ML20151H258
| ML20151H258 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck, 05000000 |
| Issue date: | 08/11/1982 |
| From: | Johnston W Office of Nuclear Reactor Regulation |
| To: | Lainas G Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20151H089 | List:
|
| References | |
| FOIA-88-92 NUDOCS 8209010271 | |
| Download: ML20151H258 (22) | |
Text
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MEMORANDUM FOR: Gus Lainas, Assistant Director for Safety Assessment Division of Licensing g /'. . ,
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l FROM: William V. Johnston, Assistant Director l Materials & Qualifications Engineering i Division of Engineering
SUBJECT:
REQUEST FOR EXEMPTION FROM THE REQUIREMENTS OF APPENDIX R TO 10 CFR 50, SECTION III.G 1 Facility: Haddam Neck I
' Licensee: Northeast Utilities Docket No.: 50-213 Responsible Branch: ORB-5 Project Manager: C. Tropf Reviewing Branch: CMEB Reviewer: D. Kubicki Status: Compliance with Section III.G of Appendix R and SER Item 3.2.1 Alternate Shutdown Capability are open. 15 exemptions requested:
n 1 granted, 5 denied, 9 awaiting information.
( ..l In our "Summary of Staff Requirements to Resolved Open Items" (transmitted to the licensee by letter dated November 24,1980), we indicated that a proposed change to 10 CFR 50 would require the alternate shutdown system modifications be completed by a specific date, independent of the SEF. We again stated that to meet both our guidelines and Section III.G of Appendix R, an alternate shutdown capability should be provided in those areas where safe shutdown capability could not be assured because of fire. These areas were to include:
- 1. Control Room
- 2. Switchgear Room -
- 3. Cable Spreading Room
- 4. Primary Auxiliary Building 5, Cable Vault
- 6. Containment We stated that this system should meet the requirements of Section III, Paragraph L of proposed Appendix R to 10 CFR 50. We requested the description of the modifications by November 1, 1980 and implemented by December 1, 1981.
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( Gus Lainas l l
By letter dated March 1, 1981, the licensee submitted plans and schedules intended to demonstrate that by a combination of compliance.
with and exemptions from the specific provisions of Section III.G of Appendix R to 10 CFR 50, the objective of assuring safe shutdown capability in the event of a fire is met. The licensee contends that this submittal resolves all outstanding SER op"en items. As of January 28, 1982, the onl Alternate Shutdown Capability." y open issue is SER item 3.2.1, ,
1 The licensee's Fire Zone Analysis identified twenty six areas containing equipment necessary for safe shutdown. The licensee stated that five zones presently comply with Section III.G of Appendix R to 10 CFR 50 and that pending completion of proposed modifications, six additional zones will be in full compliance. The licensee requested exemptions for fifteen areas to the extent that redundant safe shutdown related ,
cable and equipment are not separated and/or protected in accordance with Section III.G.
The licensee has justified the exemptions based on a number of factors such as: proposed modifications (relocation of equipment, rerouting of cable and installation of additional fire protection systems) which alone would be insufficient to achieve compliance with Appendix R;
[,~ ,,] implementation of "customized adminstrative controls;" the use of fire modeling and a probabilistic risk assessrent; discussion of existing conditions (construction, fuel loading, fire protection) i as they relate to the ability to maintain safe shutdown capability; 1 references to commitments made and documented in the staff Safaty Evaluation Report; and postulated adverse effects (greater fault potential, spurious operation, etc.) which would result if an -
alternate shutdown system were installed.
Based on our evaluation, we conclude that the licensee's proposals for the following five areas do not represent an acceptable level of safety to that which would be achieved with compliance with the requirements of Section III.G of Appendix R to 10 CFR 50:
- 1. Service Building Control Room (S-1)
- 2. Service Building Switchgear Room (S-8)
- 3. Service Building Cable Spreading Area (S-17)
- 4. Screenwell Pumphouse Pump Motor Room (P1 and P2)
- 5. Auxiliary Feedwater pump room (R-5)
Therefore, the licensee's request for exemptions for these areas should be denied.
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( Gus Lainas . . .
In one area of the plant, we agree with the licensee that modifications required to meet Section III.G would not enhance fire safety above that provided by existing and proposed alternatives. Therefore, the licensee's request for exemptions for the Service Building Men's Locker and Shower area (S-9) should be granted.
For the remaining nine areas for which an exemption was requested, the licensee, in a meeting with the staff on May 13, 1982, agreed to re-analyze conditions and to submit additional information. Pending receipt of that information, we will defer action on those exemption requests.
Enclosed is our evaluation of the licensee's exemption request.
(Y A{L Y 1,wT~c William V. Johnsto , Assistant Director Materials & Qualifications Engineering Division of Engineering
Enclosure:
As stated C., '!
Contact:
D. J. Kubicki X24564 cc: R. Vollmer D. Eisenhut T. Novak D. Crutchfield -
T. Wambach
- 0. Parr V. Benaroya R. Ferguson V. Panciera J. Taylor T. Sullivan C. Tropf S. Pawlicki D. Kubicki R. Eberly J. Stang S. Ebneter, Region I T. Conlon, Region II C. Norelius, Region III G. Madsen, Region IV P. Sternberg, Region V
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Enclosure
! Chemical Engineering Branch / Fire Protection Section Exemption Request I Haddam Neck Docket No. 50-213 i
1.0 Introducton By letter dated May 1, 1982, the licensee requested exemptions, !
for fifteen areas of the plant, from the requirements of Section ,
III.G, "Fire Protection of Safe Shutdown Capability," of Appendix R '
to 10 CFR 50 to the extent that it requires physical separation :
and/or fire protection systems to protection redundant trains of I safe shutdown related cable and equipment. On May 13, 1982, representatives of the staff and the licensee met to discuss the ,
bases for the exemptions. At this meeting, the licensee stated tnat additional information would be provided for nine of these ;
areas. We reviewed the following six areas: !
- 1. Service Building Control Room (S-1) ,
- 2. Service Building Switchgear Room (S-8) l
- 3. Service Building Men's Locker Room (S-9)
- 4. Service Building Cable Spreading Area (S-17)
... 5. Screenwell Pumphouse Pump Motor Room (P-1 & P-2)
( 6. Auxiliary Feedwater Pump Room (R-5)
We will defer action on the exemption requests for the remaining nine areas listed below pending receipt of the additional information.
- 7. Service Building Machine Shop (S-21)
- 8. Service Building Maintenance Office (S-22)
- 9. Service Building Tool Crib (S-23)
- 10. Service Building Electricians Shop (S-24)
- 11. Service Building Warehouse Office (S-25)
- 12. Service Building Warehouse (S-26)
- 13. Auxiliary Boiler Room (T-2)
- 14. Primary Plant Containment Cable Vault (R-1)
- 15. Primary Plant Reactor Containment General Area (R-4) 2.0 Service Building Control Room (Fire Zone one S-1) 2.1 Exemption Requested The licensee requested an exemption from Section III.G.2 to the extent that it requires physical separation and the installation of fixed fire protection systems to protect redundant trains of safe shutdown related cable and equipment.
J 2.2 Discussion _. __
The Control Room is enclosed by reinforced concrete shielding walls. Existing fire protection consists of portable fire extinguishers, manual hose stations, and fire detectors in the main control board interior corridor and in areas that are "outside the line of vision of the operators at the console."
Safe shutdown equipment located in the fire zone consists of the main control board and wiring from both divisions. The control board is not partitioned, and the licensee did not specify the separation of redundant systems.
The licensee proposes to implement "customized administrative controls" to reduce the probability of introducing flamable liquids in the control room. The controls would limit the introduction of flamable liquids to quantities less than one pint during all modes of operation. If it became necessary to introduce quantities of flamable liquids in excess of one pint, written permission from the shift supervisor would have to be obtained and a fire watch would be established to ensure that the flammable liquid would not threaten the safe shutdown capability.
[,'i The licensee justified the exemption based on the following considerations:
- 1. The control room is continuously manned by licensed operators.
If a fire did occur, it would be discovered and extinguished promptly by the operators using portable extinguishers. -
- 2. The control room is a restricted area. This fact, coupled with the implementation of customized adminstrative controls, would result in no significant quantities of flamable liquids being present in the control room, thus limiting the fire hazard. -
- 3. The control room contains no high/ medium voltage sources and would present a reduced threat from the standpoint of ignition sources.
Finally, the results of an analysis featuring a fire model
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were presented to demonstrate that a fire involving one gallon of flamable liquid and external to the control board would not affect the ability to achieve safe shutdown from the control board.
k' 2.3 Evaluation In our Safety Evaluation Report dated October 3, 1978, we reported ;
that after a review of the physical separation of safe shutdown cable and equipment and with consideration of the liccasee's proposed improvements in the plant fire protection program, we were of the opinion that "a sufficient basis has not been ,
provided to assure that fire damage could not result in the I loss of the capability to safely shutdown." This conclusion was based on the limited distance separating redundant systems.
As a result, a licensee condition was imposed to evaluate and design an alternate means to achieve safe shutdown which was i independent of areas where redundant systems could be damaged by fire. The licensee's proposals made in conjunction with the exemption request do not satisfy that condition.
The control room contains the majority of the controls essential for normal station operation and for shutdown of the plant under abnormal conditions. Redundant systems necessary for safe shutdown are located in close proximity within the control console and, without adequate protection, would be damaged by a single
, fire of significant magnitude. With the present design, if such
! a fire occurred, there is no capability to achieve safe shutdown
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independent of the control room.
Administrative controls, alone, do not provide reasonable assurance that hazardous accumulations of flammable liquids and combustible materials will not be present in individual plant areas. As documented in recent Inspection and Enforcement Branch Reports, -
recent inspections at plants such as Davis Besse (50-346/82-03, April 1, 1982), Duane Arnold (50-331/81-25, January 11, 1982), D. C.
Cook (50-315/81-11, December 31, 1981), and Nine Mile Point (50-220/82-09), have demonstrated that substantial quantities of hazardous substances such as 55 gallon drums of waste oil are ,
located in even highly restricted and controlled entry areas. l The most important aspect of the licensee's proposed administrative controls is the stipulation that quantities of flammable liquids in excess of 1/2 pint shall only be permitted in indiviual areas when:
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- 1. Written permission is obtained from the Supervising Control Operator or the Shift Supervisor. j
- 2. The flammable liquids are contained in a "suitable" container not to exceed one pint in volume, and
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- 3. A dedicated fire watch with the proper fire fighting equipment is assigned to the activity.
There is, however, no significant difference between the above controls and those required to satisfy current NRC guidelines. l Consequently, no significant increase in fire safety can be :
expected by their implementation. The licensee's proposed I adminstrative controls do not address flammable solids or gases, the presence of which in any area would represent a distinct fire hazard. Even with the customized administrative controls in place, hazardous accumulations of flammable or combustible materials could still be brought into an area, with the consent of responsible individuals who may be not -fully cognizant of the resulting danger.
Withregardtothecontrolroombeingconstantlymanned,wedo not have reasonable confidence that prompt" fire discovery and fire fighting activities by control room operators would assure that no dammage would be sustained by redundant safety related cable and equipment. The uncertainties concerning the location of the fire, the degree of physical separation of redundant
,, trains, fire propagation speed, the fire damageability of cable
( i and equipnient, the timeliness and effectiveness of operator actions s and extinguishing efforts, prevent prediction of damage from fire of fire suppresants. Consequently, the presence of control room operators and portable fire extinguishers by themselves would not assure that redundant trains would be free of signficant fire damage. However, they would provide a sufficient basis for exempting the control room from the fixed suppression require-ment of Section III.G, if an alternate shutdown capability is proviced for the control room.
While it is true that the lack of high/ medium voltage sources in the control room may represent a reduced fire risk, other pctential ignition sources are present (such as smoking materials, light i ballasts, small appliances, and power connections, among others).
Each of these, plus the possibility of an exposure fire originating in an adjoining area, represents a possible threat to the safe shutdown capability. This threat must be considered in light of the extreme vulnerability of the control console, with its close-spaced, unprotected, shutdown-related components, to fire damage.
Therefore, we cannot find that there is reasonable assurance that a fire would not affect the control console.
The fire model that the licensee presents as support for the contention that safe shutdown capability would be unaffected by l fire suffers from several significant limitations. The model
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i features an exposure fire consisting of flammable liquid in a metal pan located on the floor adacent to the control console.
This represents an unrealistic fire scenario for a plant control room and merely demonstrates that, under the postulated conditions, safe shutdown could be achieved.
The licensee's fire analysis was limited to one postulated fire which did not involve in situ combustibles. The impact of a fire located in other' areas of the control room, such as within the control console, which would involve in situ combustibles, was not considered. The licensee assumed that a one gallon heptane fire located adjacent to the control panel is a "worst case" fire. A similar fire inside the control console would essentially destroy the control circuits for thany shutdown systems. There-fore, there is not reasonable assurance that the plant could be safely shutdown after such a fire.
2.4 Conclusion Based on the above evaluation, we conclude that the alternative proposed for the control room (i.e., customized administrative controls) does not provide a level of fire protection equivalent h ,! to that provided by Item III.G.2. Modifications implemented to meet the requirements of Appendix R.Section III.G would significantly increase fire safety of the plant. Therefore, the licensee's request for exemption from Section III.G.2 of Appendix R to 10 CFR 50, for the control room should be denied.
However, an exemption to the requirements for a fixed suppression system in the control roon (Section III.G.3) should be granted -
if an acceptable alternate shutdown capability is provided.
3.0 Service Building Switchgear Room (Fire Area S-8) 3.1 Exemption Requested The licensee req'uested an exemption from Section III.G.2 to the extent that it requires physical separation and/or the installation of fixed fire protection systems to protect redundant trains of safe shutdown related cable and equipment.
3.2 Discussion The switchgear room is enclosed by walls, floor and ceiling of reinforced concrete construction. Existing fire protection for the area consists of a smoke detection system, automatic halon fire extinguishing system, manual hose stations and portable
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fire extinguishers. Safe shutdown equipment located in the fire area consists of:
Battery Banks A & B ,
Battery Chargers 1A & IB 1 DC buses 1 & 2 DC/AC inverters A, B, C, and D 3 4160/480V transformers i 480V Switchgear l MCC 51 and 61 Safe shutdown related cable
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All cables are coated with a fire retardant material.
The licensee proposed to make the following modifications:
- 1. Relocate one of the station batteries to provide a minimum of twenty feet separation.
- 2. Relocate one battery charger and DC bus to provide a minimum 1 of tweenty feet separation.
I i 3. Relocate two of the static inverters to provide a minimum of
, twenty feet separation. l
- 4. Reroute one battery related division of the instrumentation cable.
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- 5. Provide an automatic Halon fire extinguishing system for -
individual cubicles of the 480 volt load centers and to !
Motor Control Center 51. I
- 6. Implement "customized administrative controls" to reduce the probability of introducing flammable liquids in the switch-gear roca.
The licensee justified the exemption based on the "improvement" in l physical separation of redundant safe shutdown related equipment and cable achieved by the proposed modifications.
The installation of the additional Halon fire extinguishing system would limit damage from fire in the MCC 51 and the 480 volt load center to the area of fire origin.
The use of administrative controls would reduce the quantities of flammable liquids present in the switchgear room.
Finally the results of a probabilistic risk assessment were presented l to demonstrate the beneficial consequences to fire risk associated with the implementation of the proposed fire area modifications.
1 i 3.3 Evaluation The switchgear room is located below the control room. This area contains both devisions of cabling and equipment, such as batteries, switchgear, and motor control centers necessary for safe shutdown. Redundant components are located in close proxicity l and, without adequate protection, would be damaged by a single fire of signficant magnitude. If such a fire decurred, there is no capability to achieve safe shutdown independent of the switchgear room.
As indicated in our evaluation of the exemption request for the control room (refer to Section 2.3), because of the lack of physical separation of redundant systems, ur Safety Evaluation Report for Haddam Neck concluded that a sufficient basis had not been provided to assure that fire damage could not result in the loss of safe shutdown capability. As a ,
result a license condition was imposed to evaluate and design I an alternate means to achieve safe shutdown which was independent !
of areas where redundant systems could be damaged by fire. 1
..,, The licensee's proposals made in conjunction with the exemption f,
,I request do not satisfy that condition.
The relocation of select safe shutdown cables and components as proposed by the licensee represents an "improvement" over the original configuration. However, other equally critical shutdown related cabling and components are not adequately separated within the room. This lack of separation, plus the presence of intervening combustible matarials, such as cable and wire insulation and battery ;
cases, represent a signficant threat to safe shutdown capabilty.
A fire involving combustible materials located in the proximity of the redundant shutdown systems may cause failure of those systems prior to fire suppression action by the fire brigade or the fixed fire protection. In addition, there is no reasonable assurance that water from fire hoses, if used by the fire brigade, would not cause failure of the redundant systems.
l We agree with the licensee that the installation of additional i Halon fire suppression systems in the 480 volt load centers and the Motor Control Center 5-1 will mitigate the consequence of fire I within these centers. But as with the proposed relocation of equipment noted above, this limited augmentation of existing fire protection in the room does not represent an equivalent level of fire safety to that required by Section III.G.2 or III.G.3. A smoke detection system and total switchgear flooding Halon fire suppression system are installed in the switchgear room. But a time delay of potentially up to 5 minutes is associated with these protection systemt between the advent of a fire and the actual application of suppressing agent. During
v this time, damage to shutdown related cabling and equipment can occur. The physical separation requirements of Section III.G provide the necessary additional protection until the automatic fire suppression system activates or the fire brigade arrives.
Since all redundant trains in the switchgear room are not separated by at least 20 feet or protected by a one hour fire rated barrier, there is no reasonable assurance that safe shutdown capability could be maintained.
As previously stated in our evaluation of the exemption request f ir the control room (refer to Section 2.3), administrative controls :
by themselves, based on experience to date, are not adequate to exclude hazardous accumulations of flammable liquids and combustible materials in individual plant areas and do not preclude the occurence of a fire. l l
The licensee's use of probabilistic risk assessment (PRA) methodology i does not provide an accurate indication of the degree of fire I risk associated with individual plant areas or a true measure of )
the beneficial consequences of select modifications tc the arrange- i ment and location of critical safe shutdown components on the switchgear room.
hl The fire risk assessment submitted by the licensee is basee on the combination of fire frequency estimates, obtained from experience, with a fire model to predict the likelihood of failure to achieve safe shutdown. The domestic nuclear power operating experience l record was the data base for assessing the fire occurrence rate in the plant. However, it is our opinion that this data base is insufficiently broad, as of this date, to form the basis for accurate predictions of future fire occurence.
The fire spreading model utilized in the PRA is also based upon probabilities extracted from actual experience with nuclear power plant fires. But the number and severity of fires that have occurred in nuclear power plants to date is limited so as to make accurate predictions of fire propagation impossible.
The PRA methodology featured the identification for analysis key" fire zones. The selection of these areas was based only'e"ngineering on judgment" concerning their likelihood for experiencing a fire and the nature of the safe shutdown compcnents in them. The control room, however was excluded from cons Meration.
In addition, no justification was pr,ovided for ignoring ot, plant areas that may be equally important from the standpoi..c of safe shutdown. Also, the fire model only envisioned fires originating within "key" fire zones. No consideration was given for exposure fires that may develo;, beyond the boundaries of the key fire zones and spread into them through unprotected door, damper or other openings.
9-A number of questionable assumptions were made in the PRA which.
casts doubt on the validity of the analysis, such as the assumption that control functions and remotely operated valves were not considered critical to safe shutdown. Howevar if such valves or their related circuitry were damaged by fire, the ability to l achieve safe shutdown may be adversely affected. In addition, i an assumption was made that only the power supply to safety related )
pumps was a predominant factor in the risk analyses. Thegumps themselves were de-emphasized based on the statement that most pumps vital for the cooling of the plant are well protected against fire..." A concern exists for those pumps that are not I protected against fire.
3.4 Conclusion Based on the above evaluation, we conclude that the modifications l proposed for the switchgear room do not provide an acceptable level of fire protection equivalent to that provided by Item III.G.2.
Therefore, the licensee's request for exemption from Section III.G.2 of Appendix R to 10 CFR 50, for the switchgear room, should 9e denied. J
'i 4.0 Service Buildino Men's Locker Room & Shower Area (S-9) 4.1 Exemption Requested The licensee requested an exemption from Section III.G.2 to the extent that it requires phy:sical separation and the installati'on of a smoke detection system to protect redundant trains of safe shutdown related cable and equipment.
4.2 Discussion 1
The fire area is enclosed by noncombustible walls, floor and ceiling.
Existing fire protection for the area consists of an automatic l sprinkler system, manual hose stations and portable fire extinguishers. 1 Safe shutdown components located within the area consist of service l water pump power cables. Cabling from both divisions are located within a single cable chase with no divisional separation. The cable chase is enclosed on three sides by two layers of gypsumboard I and on the fourth side by concrete block.
The fire hazard in the area, as represented by the fuel load, is negligible. All combustible material compile a fuel load of approximately 14,000 BTU /Sq. Ft. which, if totally consumed, would correspond to a fire severity equivalent to about 10 minutes on the ASTM E-119 standard time temperature curse.
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4 The licensee justified the exemption on the contention that the existing fire protection for the echle trace and the room is sufficient and that modifications required to meet Section III.G would not significantly enhance fire safety.
4.3 Evaluation The requirements of Section III.G.2 are intended to provide a combination of passive (separation and/or fire barrier) and active (fire suppression / detection systems) protection to assure safe shutdown capability.
The existing fire protection for the area consists of both passive and active safety features. The gypsumboard and concrete block enclosure around the cable chase represents at least one hour fire rated barrier. This affords an acceptable level of safety in consideration of the low in situ fuel loading identified in the Discussion. Reinforcing this protection is a complete, automatic sprinkler system that protects the entire men's locker room and shower area. A waterflow alarm from the sprinkler system is annunciated in the control room In addition, portable
,m fire extinguishers and hose stations are available for manual
( ,i fire fighting. It is our opinion that this protection provides s reasonable assurance that the shutdown related cables will be free of damage from a fire in the area. .
4.4 Conclusion Based on our evaluation, we conclude that additional modifications -
to meet the requirements of Section III.G.2 would not enhance fire safety above that provided by the existing alternative.
Therefore, the licensee's request for exemption should be granted.
5.0 Service Buildina Cable Spreading Area (Fire Area S-17) 1 5.1 Exemption Requested l The licensee requested an exemption from Section III.G.2 to the extent that it requires 20 feet separation, without intervening combustibles, between redundant trains of safe shutdown related cable and equipment.
5.2 Discussion The fire area is enclosed with walls of reinforced con W r, concrete block, and metal sidiing. The floor and ceilics as of 6 inch concrete. Existing fire protection consists i a
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smoke detection system, an automatic water spray system for cable tray protection, manual hose stations, and portable fire extinguishers. Safe shutdown components located within the area consist of cable from both divisions. The cables are coated with a ,
fire retardant material. The licensee proposed to make the l following modifications ,
1
- 1. Reroute one division of required instrumentation cables. I
- 2. Reroute MOV 373 cables.
- 3. Reroute cables for one RHR pump. l
- 4. Provide a directional spray water suppression system.
- 5. Implement "customized administrative controls" to reduce the probability of introducing flammable liquids in the cable spreading area.
The licensee justified the exemption based on the "improvement" in fire safety achieved by the proposed modifications. This improvement was quantified in terms of the reduced probability of failure to 1
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i achieve safe shutdown as identified in the probabilistic risk
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assessment.
The licensee also stated that the provision of the additional fire suppression system would augment the existing protection
.against exposure fires.
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The licensee concluded that, based on the existing fire protection ,
and the proposed modifications, "sufficient" levels of defence '
in depth has been provided and that safe shutdown capability will be maintained.
5.3 Evaluation The cable spreading room contains the majority of the control and power cables necessary for normal station operation and for shutdown of the plant under abnormal conditions. Redundant cabling for safe shutdown are located in close proximity and, without adequate protection, would be damaged by a single fire of significant magnitude. If such a fire occurred, there is no capability to achieve shutdown independent of the cable spreading room.
As indicated in our evaluation of the exemption request for the I control room, (refer to Section 2.3), our Safety Evaluation Report for Haddam Neck concluded that a sufficient basis had not been provided to assure that fire damage could not result in the loss
s of safe shutdown capability. As a result, a license condition was imposed to evaluate and design an alternate means to achieve safe shutdown which wss independent of areas where redundant systems could be damaged by fire. The licensee's proposals, madeinconjunctionwiththeexemptionrequestdonotsatisfy that conditions.
As stated in our response to the exemption request for the switchgear room (refer to Section 3.3) a partial relocation of safe shutdown components will not provide reasonable assurance that safe shutdown capability will be maintained. The remaining redundant cabling in the area, located in close proximity to each other without adequate separation, would still be threatened by fire damage.
The presence of automatic fire suppression systems will mitigate the fire hazard but they do not provide instantaneous, total coverage of cabling and/or the floor area. Without the required separation distance, or the installation of a one hour fire rated barrier as required by Section III.G.2, there would not be reasonable assurance that no damage to redundant trains would occur pending activation of the suppression systems or the arrival of the fire brigade.
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\ The fire protection requirements of Section III.G.2 represent an "aggregate." comprised of active and passive components. Deleting one component (in this case separation) seriously reduces the ability of the fire protection to assure an acceptable level of safety. As previously stated in our evaluation of the exemption request for the control room (refer to Secti.on 2.3) adminstrative controls, by themselves, are not adequate to exclude hazardous accumulations of flammable liquids and combustible materials from individual plant areas and do not preclude the occurence of a fire.
As previously explained in detail in our evaluation of the exemption request for the switchgeear room (refer to Section 3.3), the use of probabilistic risk assessment methodology in this instance does not provide an accurate indication of the degree of fire risk associated with individual plant areas or a true measure of the beneficial consequences of select modifications to the arrangement and location of critical safe shutdown components.
5.4 Conclusion Based on the above evaluation, we conclude that the modifications proposed for the cable spreading area do not provide an accept-table level of fire protection equivalent to that provided by Section III.G.2. Therefore, the licensee's request for exemption
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from Section III.G.2 of Appendix R to 10 CFR 50 for the cable spreading area should be denied. l 6.0 Primary Plant Auxiliary Feedwater Pump Room (Fire Area R-S) _ _
6.1 Exemption Raquest The licensee requested an exemption from Section III.G.2 to the extent that it requires a automatic fire suppression system in this area. j 1
6.2 Discussion The fire area is enclosed by walls, floor and roof of noncombustible l construction. Existing fire protection consists only of portable l fire extinguishers. Safe shutdown equipment located in the area i consists of the auxiliary feedwater pumps and related hardware (such as the pump controls, piping and valves). The pumps are i
separated by a distance of 21 feet with "minimal" intervening ;
combustibles. Two lube oil reservoirs are located on each pump, each containing approximately one gallon of oil. The licensee !
states that because it is a limited access area, flammable / '
,,' combustible liquids would not likely be present.
i The licensee proposes to make the following modifications:
- 1. Install a fire detection system.
- 2. Extend the fire water loop and provide a manual hose station in the area.
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- 3. Implement "customized administrative controls" to reduce the
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probability of introducing flammable liquids in the pump 1 room. l l
The licensee justifies the exemption based on the assumption l that a fire at one pump would not propagate to the other redundant components.
The licensee states that an automatic water fire suppression system should not be installed because the application of water would damage the pumps and an automatic gas fire suppression system (CO,,, halon) would be ineffective due to the inability to maintain ageht econcentration.
6.3 Evaluation As previously indicated in our evaluation of the exemption request for the control room (Refer to Section 2.3), neither the fact that an area is restricted nor the implementation of "administrative
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controls" will assure that an area is free of'significant l accumulation of hazardous materials. Consequently, it is not possible to predict that a fire will be limited or non-existent by virtue of the lack of transient or in situ combustibles. For similar reasoning, it is not possible to predict that if a fire l did occur it would not damage redundant safe shutdown components. ;
The licensee states that the application of water as a fire suppression agent would damage the auxiliary feedwater pumps. l There is no experience, to date, to verify this contention, and 1 the licensee did not provide information to support their !
statement. In fact, one of the proposed modifications is to install a manual hose station near the entrance to the auxiliary feed pump room to be used for fighting fires in the area.
The licensee provides no justification for his statement that a gaseous fire suppression system would be ineffective because of the inability to maintain agent concentration. The pump l room is defined as a fire area. As such, it is required to be l enclosed by walls, floor and ceiling of fire rated construction.
Any openings are required to be protected by self closing doors, automatic dampers or penetration seals. This type of construction
[_ i is conducive to the retention of a gaseous fire suppressing agent.
In addition, even if construction featured unprotected openings, 1 design parameters for gaseous fire suppression systems direct I that agent design concentration be incrased to compensate for the openings.
As previously discussed in the evaluation of the exemption requests -
for the switchgear room (3.3) and cable spreading area (5.3),
the fire protection requirements of Section III.G.2 represent an aggregate of safety features that are both active, such as a fire detection and suppression system, and passive, such as spacial separation or a firs barrier. The passive protection provides a margin of safety for safe shutdown components until the fire is discovered and extinguished by the active fixed protection or the fire brigade. The licensee proposes to rely on the fire detection system and the plant fire brigade to provide protection for this area. However, there is a inherent time delay of up to five minutes associated with fire detector operation.
In addition, the fire brigade may not reach the scene for up to 15 minutes after receipt of the alarm. During this time delay, damage to safe shutdown systems could occur.
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6.4 Canclusion . _ , . _ _ _.
l Based on the above evaluation, we conclude that the modifications proposed for the Auxiliary Feedwater Pump Room do not provide an l
acceptable level of fire protection equivalent to that provided by i Section III.G.2. Therefore, the licensee's request for exemption '
from Section III.G.2 to 10 CFR 50 should be denied.
7.0 Screenwell Pumphouse Pump Motor Room (Fire Area pl/p2) 7.1 Exemption Requested I
The licensee requested an exemption from Section III.G.2 to the extent that it requires an automatic fire suppression system in this area.
7.2 Discussion l 1
The fire area is enclosed by walls, floor and roof of concrete )
construction. Existing fire protection consists of a partial fire- i detection system, partial sprinkler system (diesel equipment area),
manual hose stations and portable fire extinguishers. Safe shutdown
( ...i . ,' equipment located in the area consists of four service water pun,ps
, and related cabling. -
The licensee proposed to implement the following modifications:
- 1. Enclose each service water pump with a curb / dike. l
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- 2. Enclose the cable runs for two service water pumps in a one hour fire rated barrier.
The licensee contends that, considering the proposed modifications, a flammable liquid spill fire would not propogate to the extent necessary to cause damage to redundant devisions. The curb / dike and existing drainage would limit the extent of the spill, the cable wrap and pump separation distance would sufficiently protect safe shutdown components, and the fire detection system would summon the plant fire brigade in a timely manner to extinguish the fire. The licensee concludes that no substantial additional protection would be achieved by the installation of an automatic suppression system, 7.3 Evaluation All four service water pumps are located in a single area and, without acceptable protection, would all be vulnerable to damage
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( from an exposure fire within the room. Specifically, the four pumps are located in a line such that the separation distance between the end pumps is twenty three feet, 3 feet more than the minimum distance required by Section III.G.2 Under the alternative proposed by the licens6e, fire protection for the area would deviate from the requirements of Section III.G.2 in all three aspects as follows.
- 1. An automatic fire suppression system is provided to protect only a fraction of the total room floor area (over the diesel fire pump) in lieu of total area protection.
- 2. Fire detectors are located only in the upper level of the fire area (21'-0") as opposed to both levels as mandated by Section III.G.2.
- 3. Compliance with the 20 feet separation requirement l of Section III.G.2 would necessitate that there be no intervening combustible material between redundant snutdowncomgonents. The licensee identified the
'hi presence of minimal intervening combustibles" in
- s. the form of pump lubricating oil.
The installation of curb / dike at the service water pumps will mitigate the fire hazard associated with a flammable liquid spill but it will not eliminate the hazard nor will it provide ,
protection from an exposure for originating in another part of -
i the fire area. l Enclosure of pump cable runs in a one hour fire rated be.rrier provides acceptable partial protection according to Section III.G.2, but the pumps themselves are-not similarly l protected and are, consequently, subject to damage by fire. l As previously stated in our evaluation of the exemption request for the Auxiliary Feedwater Pump Room (Refer to Section 6.3), i there are inherent time delays associated with the activation of l fire detectors and fire brigade response. This factor is compounded by the lack of a complete fire detection system in the fire area. The time delays, coupled with the lack of a complete fire suppression system and the close proximity of the four pumps, result in a situation where a fire could cause damage to the pumps prior to the arrival of the fire brigade and the application of a fire suppression agent.
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The licensee contends that due to the detrimental effect on the.
service water pumps caused by water impingement, the installation of a water-based fire suppression system would be impractical.
This does not justify the exclussion of the suppression syt, tem outside of the immediate area of the pumps. Nor does it take into account possible remedies to the problem, such as the installation of a water barrier, baffle or screen around one or more of the pumps. And it neglects to consider the actions of the fire brigade in their use of the manual fire hose system during firefighting operations, who may be unable to direct a water stream with sufficient precision to avoid damage to the pumps.
As previously stated in our evaluation of the exemption request for the Auxiliary Feedwater Pump Room, the lack of both active and passive fire protection for the safe shutdown components ;
in the fire area results in the lack of reasonable assurance that fire damage would not occur.
7.4 Conclusion j
-... ' Based on the above evaluation, we conclude that the modifications
( proposed for the Pump Motor Room do not provide an acceptable level of fire protectiom equivalent to that provided by Section III.G.2. :
Therefore, the licensees request for exemption from Section III.G.2 of Appendix R to 10 CFR 50 should be denied.
8.0 Alternative Shutdown Cacatrility 8.1. Licensee Statement In Section VII of a letter from W. G. Counsil to D. G. Eisenhut, dated March 1,1982, the licensee provided additional justification for its approach of equivalent protection. These justifications include the following licensee stated concerns with regard to inherent disadvantages in the alternative shutdown approach:
(1) "Compliance achieved via the introduction of thousands of 4 electrical isolation contacts raises serious questions '
regarding the reliability of circuits.."
(2) "In order to comply with applicable design criteria, provisions must be made to allow for verification testing necessary to assure that upon return to main control room control, operability of all transfered functions including manual control, diesel generator sequencing, reactor protection system actuation, etc. have been properly restored."
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(3) These new features introduce greater fault potential, the probability for spurious operation is increased..."
(4) "A probabilistic risk assessment oriented evaluation of these additional circuitry complication would likely demonstrate reduced reliability and reduced probability of proper operation..."
8.2 Staff Comments We have reviewed the licensee's concerns and conclude that the licensee may have identified some inherent disadvantages in the alternative shutdown approach. However, these and similiar disadvantages were considered in formulating $cction III.G of Appendix R and the disadvantages do not outweight the advantages of an alternative shutdown approach. Areas that require alternative shutdown methods, are areas that contain redundant divisions of safe shutdown equipment which can not meet the separation criteria.
A single fire in these areas could potentially disable all methods of achieving and maintaining safe shutdown. Additionally, the Browns Ferry fire showed the necessity of divisional separation
("1 of the associated circuits of the control cables to prevent the
[' disabling of safety systems by a single fire. Consideration of associated circuits is necessary to ensure that safe shutdown systems will be able to function properly in the event of a fire.
The requirements of Section III.G of Appendix R allows a licensee options for providing one train of systems needed for hot shutdown to be free of fire damage and permits repairs for systems needed for cold shutdown. - -
8.3 Conclusion The staff concludes that in spite of the inherent disadvantages cited by the licensee, alternative shutdown capability improves overall safety with regard to potential fires in critical areas of nuclear power plants.
9.0 Conclusion Based on our evaluation, we conclude that the licensee's proposals for the following five areas do not represent an acceptable level of safety to that which would be achieved with compliance with the requirements of Section III.G of Appen Jix R to 10 CFR 50:
- 1. Service Building Control Room (S-1)
- 2. Service Building Switchgear Room (S-8)
- 3. Service Building Cable Spreading Area (S-17)
- 4. Screenwell Pumphouse Pump Motor Room (P1 & P2)
- 5. Auxiliary Feedwater Pump Room (R-5)
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{ Therefore, the licensee's request for exemptions for these areas should be denied.
In one area of the plant, we agree with the licensee that modifi-cations required to meet Section III.G would not enhance fire safety above that provided by existing and proposed alternatives. Therefore, the licensee's request for exemptions for the Service Building Men's Locker and Shower area (S-9) should be granted.
For the remaining nine areas for which an exemption was requested, the licensee, in a meeting with the staff on May 13, 1982, agreed to reanalyze conditions and to submit addition 1 information. Pending receipt of that infnrmation, we will defer action on those exemption request.
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