Keeping Tabs on Diablo Canyon’s Evolving Seismic Situation

Lara Uselding
Public Affairs Officer
Region IV

diabloThe NRC has added two items to the growing list of documents on seismic issues related to the Diablo Canyon Power Plant, near San Luis Obispo, Calif. Our Region IV office in Arlington, Texas, sent the plant operator, PG&E, an inspection report and our headquarters Office of Nuclear Reactor Regulation in Rockville, Md. sent PG&E a letter about the plant’s seismic hazard reevaluation due in March 2015.

The Region IV inspection report discusses the agency’s independent assessment of the operability determination completed by PG&E associated with its September report on the Shoreline and other faults near the plant. PG&E provided the report to the state under California Assembly Bill 1632. That bill required the report so the California Energy Commission could assess if California’s largest baseload power plants are vulnerable to a seismic event as those plants age.

The NRC did not request this analysis, but PG&E committed to keep us updated on any new information that would indicate the Shoreline fault is more energetic or capable than was presented in the January 2011 Shoreline Fault Report. PG&E further committed to provide the NRC with an interim analysis of any new Shoreline-related information before the post-Fukushima evaluations are due in March 2015.

Our regional review of PG&E’s operability determination indicates there is considerable design margin for the plant’s systems, structure, and components. The staff did not identify any concerns with PG&E’s determination that the plant is operable. The analysis adds to the evidence that the plant’s systems, structures, and components would function properly after an earthquake and not pose undue risk to public health and safety.

Our letter from headquarters confirms PG&E will incorporate the September report’s findings into its ongoing, post-Fukushima, full seismic re-analysis due in March 2015. The NRC believes this more rigorous analysis will provide the most accurate assessment of faults affecting the site.

The bottom line is that the effect of earthquakes has been extensively evaluated during the construction, licensing, and operation of the plant. Diablo Canyon’s systems, structures, and components are designed to withstand the area’s earthquakes and perform their safety functions.

Sixty-Plus Years of Reactor Safety Advice — and Still Going Strong

Ed Hackett
Executive Director
Advisory Committee on Reactor Safeguards

For as long as the United States has worked on commercial nuclear power plants, a group of experts has given regulators independent safety advice. Since Congress passed the Atomic Energy Act of 1954, the group’s been called the Advisory Committee on Reactor Safeguards.

The committee’s dozen or so members contribute decades of academic and/or practical experience in their specialties, which include risk assessment, health physics, accident analysis and several types of engineering. Past and present committee members have also lent their expertise to international regulators.

Members of the ACRS brief the NRC Commission.
Members of the ACRS brief the NRC Commission.

When there’s an opening on the committee, the Commission chooses a replacement from nominees among the leading experts in a given specialty. Committee members are supported by a small group of NRC staff who focus solely on the committee’s independent activities.

The full committee meets 10 times a year, spending several days each time to discuss a broad range of topics. For instance, this month’s meeting agenda included a developing new rule related to safety enhancements based on lessons learned from the Fukushima nuclear accident. Other meetings have covered reviews of new reactor licensing topics and operating reactor license renewal, as well as proposed facilities to create radioactive material for medical uses.

Committee members ask detailed questions of both NRC staff and industry representatives. If members feel an issue needs more explanation or analysis, they’ll keep asking questions and challenging assumptions until they’re satisfied. All of this interaction contributes to the committee’s opinions on the topics.

The committee’s conclusions, which are independent of the NRC staff’s work, are provided in formal letters to the NRC’s Chairman. The Commission takes the committee’s views into account when it considers licensing or policy matters. The committee also meets publicly with the Commission at least once a year to discuss major topics. The Commission uses the advice provided by the committee, in addition to the information provided by the NRC staff, in reaching its decisions on regulatory matters.

The committee also has an obligation to advise the U.S. Navy on its nuclear reactor program, as well as the Defense Nuclear Safety Board, which deals with Department of Energy-controlled facilities.

The committee does all of this work according to the requirements of the Federal Advisory Committee Act. This means all committee meetings are public, except when discussing sensitive information the NRC needs to protect. It also means the public can speak and present information to the committee. Keep an eye on our schedule to see when we’ll discuss something you’re interested in. Also, see our YouTube videeo on the ACRS.

%d bloggers like this: