ML18152B413
| ML18152B413 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/11/1999 |
| From: | Edison G NRC |
| To: | NRC |
| References | |
| TAC-M83681, TAC-M83682, NUDOCS 9905130196 | |
| Download: ML18152B413 (2) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION NOTE TO:
FROM:
SUBJECT:
WASHINGTON, D.C. 20555--0001 May 11, 1999 GSock-;t--Fii-~s-so,,2ao_a~d-_so-2a 1 Gordon E. Edison#
REQUEST FOR ADDITIONAL INFORMATION (RAI) (TAC NOS. M83681 AND M83682)
On May 5, 1999, I faxed the enclosed RAI for IPEEE that was sent to DLPM by Office of Research (Mark Cunningham), dated April 26, 1999. I called the licensee (Gary Miller) and he agreed to a 60-day response, subject to change if their engineering staff determine more time is needed.
cc: PDR Alan Rubin (RES) 9905130196 990511 PDR ADOCK 05000280 P
---r-,
ATIACHMENT SURRYIPEEE Supplemental Request for Additional Information Based on your submittal and response to requests for additional information (RAls) received to date (in your September 28, 1998 letter entitled "Virginia Electric and Power Company, Surry Power Station Units 1 and 2, North Anna Power Station Units 1 and 2, Individual Plant Examination of External Events (IPEEE),* Request for Additional Information") for the Surry IPEEE, the staff is unable to conclude at this time that you have met the intent of Supplement 4 to GL 88-20, and we need more information before we can complete our review.
In particular, the response provided to the previous fire RAI #3 has not fully answered the question. The Surry 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, but this value is significantly optimistic in comparison to piloted ignition temperatures observed in more recent 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 will be as low or lower than the thermal damage threshold. The FIVE methodology (p 10.4-7 and Table 1 E) provided guidance consistent with these newer 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 qualified cables). The use of the higher piloted ignition temperature in the Surry 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 IEEE-383 qualified cables. The response to the previous fire RAI #3 did not fully substantiate that the cables at Surry are indeed equivalent to IEEE-383 rated cables because the cited flammability tests do not appear to be equivalent to the full spectrum of tests associated with IEEE-383 qualification. More specifically, the response did not substantiate that the damage temperature used is an appropriate indication of the damage threshold of the cables actually used at Surry. The assessment of damage threshold should consider the type of insulation material used in cable construction and the available test data tor various cable types.
(1) Provide an assessment of the impact on the analysis results (GDF) if the cable piloted ignition temperature is assumed to be the same as the cable damage threshold.
(2) Please provide a more complete technical basis for assuming that the cables used at Surry are equivalent to IEEE-383 qualified cables. In particular, describe the type of insulation and jacketing materials used at Surry 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 GDF if properties of non-qualified cables are assumed.