The risks for catastrophe change as nuclear reactors age, much like the risks for death by accident and illness change as people get older. Protection schemes must evolve to remain correlated with age if the threat level is to be minimized. For people, it means replacing protective measures for toddlers (such as safety plugs in electrical outlets) with parental watchfulness against teenage drinking and driving. It also means testing for signs of age-related illness (such as glaucoma, heart disease, and osteoporosis) as people get older. For nuclear reactors, it means aggressively monitoring risk during the three stages of plant lifetime: the break-in phase, middle life phase, and wear-out phase. The risk profile for these three phases of life curves like a bathtub. The Union of Concerned Scientists (UCS) identified the best ways to manage the risks from nuclear power at all points along the bathtub curve.
The break-in phase
Any new reactors that are built will start out on the high-risk break-in segment of the curve. Several nuclear plant disasters—Fermi, Three Mile Island, and Chernobyl to name just a few—demonstrated the perils of navigating this part of the curve. Literally thousands of unexpected safety problems surfaced at other nuclear plants. These surprises drove safety levels down and nuclear power's costs up unnecessarily. Public intervention in licensing proceedings led to numerous safety improvements, but recent changes to the licensing process limit the public's role to essentially that of a casual observer. If new reactors are built, we must benefit from these hard and expensive lessons by: (1) excluding new reactors from federal liability protection under the Price Anderson Act, thereby removing the current disincentive for vendors to design safety upgrades; (2) verifying safety performance against expectations on prototype reactors before commercial reactors are built; (3) conducting extensive inspections of new reactors during design and construction to verify compliance with safety requirements; and (4) allowing meaningful public participation in the licensing process.
The middle life phase
Increasing the maximum power output while cutting back on safety inspections at existing reactors reduces the margin for error along the middle segment of the bathtub curve. The fact that 27 nuclear reactors have been shut down in the past two decades for safety problems that took a year or longer to fix demonstrates that errors are abundant and margins for error are still necessary. Many of the safety cutbacks at nuclear plants are being justified based on deficient risk assessments. These risk assessments have resulted in poor management decisions, such as the decision in 2001 allowing the Davis-Besse nuclear plant in Ohio to continue operating in an unsafe manner. Risk at existing reactors can be best managed by: (1) improving the oversight of methods used by plant owners to find and fix errors; (2) ending the practice of risk-informed decision making using flawed risk studies; and (3) using risk insights not just to reduce unnecessary regulatory burdens but also to shore up regulatory gaps as well.
The wear-out phase
Today's aging reactors, and any reactors granted 20-year extensions to their current 40-year operating licenses, face the high-risk wear-out segment of the bathtub curve. Despite efforts to monitor the condition of aging equipment, there are recent age-related failures caused by monitoring the right areas using the wrong techniques and by monitoring the wrong areas using the right techniques. In addition, nuclear plants seeking license renewal conform not to today's safety standards, but to a unique assortment of regulations dating back nearly 40 years with countless exemptions, deviations, and waivers granted along the way. While each individual exemption or waiver may be justified as not reducing safety margins, the cumulative effect of so many exceptions can adversely affect safety. To properly manage the risk at aging reactors: (1) multiple inspection techniques must be required for high-risk equipment; (2) expanded inspections must be required for equipment currently considered less vulnerable to aging; and (3) all differences between today's safety regulations and the mix of regulations applicable to today's reactors must be identified and reviewed to verify that no safety gaps exist.
What needs to be done
While the risks and reasons for the risks vary along the bathtub curve, the consequences of failing to manage the risks remain nearly constant—potentially massive releases of radioactivity into the atmosphere with devastating harm to people and places downwind.
An aggressive regulator consistently enforcing federal safety regulations provides the best protection against these risks. Sadly, America lacks such protection. Since UCS began its nuclear safety project nearly three decades ago, we have engaged the Nuclear Regulatory Commission and its predecessor, the Atomic Energy Commission, countless times. We advocated enforcement of existing regulations far more often than for adoption of new regulations. Regulations might provide adequate protection, but only when they are followed. By failing to consistently enforce the regulations, the NRC exposes millions of Americans to greater risk than necessary. The federal government must reform the NRC into a consistently effective regulator so it properly manages the risk at all points along the nuclear bathtub curve.