ML030800390

Request for Additional Information on Small-break LOCA Evaluation in Support of Proposed Technical Specifications Changes and Exemption Request to Use Framatome Anp Advanced Mark-BW Fuel

ML030800390
Person / Time
Site:	North Anna
Issue date:	03/21/2003
From:	Stephen Monarque NRC/NRR/DLPM/LPD2
To:	Christian D Virginia Electric & Power Co (VEPCO)
Monarque S, NRR/DLPM, 415-1544
References
TAC MB4714, TAC MB4715
Download: ML030800390 (6)

Text

March 21, 2003 Mr. David A Christian Senior Vice President - Nuclear Virginia Electric and Power Company 5000 Dominion Blvd.

Glen Allen, Virginia 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION ON SMALL-BREAK LOCA EVALUATION IN SUPPORT OF PROPOSED TECHNICAL SPECIFICATIONS CHANGES AND EXEMPTION REQUEST TO USE FRAMATOME ANP ADVANCED MARK-BW FUEL (TAC NOS. MB4714 AND MB4715)

Dear Mr. Christian:

By letter dated March 28, 2002, Virginia Electric and Power Company (VEPCO) requested amendments and exemptions to support the transition to Framatome ANP Advanced Mark BW Fuel at North Anna Power Station, Units 1 and 2 (NA1&2). In a letter dated August 2, 2002, VEPCO submitted its small-break loss-of-coolant accident (SBLOCA) evaluation in support of this action. In its letter dated November 15, 2002, VEPCO stated that based on interactions with the NRC staff, it had changed the methodology for addressing large-break (LB) LOCA.

The new method will rely on Framatome ANP's Topical Report EMF-2103(P), Realistic Large Break LOCA Methodology for Pressurized Water Reactors. VEPCO will submit the revised LBLOCA analysis after the NRC staff has completed its review and approval of Topical Report EMF-2103(P). Furthermore, in the November 15, 2002, letter, VEPCO indicated that the SBLOCA submittal was unaffected by the change in the LBLOCA approach and requested that the NRC continue its review of the SBLOCA evaluation. In addition, VEPCO agreed to have the reanalysis of the SBLOCA completed no later than April 30, 2005, in order to address Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46 reporting requirements.

The NRC staff has evaluated VEPCOs proposed SBLOCA evaluation presented in the August 2, 2002, submittal and has found this approach to be unacceptable because it does not (1) provide the quantification necessary to benchmark the Framatome ANP Advanced Mark BW Fuel in order to determine which type of fuel is limiting for SBLOCA, (2) demonstrate that the licensing basis for NA1&2 has an SBLOCA analysis that is capable of evaluating Framatome ANP Advanced Mark BW Fuel, and (3) provide analyses of record for the Framatome ANP Advanced Mark BW Fuel as a baseline for the emergency core cooling system reporting requirements of 10 CFR 50.46 (a)(3)(i) and (ii). Furthermore, in its August 2, 2002, submittal, VEPCO referenced Topical Report BAW-1017A, Revision 1, Mark-BW Reload LOCA Analysis for the Catawba and McGuire Units, dated September 1992 and the NRC staffs letter dated September 24, 1991, that forwarded the safety evaluation for Topical Report BAW-10177, Mark-BW Reload LOCA Analysis for the Trojan Plant, as supporting analyses for the SBLOCA evaluation. The NRC staff has determined that neither of these reports is an acceptable reference for the following reasons: (1) the Framatome Mark-BW and Westinghouse optimized fuel assemblies involved had greater similarity than the advanced fuels discussed in VEPCOs

D. A. Christian August 2, 2002, submittal; (2) the proposals from Trojan, McGuire, and Catawba Nuclear Stations were supported by mixed-core analyses that were not provided in the August 2, 2002, submittal for NA1&2; and (3) both Framatome and Westinghouse methodologies have changed over the past 10 years. Comparisons performed long ago using different codes would not necessarily apply to the licensing basis of NA1&2. For these reasons, VEPCO is requested to perform explicit SBLOCA analyses of Framatome ANP Advanced Mark BW Fuel for NA1&2.

While the NRC staff finds the above reasons sufficient to find the proposed SBLOCA approach to be unacceptable, our review of the August 2 and November 15, 2002, submittals provided the development of questions in this request for additional information (RAI). VEPCO is requested to provide a response in order for the NRC staff to complete its review. The NRC staff requests a response to the RAI by May 31, 2003. This response date was discussed with Mr. Gary Darden of your staff on March 12, 2003, who indicated that VEPCO will be able to meet this date.

Sincerely,

/RA/

Stephen R. Monarque, Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-338 and 50-339

Enclosure:

RAI cc w/encl: See next page

D. A. Christian August 2, 2002, submittal; (2) the proposals from Trojan, McGuire, and Catawba Nuclear Stations were supported by mixed-core analyses that were not provided in the August 2, 2002, submittal for NA1&2; and (3) both Framatome and Westinghouse methodologies have changed over the past 10 years. Comparisons performed long ago using different codes would not necessarily apply to the licensing basis of NA1&2. For these reasons, VEPCO is requested to perform explicit SBLOCA analyses of Framatome ANP Advanced Mark BW Fuel for NA1&2.

While the NRC staff finds the above reasons sufficient to find the proposed SBLOCA approach to be unacceptable, our review of the August 2 and November 15, 2002, submittals provided the development of questions in this request for additional information (RAI). VEPCO is requested to provide a response in order for the NRC staff to complete its review. The NRC staff requests a response to the RAI by May 31, 2003. This response date was discussed with Mr. Gary Darden of your staff on March 12, 2003, who indicated that VEPCO will be able to meet this date.

Sincerely,

/RA/

Stephen R. Monarque, Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-338 and 50-339

Enclosure:

RAI cc w/encl: See next page Distribution: SMonarque FOrr MKowal PUBLIC RidsOGCRP RidsRgn2MailCenter UShoop PDII-1 Reading AcrsAcnwMailCenter EDunnington (paper copy)

DJackson RLobel JNakoski Adams: ML030800390 *See previous concurrence OFFICE PM:PDII/S1 LA:PDII/S1 SRXB SC:PDII/S1 NAME SMonarque EDunnington FAkstulewicz* JNakoski DATE 03/19/03 03/21/03 03/14/2003 03/21/03 OFFICIAL RECORD COPY

REQUEST FOR ADDITIONAL INFORMATION NORTH ANNA POWER STATION, UNITS 1 AND 2 SMALL-BREAK LOSS-OF-COOLANT ACCIDENT EVALUATION

1. Provide the results of sensitivity studies that identify which fuel type is limiting.

2. The Virginia Electric and Power Company (VEPCO) methodology currently contains a number of changes and errors with a cumulative significant uncertainty. As such, VEPCO is requested to address the following items.

a. Discuss how the present analyses bound the loss-of-coolant accident performance of both fuel types.

b. Provide information indicating which fuel type is bounding after factoring in the uncertainties.

c. Describe how a mixed-core penalty would be validly calculated using an out-of-date model.

3. The fourth paragraph of page 2 of the August 2, 2002, letter states that the suppression of core steam production further depressurizes the reactor coolant system (RCS).

It seems that, all else being equal, pressurization of the RCS would also suppress steam production. This, combined with the above statement, would lead to the conclusion that the pressurization of the RCS depressurizes the RCS. The quoted statement is confusing.

Provide a clearer description.

4. If the Framatome Advanced Mark-BW fuel is somewhat cooler near the mid-span mixing grids than the North Anna Improved Fuel (NAIF), then would the present calculations still be bounding?

5. Regarding the discussion of actual flow versus design flow, the design flow is lower than the actual flow to accommodate uncertainties in actual flow, not errors in design flow. In either event the design flow must always be lower than the actual flow to assure that the analyses are conservative. The information provided in paragraph three of page 3 only assures that one design parameter is correctly specified; it isnt clear that it supports the conservatism of the treatment of Framatome Advanced Mark-BW fuel. Does it indicate that the RCS flow specified in the Technical Specifications should be at a higher rate?

6. Pages 3 and 4 discuss swelling and rupture. If NAIF ruptures sooner than Advanced Mark-BW fuel, might it also swell at a different rate? If so, the resulting effect on peak cladding temperature (PCT) could alter the estimated PCTs for both fuels.

Enclosure

Mr. David A. Christian North Anna Power Station Virginia Electric and Power Company Units 1 and 2 cc:

Mr. C. Lee Lintecum Mr. David A. Heacock County Administrator Site Vice President Louisa County North Anna Power Station P. O. Box 160 P. O. Box 402 Louisa, Virginia 23093 Mineral, Virginia 23117-0402 Ms. Lillian M. Cuoco, Esq. Mr. Richard H. Blount, II Senior Nuclear Counsel Site Vice President Dominion Nuclear Connecticut, Inc. Surry Power Station Millstone Power Station Virginia Electric and Power Company Building 475, 5 th floor 5570 Hog Island Road Rope Ferry Road Surry, Virginia 23883-0315 Rt. 156 Waterford, Connecticut 06385 Mr. Robert B. Strobe, M.D., M.P.H.

State Health Commissioner Dr. W. T. Lough Office of the Commissioner Virginia State Corporation Virginia Department of Health Commission P. O. Box 2448 Division of Energy Regulation Richmond, Virginia 23218 P. O. Box 1197 Richmond, Virginia 23209 Mr. William R. Matthews Vice President-Nuclear Operations Old Dominion Electric Cooperative Virginia Electric and Power Company 4201 Dominion Blvd. Innsbrook Technical Center Glen Allen, Virginia 23060 5000 Dominion Boulevard Glen Allen, Virginia 23060-6711 Mr. Stephen P. Sarver, Director Nuclear Licensing & Operations Support Virginia Electric Power Company Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen, Virginia 23060-6711 Office of the Attorney General Commonwealth of Virginia 900 East Main Street Richmond, Virginia 23219 Senior Resident Inspector North Anna Power Station U. S. Nuclear Regulatory Commission 1024 Haley Drive Mineral, Virginia 23117