ML111861813

G20110458/LTR-11-0348/EDATS: SECY-2011-0358 - Ltr. to Susan Harvey, NRC Hearing in San Luis Obispo on June 15, 2011 Regarding Diablo Canyon Nuclear Power Plant

ML111861813
Person / Time
Site:	Diablo Canyon
Issue date:	07/05/2011
From:	Anton Vegel Division of Reactor Safety IV
To:	Harvey S North County Watch
References
G20110458, LTR-11-0348, SECY-2011-0358
Download: ML111861813 (4)

Text

UNITED STATES NUC LE AR RE G UL AT O RY C O M M I S S I O N R E GI ON I V 612 EAST LAMAR BLVD , SU I TE 400 AR LI N GTON , TEXAS 76011-4125 July 5, 2011 Ms. Susan Harvey North County Watch P.O. Box 455 Templeton, CA 93465

Dear Ms. Harvey:

Thank you for participating in our public meeting process. The publics active involvement in the NRCs processes helps us not only fulfill our mission of keeping you safe, but it also helps us do our jobs openly and transparently.

The NRC remains convinced that U.S. nuclear power plants are designed and operated in a manner that protects public health and safety. All U.S. nuclear power plants are built to withstand external hazards, including earthquakes, flooding, and tsunamis, as appropriate.

Even those plants that are located in areas with low and moderate seismic activity are designed for safety in the event of such a natural disaster. Each plant is designed to withstand the possible ground movement that is appropriate for its location, given the earthquake sources that may affect the site. Ground movement is a function of both the magnitude of the earthquake and the distance from the fault to the specific site. The seismic responses of the structures, systems, and components associated with these facilities are site-specific, based on either identified faults and tectonic capabilities in the area or the regions seismic zone activity, whichever can generate stronger ground motion. The Diablo Canyon plant is located in a region that experiences higher levels of seismic activity than most of the United States and is designed accordingly.

The events that occurred in Japan are the result of a combination of highly unlikely natural disasters. These include the fifth-largest earthquake in recorded history and the resulting devastating tsunami. This earthquake occurred on a subduction zone, a tectonic plate boundary where one tectonic plate is pushed under another plate and creates enough stress in the Earths crust to produce earthquakes of the largest magnitude. Subduction zone earthquakes are also required to produce the kind of massive tsunami seen in Japan. In the continental United States, the only subduction zone is the Cascadia region, off the coast of northern California, Oregon and Washington, and this is the only U.S. location that could generate a continental earthquake and tsunami as large as the March 11 event in Japan.

Outside of the Cascadia subduction zone, earthquakes are not expected to exceed a magnitude of approximately 8.5.

S. Harvey In addition to the NRCs usual inspection activities, since the events at Fukushima the agency has twice inspected all U.S. nuclear power plants specifically for issues related to emergency procedures and resources. Both inspections showed U.S. plants are prepared to use those emergency measures to keep the public safe. Temporary Instruction 2515/183 provided instructions for NRC inspectors to perform independent assessments of measures, that would be used to help keep the reactors and spent fuel pools safe even after the sudden loss of significant areas of the plants. The results of these inspections indicated that although some deficiencies were identified and subsequently corrected, the licensees plans would still ensure that critical cooling functions would be provided. The individual inspection reports are available at theNRCs public website at the following link:

http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/follow-up-rpts.html.

Temporary Instruction (TI) 2515/184 provided instructions for NRC inspectors to examine the plants severe accident management guidelines (SAMGs), which are meant to reduce the severity of situations where a reactor core has been damaged. The inspectors were told to determine: (i) that the severe accident management guidelines (SAMGs) are available and how they are being maintained, and (ii) the nature and extent of licensee implementation of SAMG training and exercises. The results of these inspections also indicated that although some deficiencies were identified they have either been corrected or entered into Correction Action Programs and the identified deficiencies did not preclude any critical mitigation functions from being performed. Individual inspection reports associated with the inspections are also available on the NRCs public website: http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/SAMGs.html.

In addition, the NRC issued Bulletin 2011-01 requiring all holders of operating licenses for nuclear power reactors to provide a comprehensive verification of their compliance with the regulatory requirements associated with mitigating strategies for beyond design basis events.

The 30-day licensee responses to Bulletin 2011-01 reviewed to date, have identified no cases where mitigating equipment was not available or the mitigation strategies were not workable.

The NRC established a senior level task force to conduct both short- and long-term analysis of the lessons that can be learned from the situation in Japan. The task force is examining all the available information from Japan to understand the events implications for the United States.

They are performing a systematic and methodical review to see if there are changes that should be made to NRC programs and regulations. This will undoubtedly lead to the identification of issues that warrant further study in the longer term. The task force is scheduled to provide a report to the Commission in this month (July 2011), identifying the results of its review and providing recommendations for short-term actions, if necessary, and longer-term study. The NRC will assess all of the available information and evaluate whether enhancements to U.S.

nuclear power plants are warranted.

The NRC remains convinced that U.S. nuclear power plants are designed and operated in a manner that protects public health and safety. The implementation of the defense-in-depth principles by the NRC and industry, conservative decision making, use of risk insights, the results of the recent TI inspections and continuous routine inspections performed by the NRCs Resident Inspectors, industry initiatives and actions coordinated through the Institute of Nuclear

S. Harvey Power Operations, robust corrective programs, and an absence of complacency in responding to the events at Fukushima provides for further assurance that the U.S. nuclear power plants continue to remain safe.

Sincerely,

/RA/

Anton Vegel, Director Division of Reactor Safety

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