ML20216K066
| ML20216K066 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/14/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20216K059 | List: |
| References | |
| NUDOCS 9011200025 | |
| Download: ML20216K066 (2) | |
Text
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k UNITED STATES
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g NUCLEAR REGULATORY COMMISSION h E WASHINGTON, D. C. 20555
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i SAFETY EVALUATION BY THE'0FFICE OF NUCLEAR REACTOR REGULATION f,
10 CFR PART 50, APPENDIX R REQUIREMENTS FOR FIRE AREA 34B m*
FT. CALHOUN STATION, UNIT 1 DOCKET NO. 50-285 "1.0 INTR 000CTION d
Byl letters dated February 21 and June 22, 1990, the.0maha Public Power
. District (che >1icensee). requested an exemption from. Appendix R for Fire
, Area 34B. the upper electrica1' penetration room.
The licensee specifically.
requestr.d an exemption'from the technical _ requirements-of Appendix R,
- Sectir.1 III.G,2, in that, redundant safe' shutdown; cabling associated with reaccor coreLreactivity monitoring capabilities ~are routed through this fire-area and areLnot provided with the required level of fire protection.
12.0 EVALUATION =
Pursuant to 10'CFR 50.12, the' licensee requested an exemption to the. technical-requirements.of Appendix R,LSection III.G.2, for the wide range nuclear power Linstrumentation cabling located in the upper electrical penetration room (Fire
- Area.34B).
Channel 1 (cables dA3015, EA3016, EA3017, and.EA3018) and redundant Channel 3 (cables EC3022, EC3023, EC3024, EC3025, EC3026, and
.EC3027) cabling are routed through>this fire area.;-In Fire Area 34B,-the
. conduit cont' ining.theichannel 1 cable is separated'from the Channel 3 a
conduit by 34 feetQ The intervening space between these conduits co.itains
- combustibles in the form of' exposed cabling routed in cable trays.
)
Ionization-typeismoke detection capabilitys is_ provided throughout.the' fire area and;is. appropriately alarmed and annunciated both-locally'and in the control room.-;However, no-division of cabling is completely enclosed in a i
p 1-hour' fire barrier; and no automatic suppression system exists-ir the area.
The711censee's; req'estforan' exemption'fromthhseAppendixRreoairements u
for the' subject cables 'is. based on, an assumption' that actions described in.
4
-the station s Abnormal 10perating Procedures (AOPs)'and Emergency Operating.
Procedures (EOPs), which are required to maintain; safe shutdown of the plant, Lwill not-be negatively;affected by the potential--loss of core monitoring l
capability due.nto a' fire in the; upper.~ electrical penetration room.
The
- licensee propo'ses-that,iin the event of a worst' case fire in this area, monitoring-of the, core power level will. not.be.a significant factor.
1 L
Control Element' Assemblies will.have been previously inserted and emergency j
boration/ safety' injection 1(using,the boric acid storage tanks and, if f,
necessary, the-safety injection refueling water tank as a source of-borict I
acid),may be~in process or completed if the reactor coolant system-(RCS).
^
- parameters dictate.
The licensee holds that once negative reactivity insertion
'has;taken place -or is underway,~ the plant will meet or exceed the Technical Specification 2.10.2(1)_ shutdown-margin requirement of 4% delta k/k under any-analyzed reactivity excursion, and that the capability to monitor t' e core 1
n power,levelewill not affect the analyzed ability to remain shut down.
9011200025 901114 PDR ADOCK 05000205 7
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2-The staff, as a result of its'own evaluation, finds the licensee's exemption
?
request unacceptable.
The staff is concerned that the licensee does not have the capability to directly verify that the reactor has inde ed been shut down.
In the event that a' worst case fire occurs in Fire Area _34B, the fire could
- affect cabling associated with the pressurizer backup heaters, RCS sampling l:
capability, rod bottom control room indication, and wide range nuclear power instrumentation.
Therefore, the staff is_ concerned that a fire in this area could cause a loss of.the following:
(1) The wide range cabling routed through Fire Area 34B supplies the source, ss intermediate, and power range instrumentation in control room.
Loss of O
t these cables will. result in the loss of neutron flux indication in the N
cable room.
'(2); Cabling associated with-the rod bottom indication on the control room
~
-panel also passes through this fire area.
Fire in this area could affect the capability to verify that all the control rods were actually inserted.
y L
.(3). RCS sampling cannot be performed to determine actual boron concentration-as a. result of the fire affecting the control cable for the sampling: valve.
~
~(4) RCS pressure control could also b6'affected.: The fire could cause the-loss'of: redundant' cabling associated with-the pressurizer backup he'aters. : This requires the licensee to utilize-alternative shutdown-L capability for pressurizer pressure ar.d level control by= utilizing _the-auxiliary feedwater system,Lin manual control, to feed the' steam l
4 1:
generators.
R L'
The licensee' states that applicable'A0Ps and E0Ps to this scenario do not W
require 3" sampling" for boron concentration and that these procedures direct ithe= plant operators to trip the reactor and to emer? ncy borate. :The licensee-'
L would then rely on a calculated shutdown margin,- based on the quantity (and j
reactivity worth) of-boric acid injeci.d into:the"RCS:from-the start of the-scenario. LHowever, the' staff concludes that this_ method <is not an acceptable l
a'iternativetto directly verifying -that:there has been an effective: distribution
~
0, of > boric l acid in the RCS'during:the subject scenario, and that with none. of'
- the othercprocess monitoring parameters available, the licensee cannot be -
' assured'that the reattor has indeed been brought ~to safe shutdown
'i
~ 3.0 -CONCLUSION Ba'sedTon the' abova evaluation,.the; staff' concludes that the: current' level:
[
.of fire protecticn in Fire Area?34B;(upper electrical penetration room) does F
not provide 'an ec,uivalent level.ofj protection,l for wide range nuclear-: powert 0
- instrumentationichannels', to thatirequired by the technicalirequirements of-Appe'ndix R,Section III.G.2.
Therefore, the staff finds the' licensee's--
request lfor an: exemption from~the requirements of 10 CFR Part 50, Appendix R, Section'III'G.'2, to be unacceptable, and therefore, itlis denied.
4 Dated: _ NovemberL 14,--1990 '
~
Principal Contributor:
.D. Roberts t
.