23rd Annual Report, Pacific Gas and Electric’s Response to the Diablo Canyon Independent Safety Committee Twenty-third Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations–July 1, 2012, to June 30, 2013

December 19, 2013

PG&E Letter ISC-13-002

Dr. Per F. Peterson
c/o The Diablo Canyon Independent Safety Committee
857 Cass Street, Suite D
Monterey, CA 93940

Response to the Diablo Canyon Independent Safety Committee Twenty-Third Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations–July 1, 2012, to June 30, 2013

Dear Dr. Peterson:

Pacific Gas and Electric Company’s (PG&E) response to the Diablo Canyon Independent Safety Committee’s (DCISC) Twenty-Third Annual Report on the Safety of Diablo Canyon Operations for the period of July 1, 2012, to June 30, 2013, is provided in the enclosure to this letter.

We are pleased that the DCISC has once again concluded that PG&E operated Diablo Canyon Nuclear Power Plant (DCPP) safely during the report period. As you are aware, operating the plant conservatively to protect public health and safety is our highest priority, and we will continue to ensure that we fulfill this commitment.

As discussed in the enclosure, we have reviewed and are taking actions to address your recommendations. We welcome the DCISC’s recommendations, and believe that addressing them will further contribute to the continued safe operation of DCPP.


Edward D. Halpin



Dr. Robert J. Budnitz
Dr. Peter Lam
David C. Linnen
Ferman Wardell
Robert R. Wellington


Because of the relatively large increase in Licensee Event Reports from the previous reporting period, continuing high number of Non-Cited Violations, and the number of items in the Conservative Decision Making Cross-Cutting Aspect, the DCISC recommends that DCPP review the effectiveness of its Regulatory Excellence Action Plan.

Reporting Period NRC-Identified Self-Revealing NCVs
7/1/10–6/30/11 37
7/1/11–6/30/12 17
7/1/12–6/30/13 13

PG&E continually strives to improve Diablo Canyon’s regulatory performance. The efforts that led to the successes above will be continued to assure that progress continues.


The DCISC recommends that DCPP evaluate the various constraints on how fast spent fuel bundles can be loaded into the Independent Spent Fuel Storage Installation (ISFSI), and develop an estimate of, and the rationale for, the practical limit on the number of spent fuel bundles that can be loaded into the ISFSI on a per year basis.

As a nuclear licensee, PG&E’s highest priority is to safely manage and protect the nuclear fuel at its nuclear facilities–whether the fuel is in the reactor, the Spent Fuel Pool (SFP), or the ISFSI. PG&E’s highly effective used fuel management strategy, specifically the aspects related to the rate at which fuel is transitioned from wet to dry storage, is supported by a recent NRC study. In a draft memorandum entitled “Staff Evaluation and Recommendation for Japan Lessons- Learned Tier 3 Issue on Expedited Transfer of Spent Fuel,” the NRC Staff concludes that the expedited transfer of spent fuel to dry cask storage would neither provide a substantial increase in the overall protection of public health and safety nor sufficient safety benefit to warrant the expected implementation costs. The NRC staff recommends that no regulatory actions be taken to require the expedited transfer of spent fuel.

Additionally, there are several considerations when managing the movement of spent fuel to the ISFSI from storage in the spent fuel pools such as:

  1. Regulatory requirements
  1. Thermal limits of the cask system– Fuel must cool in the spent fuel pool for at least 5–15 years to achieve the allowable cask thermal loading limits.
  2. SFP thermal mass–A SFP high heat load regulatory commitment that requires each freshly unloaded fuel assembly to be surrounded by four older assemblies for thermal mass considerations.
  1. ISFSI space–Only the first two ISFSI pads (of seven total) were constructed (although the entire facility was fully licensed and permitted). PG&E will complete construction the remaining five pads in 2014.
  2. Plant operational focus–Plant activities, such as refueling outages, limit the time-frames that dry cask activities can be effectively performed.
  3. Cask Procurement–Cask procurement requires a two-year lead time.

With these considerations in mind, PG&E’s existing plan has already been optimized to achieve the minimum SFP inventories allowed by regulations, and to achieve that goal as safely and as efficiently as possible. The minimum allowable SFP inventory will be achieved by the end of 2016.

For more information contact:

Diablo Canyon Independent Safety Committee
Office of the Legal Counsel
857 Cass Street, Suite D, Monterey, California 93940
Telephone: in California call 800-439-4688; outside of California call 831-647-1044
Send E-mail to: dcsafety@dcisc.org.