ML20206U744

Informs That NRC Unable to Conclude That NAPS Has Met Intent of Supplement 4 to GL 88-20.RAI Re Fire Area of IPEEE Encl. Response Requested within 90 Days of Submittal Date

ML20206U744
Person / Time
Site:	North Anna
Issue date:	05/20/1999
From:	Kalyanam N NRC (Affiliation Not Assigned)
To:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
References
GL-88-20, TAC-M83647, TAC-M83648, NUDOCS 9905250325
Download: ML20206U744 (6)

Text

,._ Mr. J. P. O'Hinlon May 20,1999 l Senior Vica PrcsidInt Virginis Eltetric and Power Company 5000 Dominion Boulevard i Glen Allen, VA 23060

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION (RAI) ON INDIVIDUAL PLANT EXAMlliATION FOR EXTERNAL EVENTS (IPEEE) SUBMITTAL FOR NORTH ANNA POWER STATION (NAPS), UNITS 1 AND 2 (TAC NOS. M83647 AND M83648)

Dear Mr. J. O'Hanlon:

Based on our ongoing review of the North Anna IPEEE submittal and your responses to our previous RAls, we are unable to conclude at this time that NAPS has met the intent of I Supplement 4 to Generic Letter 88-20. Therefore, we have developed the attached RAI (additional or follow-up to previous RAls) related to the fire area of the IPEEE. The RAI on the fire area was developed by our contractor, Sandia National Laboratories (SNL). All the questions on the RAI were reviewed by the " Senior. Review Board," comprised of NRC staff and SNL staff with probabilistic risk assessment expertise in external events. There is no RAI in the seismic area or high wind, flood, and other external events areas of the IPEEE submittal.

The staff requests a response to the RAI within 90 days of the submittal date. This response date was discussed with Mr. Tom Shaub of your staff on May 14,1999, who indicated that Virginia Electric and Power Company will be able to meet this date. The staff appreciates the efforts expended with respect to this matter.

Sincerely, original signed by:

N. Kalyanam, Project Manager, Section 1 Project Directorate 11 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos.: 50-338 and 50-339

Enclosure:

Request for Additional Information cc w/ encl: See next page t 1

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Docket File PUBLIC PDllRF ACRS R. Haag Ed . Con reN J. Zwolinski/S. Black OGC Alan Rubin (MS-T10E50) Ed Chow /

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j UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20006 0001 May 20,1999

\*****[2 Mr. J. P. O'Hanlon Genior Vice President Virginia Electric and Power Company 5000 Dominion Boulevard Glen Allen, VA 23060

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION (RAI) ON INDIVIDUAL PLANT EXAMINATION FOR EXTERNAL EVENTS (IPEEE) SUBMITTAL FOR NORTH '

^

ANNA POWER STATION (NAPS), UNITS 1 AND 2 (TAC NOS. M83647 AND M83648)

Dear Mr. J. O'Hanlon:

Based on our ongoing review of the North Anna IPEEE submittal and your responses to our previous RAls, we are unable to conclude at this time that NAPS has met the intent of Supplement 4 to Generic Letter 88-20. Therefore, we have developed the attached RAI (additional or follow-up to previous RAls) related to the fire area of the IPEEE. The RAI on the fire area was developed by our contractor, Sandia National Laboratories (SNL). All the questions on the RAI were reviewed by the " Senior Review Board," comprised of NRC staff and SNL staff with probabilistic risk assessment expertise in extemal events. There is no RAI in the seismic area or high wind, flood, and other external events areas of the IPEEE submittal.

The staff requests a response to the RAI within 90 days of the submittal date. This response date was discussed with Mr. Tom Shaub of your staff on May 14,1999, who indicated that Virginia Electric and Power Company will be able to meet this date. The staff appreciates the efforts expended with respect to this matter.

Sincerely, 1

m .

N. Kalyanam, Project Manager, Section 1 Project Directorate ll Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos.: 50-338 and 50-339

Enclosure:

Request for AdditionalInformation cc w/enet: See next page

[

,,Mr. J. P. O'Hanlon North Anna Power Station Virginia Electric & Power Company Units 1 and 2 cc:

Mr. J. Jeffrey Lunsford Mr. W. R. Matthews 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 Mr. Donald P. Irwin, Esquire Mr. E. S. Grecheck Hunton and Williams Site Vice President Riverfront Plaza, East Tower Surry Power Station 951 E. Byrd Street Virginia Electric and Power Compo.y Richmond, Virginia 23219 5570 Hog Island Road Surry, Virginia 23883 Dr. W. T. Lough Virginia State C rporation Robert B. Strobe, M.D., M.P.H.

Commission State Health Commissioner Division of Energy Regulation Office of the Commissioner P. O. Box 1197 Virginia Department of Health Richmond, Virginia 23200 P.O. Box 2448 Richmond, Virginia 23218 Old Dominion Electric Cooperative 4201 Dominion Blvd.

Glen Allen, Virginia 23060 Mr. J. H. McCarthy, Manager.

l Nuclear Licensing & Operations Supoort Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen. Virginia 23060 Office of the Attomey 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 l

i

s l

k l Supplemental Request for Additional Information (RAI) on North Anna individual Plant Examination of External Events (IPEEE)

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1. The response to previous fire RAI #1 has not fully answered the question. To reiterate, NUREG-1407, Section 4.2 and Appendix C, and Generic Letter 88-20, Supplement 4, request that documentation be submitted with the IPEEE submittal with regard to the fire risk scoping study (FRSS) issues, including the basis and assumptions used to address .

these issues, and a discussion of the findings and conclusions. NUREG-1407 also I requests that evaluation results and potentialimprovements be specifically highlighted. l Control system interactions involving a combination of fire-induced failures and high l probability random equipment failures were identified in the FRSS as potential contributors to fire risk. ,

The issue of control systems interactions is associated primarily with the potential that a fire in the plant (e.g., the main control room (MCR)) might lead to potential control systems vulnerabilities. Given a fire in the plant, the likely sources of control systems interactions could happen between the control room, the remote shutdown panel, and shutdown systems. Specific areas that have been identified as requiring attention in the resolution of this issue include:

(a) Electricalindependence of the remote shutdown control systems:

The primary concern of control systems interactions occurs at plants that do not provide independent remote shutdown control systems. The electrical independence of the remote shutdown panel and the evaluation of the level of indication and control of remote shutdown control and monitoring circuits need to be assessed.

(b) Loss of control equipment or power before transfer:

The potential for loss of control power for certain control circuits as a result of hot shorts and/or blown fuses before transferring control from the MCR to remote shutdown locations needs to be assessed.

(c) Spurious actuation of components leading to component damage, loss-of-coolant accident (LOCA), or interfacing systems LOCA:

The spurious actuation of one or more safety-related to safe-shutdown-related components as a result of fire-induced cable faults, hot shorts, or component failures leading to component damage, LOCA, or interfacing systems LOCA, prior to taking control from the remote shutdown panel, needs to be assessed. This assessment also needs to include the spurious starting and running of pumps as well as the spurious repositioning of valves.

Enclosure

l (d) Totalloss of system function:

I The potential for total loss of system function as a result of fire-induced redundant component failures or electrical distribution system (power source) failure needs to be addressed.

New guidance from the Electric Power Research Institute (EPRI) is anticipated relative to the above control systems interactions issues. Please review and reconsider the response to the original RAI once the new guidance from EPRI is available. As requested in the original RAI, please 1) describe how plant procedures provide for transfer of control to the remote station (s),2) provide an evaluation of whether loss of control power due to hot shorts and/or blown fuses could occur prior to transferring control to the remote shutdown location and identify the risk contribution of these types of failures (if these failures are screened, please provide the basis for the screening), and

3) provide an evaluation of whether spurious actuation of components as a result of fire-induced cable faults, hot shorts, or component failures could lead to component damage, a LOCA, or an interfacing systems LOCA prior to taking control from the remote shutdown panel (considering both spurious starting and running of pumps as well as the spurious repositioning of valves).  ;

1

2. As part of previous fire RAI #4, the licensee was asked to quantitatively analyze the ]'

turbine building, auxiliary feedwater (AFW) pump rooms, and plant emergency diesel generator (EDG) areas, and provide the results. This information has not been provided.

Each of these areas had originally been qualitatively screened. The quantitative screening was done based on an assertion that the approach used was consistent with  ;

the fire-induced vulnerability evaluation (FIVE) method that was available at the time of the North Anna screening analysis.. This is not an appropriate basis because the FIVE methodology was specifically modified in this regard based on USNRC concerns that the original FIVE approach might lead to inappropriate screening of risk-important fire scenarios. The licensee has not substantiated that for North Anna screening of the three areas cited above is appropriate. The licensee further contends that the results of the j Surry IPEEE fire analysis, which used the revised version of FIVE, justified the North Anna qualitative screening. The Surry submittal results are not adequate to confirm this contention.

As in the previous fire RAI #4, please provide a quantitative analysis of fire risk for the Turbine Building, AFW pump rooms, and plant EDG areas and discuss the results. This should include a quantitative screening analysis of each area and detailed analysis of any of the areas that do not screen quantitatively.

3. The response provided to the previous fire RAI #7 has not fully answered the question.

The North Anna fire analysis assumed a cable ignition temperature of 773*K (932*F)

(see page 4-18 of the submittal). The study cites NUREG/CR-4550 as the basis for this value, but this temperature is significantly optimistic in comparison to piloted ignition temperatures observed in tests by Sandia National Laboratories (SNL) (ref.

NUREG/CR-5546) and recommended in FIVE. The SNL tests show that the piloted

\

Ignition temperature for cables are as low as or lower than the thermal damage threshold. The FIVE methodology (p 10.4-7 and Table 1 E) provided guidance  !

consistent with these SNL tests. Specifically, FIVE recommends that the piloted ignition '

and damage threshold temperatures be assumed to be the same (425'F for unqualified cables and 662*F for qua!ified cables). The use of the higher piloted ignition temperature in the North Anna analysis may have resulted in the optimistic treatment of cable fire growth behavior.

Further, the analysis has assumed a damage temperature of 623'K (662'F). This value is only appropriate for lEEE-383 qualified cables. The licensee response to the previous fire RAI #7 did not fully substantiate that the cables at North Anna are indeed equivalent to IEEE-383 rated cables because the cited flammability tests do not appear to be 1 equivalent to the full spectrum of tests associated with IEEE-383 qualification. More  ;

specifically, the licensee has not substantiated that the damage temperature used is an I appropriate indication of the damage threshold of the cables actually used at North Anna. The assessment of damage threshold should consider the type of insulation material used in cable construction and the available test data for various cable types.

In light of the above discussion, please provide the following:

(a) An assessment of the impact on the core damage frequency (CDF) analysis results if the cable piloted ignition temperature is assumed to be the same as the cable damage threshold.

(b) A more complete technical basis for assuming that the cables used at North Anna are equivalent to IEEE-383 qualified cables. In particular, describe the type of insulation and jacketing materials used at North Anna and demonstrate these materials are typical of cable constructions known to pass the IEEE-383 qualification standard. If this assumption cannot be substantiated on this basis, provide an assessment of the impact on CDF if properties of non-qualif5d cables are assumed.

Seismic There is no RAI in the seismic area.

Hioh Wind. Flood and Other External Events (HF ~ '

There is no RAI in the HFO area.