IR 05000275/2012008

Errata for Diablo Canyon Power Plant, Units 1 and 2 - NRC Triennial Fire Inspection Report (05000275/2012008; 05000323/2012008)

ML13193A278
Person / Time
Site:	Diablo Canyon
Issue date:	07/11/2013
From:	Geoffrey Miller NRC/RGN-IV/DRS/EB-2
To:	Halpin E Pacific Gas & Electric Co
References
IR-12-008 Errata
Download: ML13193A278 (3)

Text

UNITE D S TATE S NUC LEAR RE GULATOR Y C OMMI S SI ON R E G IO N I V 1600 EAST LAMAR BLVD AR L I NGTON , TEXAS 7 60 11 - 4511 July 11, 2013 Mr. Edward Senior Vice President and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 56, Mail Code 104/6 Avila Beach, CA 93424 SUBJECT: ERRATA FOR DIABLO CANYON POWER PLANT, UNITS 1 AND 2 -

NRC TRIENNIAL FIRE INSPECTION REPORT (05000275/2012008; 05000323/2012008)

Reference: PG&E Letter DCL-13-060, Correction of Information Provided to NRC Inspectors During the 2012 Triennial Fire Protection Inspection, dated May 30, 2013 (ADAMS Accession No. ML13150A283)

Dear Mr. Halpin:

Please insert the enclosure to this letter as a replacement for page 13 of NRC Inspection Report 05000275; 05000323/2012008 (ADAMS Accession Number ML13038A714). This page corrects an error in the characterization of a licensee analysis referenced in the inspection report as identified in PG&E Letter DCL-13-060 (ML13150A283), dated May 30, 2013. The inspectors determined the corrected information does not alter the findings in the subject inspection report or the identification and disposition of the violation. In addition, the inspectors concluded the error on the part of PG&E was appropriately entered into the corrective action program. Consistent with the NRCs Enforcement Policy at Section 2.3.11, no action will be taken.

In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of the NRCs document system, ADAMS.

ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Geoffrey B. Miller, Chief Engineering Branch 2 Division of Reactor Safety Dockets: 50-275; 50-323 Licenses: DPR-80; DPR-82 Enclosure: Triennial Fire Protection Inspection Report Page 13 Electronic Distribution to Diablo Canyon

ML13193A278 ADAMS: No Yes SUNSI Review Complete Reviewer Initials: JMM Publicly Available Non-Sensitive Category A. Non-publicly Available Sensitive KEYWORD: SUNSI Review Complete RIV:DRS/EB2/SRI C: DRP/B RN:OGC C: EB2 JMMateychick NFOKeefe KFuller GBMiller

/RA/ /RA/ /RA/ /RA/

7/8/13 7/8/13 7/9/13 7/11/13

shutdown procedure and determined that the procedure did not provide operators with instructions on ensuring the 480V feeder breakers were closed. As noted in the next violation, (1R05.05.b.2), the safe shutdown analysis determined that operator actions were required to ensure the 480V feeder breakers were closed, but this requirement was not carried forward to the alternative shutdown procedure.

Example 4: Potential Overfilling of the Pressurizer The fourth example involved three fire scenarios that could result in overfilling the pressurizer. Two of these scenarios could also result in voiding in the core due to rapid depressurization of the reactor coolant system.

The first scenario involved a control room or cable spreading room fire with a spurious safety injection signal. The second scenario involved a control room or cable spreading room fire with the spurious actuation of a pressurizer power-operated relief valve, resulting in a rapid depressurization of the reactor coolant system and subsequent safety injection signal within approximately one minute. The third scenario involved a control room or cable spreading room fire with the spurious opening of a pressurizer auxiliary spray valve (8145 or 8148), resulting in a slightly slower depressurization of the reactor coolant system and subsequent safety injection signal within a maximum of four minutes (depending of the number of charging pumps running). In all three scenarios, the safety injection signal results in the two emergency core cooling system charging pumps starting and injecting water into the reactor coolant system through the charging injection valves (8801A, 8801B, 8803A, and 8803B).

The licensee examined the spurious actuation of the safety injection system in the Final Safety Analysis Report Section 15.2.15. The licensees analysis assumed the safety injection signal occurred at 100 percent power, the emergency core cooling system actuated, and letdown isolated. The licensee concluded that operators had 8.5 minutes to control charging prior to the pressurizer reaching a water solid condition.

The team determined this time limit was not conservative for all three scenarios. First, the time limit was based on reaching a water solid condition in the pressurizer, not maintaining the level within the indicating region, as required by the approved fire protection program. Second, the analysis was based on an injection from the charging pumps. In the second and third scenarios, the depressurization of the reactor coolant system could lower the pressure quickly enough that the safety injection pumps would also be able to inject water into the reactor coolant system, thereby reducing the amount of time available prior to exceeding the indicating region of the pressurizer or reaching a water solid condition in the pressurizer.

The team determined that operators could mitigate all three scenarios by controlling charging at the hot shutdown panel. The alternative shutdown procedure provided steps for operators to control charging and maintain the pressurizer level between 22 percent and 70 percent, and it provided steps to stop the charging pumps if level could not be maintained. Based on the timed walkdown, the team determined that operators would reach this step nearly 30 minutes after the reactor trip. Since this time exceeded the amount of time allowed for all three scenarios (even though this limit was not

- 13 - Enclosure