ML063600318

Request for Additional Information Regarding the Generic Safety Issue 191

ML063600318
Person / Time
Site:	North Anna
Issue date:	12/28/2006
From:	Siva Lingam NRC/NRR/ADRO/DORL/LPLII-1
To:	Christian D Virginia Electric & Power Co (VEPCO)
Lingam, Siva NRR/DORL 415-1564
References
TAC MD3197, TAC MD3198
Download: ML063600318 (5)

Text

December 28, 2006 Mr. David A. Christian Senior Vice President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNIT NOS. 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING THE GENERIC SAFETY ISSUE (GSI) 191 (TAC NOS. MD3197 AND MD3198)

Dear Mr. Christian:

By letter dated October 3, 2006, Virginia Electric and Power Company (the licensee), submitted a license amendment request regarding the resolution of the Nuclear Regulatory Commissions (NRCs) GSI 191 and NRC Generic Letter (GL) 2004-02. The proposed license amendment will revise the Technical Specifications and licensing basis to support the resolution of NRCs GSI 191, assessment of debris accumulation on containment sump performance and its impact on emergency recirculation during an accident, and NRC GL 2004-02. The NRC staff is reviewing the submittal and has determined that additional information is required to complete its evaluation.

The NRC staffs RAI is enclosed. The licensee is requested to provide a response to the RAI within 30 days.

Sincerely,

/RA/

Siva P. Lingam, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-338 and 50-339

Enclosure:

RAI cc w/encl: See next page

ML063600318 NRR-088 OFFICE NRR/LPL2-1/PM NRR/LPD2-1/LA NRR/DSS/SCVB/BC NRR/LPL2-1/BC NAME SLingam MOBrien RDennig EMarinos DATE 12/27/06 12/28/06 12/20/06 12/28/06 REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC SAFETY ISSUE 191 TECHNICAL SPECIFICATION AMENDMENT NORTH ANNA POWER STATION, UNIT NOS. 1 AND 2 DOCKET NOS. 50-338 AND 50-339

1. Attachment 4, Insert # 4, last two sentences of your application dated October 3, 2006, state: An operator can initiate [recirculation spray] RS at any time from the control room by using the pump control switch. The manual function would be used only when adequate water inventory is present in the containment sump to meet the RS sump strainer functional requirements. Please explain how the operator would verify that adequate water inventory is present in the sump that meets the RS pump minimum net positive suction head (NPSH) requirement in order to prevent an erroneous pump start.

2. Attachment 4, Insert # 9, first sentence states: Refueling water storage tank (RWST)

Level-Low coincident with Containment Pressure-High High provides the automatic start signal for the inside RS [IRS] and outside RS [ORS] pumps. Please explain how does the automatic logic verify that adequate water is present in the sump that meets the RS pump minimum NPSH requirement in order to prevent an erroneous pump start.

3. Attachment 2, proposed Technical Specification Section 3.6.5 revises the upper limit of the containment average air temperature from #120 O F to #115 O F. Section 9.4.9.1, second paragraph of the Updated Final Safety Analysis Report (UFSAR) states: The ventilation systems are designed to maintain the containment bulk air temperature within the Technical Specification limits when two of the three recirculation system fans and three dome recirculation fans are running, the [control rod drive mechanism] CRDM cooling systems are operating, and the cooling system for the reactor coolant pump motors is functioning. Normally, all three main recirculation fans will be operating during summer periods. Please confirm that the existing containment ventilation system design has been re-evaluated to verify that it has sufficient capacity to maintain the containment bulk air temperature #115 O F under the worst design conditions.

4. Attachment 1, Section 2.2, under the heading Plant Safety Analysis Impact, fifth bullet, third sentence states: This pump [ORS and IRS] start delay reduces the early loads on the emergency diesel generator. However, since the loading of diesel generator with ORS and IRS motor loads is delayed, please confirm that the revised loading sequence has been re-evaluated to verify that it meets Regulatory Position 4 of Safety Guide 9 as it pertains to its load accepting capability of the ORS and IRS motor loads in conjunction with other Engineered Safety Features (ESF) step loads with which the system is loaded. Position 4 of Safety Guide 9 states: At no time during the loading sequence should the frequency and voltage decrease to less than 95 percent of nominal and 75 percent of nominal, respectively. During recovery from transients caused by step load increases or resulting from the disconnection of the largest single load, the speed of the diesel generator set should not exceed 75 percent of the difference between Enclosure

nominal speed and the overspeed trip setpoint or 115 percent of nominal, whichever is lower. Voltage should be restored to within 10 percent of nominal and frequency should be restored to within 2 percent of nominal in less than 40 percent of each load sequence time interval.

5. Attachment 1, Section 3.9, fourth sentence states: Composite pressure and temperature profiles were developed that bounded the [loss-of-coolant accident] LOCA and [main steam line break] MSLB pressure and temperature profiles from GOTHIC.

Please provide the developed composite pressure and temperature profiles which are the revised basis for equipment qualification.

6. Attachment 4, Insert # 13, last sentence states: This frequency has been found to be sufficient to detect abnormal degradation and is confirmed by operating experience.

Please specify what kind of abnormal degradation has been found in sump components that are confirmed by operating experience.

7. Attachment 4, pages B 3.6.1-2 and B 3.6.2-2, under Applicable Safety Analyses on both pages, the current value of Pa of 44.1 psig is shown deleted. Please replace it with the revised value.

8. Attachment 1, Section 3.2.1, fifth paragraph, last sentence refers to Response #8 to the Nuclear Regulatory Commissions Request for Additional Information on the Surry GOTHIC analysis submittal. Please correct Response [No.] # 8" to Response No. 9."

9. Attachment 1, first bullet in Section 3.1.4 states: "The minimum surface area for metal heat sinks in containment was changed based on a revised inventory that was documented in an internal calculation. The passive heat sink data used in the GOTHIC analyses is provided in Table 3.1-3. The metal and concrete heat sink minimum surface areas are 5% less than the nominal calculated values." Please explain the following:

(a) What does "Minimum Surface Area" mean and how did you determine that?

(b) What is the basis for 5%?

(c) Noting that the minimum surface area would give conservative results for the containment peak pressure calculation while the maximum surface area would give conservative results for available NPSH calculations, please explain and justify what areas you used for these calculations.

North Anna Power Station, Units 1 & 2 cc:

Mr. David A. Christian Senior Resident Inspector Senior Vice President North Anna Power Station and Chief Nuclear Officer U. S. Nuclear Regulatory Commission Virginia Electric and Power Company P. O. Box 490 Innsbrook Technical Center Mineral, Virginia 23117 5000 Dominion Boulevard Glen Allen, VA 23060-6711 Mr. Daniel G. Stoddard Site Vice President Mr. C. Lee Lintecum North Anna Power Station County Administrator Virginia Electric and Power Company Louisa County Post Office Box 402 Post Office Box 160 Mineral, Virginia 23117-0402 Louisa, Virginia 23093 Dr. Robert B. Stroube, MD, MPH Ms. Lillian M. Cuoco, Esq. State Health Commissioner Senior Counsel Office of the Commissioner Dominion Resources Services, Inc. Virginia Department of Health Building 475, 5 th floor Post Office Box 2448 Rope Ferry Road Richmond, Virginia 23218 Waterford, Connecticut 06385 Dr. W. T. Lough Virginia State Corporation Commission Division of Energy Regulation Post Office Box 1197 Richmond, Virginia 23218 Old Dominion Electric Cooperative 4201 Dominion Blvd.

Glen Allen, Virginia 23060 Mr. Chris L. Funderburk, Director Nuclear Licensing & Operations Support Dominion Resources Services, Inc.

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