ML20094R201
| ML20094R201 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 07/31/1984 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | NORTHERN STATES POWER CO. |
| Shared Package | |
| ML20094R203 | List: |
| References | |
| OL, TAC-53558, TAC-53559, NUDOCS 8408200489 | |
| Download: ML20094R201 (7) | |
Text
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UNITED STATES OF AMERICA NUCLEAR REGULATORY C0petISSION In the Matter of l
NORTHERN STATES POWER COMPANY.
Docket Nos. 50-282 and 50-306 i
(Prairie Island Nuclear Generating Plant Unit Nor. 1 and 2)
)
EXEMPTION
' ' I.
The Northern States Power-Company (the Ticensee) is the holder of Facility Operating License. Nos..DPR-4Z and. DPR-60 which authorize operation of the Prairie Island Nuclear Generating PTant, Unit Nos.1 and 2_
These Ticenses provide, among other things that they are subject to alt rules, regulations and Orders of the Comission now cr hereafter in effect.
The facility comprises two pressurized water reactors at the l'icensee's site located in Goodhue County, Minnesota.
II..
On November 19, 1980, the Comission published a revised Section 10 CFR 50.48 and a new Appendix R tn 10 CFR 50 regarding fire protection features of nuclear power plants (45 FR 76602). The revised Section 50.48 and Appendix R became effective on February 17, 1981.Section III of Appendix R contains fifteen subsections, lettered A through 0, each of which specifies requirements for a particular aspect of the fire pro-l tection features at a nuclear power plant. Two of these fifteen subsections, I
III.G. ana III.0, are the subject of this exemption request. Specifically, Subsection III.G.2 requires that one train of cables and equipment necessary l
to achieve and maintain safe shutdown be maintained free of fire damage by:
" Separation of cable and equipment and associated non-safety circuits of i
8408200489 840731 PDR ADOCK 05000282 F
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2-of redundant trains by a horizontal distance of more than 20 feet with with no intervening combustibles or fire hazards." This requirement is app 11 cable because the fire areas being considered are inside a noninerted containment Subsection III.0 requires that the reactor coolant pumps shall be equipped with an off coTiectiom system capable of collecting lube oil front all potential pressurized and unpressurized leakage sites and drained to a vented. closed container that can hold the entire lube oil system in-ventory.
III.
'By letter dated January 23,1984 as supplemented by Tetters dated 2
. the Ticensee requested an exemption from the require-April 5 and May 22,1984, ment of Subsection III.G.Z of Appendix R in two (2) fire areas as fI)1 Tows:
1 Fire Area 1 containment Unit 1 all elevations Fire Area 71 containment Unit 2 all elevations In the same submittals, the licensee also requested an exemption from the requirements of Subsection III.0 related to draining the reactor coolant pump lube oil leakage to a vented closed container.
IV.
Fire Area 1 (Unit I Containment) and Fire Area 71 (Unit 2 Containment)
.The licensee requested an exemption from Subsection III.G.2 to the extent that these areas have intervening combustibles between components of redundant trains needed for safe shutdown.
In addition, except for the redundant cabling associated with the pressurizer level transmitters for 1
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l unit 2 (Fire Area 71), all other redundant components are separated by twenty feet or more. The redundant cabling associated with the pressurizer level trans-mitters is separated by ten feet. For this: cabling the licensee has committed tar p;otecting one division with a one-hour fire barrier.
The combustibles in these fire ' areas. are Tubricating oiT and cable 2
insulation. having a totaT fuel load, of 22,520 Btu /ft for Fire Area 1 (Unit I Z
containment) and 22,915 Btu /ft for Fire Area 71 (Unit Z containment).
Approximately 50% orthfs fuel (Toad consists of the reactor coolant pump lube oil that, if a leak should occur, would drairr to-the containment sump. The ignition of the Tube oiT would result in fire damage to only one of the redundant trafns since in the area okthe sump fire the other train is protected
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=v by arr 18 inches thicic concrete floor) spanning the entire horizontal plane of the containment butiding except for the stairwell. at the perimeter Isf the buf1 ding. The onTy other combustible existing within the spacing of the redun-dant trains in Fire Area 1. is cable insulation representing a fuel load of 9,965 2
Btu /ft with no areas of concentrated. combustibles. This fuel, if totally con-sumed, would correspond to a fire severity of 7~.5 minutes on the ASTM E-119 standard temperature curve. Similarly, in Fire Area 71, the only other combus-tible existing within the spacing of the-redundant trains is insulation cabling 2
representing a fueT load of 10,320 Btu /ft. This fuel, if totally consumed, would yieTd a fire severity of 7.7 minutes on~the ASTM E-119 standard time tem perature curve.
In addition, as stated by the licensee, all cabling in both fire areas is qualified to IEE-Std-383. The cable has a high resistance to flame propagation and excellent flame retardant qualities.
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I
9.
I The fire protection in these areas consists of ionization smoke detectors on all floor Tevels with aTarms to the control room and j
standpipe hose' stations on each floor level. In addition, access to these fire areas is restricted during power operation due to existing high radiation fields during: these periods.
We agree with the licensee chat, because of the relatively small amount l
of inter.vening combustibTes in the areas between redundant trains,.and because aTT cables in the fire areas are IEEE-383-qualified, any postulated fire of potentially hazardous size would be caused by transient combustibles Hazardous quantities of transient' combustibles would not be expected in these fire areas
~ for the reason mentioned above (resth.eted during operation).
Transient com-bustibTes are not normaTTy aTTowed in containment _ On-rare occasions, when a Timited amount of transient combustibles. is permitted, administratiIre controis require as _.a minimum,. a dedicated fire watch armed with a fire extinguisher-(
r The existing passive protection is adequate for redundant cabling until the fire brigade can extinguisit the fire.
l Based on our evaluation, the level of existing protection for Fire 1
Areas 1 and 71 provides a level of protection equivalent to the require-ments specified in Subsection III.G.2 of Appendix R.
Therefore, the exemption from the requirements specified in Subsection III.G.2 for these fire areas is granted.
e i
- 5.-
Reactor Coolant Pump Lube Oil Collection-System - Subsection III. O of Appendix R-The Ticensee requested an exemption from Subsection III.0 to the extent that the reactor coolant pump:1ube oft collection system is piped to the-sump inside containment. The contents of the sump can be pumped to a closed vented container located:in the> auxiliary buiTding. The licensee states that the sump in the basement of the containment is a concrete pit having a capacity of 990 gallonn whicir. is more than the capacity needed to contain the total inventory of~ Tube oil for the two reactor coolant pumps-for each unit There is no safe shutdower equipment in the area. The sump is designed
- n to automaticaT1y pump down.at a'presc'ribed sump level and an alarm will sound in t.t :-; y the control room if this level, is exceeded. The operator can initiate manual control of the sump pump at ny tin $e overriding the automatic conthl of sump-leveT. The. sump is normally drained to vented containers in the auxiliary-building having a total capacity of 2600 gallons. The basis for the design of this collection system is to collect any contaminated water from the pump seal Teakage as well es any oil leakage.
In addition, the pipe from the sump to the vented container in the auxiliary building has been designed to seismic category Class III which l
meets the requirement of Regulatory Guide 1.29, paragraph C-2..
If failure of this pipe were to occur during a seismic event, the functions of plant features described in paragraph 1 (a through q) of Regulatory Guide 1.29 will not be affected and the plant can be brought to cold shutdown. This is based on a review conducted by the licensee and confirmed by letter dated May 22, 1984.
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~6-We agree with the Ticensee that, although lube oil leakage is collected in the sump before it is pumped to a vented container, the sump design at this plant assures us that oiT collected there will not lead to fire during normal or design basis accident concitions. The capacity of the sump and the vented containers is adequate to safely con-tain any anticipated Tube oil' leakage and-the existing controls provide reasonable assurance that any tube oil collected in the sump can be safely pumped to the vented container in the auxiliary building.-
Based on our evaluation, the exi ting lube oil collection system for reactor coolant pumps provides a leveT of protection equivalent to the requirements specified in Subsection III.0 of Appendix R.
Ther*efore,
the exemption from the requirements specified in Subsection III.0 for the lube oil collection system is granted.
V.
Accordingly, the Connission has detennined that, pursuant to 10 CFR 50.12, an exemption is authorized by law and will not endanger life or property or connon defense and security and is otherwise in the public interest and hereby grants an exemption from the requirements of Subsections III.G.2 and III.0 of Appendix R to 10 CFR 50 to the extent discussed in Section IV above.
L
. l Pursuant to 10 CFR' 51.32, the Commission has detennined that the issuance of the exemption will have no significant impact on the environment (49 FR 29169 ).
This Exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY COMMISSION 11 Alnl 1Y Tarirel
. Usenist,Tirector Division of Licensing Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 31 day of July,1984
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