ML20205R995
| ML20205R995 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/04/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20205R999 | List: |
| References | |
| NUDOCS 8811100211 | |
| Download: ML20205R995 (3) | |
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ENCLOSURE SAFEi? EVALUATION BY THE OFFICE OF SPECIAL PROJECTS RELATIVE 'O RE0 VEST FOR A CEVIATION FROM APPENDlX R RE0ll!RENENTS TENNESSFE VALLEY AUTHORITY
{E0l'0YAH NUCLEAP P3WER PLANT. UNITS 1 AND 2 DOCKJTNOS.503?7AND50-378
1.0 INTRODUCTION
By letter dated Ltober 13, 1988, the licensee requested NRC approval of a deviation from 10 CFR Part S0, Appendix R Section !!I.G.2 in regard to fire resistance of fire barriers around redundant trains and the required
- re suppression systen.
Section I!!.G.2 of Aopendix R requires that reo ) dant safe shutdown components be seDarated from each other by one of the followi. I rrethods:
- 1) Separation of cables and equiprent and associated non-safety circuits of redundant trains by a fire barrier having a 3-hour rating.
Structural steel forning a part of or supporting such fire barriers shall be protecte. to provide fire resistance equivalent to that required of the barrier.
- 2) Senaration of cables and equ'pw nt and associated non-safety cire.dts of redundant trains by a horizontal distance of rare than 20 feet with no intervening cerbustible or fire hazards.
In addition, fire detectors and an automatic fira suppression system shall be instal ed in the fire area.
Accort.ing to the Sequoyah fire hazards analysis (FPA), all of the battery board rooms are protected by automatic preaction surpression system and by one-hour fire resistant wrap in ccepliance with Item C of Section III.G.2 On October 5, 1988, the licensee discovered that the creaction suppression syste4,was dctually controlled by hand valves rather than detector activated preaction valves.
This was identified as a noncorpliance with Section !!!.G.? of Appendix R.
The licensee notified the N2C and initiated Condition Adverse tn Quality Peport (CAQR) Snp 880513, 8311100211 831104 FDR ADOCK 05000327 p
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2.0 EVALUATION The interactions in the 125 volt vital battery board rooms are as follows:
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- 1) Cables IPP750A and IPP759A (6.9 LV feeds to 480 volt shutdown boarc transformers 1A-A and 1A2-A, ressectively) were routed and protected through the fifth vital baMery board room. A fire in the fifth vital battery board room with the fifth vital battery I
system in service to vital battery systems !! or !Y could cause loss of either of these train B associated uc power systems,
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and loss of the above specified Unit I train A shutdown board i
transformer feeds, j
?) Cable B1641 1. routed through vital battery board room II and provides power supply from the fif th vital battery to battery boa rd I.
Cable B1681V is routed through vital battery board reon III and provides a power supply f rom the fif th vital l
battery to battery IV. With the fifth vital battery in service, t
a fire in either of thase two rooms could cause loss of two redundant channels of de vital power systemc.
- 3) Cables 182511 and 1830l! were installed in battery room I and cables PP11111 and 2B16111 were installed in battery board room IV.
These cables are the normal de ocwer supply cables to 4BO-V shutdown boards IB1-B, IP2 0. ?Al-A and 2A2-A. A fire in either of these l
rooms could cause loss of a de power control bus of the boards, pl-l loss of the aoolicable channel of vital de sucoly.
l The licensee has already provided an hnurly fire watch as a compensatory rteasure for the affected areas.
The dev!ation request is to allow
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restart of Unit 1 and continued operatten of Unit 2 with the compensatory reasures now in place.
The licensee,iustifies this deviation on the basis of the low fire loadinq inside the rooms.
According to the licensee's FWA, loading in the 125 volt i
vital battery board rooms is about 20,000 BTU /ft' which corresponds to an i
equivalent f.re severity of 15 ninutes under the standard curve.
The staff l
inspected these reces on Septerber 5, 1988 and agrees with the description of f
fire loading in the FHA.
Sore of this fire loading is in conduits, I
it is the staff's conclusion that a fire in one of the vital battery roocs would not damage the redundant protected train even with the lack cf automatic Suppression.
The hourly fire watch will assure that transient combustibles, which could increase the fire leading, are not inadvertently stored in the i
- rooms, j
By letter of October ?0, 1983, the licensee requested that the tern of the
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deviation be ia effect until the Unit 1 Cycle 4 refueling outage.
This date is consistent with TVA's present comitrents for corrpletion of redificatiens for Interaction Nos. 90 and 91 for source rarre instrumentation and long term I
corrective actions to prevent spurious operation of the voluFe control tank outlet valves (Interaction No. 120).
The licensee also cemitted to subnit to l
NRC by Decerber 21. 1988, the long-term actions to te taken at the plant to l
resolve this deviation.
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3.0 CONCLUSION
The staff concludes that the deviation request, in recard to Section !!!.G.?
in the 125 volt vital battery board rooms, should be granted.
The compensatory measures initiated by the licensee rust remain in effect during that period that thi. deviatir.1 is granted er until the plant is returned to compliance with Appendix P, Section !!1.G.?.
The staff also concludes that the existing clant condition with a low fire loadino and the compensatory reasures for the vital battery load rooms have l
provided an ecuivalent level of fire protection to Section !!!.G.2 and the plant remains within the requirenents of r,eneral Design Criterion 3. Fire Protection, of Appendix A to 10 CFR Part 50.
It is the staff's conclusion that, with th' fire loading for the rooms, a fire in one of the rooms would not damage the redundant protected train even with the lack of automatic i
suppression.
Principal Contributor:
R. Wesecct i
Dated: NOV 4 199 4
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