ML20057A209
| ML20057A209 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 08/31/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057A204 | List: |
| References | |
| NUDOCS 9309130204 | |
| Download: ML20057A209 (8) | |
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UNITED STATES
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j NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20 lie 64001 o
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUtATION RELATED TO A RE0 VEST FOR EXEMPTION FROM FIRE PROTECTION REOUIREMENTS OF 10 CFR PART 50. APPENDIX R COMMONWEALTH EDISON COMPANY ZION NUCLEAR POWER STATION. UNITS I AND 2 DOCKET NOS. 50-295 AND 50-304
1.0 INTRODUCTION
By letter dated August 5,1992, Commonwealth Edison Company (Ceco, the licensee) provided additional infc,rmation concerning the in-situ combustible r
l loading level in eight areas at the Zion Nuclear Power Station, Units 1 and 2.
For each of these eight areas, the staff previously reviewed and approved l
exemptions from specific requirements of 10 CFR Part 50, Appendix R, Section III.G in letters dated March 7,1983, and June 7,1988. A recent survey of each area by the licensee indicated that the values of the combustible loadings stated in the licensee's exemption requests dated July 30, 1982, and July 27,1984, as supplemented by letters dated August 31, 1984, January 24, i
1985, February 23, 1988, February 18, 1989, February 9, 1987, and January 21, 1988, were no longer accurate. The in-situ combustible loading in each area had increased. The majority of the increase in combustible loading in each area is due to cable insulation installed for various modifications. Once the licensee discovered that the combustible loading in the areas was no longer t
accurate, compensatory measures were put into place in the form of roving fire watches.
The staff visited the site on June 25, 1993, to review each area discussed in the licensee's August 5,1992 letter. Below is the staff's evaluation of each of the eight areas. The staff reviewed the amount, type, and configuration of the new combustible loading values to determine if conclusions reached previously in granting exemptions from Appendix R remain valid. The licensee's August 5,1992, letter also requested that the staff review and approve combustible loading limits higher than the existing in-situ combustible loading because future modifications which may occur at the plant i
may add combustibles to the fire areas. The staff can not approve such requests because without knowing the specific type, nature, and geometry of the combustibles, the staff would not have reasonable assurance that an i
adequate level of fire protection will be maintained. Therefore, the adequacy of each area discussed below is based on combustible loading values as they currently exist in the plant as stated in the licensee's Zion Station Fire Protection Report dated September 15, 1992.
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2.0 EVALUATION 2.1 Fire Area / Zone 2.0-0: Main Control Room An exemption from the requirements of 10 CFR Part 50, Appendix R, Section III.G.3 to install an area wide fixed fire suppression system was previously granted for this area in a safety evaluation dated June 7, 1988. The justification for granting the exemption was based on the presence of early warning fire detectors and the continuous manning of the control room, allowing a probable fire to be detected in its incipient stages and be extinguished by the fire brigade.
In addition, another factor in reducing fire risk is the installation of alternative shutdown capability independent of the control room. The fyel load evaluated in the exemption was approximately 39,000 BTU /ft. The existing in-situ combustible loading is approximately 68,000 BTU /ft,. The increase in combustible loading is primarily cable insulation from additional cabling installed in support of various plant modifications. The majority of the cables have been installed in existing horizontal cable trays and are qualified to IEEE Standard 383.
Appendix R,Section III.G 3 requires the installation of a fixed fire suppression system for all areas in which alternative shutdown capability is selected in lieu of separation of redundant safe shutdown components to preclude anticipated fires from spreading from the area / zone / room under consideration.
The increase in the amount, type, and configuration of the combustibles in the controi room does not significantly increase the probability of a fire overcoming the existing fire protection features of the control room. A fire in the control room would be detected in its incipient states allowing easy extinguishment by the fire brigade. The alternate shutdown capability would ensure safe shutdown of the plant if damage to redundant cabling.or controls occurred.
The staff finds the increase in the combustible loading value in the control room does not alter the conclusions reached in the previous exemption.
Further, the staff continues to find that the installation of an area wide fixed suppression system would not significantly increase the level of fire protection in the control room.
2.2 Fire Areas 5.6-1 and 5.6-2: Auxiliary Electric Eouipment Rooms An exemption from t h requirements of 10 CFR Part 50, Appendix R, Section III.G.3 to install an area wide fixed fire suppression system was previously granted for these two areas in a safety evaluation dated June 7,1988. The justification for granting the exemption was the installation of early warning fire detectors coupled with the alternative shutdown system which has been installed independent of the fire areas. Thecombustibleloadinginthefire areas evaluated in the exemption was approximately 63,000 BTU /ft for each The in-situ combustible loading in each area is approximately 147,000 area.
BTU /ft' for Fire Area 5.6-1 and 121,000 BTU /ft for Fire Area 5.6-2.
The 2
increase in combustible loading is primarily cable insulation from additional insulated cables installed in support of various plant modifications. The added cables are qualified to IEEE Standard 383.
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III.G.3 requires the 3-
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alternative l
50, Appendix R, Section where system is l
areas system for suppressionunder not CFR PartsuppressionThe fixed firearea/ zone / room area does
>dicated above,10 area, overcoming fire of a fixed fire rovided.
in each spread of fire from the load is h
l capability has been p le loading either l
allation the majority of whic f a fire, inadditional combustib e additional combustib the rated, with
, iired to preclude down ase the probability oexisting cable trays, The are 3-hour firedampers, and penetratio The fire protection features. surrounding each area l sideration..nificantly incre rated doors,ld be detected in its i
installed in and extinguishedwould contain
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l3 existingom qualified cablested with approved f rein either a it wou system walls i
affected redundant The e horizontal.
startearly warning The fire If a firedependent of these fire
.Jenings protecShould a fire shutdown panels, in the fire brigade.within the two fire areas.
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' ncipient states by t e eals.
alternative down the plants.
vith manual hoses byany anticipated firesequipmentuse the l
combustible loading,installationtly increase the safely shut l
valid and the shutdown safe areas, would be ite the increase instaff remainwould not significan l
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staff finds that desp+ ched by the system 94 two l
suppressionareas.
1 va on conclusions previous ywide fixed firetection in these The om m
' n staff concluded that aendix R, Sect 1 G2 area Remov the level of fire pro Re idual of an ea
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d June 7,1988, the and automatic fireredundant uildin of 10 CFR Part 50, Appt of separat uxiliar n
2.3 safety evaluation date tection and to provide 20 feeearly warning fire de quirements of the his aluated in drawing t exemption from the re 42 foot elevation is In a combustible loadingloading is prima wide to install areacomponents for the 5 combustible loading ev support of systems actual in-situ l
suppression additional combustib e E Standard ables installed inare qualified to shutdown The The was not required.was 5,000 BTU /f t',.
majority safe The The additional insulated c BTU /ft.
ble trays.
the new cables zone 11.1-0 which is approximately 18,000 conclusion existing horizontal ca major The The (RHR) pump cable insulation from auxiliary building. residual heat tions.
was in fire various plant modifica llcd in 383 and have been instacombustible loadingon this sepa increase of the and to have elevation of the Appendix R, Sectionrepaired site j
on area ble of the area is the Due to the limited separ sufficient qualified ca i
general accessconcern in this The with 10 CFR Part 50, it could becold shutdown.in
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each un cables.
maintain achieve start could accordancefor one RHR pump forrequired to were to de powerhad committed to If a firecables, the fire brigaoperator repair procedures in affect l
were III.G.I.b so that cablescombustible loading isRHR the pumps minimal.
ystem being required 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> following a fire before redundant and make thetem prior to the RHR s increase inand damage the at least fire uired for still extinguish the area repairs to the RHR sysThe RHR system is not req l
i ower.
I the scram from 100 percent p shutdown.
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The staff finds that despite the increase in combustible loading, the conclusions previously reached by the staff remain valid and that for this area, the fire protection features continue to meet the requirements of 10 CFR 50, Appendix R, Section III.G.I.b.
An exemption is, therefore, still not required.
2.4 Auxiliary Buildina Elevation 560 feet:
Component Coolina Water Pumo Area An exemption from the requirements of 10 CFR Part 50, Appendix R, Section III.G.2.b to install area wide automatic fire suppression and detection systems and to provide 20 feet of separation between redundant components was previously granted in a safety evaluation dated June 7, 1988. This area of the auxiliary building contains 16 separate fire zones. The main safe shutdown components in this area of the auxiliary building are the five component cooling water (CCW) pumps and their associated power and control cables. Automatic fire suppression and detector systems have been installed in the vicinity of the CCW pumps and their associated power and control cables. The combustible load evaluated for the original exemption was 2
approximately 21,000 BTU /ft. The current in-situ combystible loading in the CCW pump area fire zones is approximately 55,000 BTU /ft.
The majority of the increase in combustible loading in the various zones on the 560 foot elevation is due to insulated cable installed in support of various plant modifications.
The additional cables have been routed in the existing cable tray system without the need for physical changes with respect to their location relative to safe shutdown equipment and are qualified to IEEE Standard 383.
Separation of redundant CCW pumps and associated cabling remains at a minimum of 50 feet.
The combustible loading in the fire zones containing safe shutdown equipment remains relatively low.
If a fire were to start, it is expected to develop slowly with, initially, low heat release. The early warning fire detection system will alert the fire brigade of the existing fire and the automatic local application carbon dioxide (C0 ) extinguishing system installed over the 2
five CCW pumps would extinguish or contain anticipated fires prior to final j
extinguishment by the fire brigade.
j The additional combustible loading is of the type and configuration that it does not pose a threat to the existing safe shutdown capability.
The existing fire protection features and the configuration of safe shutdown equipment, despite the additional combustible loading continue to ensure that for anticipated fires, one train of safe shutdown components will remain free of fire damage. Therefore, the staff finds in spite of the increase in combustible loading, that the conclusions reached in the previous exemption remain valid.
2.5 Auxiliary Buildina Elevation 579 feet:
Auxiliary Feedwater Pumo Area An exemption from the requirements of 10 CFR Part 50, Appendix R, Section III.G.2.b to install an area wide automatic fire suppression and early warning detection system and to provide 20 feet of separation between redundant components was previously granted in a safety evaluation dated June 7,1988.
The largest combustible loading in the area of concern exists in Fire Zone l
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11.3-0, containing redundant safe shutdown equipment.
Intheopiginal j
exemption, a combustible loading of approximately 19,000 BTU /ft was evaluated r
in this Fire Zone. The actual in-situ combustible loading in Fire Zone 11.3-0 2
is approximately 48,000 BTU /ft. As indicated previously, the increase in combustible loading is primarily cable insulation from additional cabling installed in support of various plant modifications.. The cables have been installed in existing horizontal cable trays and are qualified to IEEE Standard 383.
A The 579 foot elevation of the auxiliary building includes 16 fire zones.
Safe shutdown components on this elevation consist of both units' centrifugal l
charging pumps and their associated power cables, both units' auxiliary l
feedwater (AFW) pumps and their associated power cables, and power cables for the six service water pumps. Additionally, the remote shutdown panels for both units are installed on this elevation as well as the instrumentation cables for the steam generator pressure transmitters.
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In the previous exemption for this elevation, the staff's primary concern with the level of fire protection was that because of the absence of an area wide l
automatic fire suppression system, a fire of significant magnitude could damage redundant safe shutdown systems.
The staff found that the early warning fire detection system installed in area i
zones containing safe shutdown equipment, coupled with significant spatial l
separation and the local automatic CO extinguishing system for the AFW pumps, 2
would provide adequate protection to ensure one train of safe shutdown i
equipment would remain free of fire damage.
As indicated above, the change in combustible loading is due primarily to the l
installation of qualified insulated cable in existing horizontal cable trays.
t The additional cables have not been installed in any one concentrated area, i
but throughout Fire Zone 11.3-0.
Based on the site walkdown of the area and the existing fire protection features, the staff finds that the existing early warning fire detection system, in conjunction with the local 00 automatic 2
fire suppression system and the separation of redundant safe shutdown j
equipment, provides adequate protection in spite of the increase in i
combustible loading.
l Therefore, based on the above, the staff finds that in spite of the increase in combustiFle loading on the 579 foot elevation of the auxiliary building, i
the conclusions reached in the previous exemption remain valid.
i 2.6 Auxiliary Buildino. Elevations 592 Feet. 617 Feet. and 642 Feet l
An exemption from the requirements of 10 CFR Part 50, Appendix R, Section III.G.2.b to install area wide automatic fire suppression and detection systems and 20 feet free of combustibles between redundant safe shutdown components was previously granted in a safety evaluation dated June 7,1988.
In the auxiliary building, the 592 foot elevation contains 13 fire zoles, the 617 foot elevation contains 13 fire zones, and the 642 foot elevation contains I fire zone. Safe shutdown cabling associated with the residual heat removal, t
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. component cooling water, auxiliary feedwater, centrifugal charging, and service water pumps for both units are routed through these elevations of the auxiliary building.
The previous exemption was granted with a maximum 2
combustible load of approximately 18,000 BTU /ft in Fire Zone 11.4-0 on the 592 foot elevation, approximately 23,000 BTU /ft in Fire Zone 11.5-0 on the 2
617 foot elevation, and approximately 36,700 BTU /ft in Fire Zone 11.6-0 on the 642 foot elevation. The actual in-situ combustibly loading in each of the abovefirezopeswas:
Fire Zone 11.4-0, 41,000 BTU /ft, Fire Zone 11.5-0, 56,000 BTU /ft, and Fire Zone 11.6-0, 57,000 BTU /ft. The majority of the combustible loading increase is due to cable insulation on additional cabling that has been installed primarily in existing horizontal cable trays in support of various plant modifications and is qualified to IEEE Standard 383.
The previous exemption was granted based on the location of early warning fire detectors in the area of safe shutdown cables on these elevations and the spatial separation between redundant cables on these elevations. The additional cables have been installed in such a configuration and are of a type that the increase in combustible loading will have minimal effect on the existing fire protection features on these elevations.
For anticipated fires on any of the elevations, the fire detection system will provide adequate early warning to allow a rapid response by the fire brigade. The existing l
spatial separation between the redundant cables will still provide adequate passive protection in spite of the increase in combustible load to allow adequate time for the fire brigade to respond and extinguish the fire on any of these elevations.
Therefore, the staff finds that in spite of the increase in combustible loading, the conclusions reached in the previous exemption i
remain valid.
2.7 Fire Areas 18.4A-0 and 18.48-0: Outer and Inner Cribhouse An exemption from the requirements of 10 CFR Part 50, Appendix R, Section III.G.2.a to separate redundant components by 3-hour rated fire barriers or provide an alternate shutdown capability independent of the areas was previously granted in a safety evaluation dated March 7,1983. Safe shutdown components of concern consist of six service water pumps and their associated cables. The combustible loading evaluated in the original exemptipn for Fire Area 18.4A-0, the Outer Cribhouse, was approximately 12,000 BTU /ft and Fire Area 18.4B-0, the Inner Cribhouse, was approximately 23,000 BTU /ft,for The currentin-si}ucombustibleloadinginFireArea18.4A-0isapproximate,1y 23,000 BTU /ft and for Fire Area 18.4B-0 is approximately 33,000 BTU /ft.
The majority of the combustible loading increase is due to cable insulation on additional cabling that has been installed primarily in existing horizontal i
cable trays in support of various plant modifications and 1., qual'fied to IEEE Standard 383. The principal safe shutdown equipment in these two Jire Areas l
are the safety related service water pumps and their associated cabling.
The staff previously granted an exemption from the requirements of separating redundant equipment with 3-hour rated fire barriers based on the spatial separation from combustibles of the service water pumps and their associated cabling, early warning fire detection, local application automatic fire suppression systems, and a low in-situ combustible loading. The amount of 1
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combustibles added to each area is no greater than 11,000 BTU /ft, keeping the 2
amount of in-situ combustibles in each area low. Therefore, the staff finds the current plant configuration is still within the acceptable parameters of existing fire protection in each area, and the conclusions reached in the previous exemption remain valid.
2.8 Fire Areas 18.5-1 and 18.5-2: Main Steam Pioe Tunnels l
An exemption from the requirements in Section III.G.2.b for area wide detection and fire suppression was previously granted in a safety evaluation dated June 7, 1988. The in-situ combustible loading has cot increased above the previously evaluated value, therefore, no further eva'Iuation is required.
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3.0 COMCLUSION Based on the above, the staff finds that the conclusions reached when granting f
the exemptions in the safety evaluations dated March 7,1983, and June 7, 1988, are still valid.
Principal Contributor: John Stang Date:
August 31, 1993 i
i
4 Mr. D. L. Farrar teached in the previous exemption remain valid. Therefore, additional exemptions are not required.
Sincerely, 7
?/d/'2.AbdlL M1yde Y. Shiraki, Senior Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV/V Office of Nuclear Reactor Regulation
Enclosure:
Safety Evaluation cc w/ enclosure:
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