ML20044C099
| ML20044C099 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 03/09/1993 |
| From: | Mccarthy D CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS-93-056, NLS-93-56, NUDOCS 9303170217 | |
| Download: ML20044C099 (8) | |
Text
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9 1993 SERIAL: NLS-93-056 United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 205555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 PROPOSED REVISION OF FIRE PROTECTION COMMITMENT REGARDING CABLE VAULT AREA Gentlemen:
The purpose of this letter is to provide the technical basis for revising a fire protection program commitment at Carolina Power & Light Company's Brunswick Nuclear Plant, Unit Nos 1 and 2.
The proposed revision has previously been discussed with members of the NRC staff in a January 21,1993 telephone conference call.
Carolina Power & Light Company proposes to downgrade certain Control Building block wall fire barriers to non-fire rated walls and permanently remove the access doors located in these walls.
These block walls were originally instal.ad, as discussed in the 1977 NRC Fire Protection Safety Evaluation Report (SER), to provide separation between the normal shutdown trains. The areas were later analyzed under 10 CFR 50, Appendix R, as one fire area without crediting the block wall barriers. Downgrading the barriers eliminates the need for the doors installed in the walls, allowing the doors to be permanently removed. Removal of the doors provides a vent path to stabilize pressure across the block walls during a tornado event. Enclosure 1 of this submittal provides the technical basis for this change.
In order to facilitate elimination of temporary administrative controls currently in place to monitor the door removal, CP&L requests that the NRC provide a position on this request by July 12,1993.
Please refer any questions regarding this submittal to Mr. D. B. Waters at (919) 546-3678.
Yours very truly,..
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D. C. McCarthy Manager Nuclear Licensing Section KAH/kah - (nis93056.wpf)
Enclosure ec:
Mr. S. D. Ebneter Mr. P. D. Milano.
Mr. R. L. Prevatte 170109 411 Fayettevdle Street
- P O. Box 1551
- Raleign,.N C. 27602 9303170217 930309 c -== =~~~'#EE5MIEQKEINA 1]
gDR ADOCK 05000324
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ENCLOSURE 1-i BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 NRC DOCKET NOS. 50-325 & 50-324 OPERATING tlCENSE NOS. DPR-71 & DPR-62 CABLE VAULT FIRE AREAS -
s DESCRIPTION OF THE FIRE AREA The Cable Vault Fire Areas are located in the north and south ends of the Control Building and contain the following features:
1.
The fire area boundary walls separate adjacent fire areas utilizing three-hour rated barriers on each elevation of the Control Building (Refer to Figures 1 and 2).
- 1 2.
Fire Detection is provided throughout the fire area.
3.
Manual Fire Suppression Systems are provided in adjacent fire areas.
4.
Access is limited through single tornado pressure doors from the Control and Cable Spreading Rooms on each elevation of the cable vault.
5.
No permanent electrical or mechanical equipment is located in the fire area, except for normal and emerDency lighting.
6.
The fire area acts as a cable routing path from the Reactor Building to the Control Room -
and Cable Spreading Rooms. PVC jacketed conduit, coated with flame retardant material, is.
utilized to route the cable through the fire area. No cable tray is located in the fire area.
7.
Fixed combustible loading for the area consist of the PVC jacketed conduits, coated with i
flame-retardant material.
8.
Alternate Shutdown Capability is provided independent of the Control Building.
PROPOSED PLANT CHANGE Carolina Power & Light Company proposes to downgrade the block wall fire barriers reflected on Figures 1 & 2 to non-fire rated walls and permanently remove the access doors located in these
. walls. These block walls were installed, as discussed in the 1977 NRC Fire Protection Safety Evaluation Report (SER), to provide separation between the normal shutdown trains.1The areas'
- were later analyzed under 10 CFR 50, Appendix R, as one fire area without crediting the block wall barriers. ' Downgrading the barriers eliminates the need for the doors installed in the walls, allowing.
the doors to be permanently removed. Removal of the doors provides a vent path to stabilize l
pressure across the block walls during a tornado event.
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EVALUATION The 1977 Fire Protection SER (Reference 1), Sections 3.1.1 and 5.1.G(1), identified the installation of a fire wall having a three-hour rating between the redundant safe shutdown systems inside the -
l Control Room Cable' Vaults. Carolina Power & Light Company's Fire Protection Program Evaluation
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b (Reference 2) identified the addition of these walls as necessary to mitigate the consequences of a fire, even though a separate remote shutdown system would be provided for this area. Carolina Power & Light Company also identified the addition of flame-retardant coatings and a fire detection system for these zones to mitigate the consequences of a fire.
The 1977 Fire Protection SER identified that the licensee would install a fire wall having a three-hour rating between the redundant division conduits to ensure that a single fire would not involve redundant safe shutdown systems. The Overall Objectives identified in Section 2.1 of the 1977 Fire Protection SER were to:
(1) reduce the likelihood of occurrence of fire; (2) promptly detect and extinguish fires if they occur; (3) maintain the capability to safely shutdown the plant if fires occur; and (4) prevent the release of a significant amount of radioactive materialif fires occur.
The addition of the fire wall between the redundant safe shutdown systems satisfied Objective 3 of.
the 1977 Fire Protection SER. The installation of flame retardant coatings, water hose statioris, a fire detection system, and the existing fire barriers forming a boundary for the Cable Vault areas -
Batisfied the remaining Objectives.
The NRC also identified in the 1977 Fire Protection SER that CP&L would perform an additional.
f evaluation of the effects of fires on safe shutdown where redundant cables are susceptible to the -
L same fire. Carolina Power & Light Company committed to provide this study in a future submittal;-
therefore, the 1977 Fire Protection SER did not address the Remote Shutdown Capability.
Carolina Power & Light Company submitted the Analysis of Safe Shutdown Capability 3 Fire Protection Program on November 8,1977 (Reference 3) to address the NRC's request to evaluate -
the effects of fires on safe shutdown capability. This analysis addressed the' remote shutdown-capability for the Cable Spread and Control Rooms, but did not identify the Cable Vaults as a separate area. The NRC issued Supplement 1 to the 1977 Fire Protection SER (Reference 4),
which identified that the proposed alternative shutdown capability for the Cable Spreading Room ~
and Control Room would safely bring the reactor to cold shutdown. conditions. The cables analyzed for the Cable Spread and Control Rooms must pass through the Cable Vaults to enter these fire areas; therefore, the analysis of the Cable Spread and Control Rooms envelopes the effects on shutdown capability for the Cable Vault areas.
In order to demonstrate compliance with the requirements invoked under 10 CFR 50, Appendix R,
.. CP&L submitted a new Safe-Shutdown Capability. Assessment and Proposed Modifications Report on June 30,1982 (Reference 5). This initial report sought to comply with Appendix R,-
Section Ill.G.2 for the Cable Vaults through an exemption from the separation and automatic
.g suppression requirements. This methodology was found unacceptable by the NRC to meet the :
requirements of Appendix R, and additional information concerning the Cable Vault Exemption and Attemative Shutdown Capability was provided by CP&L on May 2,1983 (Reference 6).
The May 2,1983 CP&L ietter provided justification supporting'an exemption from the fixed suppression system requirements of. Appendix R, Section Ill.G.3.--This ietter described the Cable
'I Vaults as being bounded by reinforced concrete walls, floc,rsi and the ceilings / floors as having 'a '
three-hour fire resistance rating separating the vaults from other fire areas in the Control Building.
The letter also stated that these zones would be provided with remote shutdown capability. No a
credit was taken for the interior block wall fire barriers in the Cable Vaults. ' The combustible -
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loading and safe' shutdown circuits information was provided by fire zone in the Fire Hazard and Safe Shutdown Systems Analysis sections.
The combustible loading has been recalculated to reflect combining the individual zones on each elevation. The following is a summary of the results for the fixed combustibles:
I Fire Zones Type BTU Floor Fire Area Severity i
CB-Ol a/b PVC Conduit 14,000,000 471 ft' 22 min.
CB-12a/b PVC Conduit 26,360,000
' 471 ft2 42 min.
CB-02a/b PVC Conduit 14,280,000 471 ft:
23 min.
CB-13a/b PVC Conduit 18,648.000 471 ft' 30 min.
1 The exemption request for the Cable Vault areas, dated May 2,1983, identified a fire severity for fixed combustible loading for the various zones that ranged from a 15.0 minute to 42.2 minute fire duration (severity).
This exemption request was granted by the NRC in a July 27,1983 letter (Reference 7). The exemption was granted based on low fuel loading (PVC jacketing on conduits coating with flame retardant material) and that the cable vaults are unventilated and separated from adjacent areas by complete three-hour rated fire barriers. The exemption did not mention or credit the three-hour block wall fire barriers inside the Cable Vaults.
in the May 2,1983 letter, CP&L also committed to perform a detailed Alternative Shutdown Capability Assessment for the Brunswick Steam Electric Plant. This analysis would supersede the
.i Safe-Shutdown Capability Assessment and Proposed Modifications Report which was submitted to the NRC on June 30,1982.
Carolina Power & Light Company submitted the Alternative Shutdown Capability Assessment (ASCA) Report to the NRC on April 24,1984 (Reference 8). This assessment defined the Cable Vaults as one fire area for each unit. The report confirmed that attemative sht.tdown was required j
for this area. The actions required for the Cable Vaults were the same as those for the Control -
Room Area.
l The NRC reviewed the proposed shutdown methodology and granted an additional exemption for the eighth fire zone of the Cable Vaults for not providing fixed fire suppression in a December 30, 1986 letter (Reference 9). The NRC evaluation of the exemption identified that a fire in the area would result in the loss of normal safe shutdown capability. The fire zone is equipped with.
l ionization detection systems and manual fire fighting equipment; therefore, the NRC had reasonable assurance that a fire would be detected during its early stages and extinguished by the fire brigade before adjacent safety-related areas are threatened.
The evaluation also credited the alternate shutdown capability in conjunction with the existing fire l
protection features described above. The exemption stated that if a fire damages any shutdown components before the fire brigade extinguishes the fire, the anernative shutdown capability will be used to achieve and maintain safe shutdown; therefore, the NRC had assurance that a fire would not result in the loss of safe shutdown capability.
The Updated FSAR, Section 9.5.1 (Reference 10), describes the Cable Access Ways as one fire r
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a area with four fire zones, consistent with the 1984 Alternative Shutdown' Capability Analysis j
Report and the current Safe Shutdown Analysis Report.
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CONCLUSION The 1977 NRC Fire Protection SER identified the installation of a three hour barrier between the __
redundant safe shutdown systems in the Cable Vault areas. This SER did not credit the proposed.
i remote shutdown capability for this area. The. Appendix A Safe Shutdown Capability analysis did.
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.not spec ca y address.the Cable Vault areas; however, the analysis did demonstrate the capability.
3 ifi ll to shutdown independent of the Cable Spreading and Control Rooms. The Alternative Shutdown!
d Capability Assessment Report specifically identified the Cable Vaults as one fire areaf without' "I
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crediting the interior walls as providing any level of protection to meet the Appendix R rule.
The exemptions granted for not providing suppression in the area of concern did not credit thef j
interior fire barriers. Combining the fire zones into one fire area for calculating combisstible loading of fixed combustibles does not exceed the maximum fire severity identified in the May 2,.1983
' Exemption Request, j
Appendix A to Branch Technical Position APCSB 9.5-1, Guidelines for Fire Protection for Nuclear 1
Power Plants Docketed Prior to July 1,1976, Position D.1.a.2 (Building Design) provides the -
following guidance:
.(a)
. Redundant safety related systems that are subject to damage from a single fire hazard should be protected by a combination of firo retardant coatings and fire 4 "Ji detection and suppression systems, li j
or b
(b) a separate system to perform the safety function should be provided.
dq The PVC conduits in the Cable Vaults are coated with fire retardant material with the addition of a fire detection system. Manual fire fighting capability is provided from adjacent areas, and an -
- alternate ' shutdown system is provided independent of the Control Building. Safe Shutdown ti Procedures already exist which identify the remote' shutdown steps required for a fire involving the.
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Cable Vault areas.
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Based on the review of the historical documentation associated with these interior fire barriersi the L 0
commitment to install the fire walls between the redundant safe shutdown systems has been~
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superseded by the Appendix R commitment to provide alternative safe shutdown capability for' these fira zones. The fire protection rating of the block wall. fire barriers inside the Cable Vaults -
can be deleted and the doors removed to provide tornado vent paths.
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The remaining commitments identified in the 1977 SER associated with'the Cable Vaults will continue to be maintained, including separating the Cable Vaults from the adjacent areas (Control; 1
Room, Cable Spreading Rooms and Reactor Buildings) by three-hour rated b'arriers, j
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REFERENCES 1.
NRC Fire _ Protection SER, dated November 22,1977-
- 2.
CP&L letter to Mr. Benard C. Rusche from Mr. E. E. Utley, entitled Fire Protection Program Evaluation, dated December 29,1976.
3 3.
CP&L letter to Mr. A. Schwencer from Mr. B. J. Furr, entitled Analysis of Safe Shutdown -
Capability - Fire Protection Program, dated November 8,1977.
4.
NRC Fire Protection SER Supplement 1, dated April,1979.
5.
CP&L letter to Mr. Harold R. Denton from Samantha Francis Flynn, entitled Submittal Persuant to the Requirements of 10 CFR 50, Appendix R, Section.Ill.G and Response to -
.t Generic Letter 81-12, dated June 30,1982.
6.
CP&L letter to Mr. D. B. Vassallo from Mr. P. W. Howe, entitled Appendix R - Additional Information Concerning Exemption Requests and Alternate Shutdown Capability, dated 1
May 2,1983.
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7.
NRC letter to Mr. E. E. Utley from Mr. Darrell G. Eisenhut, entitled Exemption From the Requirements of 10 CFR 50 Appendix R Section Ill.G.3, dated July 27,1983.
8.
CP&L letter to Mr. Harold R. Denton from Mr. E. E. Utley, entitled Alternative Shutdown Capability Assessment Report, dated April 24,1984.
9.
NRC letter to Mr. E. E. Utley from Mr. Daniel R. Mu!!er, entitled Exemption From the _
e Requirements of 10 CFR 50 Appendix R Section Ill.G and J, dated December 30,1986.-
10.
The BSEP 1 & 2 Updated FSAR, Section 9.5.1.5, Fire Hazards Analysis.
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