The Nuclear Regulatory Commission’s safety regulations require that nuclear reactors be designed to protect the public from postulated accidents, such as the rupture of pipes that would limit the flow of cooling water to the reactor. These regulations include General Design Criteria 34 and 35 in Appendix A to 10 CFR Part 50.
Emergency diesel generators (EDGs) are important safety systems since they provide electricity to emergency equipment if outside power is cut off to the plant—another postulated accident. This electricity, for example, would allow pumps to continue to send cooling water to the reactor vessel to prevent overheating damage to the core. So the NRC has requirements that limit how long a reactor can continue operating without one of its two EDGs under different conditions. The shortest period is 3 days while the longest period is 14 days.
An All Things Nuclear commentary in July 2017 described how the NRC allowed the Unit 3 reactor at the Palo Verde nuclear plant in Arizona to operate for up to 62 days with one of its EDGs broken, but had denied the Unit 1 reactor at the DC Cook nuclear plant in Michigan permission to operate for up to 65 days with one of its two EDGs broken. It was easy to understand why the NRC denied the request for DC Cook Unit 1 (i.e., 65 days is more than the 14-day safety limit). It was not easy to understand why the NRC granted the request for Palo Verde Unit 3 (i.e., 62 days is also more than the 14-day safety limit).
The NRC also granted a request on November 26, 2017, for the Unit 1 and 2 reactors at the Brunswick nuclear plant in North Carolina to operate for up to 30 days with one EDG broken.
NRC Inspection Findings and Sanctions 2001-2016
UCS examined times between 2001 and 2016 when NRC inspectors identified violations of federal safety regulations and the sanctions imposed by the agency for these safety violations. The purpose of this exercise was to understand the NRC’s position on EDGs and the safety implications of an EDG being inoperable.
As shown in Figure 1, NRC inspectors recorded 12,610 findings over this 16-year period, an average of 788 findings each year. The NRC characterized the safety significance of its findings using a green, white, yellow and red color-code with green representing findings having low safety significance and red assigned to findings with high safety significance. The NRC determined that fewer than 2% of its findings (242 in all) warranted a white, yellow, or red finding (“greater-than-green”).
NRC Greater-than-Green Inspection Findings and Sanctions 2001-2016
UCS reviewed ALL the greater-than-green findings issued by the NRC between 2001 and 2016 to determine what safety problems most concerned the agency over those years. Figure 2 shows the greater-than-green findings issued by the NRC binned by the applicable safety system or process. Emergency planning violations accounted for 22% of the greater-than-green findings over this period—the greatest single category. Other categories are shown in increasing percentages clockwise around the pie chart.
The 32 EDG greater-than-green findings between 2001 and 2016 constituted the second highest tally of such findings over this 16-year period—an average of two greater-than-green EDG findings per year. The NRC issued one Yellow and 31 White findings for EDG violations.
NRC Greater-than-Green EDG Inspection Findings and Sanctions 2001-2016
UCS reviewed all enforcement letters issued by the NRC for all 32 EDG greater-than-green findings to determine what parameters—particularly the length of time the EDG was unavailable—factored into the NRC concluding the findings had elevated safety implications. Several of the greater-than-green findings issued by the NRC involved EDGs being unavailable for less than the 62 days that the NRC permitted Palo Verde Unit 3 to continue operating with an EDG broken. For example:
- The NRC issued a Yellow finding on August 3. 2007, because Kewuanee (WI) operated for 50 days with one EDG impaired by a fuel oil leak.
- The NRC issued a White finding on September 19, 2013, because HB Robinson (SC) operated for 36 days with inadequate engine cooling for an EDG.
- The NRC issued a White finding on June 2, 2004, because Brunswick (NC) operated for 30 days with an impaired jacket water cooling system for one EDG.
- The NRC issued a White finding on April 15, 2005, because Fort Calhoun (NE) operated for 29 days for approximately 29 days with an inoperable EDG.
- The NRC issued a White finding on December 7, 2010, because HB Robinson (SC) operated for 26 days with an impaired output breaker on one EDG.
- The NRC issued a White finding on March 28, 2014, because Waterford (LA) operated for 25 days with inadequate ventilation for one EDG.
- The NRC issued a White finding on December 18, 2013, because Duane Arnold (IA) operated for 22 days with inadequate lubricating oil cooling for one EDG.
- The NRC issued a White finding on February 29, 2008, because Comanche Peak (TX) operated for 20 days with one EDG inoperable.
- The NRC issued a White finding on December 7, 2007, because Fort Calhoun (NE) operated for 14 days with one EDG inoperable.
- The NRC issued a White finding on April 20, 2007, because Brunswick (NC) operated for 9 days with an impaired lubricating oil system for one EDG.
- The NRC issued a White finding on August 17, 2007, because Cooper (NE) operated for 5 days with a defective circuit card in the control system for one EDG.
NRC’s Cognitive Dissonance
The NRC issued 32 greater-than-green findings between 2001 and 2016 because inoperable or impaired EDGs increased the chances that an accident could endanger the public and the environment. As the list above illustrates, many of the NRC’s findings involved EDGs being disabled for 29 days or less.
Yet in 2017, the NRC intentionally permitted Palo Verde and Brunswick to continue operating for up to 62 and 30 days respectively.
If operating a nuclear reactor for 5, 9, 14, 20, 22, 26, or 29 days with an impaired EDG constitutes a violation of federal safety regulations warranting a rare greater-than-green finding based on the associated elevated risk to public health and safety, how can operating a reactor for 30 or 62 days NOT expose the public to elevated, and undue, risk?
Benny Hill to the Rescue
Benny Hill was a British comedian who hosted a long-running television show between 1969 and 1989. On one of his shows, Benny observed that: “The odds against there being a bomb on a plane are a million to one, and against two bombs a million times a million to one.” Hence, Benny suggested that to be protected against being blown out of the sky: “Next time you fly, cut the odds and take a bomb” with you.
NRC’s allowing Palo Verde and Brunswick to operate for over 29 days with a broken EDG essentially takes Benny’s advice to take a bomb on board an airplane. Deliberately taking a risk significantly reduces the random risk.
But Benny’s suggestion was intended as a joke, not as prudent (or even imprudent) public policy.
So, while I’ll posthumously (him, not me) thank Benny Hill for much amusing entertainment, I’ll thank the NRC not to follow his advice and to refrain from exposing more communities to undue, elevated risk from nuclear power reactors operating for extended periods with broken EDGs.