DCL-16-019, Response to NRC Request for Additional Information Regarding License Amendment Request 15-03, Application of Alternative Source Term.

Response to NRC Request for Additional Information Regarding License Amendment Request 15-03, Application of Alternative Source Term.

ML16041A533
Person / Time
Site:	Diablo Canyon
Issue date:	02/10/2016
From:	Welsch J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-16-019, TAC MF6399, TAC MF6400
Download: ML16041A533 (5)

Text

Pacific Gas .and Electric Company" James M. Welsch Diablo Canyon Power Plant Vice President, Nuclear Generation P.O. Box 56 Avila Beach, GA 93424 805.545.3242 E-Mail: JMW1 @pge.com February 10, 2016 PG&E Letter DCL-16-019 U.S. Nuclear Regulatory Commission 10 CFR 50.90 ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2

• Response to NRC Request for Additional Information Regarding License Amendment Request 15-03, "Application of Alternative Source Term"

References:

1. PG&E Letter DCL-15-069, "License Amendment Request 15-03,

'Application of Alternative Source Term,"' dated June 17, 2015 (ADAMS Accession No. ML15176A539)

2. PG&E Letter DCL-15-105, "Supplement to License Amendment Request 15-03, 'Application of Alternative Source Term,"' dated August 31, 2015 (ADAMS Accession No. ML15243A363)

3. E-mail from NRC Project Manager Siva P. Lingam, "Diablo Canyon 1 and 2 - Requests for Additional Information for License Amendment Request 15-03 to Adopt the Alternative Source Term per 10 CFR 50.67 (TAC Nos. MF6399 and MF6400)," dated January 11, 2016 (ADAMS Accession No. ML16011A317)

Dear Commissioners and Staff:

License Amendment Request (LAR) 15-03, "Application of Alternative Source Term,"

was submitted by Pacific Gas and Electric Company (PG&E) Letter DCL-15-069 (Reference 1) and supplemented by PG&E Letter DCL-15-105 (Reference 2).

In Reference 3, the NRC Containment and Ventilation Branch (SCVB) requested additional information required to complete the review of LAR 15-03. PG&E's responses to the SCVB Staff's questions are provided in the Enclosure.

This information does not affect the results of the technical evaluation or the no significant hazards consideration determination previously transmitted in References 1 and 2.

A me mbe r of th e STARS ( St r ate gi c T eaming and R e s o ur ce Sh a rin g) Alli a nc e Callaway

• Diablo Canyon

• Palo Verde*

• Wolf Creek

Document Control Desk PG&E Letter DCL-16-019 February 10, 2016 Page 2 PG&E makes no new regulatory commitments (as defined by NEI 99-04) in this letter. This letter includes no revisions to existing regulatory commitments.

If you have any questions, or require additional information, please contact Mr. Hossein Hamzehee at (805) 545-4720.

I state under penalty of perjury that the foregoing is true and correct.

Executed on February 10, 2016.

Sincerely, si:~

Vice President, Nuclear Generation e1 d7/4418/50705089 Enclosure cc: Diablo Distribution cc/enc: Marc L. Dapas, NRC Region IV Administrator Siva P. Lingam, NRR Project Manager Gonzalo L. Perez, Branch Chief, California Department of Public Health Binesh K. Tharakan, Acting NRC Senior Resident Inspector A member of the STARS (Strategic Team ing a nd Resourc e Sharing) Allianc e Callaway

• Diablo Canyon

• Palo Verde*

• Wolf Creek

Enclosure PG&E Letter DCL-16-019 PG&E Response to NRC Request for Additional Information (RAI) Regarding License Amendment Request 15-03, "Application of Alternative Source Term" NRC SCVB-RAI-1 Assuming 100 cfm [cubic feet per minute] damper leakage, what impact does the installed back-draft dampers have on CR ventilation analyses assumptions or unfiltered in-leakage testing methods/results?

PG&E Response The backdraft dampers in the control room ventilation system (CRVS) were installed prior to the 2012 Diablo Canyon Power Plant (DCPP) CRVS Tracer Gas Test. The design input values used for the CRVS flows, back-draft damper leakage (assumed to be 100 cfm), and unfiltered in-leakage in the Control Room Dose Consequence Analyses reported in Attachment 4 of Alternative Source Term (AST) License Amendment Request (LAR) 15-03 conservatively encompass the test results.

For further information with respect to the referenced tracer gas test results and ventilation inputs utilized in the Control Room Dose Consequence Analyses, please refer to Pacific Gas and Electric Company (PG&E) response to NRC ARCB-RAI-12 provided via PG&E Letter DCL-16-015, "Response to NRC Request for Additional Information Regarding License Amendment Request 15-03, 'Application of Alternative Source Term,"' dated February 1, 2016.

NRC SCVB-RAI-2 Containment spray in recirculation mode following Loss-of-Coolant Accident for fission product cleanup - explain requiring operation within 12 minutes. Does this change impact any bounding containment analyses?

PG&E Response As discussed in Section 7.2 of Attachment 4 of AST LAR 15-03, the core damage sequence of an AST loss-of-coolant accident (LOCA) scenario as defined by Regulatory Guide (RG) 1.183, July 2000, addresses a delayed radioactivity release; i.e., a gap release starting at t equals 30 sees, followed by fuel melt starting at t equals 30 minutes and continuing on tot equals 1.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. At DCPP, containment spray in the injection mode is exhausted within approximately one hour after accident initiation, or earlier if full safeguards are available. Thus in order for the containment spray to continue to be effective as a fission product removal mechanism, the sprays have to be made available beyond the injection mode and continue in the recirculation mode.

PG&E has performed time and motion studies to estimate the delay time between termination of injection spray and the operator's manual initiation of recirculation spray for a double-ended pump suction break with failure of one train of the solid-state protection system. The results of the referenced time and motion studies have 1 of 3

Enclosure PG&E Letter DCL-16-019 indicated that the 12-minute delay assumed in the LOCA dose consequence analysis bounds, with significant margin, the recorded time delay experienced to initiate recirculation spray.

As documented in PG&E response to NRC EEEB-RAI-3 provided via PG&E Letter DCL-15-135, "Response to NRC Request for Additional Information Regarding License Amendment Request 15-03, 'Application of Alternative Source Term,"' dated November 6, 2015, the use of containment spray in the recirculation mode for the minimum safeguards case (i.e., recirculation spray initiated 12 minutes after termination of injection spray and continuing to approximately 6.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> following a LOCA), has no effect on the existing peak pressure and temperature inside containment, and minimal effect on the long-term pressure and temperature envelopes. Thus, the limiting DCPP licensing basis containment integrity analyses remain unchanged and conservatively bound operation of containment spray operation in the recirculation mode.

NRC SCVB-RAI-3 In Surveillance Requirement (SR) 3.6.3.1, the SR direction is to verify that the 48 inch containment purge valve is sealed closed with a frequency that is in accordance with the Surveillance Frequency Control Program. What is the initial frequency? Discuss how the frequency was determined and how the frequency may change over time.

PG&E Response The initial frequency for performing the new SR 3.6.3.1 has not been selected at this time but will be determined prior to implementation of the license amendment in accordance with Technical Specification (TS) 5.5.18, "Surveillance Frequency Control Program." Administrative Procedure XI3.1D11, "Surveillance Frequency Control Program," controls the evaluation, implementation, and management of Risk-Informed Surveillance Test Intervals (RI-STis). The RI-STis are placed in the Surveillance Test Interval List, controlled by Administrative Procedure Xl3.108, "Surveillance Test Interval Control." The process is consistent with the Nuclear Energy Institute (NEI) industry guidance document, NEI 04-10, "Risk-Informed Method for Control of Surveillance Frequencies," Revision 1.

Changes to the SR frequency over time are controlled by XI3.1D11. The procedure states that existing regulatory programs, such as 10 CFR 50.65 (Maintenance Rule) and the Corrective Action Program (CAP) required by 10 CFR 50, Appendix B, require monitoring of surveillance test failures and require action be taken to address such failures.

The new SR 3.6.3.1 is verifying the 48-inch containment purge system isolation valves remain closed under administrative control (sealed closed) during Modes 1, 2, 3, and 4.

In accordance with the Surveillance Frequency Control Program, an expert panel will 2 of 3

Enclosure PG&E Letter DCL-16-019 consider quantitative (risk-based) and qualitative factors and propose an initial surveillance frequency that will be approved by the Plant Staff Review Committee.

NRC SCVB-RAI-4 In SR 3. 6.3. 7, explain the rational for the removal of the surveillance within 92 days after opening the containment purge supply and exhaust valves.

PG&E Response The current SR 3.6.3. 7 wording describes the leakage testing required following opening the 48-inch containment purge supply and exhaust valves in Modes 1, 2, 3, and 4. The 48-inch containment purge valves will be sealed closed, and prevented from opening in Modes 1, 2, 3, and 4. This will be controlled by DCPP's Sealed Component Procedure, OP1.DC20. Therefore, the wording "AND For containment purge supply and exhaust valves only, within 92 days after opening the valve" has been removed from SR 3.6.3.7.

NRC SCVB-RAI-5 In the Bases, Containment Purge System (48 inch purge valves), the text was changed to delete the "no more than 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> per calendar year flow path limit from the 48 inch purge valves. Is there a new limit? If a limit is no longer required, please justify.

PG&E Response The current Technical Specification Bases, Section 8.3.6.3, allows either the 48-inch containment purge system valves OR the 12-inch containment pressure/vacuum relief valves to be opened up to 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> per year during Modes 1, 2, 3, and 4. The 48-inch containment purge system valves will be sealed closed and prevented from opening in Modes 1, 2, 3, and 4 via procedural controls established by DCPP's Procedure OP1.DC20. Therefore the limit for the 48-inch purge valves is no longer required because the flowpath is not allowed to be open in Modes 1, 2, 3, and 4.

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