Fission Stories #192
Much has been said and written about the Fukushima 50—the workers who remained onsite during the height of the crisis at the Japanese Fukushima nuclear plant after senior managers ordered their co-workers to evacuate because of worsening conditions.
Less has been said and written about the Palisades 50—which involves worsening conditions and workers but not quite in the same way. Palisades 50 refers to the findings by the Nuclear Regulatory Commission (NRC) during a recent inspection at this nuclear plant five miles from South Haven, Michigan.
Inspections at Palisades
The NRC conducted a Component Design Bases Inspection (CDBI) involving seven inspectors at Palisades between September 8 and November 4, 2014. The CDBI is part of the NRC’s Reactor Oversight Process. According to the NRC’s inspection report for Palisades:
“The objective of the component design bases inspection is to verify the design bases have been correctly implemented for the selected risk significant components and the operating procedures and operator actions are consistent with design and licensing bases.”
Because risk studies assume that safety systems perform successfully to prevent and/or mitigate accidents, the CDBI seeks to verify this assumption is valid. When safety systems do not perform as assumed in the studies, the plant’s risk very likely increases.
For the CDBI at Palisades, the NRC inspectors selected 20 components. The NRC then examined engineering records (such as calculations and design specifications), maintenance records, operating procedures, testing and inspection records, system health reports, training documents, and other records for these 20 components.
The NRC identified 10 safety violations from their examination of 20 components—hence, the Palisades 50. On average, 50 percent of the components examined resulted in safety violations being identified.
The NRC did not select the 20 components at random from among literally thousands of candidates at the site.
The NRC did not select the components off the top, middle, or bottom of an alphabetical listing of components.
The NRC did not select the components from among the oldest, middle-aged, or newest components installed at the site.
The NRC selected the 20 components based upon their safety significance. The NRC deliberately selected components making the highest contribution to safety levels.
The NRC reviewed the owner’s risk study and the NRC’s Standardized Plant Analysis Risk (SPAR) model to identify a scenario having a high risk of resulting in reactor core damage. The NRC picked the large break loss of coolant accident. In this postulated accident, a large pipe forming part of the reactor vessel pressure boundary instantly snaps in two, allowing cooling water to escape from both broken ends. This scenario puts a severe challenge on standby emergency pumps to quickly start up and supply makeup water to the reactor vessel before the reactor core overheats and melts down. The NRC then selected 20 components with significant roles to play in mitigating the severity of this accident.
Inspections at other plants
In 2014, the NRC reported on 15 CDBIs conducted at other nuclear plants. The average CDBI examined 18 components and identified 3.6 violations. The Palisades CDBI involved about the same number of components but nearly three times as many violations. No other CDBI yielded as many, or more, violations that the one at Palisades. Two CDBIs—at Perry and Pilgrim—identified no safety violations at all.
|Nuclear Plant||Number of Components Examined During CDBI||Number of Violations Identified During CDBI|
|Duane Arnold (IA)||21||5|
|Nine Mile Point (NY)||24||3|
|Peach Bottom (PA)||17||2|
|River Bend (LA)||19||5|
|Shearon Harris (NC)||14||4|
|South Texas Project (TX)||22||7|
|Turkey Point (FL)||16||1|
|Vermont Yankee (VT)||14||1|
The NRC conducts a CDBI at each nuclear power plant every three years. Thus, if you can count to three, you know when the next CDBI team will arrive at your plant.
The NRC notified Palisades’ owner more than three months in advance of the CDBI team arriving at the plant. Again, if you can count to three, you know when the next CDBI arrives at your plant.
Because the components examined by the NRC during CDBIs have vitally important safety functions, they get tested and inspected more frequently and extensively than components of lesser importance. Thus, there are fewer excuses for plant workers not to have found and fixed the violations before the NRC identified them.
The silver lining at Palisades and nationally is that none of the 57 violations identified during these CDBIs was classified as being more serious than Green in the NRC’s color-coded classification system (Green, White, Yellow, and Red in order of increasing severity). But dark clouds accompany that silver lining—until the violations were identified and the safety impairments they introduced understood, no one could be certain that the safety implications were not greater.
Further shadowing this silver lining is this fact—the 16 plants have far more than 287 components with important roles to play in managing risks. Nearly 20 percent of the high safety value components examined by the NRC during 2014 yielded violations. There’s no reason to believe that the hundreds of high safety value components the NRC did not examine during 2014 are not equally afflicted with violations. And since these violations remain undetected and unevaluated, no one can honestly claim that the 57 Greens are the worst out there.
In theory, the NRC’s CDBIs should verify that all high safety value components are properly designed, maintained and operated.
In practice, the NRC’s CDBIs are verifying just the opposite.
The NRC must use the results from its CDBIs to force plant owners to figure out what is wrong with their testing and inspection programs that prevent them from finding and fixing safety violations. After all, that’s the primary purpose of doing all those tests and performing all those inspections. They are not an exercise program for workers or busy work to keep them occupied until lunch break. The testing and inspection programs are supposed to demonstrate that the public is adequately protected.
That’s not happening.
That must get fixed before impaired safety components contribute to the next nuclear disaster.
“Fission Stories” is a weekly feature by Dave Lochbaum. For more information on nuclear power safety, see the nuclear safety section of UCS’s website and our interactive map, the Nuclear Power Information Tracker.