission)

Given the varied safety roles played by RHR Pumps A and B, the operating license for Grand Gulf only permits the reactor to continue running for up to 7 days when either pump is unavailable. Workers started the 7-day shutdown clock on August 22, 2017, after declaring RHR Pump A to be inoperable. The ECCS pumps are tested periodically to demonstrate their capabilities. RHR Pump A failed to operate within its design band during testing. The pump was supposed to be able to deliver at least a flow rate of 7,756 gallon per minute for a differential pressure of at least 131 pounds per square inch differential across the pump. The differential pressure was too low when the pump delivered the specified flow rate. A higher differential pressure was required to demonstrate that the pump could also supply the necessary flow rate under more challenging accident conditions.

Before the clock ran out, workers shut down the Grand Gulf reactor on August 29. Workers replaced RHR Pump A and restarted the reactor on October 1, 2017.

It is rare that a boiling water reactor has to shut down for a month or longer to replace a broken RHR pump. The last time it happened in the United States was a year ago. Workers shut down the reactor on September 8, 2016, after an RHR pump failed testing on September 4. The RHR pump was unable to achieve the specified differential pressure and flow rate at the same time. Workers could throttle valves to satisfy the differential pressure criterion, but the flow rate was too low. Or, workers could reposition the throttle valves to obtain the specified flow rate, but the differential pressure was too low. The RHR pump was replaced and the reactor restarted on January 29, 2017.

The reactor—Grand Gulf.

The failed pump—RHR Pump A.

The “solution”—replace the failed pump.

UCS Perspective

Grand Gulf has experienced two failures and subsequent replacements of RHR Pump since the summer of 2016. That’s two more RHR pump replacements than the rest of the U.S. boiling water reactor fleet tallied during the same period. Call Guinness—Grand Gulf may have broken the world record for most RHR pump broken in a year!

Records are made to be broken, not RHR pumps.

The company’s report to the NRC about the most recent RHR Pump A failure dutifully noted that the same pump had failed and been replaced a year earlier, but claimed that corrective action could not have prevented this year’s failure of the pump. Maybe the same RHR pump broken twice within a year for two entirely unrelated reasons. The Easter bunny, the tooth fairy, and Santa Claus all agree that it’s at least possible.

On October 31, 2016, the NRC announced it was sending a special inspection team to Grand Gulf to investigate the failure of RHR Pump A and other problems.  The NRC’s press release concluded with this sentence: “An inspection report documenting the team’s findings will be publicly available within 45 days of the end of the inspection.”

As of October 24, 2017, no such inspection report has been made publicly available. Call Guinness—the NRC may have broken the world record for the longest special inspection ever!

Grand Gulf was restarted on January 29, 2017, 90 days after the NRC announced it was sending a special inspection team to investigate a series of safety problems. The inspection report should have been publicly available as promised to allay public concerns that the numerous safety problems that caused Grand Gulf to remain shut down for four months had been fixed.

On June 29, 2017—241 days after the NRC announced the special inspection report—I emailed the NRC’s Executive Director for Operations inquiring about the status of this overdue report.

On October 2, 2017—95 days after my inquiry—the NRC’s Executive Director for Operations emailed me a response. He indicated that the onsite portion of the special inspection was completed on November 4, 2016, and that the inspection report “should be issued within the next few weeks.”

The NRC promised to issue the special inspection report around December 19, 2016, when the inspection ended.

The NRC promises to value transparency.

The NRC should either stop making promises or start delivering results. Promises aren’t made to be broken, either. That’s what RHR pumps are for, at least in Mississippi.

Fig. 3 (Source: Kaja Bilek Flickr photo)

 

Pages