DCL-14-007, Response to December 23, 2013, Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3 Flooding Walkdowns
| ML14029A702 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 01/29/2014 |
| From: | Allen B Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-14-007 | |
| Download: ML14029A702 (4) | |
Text
Pacific Gas and Electric Company January 29, 2014 PG&E Letter DCL-14-007 Barry S. Allen Site Vice President Diablo Canyon Power Plant Mail Code 104/6 P. O. Box 56 Avila Beach, CA 93424 805.545.4888 Internal: 691.4888 Fax: 805.545.6445 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike 10 CFR 50.54(f)
Rockville, MD 20852 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to December 23, 2013, Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3 Flooding Walkdowns
References:
- 1. NRC Letter, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated March 12,2012
- 2. PG&E Letter DCL-12-059, "Pacific Gas and Electric Company's Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendations 2.1 and 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-Ichi Accident," dated June 7,2012
- 3. PG&E Letter DCL-12-114, "Final Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Flooding,"
dated November 27,2012
Dear Commissioners and Staff:
On March 12, 2012, the Nuclear Regulatory Commission (NRC) staff issued Reference 1 to Pacific Gas and Electric Company (PG&E) requesting information per Title 10 of the Code of Federal Regulations, Section 50.54(f). Reference 1 requested that licensees conduct flooding hazard walkdowns to verify the plant configuration is within their current licensing basis. Reference 2 confirmed that PG&E would use Nuclear Energy Institute Guidance 12-06, as endorsed by NRC Letter, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features," dated May 31,2012.
A member of the STARS (Strategic Teaming and Resource Sharing)
Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- Wolf Creek
Document Control Desk January 29, 2014 Page 2 PG&E Letter DCL-14-007 Reference 3 provided PG&E's response to Recommendation 2.3 flooding for Diablo Canyon Power Plant Units 1 and 2.
On December 23, 2013, the NRC staff issued a request for additional information (RAI) associated with Near-Term Task Force Recommendation 2.3 flooding.
Enclosed is PG&E's response to the December 23, 2013, RAls.
PG&E is making no new regulatory commitments. This letter includes no revisions to existing regulatory commitments.
If you have any questions, or require additional information, please contact Mr. Patrick Nugent at (805) 781-9786.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on January 29,2014.
Sincerely, vJ dv-; 5.;ftL Barry S. A{en Site Vice President dmfn/SAPN 50601134 Enclosure cc:
Diablo Distribution cc:/enc:
Brian J. Benney, NRR Project Manager Marc L. Dapas, NRC Region IV Administrator Thomas R. Hipschman, NRC, Senior Resident Inspector Eric J. Leeds, NRC/NRR Director A
member of the STARS (Strategic Teaming and Resource Sharing)
Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- Wolf Creek
Enclosure PG&E Letter DCL-14-007 Page 1 of 2 Pacific Gas and Electric Company's Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3:
Flooding Confirmation that the process for evaluating APM was reviewed PG&E Response to RAI-1 PG&E confirms that the process for evaluating available physical margin (APM) was reviewed as requested by this request for additional information (RAI).
Confirmation that the APM process is now or was always consistent with the guidance in NE112-07 and discussed in this RAI PG&E Response to RAI-2 PG&E confirms that the APM process was always consistent with the guidance in NEI 12-07. Documentation from the initial Recommendation 2.3 flooding walkdowns was enhanced to provide clarification to show conformance with the APM process discussed in this RAI.
If changes are necessary, a general description of any process changes to establish this consistency PG&E Response to RAI-3 PG&E determined that there are no process changes necessary to establish consistency between NEI 12-07 and this RAI with previously submitted information.
As a result of the audits and subsequent interactions with industry during public meetings, NRC staff recognized that evaluation of APM for seals (e.g. flood doors, penetrations, flood gates, etc.) was challenging for some licensees. Generally, licensees were expected to use either Approach A or Approach B (described below) to determine the APM for seals:
a) If seal pressure ratings were known, the seal ratings were used to determine APM (similar to example 2 in Section 3.13 of NEI12-07). A numerical value for
Enclosure PG&E Letter DCL-14-007 Page 2 of2 APM was documented. No furiher action was performed if the APM value was greater than the pre-established small margin threshold value. If the APM value was small, an assessment of "significant consequences" was performed and the guidance in NEI 12-07 Section 5.8 was followed.
b) If the seal pressure rating was not known, the APM for seals in a flood barrier is assumed to be greater than the pre-established small-margin threshold value if the following conditions were met: (1) the APM for the barrier in which the seal is located is greater than the small-margin threshold value and there is evidence that the seals were designed/procured, installed, and controlled as flooding seals in accordance with the flooding licensing basis. Note that in order to determine that the seal has been controlled as a flooding seal, it was only necessary to determine that the seal configuration has been governed by the plant's design control process since installation. In this case, the APM for the seal could have been documented as "not small".
As pari of the RAI response, state if either Approach A or Approach B was used as pari of the initial walkdowns or as pari of actions taken in response to this RAJ. No additional actions are necessary if either Approach A or B was used.
If neither Approach A or B was used to determine the APM values for seals (either as pari of the walkdowns or as pari of the actions taken in response to this RAI), then perform the following two actions:
Enter the condition into the CAP (note: it is acceptable to utilize a single CAP entry to capture this issue for multiple seals). CAP disposition of "undetermined" APM values for seals should consider the guidance provided in NEI12-07, Section 5.8. The CAP disposition should confirm all seals can perform their intended safety function against floods up to the current licensing basis flood height. Disposition may occur as pari of the Integrated Assessment. If an Integrated Assessment is not performed, determine whether there are significant consequences associated with exceeding the capacity of the seals and take interim action(s), if necessary, via the CAP processes. These actions do not need to be completed prior to the the RAI response.
Repori the APM as "undetermined" and provide the CAP reference in the RAI response.
PG&E Response to RAI-4 PG&E used both Approaches A and B for determining the APM for all seals. If the seal pressure ratings were known, the seal ratings were used to determine the APM, as discussed in Approach A. For cases in which the seal pressure rating was not known, Approach B was used. As discussed in the response to RAI-2 above, documentation from the initial 2.3 flooding walkdowns was enhanced to provide clarification to show conformance with the APM process discussed in this RAI.