ML102990293
| ML102990293 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/26/2010 |
| From: | Price J Dominion, Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-183B | |
| Download: ML102990293 (9) | |
Text
10 CFR 50.90 VIRGINIA ELECTRIC AND POWER C O MPAN Y RICHMOND, VIRGINI A 23261 October 26, 2010 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Serial No.
NL&OS/ETS Docket Nos.
License Nos.
10-1838 RO' 50-280 50-281 DPR-32 DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
SURRY POWER STATION UNITS 1 AND 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST REGARDING RISK-INFORMED JUSTIFICATION FOR THE RELOCATION OF SPECIFIC SURVEILLANCE FREQUENCY REQUIREMENTS TO A LICENSEE CONTROLLED PROGRAM (ADOPTION OF TSTF-425, REVISION 3)
In a letter dated March 30, 2010 (Serial No.10-183) and supplemented on August 23, 2010 (Serial No.10-183A),
Dominion requested amendments to Facility Operating License Numbers DPR-32 and DPR-37 for Surry Power Station Units 1 and 2, respectively. The proposed amendments will modify Surry TS by relocating specific surveillance frequencies to a licensee-controlled program with the implementation of Nuclear Energy Institute (NEI) 04-10, "Risk-Informed Technical Specifications Initiative 5b, Risk-Informed Method for Control of Surveillance Frequencies."
In a September 30, 2010 e-mail from Ms. Karen Cotton to Mr. Gary Miller, the NRC staff requested additional information to complete the NRC review of the amendment request.
The attachment to this letter provides the requested information.
The information provided in this letter does not affect the conclusion of the significant hazards consideration discussion provided in the Dominion letter dated March 30, 2010 (Serial NO.10-183) for Surry.
Dominion continues to request approval of the proposed license amendments by April 1, 2011, with the amendment being implemented within 120 days.
Serial NO.1 0-1838 Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 2 of 3 If you have any questions or require additional information, please contact Mr. Thomas Shaub at (804) 273-2763.
Very truly yours, Commitments made in this letter:
Dominion will assess the PRA model gaps for each surveillance frequency change until the PRA model of record is updated.
Attachment:
Response to Request for Additional Information COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by J. Alan Price, who is Vice President - Nuclear Engineering, of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this;?tp7J'day of O(lhb.J, 2010.
My Commission Expires:,~ 31, aOI¥:
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~'/LL-tIdL Notary Public
Serial No. 10-1838 Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 3 of 3 cc:
U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Senior Resident Inspector Surry Power Station Ms. K. R. Cotton NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G9A 11555 Rockville Pike Rockville, Maryland 20852 Dr. V. Sreenivas NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 H4A 11555 Rockville Pike Rockville, Maryland 20852
Serial No. 10-1838 Docket Nos. 50-280/281 Attachment RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RELATED TO AN AMENDMENT TO IMPLEMENT TSTF-425 REVISION 3 I
VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
SURRY POWER STATION UNITS 1 AND 2
Serial NO.10-1838 Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 1 of 5 Response to Request for Additional Information Related to an Amendment to Implement TSTF-425 Revision 3 Surry Power Station Units 1 and 2 Virginia Electric and Power Company (Dominion) identified that it performed al self assessment of its internal events probabilistic risk assessment (PRA) model to the requirements of the standard referenced in Regulatory Guide 1.200 Revision 1. IThe structure of the standard provides high level and supporting requirements, including separate documentation requirements.
NRC Questions 1 and 2
- 1. In Table 1 of Attachment 2 of the submittal, the licensee presented a summary of the remaining (eight) open findings from this assessment as well as their dispositioh for this application. In its review, the staff noted that each of the items was identified against a specific non-documentation supporting requirement of the standard! but,
each was dispositioned as only a documentation issue.
Since each high level requirement of the standard has a separate documentation part, it is not clear to the staff why the concerns from an internal self assessment were not identified as-relevant to the documentation requirements, rather than the technical requirements, since the licensee controls the process.
- 2. Further, one item identified as "Gap #2" is identified as a documentation issue, but then it is stated that the issue will be addressed as a sensitivity for this appllcatlon. If I
the issue is documentation, it is not clear how a sensitivity analysis would be applicable.
Dominion Response In early 2007, Dominion started the self-assessment process for each of the five fleet PRA Models.
The Surry Power Station (SPS) PRA was the first model to undergo a self-assessment. At the time, the decision was made in order to Meet Category II for a Supporting Requirement (SR), there had to be documented evidence that the SR was met. For example, Gap #1 is to address the lack of documentation for screening out flooding events inside the containment. The Containment Building has been screened out since the equipment contained in the containment is designed to operate in a post-LOCA, flooded environment. However, this reasoning was not clearly documehted in the internal flooding notebooks.
Gap #2 addresses the lack of documentation on jet impingement, pipe whip, humidity and other types of failure impacts on plant systems. This issue was also identified in the focused PWR Owners Group (PWROG) PRA Peer Review in February 2010
Serial No. 10-1838 Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 2 of 5 (See Gap #11 in this attachment).
In particular, the peer review identified the lack of component spatial information on the walkdown sheets that would document direct effects (e.g., submergence and critical flood height) and indirect effects (e.g. spray, jet impingement, humidity or pipe whip). The current walkdown sheets only contain check marks for equipment vulnerability.
To address Gap #2, the walkdown sheets will be updated to include "yes", "no" or "see comments field" in order to enhance the documentation for model upgrades and peer reviews.
The column "importance to application" in the attached table has been updated to reflect the importance of updating the internal flooding walkdown sheets.
In Attachment 2 of the March 30, 2010 submittal, Dominion stated the Surry PRA model underwent a PWROG focused peer review in February 2010 using the PRA Peer Review Certification process.
Updated documentation on modeling uncertainty and related assumptions were included for the PWROG focused peer review.
The final assessment was not available before the SPS RITS 5b submittal.
Since then the PWROG has provided the results of the focused peer review.
The peer re'view identified that Gap #6 had been addressed.
New Gaps identified by the PWROG have been included in the following Table 1.
Serial No. 10-183B Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 3 of 5 Table 1 Status of Identified Gaps to NEI 00-02 and Capability Category II of the ASME PRA Standard Title Description NEI Element Current Status/Comment Importance to Application
/ASME SR Gap #1 For each flood area, IF-B1 No documentation on why floods in None. This is judged to be a documentation identify the potential containment were screened out.
consideration only and does not affect the technical sources of floodinq.
adequacy of the PRA model.
Gap #2 The NRC clarification IF-C3 No documentation discussing how Significant: This issue is important for any potential for Cat II says to jet impingement, pipe whip, Surveillance Test Interval (STI) change impacted by address jet humidity and other types of failures internal events. Therefore, the walkdown sheets will be impingement, impact plant systems.
completed to contain all requested information. Any humidity, etc.
impact to flooding scenarios will be added to the qualitatively using sensitivity PRA model when quantifying the effect of a conservative proposed individual STI revision for comparison to assumptions acceptance criteria in NEI 04-10, Revision 1.
Gap #3 Document the relative LE-G3 No documentation of LERF None. This is judged to be a documentation contribution of contributions for accident consideration only and does not affect the technical contributors to LERF sequences.
adequacy of the PRA model.
Gap #4 Uncertainties shall be QU-E1 Sources of model uncertainties None. This is judged to be a documentation characterized and QU-E2 and assumptions were not consideration only and does not affect the technical documented.
QU-F4 identified and documented.
adequacy of the PRA model.
SC-C3 Gap #5 Estimate uncertainty LE-F3 No parametric uncertainty analysis None. This is [udqed to be a documentation intervals associated QU-E3 was performed.
consideration only and does not affect the technical with parameter QU-F2 adequacy of the PRA model.
uncertainties.
Gap #6 Evaluate the QU-E4 Documentation has been updated None. Documentation has been updated to categorize sensitivity of the to address QU-E4.
model uncertainty in some individual element results.
notebooks. The SPS QUA notebook documents the inteqrated consideration of model uncertainty.
Gap #7 Document the system SY-C2 All documentation requirements None. This is judged to be a documentation functions and are considered met except for consideration only and does not affect the technical boundaries.
completion of walkdown checklists.
adequacy of the PRA model.
Serial No. 10-1838 Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 4 of 5 Table 1 Status of Identified Gaps to NEI 00-02 and Capability Category II of the ASME PRA Standard Title Description NEI Element Current Status/Comment Importance to Application
/ASME SR Gap #8 Document AS-C3 Document uncertainties and None. This is judged to be a documentation uncertainties and DA-E3 assumptions associated with:
consideration only and does not affect the technical assumptions.
HR-13 accident sequence adequacy of the PRA model.
IE-D3 analysis IF-F3 data analysis SC-C3 human reliability analysis SY-C3 initiating event analysis internal flooding analysis success criteria development system analysis
- Gap #9 Initiating Event Fault IE-C10 IE-C10: Not all possible Significant: This issue is important for any potential Tree Modeling.
IE-C12 combination of cutsets are STI change modeled as support system initiating
- captured, events. Therefore, the system-level initiating events will be revised using the methodology in EPRI IE-C12: No comparison with TR-1 013490 methodology. This will be added to the generic sources for initiating sensitivity PRA model when quantifying the effect of a events modeled using fault trees.
proposed individual STI revision for compa rison to acceptance criteria in NEI 04-10, Revision 1.
- Gap #10 Use of SPAR-H HR-E3 New Human Error Probabilities Significant: This issue is important for any potential methodology, which HR-G4 (HEPs) added to the SPS PRA STI change impacted by HEPs. Therefore, HEPs does not meet the HR-G6 were based on SPAR-H. The Peer developed using the SPAR-H methodology will be intent of several SRs HR-12 Review identified the SPAR-H updated using a more appropriate methodology in the in the HR element.
HR-13 methodology is not a consensus EPRI HRA Calculator. This will be added to the HR-E4 model and has some limitations.
sensitivity PRA model when quantifying the effect of a HR-G1 proposed individual STI revision for comparison to HR-G3 acceptance criteria in NEI 04-10, Revision 1.
HR-G5
Serial No.1 0-183B Docket Nos. 50-280/281 Response to Request for Additional Information Relocate Surveillance Frequencies from TS Page 5 of 5 Table 1 Status of Identified Gaps to NEI 00-02 and Capability Category II of the ASME PRA Standard Title Description NEI Element Current Status/Comment Importance to Application
/ASME SR
- Gap #11 Walkdown sheets do IFSO-B2 IFSO*B2: Complete the walkdown Significant: This issue is important for any potential not contain all the IFQU-A9 sheets and verify no impact to IF STI change impacted by internal events. Therefore, requested information.
events.
the walkdown sheets will be completed to include the IFQU-A9: Similiar to IFSO-B2, requested information. Any impact to flooding need to clearly document the scenarios will be added to the sensitivity PRA model spatial relationship between flood when quantifying the effect of a proposed individual sources and PRA equipment.
STI revision for comparison to acceptance criteria in NEI 04-10, Revision 1.
- Gap #12 Document limitations QU-F5 Need to update PRA Notebook Significant: It is important to identify modeling in the quantification QUA to include a discussion on limitations before assessing the impact of any potential process that would model limitations.
Surveillance Test Interval (STI) changes. Therefore, impact applications.
this Gap will be addressed before any STI changes.
"Gaps 9 throuqh 12 were identified durinQ the 2010 PWROG focused PRA peer review.