ML20205E834
| ML20205E834 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/21/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20205E822 | List: |
| References | |
| GL-86-10, NUDOCS 8810270484 | |
| Download: ML20205E834 (20) | |
Text
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UNif ED STATES
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SAFETY EVALUATION BY THE OFFICE OF S.'ECIAL PROJECTS PELATIVE TO APPENDIX R EXEPPTIONS RE00ESTED lENNESSEE VALLEY AUTFORITY F0P PROWS FERRY NUCLEAR FL ANT UNITS 1, 2, AND 3 OgET f 05, 50-259/260/296
1.0 INTRODUCTION
By letter dated January 31, 1986, the Tenness ' Valley Authority (TVA or the licensee) submitted a revised plan for compliance with 10 CFR 50, Appendix R tor the Browns Ferry fluclear Plant (BFNP) Units 1, 2, and 3.
This revised plan was the result of a complete reevaluation of the Licensee's Apcendix R prograr, which sought to bring the plant in conformance with the NRC staff positions ar.d Appendix R requirements. This submittal identified several exerptions from the Appendix R requirements.
By letters dated June 2, and November 21, 1986, May 26, 1987, Septemb2r 14, 1987, and April 4, 1988 the Licensee supplemented their revised plan and modified some exenption requests. The final exemption request consists of one request for extmption to Section III.L of Appendix R and four exemptions from Section III.G of Appendix R.
This Safety Evaluation (SE) is based in part on the attached Technical Evaluation Report (TER) generated by a NRR contractor, Franklin Research Center (FRC).
This SE covers only the requested exemptions and the engineering evalections submitted in accordance with Generic letter 86-10 Staff approval of other parts of the Prowns Ferry Fire PNtection Program is not intended by this SE.
Section !!!.L.1 of Appendix R requires that the alternative shutdown capebility be eble to maintain the reactor coolant system process variables within those predicted for a loss of normal ac power during the postfire shutdown. Section
!!!.L.2.b. of Apper. dix R requires that the alternative shutdown capability be capable of maintaining the reactor coolant level above the top of t,he core for PWPs.
The licensee recuested an exemption from Section III.L of /,ppendix P to the extent that some core uncovery may be experienced as noted in the licen.
see's analyses of fire events and sore process variables may exceed those predicted for a loss of ac power event.
Sectic'1 !!!.G.1 of Appendix R requires fire protection features to be provided for structures, systems, and corponents irportant to cafe shutdown and capable of liniiting fire damage so that:
a.
One train of systens recesscry to achieve and maintain hot shutdown conditions frm either the control rcen or emergency control station (s) is free of fire damaget and i
8810270494 881021 i
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2 b.
Systems necessary to achieve and maintain cold shutdown from either tne control room or emergency control station (s) can be cepaired within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Section III.G 2 of Appendix P requires that one train of cables and equipment necessary to achieve and maintain safe shutdown be ruintained free of fire damage by one of tae following means*
i Separation of cables and equipment and associated ron-safety circuits a.
of redundant trains by a fire barrier having a 3-hour rating.
Structural steel forming a part of or supporting such fire barriers shall be protected to provide fire resistance equivalent to that l
required of the berrier.
l b.
Separation of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance o' rore than 20 feet with no intervening combustibles or fire hazards.
In addition, fire r
I detectors and an autcmatic fire suppression system shall be installed in the fire area.
Enclosure of cable and equipment ant' associated '1on-safety circuits c.
of one redundant train in L fire barrier having a 1-hour rating.
In addition, fire detectors and ar automatic fire suppression system shall be installed in the fire area, n
If t5e above conditions are not ret. Section li!.G.3 requires an alternative f
shutdown capability that is independent of toe area, room, or zorie of concera.
It also requires that fire detection and a fixed suporession system be ir: stalled in the areas, room, or rene of concern.
These alternative requirements are not i
T deemed to be equivaient; however, they provide an acceptable level of fire protection for those configurations in which they are approved by the staff.
Because it is not possible to predict the specific conditions under which fires raay occur and propagate, the design basis protective features rather than the l
desion basis fire are specified in the rule. Plant-specific features nay re-l I
quire protection different from the neasures specified in Secticn !!!.G.
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j such a case, the licensee must demonstrate by reans of a detailed fire hazards onalysis that existing protection or existing protectien in conjunctica with proposed modifications will provide a level of safety equivalent to the i
technical requirements of Section !!!.G of Appendix R.
l In sumary, Section ll!.G is related to fire protection featut es to ensure that systens and csfociated circuits used to achieve and raintain safe shutdown are l
free of fire damage.
Either the fire protection configurations must meet the I
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specific recuirements of Section III.G or an alternative fire protection configuration must be justified by a fire hazards analysis.
Generally, the staff will accept an alternative fire protection configuration if:
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The alternative ensures that one train of equipment necessary to achieve hot shutdown from either the control room or emergency control systems is
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free of fire damage.
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The alternative ensures that fire damage to at least one train of equipment necessary to achieve cold shutdown is limited so that it can be rapaired wii.hin a reasonable time (minor repairs using components stored on the site).
Fire-retardant coatings are not used as fire barriers.
l' Modifications required to meet Secticn !!!.G would not enhance fire protection safety levels above those provided by either existing or proposed alternatives.
l Modifica*. ions required to meet Section !!!.G would be det'.aimental to l
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overall facility =afety.
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Generic Letter 66-10 (April 74, 1986), Attachment, "Interpretations of Appendix i
R." allows for fire area beundaries which are not completely seated i
j floor-to-ceiling, wall-to-wall 3-hour fire cated boundaries to be accepted i
without formal eFeript on from Section III.G of Appendix P..
The Generic Letter l
requires that licensees perform an evaluation to assess the adequacy of fire l
3 boundaries in their plants to detemine if the boundaries will withstand the hazards associated with the area. This analysis or engineering evaluation must be perfor:aed by it least a fire protection enoineer and, it' required, a systems l
engineer. Licensees may submit their evaluatior.s for staff review and concurrence, although this is not required. The licensee rust retain the
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analyses for subsequent NRC audits wnether or not the analyses aK submitted.
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j Altogether eight exemptions from Section !!!.G were requested:
i Exemptiers from fixed supprest, ion in the main control rooms; I
Exemption for RHR pump rooms; l'
i Exemption for fire doors; Exemption for intervening combustibiec; Exemption for reactor buildin0 and refuel floor; Exemrtion for fixed suppression aad detection; i
Exemption for lack of fire dampers in HVAC ducts in 3-hour fire barriers; i
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and j
Exenption for use of water curtains in res: tor buildings.
Of these eight exemption requests, the provisions of Gwe-ic letter 86-10 to 2
3 do an engineering evaluation were found to ue applicable to four of them.
i These four were:
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i Exemption for fire doors; Exemption for reactor building refuel floor; 4
Exetaption for lack uf fire dampers in HVAC ducts; and Exemption for me of water curtains la reactor buildings.
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. l Each of the exemptions requested by the licensee is evaluated below. The four ex eption requests to be reviewed as engineering evaluations under Generic l
Lettar 86-10 are discusced in Section 3.0 of this SE following discussions of the other exemptions.
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J 2.0 EXEMPTIONS t
2.1.0 Core Uncovery t
2.1.1 Exemption Reauested 3
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By a November 21, 1986 submittal (R. Gridley to D. Muller) TVA requested an
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exemption from "no core uncovery," 1.e., Section !!I.L.1 of Appendix R requires t
4 that the alternative shutdown capability be able to maintain the reactor 1
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coolant system process variables within those predicted for a loss of norm.1 Section !!!.L.2.b of Appendix
- raquires that the altarnative i
ac power.
I thutdown capability be able to maintain reactor coolant inventory above the core for a BWR, Contrary to this, some cora uncovery may be experienced as
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noted in the analysis for the evaluation fire event.
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i TVA summarized their justification for the exemption essentially as follows:
When the alternate shutdown capability is used in response to a fire, the t
process variables would exceed those predicted for a loss of normal ac t
power. Althovah some momentary cors unrovery can be expected for the systems used for BFN, the core uncovery will not result in any fuel damage, j
which satisfies the requirement specified in Section !!I.L.1 of Appendix R.
Sections 3 and 6 of NEOC-S1119 are referenced as presenting the development t
of the design requirements for the BFN safe shutdown system and the safe I
i shutdown analysis.
i 2.1.2 Discussion j
i As described in NEDC-31119, the alternate shutdown systems to satisfy Appendix R were sele:ted to irclude those which may be used when offsita l
power is available and thise which may be used when offtite power is i
not available. The systems were further reduced to a set of minimun systems i
including the auxiliary support systems.
A safe shutdown analysis was performed for each fire area to confim that at least one train was available to provide miriimum safe shutdown fur.ctions.
The reactor :oolant systee i
response was evaluated by thi SAFE code. Core heat-up response was detemined i
J by the CHASTE ccde.
Suppression pool response was determined from heat and
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I mass balance calculations.
i 2.1.3 Evaluation j
Considering only the reactor core variables Appendix R.Section III.L requires.
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l in essence, a dedicated system or systems which may be used to bring the plant i
tu hot or cold shutdan without fuel damage regardless of where the fire may i
OCur.
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l In the analysis of ea:h event, if it can be confirmed that there will be no core tncovery, or that the process variables will be maintained within these i
predicted for a loss of normal ac power, or if an acceptable detailed heat l
l transfer analysis of the core confirms the absence of fuel clad damage, the NRC j
l will accept that the alternate or dedicated shutdown capability is adequate.
The minimum safe shutdown systems for a BFN fire affected unit includes only
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l the manual control of the main steam relief valves (MSRVs), residual heat i
removal system (RHR) in the low pressure coolant in j
and the residual heat removal service water (RHRSW)jection system (LP j
systems. When the reactor pressure is reduced to allow low pressure injection, the froth level surrounding the core momentarfly drops below the top of the core (resulting in core uncovery and exceeding process variables associated with loss of offsite j
i powerevent). GE has analyzed those events relying upon minimum systems using i
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codes found acceptable to the NRC. The analyses have confirmed that no core j
damage would occur.
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1 In the November P1, 1986 submittal, RHP/LPCI injection was assumed at 20 l
j minutes after manual scram. The RHRSW was assumed to provide cooling after two hours rather than three hours as in the January 1986 submittal.
The staff has j
s been ao.ised that RHRSW system actuation within two heurs has been incorporated j
j in the operating procedures. This has alleviated the staff's concerns about i
inadequate ret pump suction head (NPSH) for RHR pumps late in the event.
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2.1.4 Conclusion 1
j Based upon the above evaluation the staff recomends that the requested I
4 exemptions to Section !!I.L of Appendix R to 10 CFR 50 be granted.
The staff will audit the Appendix P, abnormal occurrence operating procedures to assure l
I that RHR$W system actuation is initiated within two hours, j
2.2.0 Fain Control Rooms Fire Arca 16 f
I 2.2.1 Exemption Reouested l
An exer 7 tion was requested from Section !!!.G.3 of Appendix R to the extent l
i that it requires installation of a fixed fire suppression system in a fire i
area (Fire Area 16) for which an alternative shutdown capability is provided.
I 2.2.2 Discussion a
The main control rooms for all three units are located in the control building 1
I (Fire Area 16) which is a shared, reinforced concrete structure. The main control rooms are a ceitral location for manual and automatic controls for all plant systems.
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The most severe postulated fire would affect all three units.
Therefore, an independent alternative safe shutdown system is required for the control rooms.
The current alternative shutdown system at BFNP includes backup control stations and other manual controls. The backup control stations are located in the 4-KV shutdown board rooms A C, and E for Units 1, 2, and 3, respectively.
The backup control stations have manusl controls for reactor core isolation cooling system (RCIC), main steamline isolation valves (tiSIVs) FSRVs and associated instrumentation. The manual trip capability for the MS!Vs and PSDVs provides additinnal assurance that spuriously opened valves can be closed. The i
manual control of the MSRVs with automatic depressurization system (ADS) function assures that the MSRV requirements for mininum safe shutdown systems are satisfied. The licensee has comitted to re-route certain cables to assure instrumentation availability at the backup control stations.
In sumary, the alternative safe shutdown system is physically and electrically indepentient of the control building for all three units.
2.2.3 Evaluation The fire protection in this fire area (main control rooms) does not comply with the technical requirements of Section !!!.G 3 of Appendix R because a fixed fire suppression system is not installed in a fire area for which alternative shutdown capability is provided.
The primary concern for this fire ares was that a fire in the rain control rooms could cause the loss of normal shutdown capability. However, should a fire occur within the main control rooms, it is expected to be promptiy detected by the automatic fire detection system, the station personnel, or the fire brigade.
Should fire damage be extensive, necessitating the cont-ol rooms' evacuation, then the alternative safe shutdown system can be utilized to safely shut down the plant. Except for the battery a.7d battery board rooms, the control building has 3. hour fire rated adjacent barriers. The battery and battery board rooms which have a combustible loading of less tht.n 30 minutes, have 1-1/2 hour rated barriers and fixed detection and suppression. Therefore, it is expected that a f
fire starting anywhere in the contrnl building would not spread to adjacent fire The staff finds that the installation of a fixed suppression system would areas.
not significantly increase the level of fire protection in the rein contrcl rooms.
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2.2.4 Conclusion i
Based on the above evaluation, the staff concludes that the existing fire protectico features corrbined with the alternative shutdown e.apability in the aforementioned fire area provide a level of protection equivalent to the technical requirements of Section !!!.G.3 of Appendix R.
Therefore, the exerption frnm fixed fire St.ppression in the main control rooms should be g ra r.t ed.
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2.3.0 RHR Pump Rooms (Fire Zones 1-1, 1-2, 2-1, 2-2, 3-1, and 3 2) and Excianger Rooms (Fire Zones 1-3. 2-4, and 3-3) l 1
2.3.1 Exenption Recuested i
An exemption was requested from Section III.G 2.b of Appendix R to the extent l
i that it requires that cable, equipment, and associated circuits of redundant i
trains be sepacated by a horizontal distance of 20 ft, or more and installation
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of an automatic fire suppression system in the RHR pump / heat exchanger rooms.
1 2.3.2 Discussion i
I The licensee stated that circuits and equipment of both divisions of the RHR located on elevation 519 are separated from each other by a cumulative l
horizontal distance of more than 20 feet; however, automatic suppression is not j
- provided, j
j The RHR pumo rooms and heat exchanger roons are constructed of reinforced
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i concrete and are located within the reactor buildings on elevation 519 feet.
t Open metal prating exists at slevations 541 and 565 feet of the RHR punp rooms.
l A portion of the heat exchangar room floor is metal grating which is the ceiling of the R!!R pump room. The distance between the unprotected openings of the two i
j RHR pump rooms for each unit is about 70 feet with no significant intervening l
5 combustibles. The height to the solid ceiling located below elevation 621 feet 1
is 101 feet. The RHR purps are located in two of the four corner rooms of each reactor building.
Each core spray /RCIC corner room is in the same fire rene and on the same side of the RHR pump rooms, but on the opposite side of th( building.
l A HPCI coom adjoins one RHR corner roem on each unit reactor building.
l The fire lead in the RHR pump rooms primarily censists of pump lube oil.
plastics, and cables. The average WHR pump room fire load is 14.000 Stu per i
j square foot, which translates into an equivalent fire severity of 11 minutes as represented by the ASTM E-119 fire test curve.
The fire leading in the core i
spray /RCIC and torus area is negligible.
In the HpCI room the fire load is j
also low (15.500 Btu per square foot),
t The safe shutdown system components located in the subject fire zones include j
both divisions of.
1 RHR purps RHR heat exchangers l
j associated cables I
teveral circuits of RHR Division 1 pass across the ceiling of the Division !!
j heat exchanger room, resultin in a separation of approximately 15 feet 2
horizontally and 80 feet vert cally between disistonal cables.
There are otber interdivisional valves to RHR equipment with separations between 12 to 20 feet i
horizontally and 80 feet vertically, i
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Fire protection coverage for the RFR purp and heat exchanger rooms is in the form of hose stations and portable fire extinguishers.
The Itcensee.has 1
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comitted to provide cross-zoned fire detectors on the ceilings of the RHR pump The licensee has installed a water curtain and draft stop to separate the RHR heat exchanger rooms and the fire zone on elevation 593 feet.
rooms.
The general area at elevation 593 feet is protected by fire detection and autcratic fire suppression systems. One of the RHR pumo rooms for each unit is J
l adjacent to a high pressure coolant injection system (HPCI) room.
The HPCI room has autematic fire suppression and detection systems that protect the lube l
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oil tank fire hazards located there.
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2.3.3 Evaluation f
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The fire protection in the RHR pump and heat exchanger rooms does not comply with the technical requirements of Appendix R because an automatic fire i
suppression system has not been installed in the fire zones per Section
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!!!.G.2.b.
The principal concern with the level of fire protection in the RHR pump and l
i heat exchanger rooms was that because of the absence of an automatic fire i
suppression system, a fire of significant magnitude could develop and damage l
redurdant RHR system components. However, the fire load inside these fire zones and adjoiniro locations is low to negligible.
If a fire were to occur, l
it would d2velop slowly with lor heat release and slow room temperature rise, 1
i The water curtains and draft stops installed around the open grating between the PPR pump rooms and the RHR heat exchanger rcoms vill prevent spread of fire A
between these rooms. Also, the open grating will perait some heat to dissipate to the 671 foot elevation where the volume of space 's large relative to the 2
voluma e.u fire h,0d of the RHR pump rooms.
Because of the early warning fire e tection systems in de RHR pump and heat exchanger rooms' ceilings, the fire l
would be detected in its incipient stages and would summen the plant fire brigade. Until tne fire u s extinguished, the low fuel load, concrete i
i harriers, and high ceilings would prevent the fire from damaging or spreading s
L w -edundant RHR systen coetonents located over 70 feet away, Should a fire j
cecer in the HPCI room, torut area, or core spray /RCIC rooms, it is not 4
eNpected tc spread to the RER pump and heat exchanger roons because of the r,egligib'.e i s rvening fire: loads. The water spray system in the HPCI room
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t would contain the lube ol'. fire hazard located therein, I
The staff finds th u the installation of an autmatic fire suppression system l
would not significantly increase the level of fire protection in the RHR pump and heat exchanger rooms.
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i 2.3.4 Conclusion j
I Based on the above evaluation, the staff concludes that the existing fire pro.
tection reasures for the RHR purp and heat exchanger roecs provides a level of l
J fire protectico equivalent to the technical requirements fo-Section !!!.G.2.b of Appendix R.
Therefore, the exemptinn reouest for the aforementioned zones i
should be granted.
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2.4.0 Reactor Buildings 2.4.1 Exemption Requested i
An exenption was requested from the specific requirements of Section !!!.G.2.b to the extent that it requires no intervening combustibles within a 20-foot separation space between redundant safe shutdown system components, j
i 2.4.2 Discussion Each reactor building has open ladder-type cable trays Iccated between l
redundant safe shutdown system components separated by a distance equal to or t
i greater than 20 feet.
The intervening combustibles consist of the cable insulation in the cable trays.
l The locations within the reactor buildings having the aforementioned concern have no other in-situ fire hazards or fire loads except for the cable
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j insulation. The average fire load is equivalent to a fire severity of 30 minutes as represented by the ASTM E-119 fire test curve. The cables and trays l
i have been liberally coated with flamastic compound, which is a fire retardant
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The licensee has further cemitted that any new cable additions to material.
the trays will conform to the fire resistance properties of IEEE Std. 383.
The reactor buildings are constructed of reinforced concrete and the ceilings are 20 to 30 feet high.
Area wide fire detection and sprinkler systems coupled with local supplemental sprinkler coverage and manual extinguishers and hose f
stations are provided to protect the intervening cables in the affected areas.
i Where sprinkler system coverage does not exist. the licensee has comitted to 1
provide additional sprinklers as necessary as delineated in the January 31.
1986 submittal and to provide additional sprinkler coverage to nitigate the effects of a floor level and transient exposure fire.
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l 2.4.3 Fvaluation i
e fire protection in the reactor buildings does not comply with the technical i
requirements of Section lil.G 2.b of Appendix R because there is not ?O feet of l
spatial separation free nf intervening combustibles between redundant safe shutdown system components.
l There was concern regar;tng the level of fire protection in the reactor building areas because of the presence of intervening combustibles.
A fire of significant r'agnitude could develop and spread threugh the 20-foot space i
between the redundant safe shutdown divistens.
The primary fire load of s
concern is cable insulation which has been coated with a fire retardant f
material.
There is not sienificant fire loading on the floor except for the possibility of a transient exposure fire.
Should a fire occur, it is expected i
to be seall and develop slc aly.
Also, the actuation of the fire detection system (s) weuld alam and sumon the fire brigade. Until the fire was i
extinguished, the low fire load, the spatial separation eeual to or greater 1
than 20 feet, the high ceilings, the fire retardant coatinc en cable insulation, and the sprinkler system coverage above and below the cable trays 1
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I would provide reasonable assurance that the fire wottld not simultaneously threaten redundant safe shutdown system components.
It is expected that the
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fire would remain small and be easily extinguished by the fire brigade.
l 2.4.4. Conclusion Based on this evaluation, it is concluded that local supplemental sprinkler f
coverage on intervening combustible loads between redundant trains separated by I
a horizontal distance of 20 feet or more under the conditions as described by l
the licensee is equivalent to the separation requirements of Section !!!.G.2.b l
of Appendix R in regard to horizontal separation.
However, the placement of a local supplemental sprinkler system does not exempt the licensee from the other requirements of Section !!!.G.2.b (installation of detection and suppression in the fire area). This supplemental sprinkler system should serve as an independent defense against fire spread and rieet the intent of the defense in i
depth philosophy inherent in Section !!!.G.2.b.
The criteria developed for supplemental sprinkler protection for Watts Bar and Seo.uoyah may also be used (as approved for Deviatien 11 - Appendix R SON, Youngblood to White letter of f
May 29, 1986). Applicability of this criterien will depend on the comparability l
of suppression capability at Browns Ferry to the plant', for which the criterion
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was approved.
Therefore, the exemption should be granted with the condition that an evaluation of the existing and supplem ntal suppression coverage be available i
for NRC audit for each use of the exemption.
2.5.0 Control Building (Fire Area 16) 2.5.1 Exemption Requested An exemption was requested from Section III.G.3 to the extent that it requires I
installation of fire detection and fixed fire suppression systems in the fire l
areas for which an alternative shutdown capability has been provided. This t
request for exemption originally included Shutdown Board Rooms inside the I
Reactor Buildings, consisting of fire areas 4 throuch 15; Shutdown Board Rooms inside the Unit 3 Diesel Generator Butidings consistir.g of fire areas 22 through 24; and the Turbine Building consisting of Fire Area 25. These areas were deleted frora the requests for exerption by the licensee in its letter of
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November 21, 1986. Hence, this exemption request is for the Control Building
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1 2.5.2 Discussion I
The control building is a separate fire area enclosed by reinforced concrete
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barriers equivalent to a 3-hour fire rated barrier except for the battery and battery board rooms (Fire Areas 17, 18 and 19).
Some of these walls are 1-1/2 hour fire rated. Hewever, the battery and battery board rooms have fire detection and fire suppression systems as well as a combustible loadirg of less than 30 minutes.
The lack of a fixed fire suppression system in the main control rooms is addressed in a separate exemption rtluest evaluated in i
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I 2.2.0 of this report. All areas in the Control Building without detection acd suppression are listed below:
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Control Building Areas Without Fire Detection and Suppression c
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i Room F.levation f
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Corridor 593 i
Computer Services Room 593 l
Stairs 593 Stairs 606 i
Stairs 617 l
Corridor 617 t.unch Room 617 j
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l Control Building Areas Without Fire Suppression i
Room Elevation j
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Computer Paintenance Room 593 j
Electrical Pooms 593 8
Corridor 593 MG Set Room 593
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i Corrunication Room 593 l
l Comunication Battery Board Room 593 J
Comunication Battery Room 693 j
j Pechanical Fquipment Room 593 j
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Fire extinguishers and hose stations are available within Fire Area 16.
The control building has redundant safe shutdown system components, but j
alternative shutdown capability has been provided which is independent of Fire Area 16 (Control Putiding),
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1 2.5.3 Evaluation l
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The fire protection in the Control Building does not comply with the technical i
requirements of Section !!!.G.3 of Appendix R because fire detection and fixed fire suppression systens have not been installed in the fire areas for which an 1
j alternative shutdown capability is provided.
The principal concern was that fire in one of these fire areas could spread to l
a critical area and cause a loss of normal shutdown capability. However, the low fire load and fire barriers provide reasonable assurance that a fire would not propagate beyond the specific area of fire origin.
There is also
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reasonable assurance that a fire in these areas can be readily extinguished by j
the fire brigade.
Fire detection systems are provided for the subject areas I
j except as noted in the above table.
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Should a fire damage redundant normal safe shutdown system components in the f
subject fire areas before the fire is extinguished, alternative shutdown The staff finds that the j
capability is available to maintain safe shutdown.
installation of fixed fire suppression systems and area wide detectors would j
j not significantly increase the level of fire protection for these areas.
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2.5.4 conclusion l
Based on the above evaluation, the staff concludes that the existing fire rated barriers and fire protection features combined with the alternative shutdown
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capability in the Control Building provides a total level of protection i
j equivalent to the technical requirements of Section III.G.3 of Appendix R.
Therefore, this exemption should be granted as requested. With respect to j
withdrawing the exemption requests for the Shutdown Board Rooms inside the i
Reactor Buildings (Fire Areas 1 through 15), in the Unit 3 Diesel Generator i
i Building (Fire Areas 22 through 24) and the Turbine Building (Fire Area 25),
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1 compliance with the requirements of Section !!!.G of Appendix R will be verified by the staff during the regular Appendix R audit prior to f
i authorizing the licensee to return to power, t
3.0 EXEMPTION REQUESTS IN REGARD TO FIRE AREA BOUNDARIES AS PER GENERIC l
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LETTER 86-10 The followirg exemption requests were evaluated under the provisions of Generic Letter 86-10.
l 3.1.0 Fire Doors. Reactor Buildines Elevations 505. Sal and S19 Feet i
l 3.1.1 Exemption Requested i
An exemption was requested from the specific requirerent of Section !!!.G 2.a to the extent that 3-hour rated fire doors are not provided for certein fire l
rated barriers.
i 3.1.2 Discussion l
1 Fire rated barriers are required to have door openings equipped with a fire j
rated door assembly.
The fire rating of the door assembly should equal that i
reoutred of the fire rated barrier. Contrary to this requirenent, the
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following unrated fire doors are used in 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire rated barriers:
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(a) The door openings into the main stean ard feedwater piping *.unrels which separate the reactor buildings from the turbine building at l
elevation 565 feet. These doors are identified as door Nos. 220
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239 and 252 for Units 1. 2. and 3. respectively.
l (b) The doors between the reactor buildings on elevations 519 and 541 feet. They are identified as door nos. 30, 31, 34, 35, 36, 37, 40
- 41. 42. 43, 44, and 45.
I
l l (c) The personnel locks and the equipment access locks on the turbine building entrance to Units 2 and 3 reactor buildings at elevation 565 feet.
These doors are identified as numb rs 2.15 and 248 for the personnel locks and nuebers 237 and 2 ) for the equipment access locks.
The affected unrated fire doors are identified by number, culumn line, and elevation in the following tabulation:
Door No Column t.ine Elevation 30 R7-n 519 31 R7-r 519 34 R8-r 510 35 R8-n 519 36 R14-n 519 37 R14-r 519 40 RIS-r 519 41 R15.n 519 42 R7-r B41 43 R8-r 541 44 R-14-r 541 45 R15-r 541 220 R3-n 565 235 R8-n 565 237 R9-n 565 239 R10-n 565 248 R15-n 565 250 R16-n 565 252 R17-n 565 w in Steam and Feedwater pipino Tunnels, Door 3.1.2.1 Fire Doors of the a
Nos. 220, 239, and 252 The train steam and feedwater piping tunnels have walls, floors, and ceilings with a fire rating in excess of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. The fire load is regligible.
The main steam and feedwater piping tunnels are in between each reactor butiding and the turbine building. On the reactor building side the interface is a door opening and a blowout panel. On the turbire building side, (approximately 40 I
feet from the blowout panel) the piping tunnel opens into the moisture separator area. This area has several openings into the general area of the turbine building and the main condenser room.
Fortable fire extinguishers and hose stations are available to the area. No safe shutdown cables or equipment are located in these areas.
3.1.2.2 Fire Doors Between Peactor Buildings, Door Nos. 30, 31 34, 35, 36, 37, a0, 41, 47, a3. 4a. and 45 The walls between the reactor buildings are equal to or greater than 3-foot-thick reinforced concrete. There is a door on each side of the opening through the wall on elevations 519 and 541 feet. Petween Units 1 an4 2, the F
wm www y=
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-w wn,g. g
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j j
i I I doors connect Unit 1 RHR pump roon and core spray pump room to the Unit 2 RHR purrp room and the core spray /RCIC pump room at the 519-foot elevation. At the t
541-foot elevation, two doors connect Units 1 and 2 through the RHR pump rooms.
I The door connections between Units 2 and 3 are similar to those between Units 1
[
and 2.
Each door is a heavy equipment bulkhead door of all metal construction (5/16-inchthickplate). Labeled doors are not available for this type of l
application.
I The fire load in the rooms on either side of the subject doors is low and is I
t equivalent to a fire severity of about 12 minutes. The RHR pump rooms at the zone interface will be provided with water curtains actuated by cross-zoned fire detectors.
3.1.2.3 Personnel Locks and the Couipment Access Locks. Doors Nos. 235, 237, f
t 248 and 250 The walls between the reactor buildings and the turbine buildings are 2-foot-thick reinforced concrete.
Persennel locks and equipment access locks t
are provided for access between the turbine building and the reactor buildings.
These doors are at the following locations:
Personnel lock (door 235) on the turbine building entrance to Unit 2 a.
reactor buildirg at elevation 565 feet.
f b.
Equipment access lock (door 237) on the turbine building entrance to Unit 2 reactor building at elevation 565 feet.
r Personnel lock (door 248) on the turbine building entrance to Unit 3 f
c.
reactor building at elevation 565 feet.
d.
Equipment access lock (door 250) on the turbine building entrance to l
Unit 3 reactor building at elevation 565 feet, j
These doors are heavy equipnent bulkhead type doors of all metal (1/4-inch-thick) construction. Labeled doors are not available for these types of applications.
These doors are part of the enclosures that separate the reactor buildings and the turbine building to natntain the secondary contairment bnundary. For the personnel access locks, the erciosures are of reinforced l
concrete with a fire rating of three hours. The doors between the enclosures and the reactor building are heavy steel doors without a fire rating. The equipnent lock enclosures have 7-5/8-inch hollow concrete block walls with seismic reinforcement.
The ceilings are 4-inch reinforced concrete with a j
fire rating of one hour. The doors in these enclosures are the same as the personnel access doors and are not fire rated.
l There are no fire loads within the enclosures separating the reactor and turbine buildings. For a fire to spread between these two buildings it would have to propagate through one of the enclosure doors and through a second metal door. The fire lead and/or fire hazards on either side of these locks is not sufficient to permit fire to spread to the two buildings.
t i
3.1.3 Evaluation The fire protection in the affected plant areas does not comply,@J. the technical reouirements of Section !!!.G.2.4 of Appendix R because fire rated j
door assemblies have not been installed in fire rated barriers btitween fire areas or zones.
The principal concern with the level of fire protection is that because of the absence of complete 3-hour fire rated barriers, a fire of significant magnitude r
i could develop and darage redundant and/or cultiple unit safe shutdown system l
However, there are not concentrated fire loads near the unrated components.
j fire door locations and the average fire load is negitgible to low (less than a t
12-minute fire severity). Should a fire occur, it is expected to develop
.{
slewly, remain small, and be easily extinguished by the fire brigade.
The rain steam and feedwater tunnels have walls, floors, and ceilings of 3-hour fire i
2 f
rated construction. There are not safe shutdown systems within the area.
For the reactor building and personnel lock locations, each door is a heavy, all retal construction door and, based on our judgment, can withstand a 12-minute i
l The staff finds that the provision of 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire rated door fire severity.
assemblies for the affected plant locations would not significantly increase
.I the level of fire protection.
J 3.1.4 Conclusion Based on the above evaluation, it is concluded that the existing and proposed
(
fire protection reasures provide a level of fire protection equivalent to the technical requirements of Section !!!.G.2.a of Appendix R.
Therefore, no 2
)
exemption is necessary in accordance with the provisions of Generic L.etter i
l I
3.2.0 Reactor Puilding Refuel Floor, tinits 1, 2, and 3 3.2.1 fxerption l
An exerrption was requested from Section !!!.G.2 of Appendix R to the extent i
that it requires installation of auteratic fire detection and suppression j
?
systems in an area that does not have 3-hour fire rated barriers between l
)
redundant safe shutdown equipment and circuits.
i I
f 3.2.2 Otscussion The refuel ficer is a comen area at elevation 6E4 feet of each unit's reactor buildirg. The refuel floor is nnt separated from the three reactor building I
fire areas by cceplete 3. hour fire rated barriers. However, each lower I
elevation within the reactor building is separated frm each other by a reinforced concrete floor slab. The licensee has rade a corinitrent that i
stairways and eouiprent batches will have water curtains installed around the j
openines through the floor slabs at elevations 593, 621, and 639 feet to J
i raintain fire zone separations. Also, on these three elevations the HVAC ducts will have either a fire rated damper or a fire rated wrap. Other mechanical 1
1 I
4
i 16-penetrations on these elevations will be sealed with fire rated seals.
The refuel floor (elevation 664 feet) is separated from the rest of the reactor j
building by a reinforced concrete floor with an eouivalent 3-hour fire rating.
i The stairways and elevator shafts are enclosed by concrete block walls and l
doors with 1-hour fire ratings. The ceiling height from the refuel floor is 51 feet and the room volume is 2.745,000 cubic feet. The refuel floor is spatially separated by about 37 feet from the turbine building and the only l
interface is along the north wall where the ventilation towers from Units 1, 2, J
The ventilation and 3 contain the main exhaust ducts from the refuel floor.
j towers are constructed of r'etal panel walls, j
During plant operation the fire load for the refuel floor area is negligible i
and there are no significant fire hazards.
Portable fire extinguishers and hose stations are available to the area.
The refuel floor contains to safe shutdown system equipment or cables.
3.2.3 Evaluation The fire protection concern for the refuel floor area is threefold and includes the following scenarios:
I (a) A fire starts in the refuel finne area and spreads down to the lower l
i reactor building elevations containing redundant safe shutdown system components.
i (b) A fire starts within one reactor building, spreads up to the refuel floor, propagates across the refuel floor, then spreads down into I
I lever elevations of an adjacent reactor building.
I (c) A fire initiates in the turbine buildino, spreads to the refuel floor, then down through the reactor buildings, j
All three scenarios rely on a comon denominatnr that the refuel floor has to l
l i
have sufficir st fire loadings or fire ha:ards to allow a fire to start or l
Because the refuel floor has a realigible fire load, j
support propagation.
there is reasonable assurance that a fire will not develop and propagate 1
through the floor area.
It is expected that since a fire on the refuel floor would be quite small, the high ceiling (51 feet) and large volure would safely j
dissipate the heat and smoke. This also provides reasonable assurance that a j
fire would not spread down through an open equipment batch to the lower elevations. However, if it dice the redundant safe $butdown system components l
l located within the reactor buildings on lower levels are in accordance with the j
i provisions of Appendix R; therefore, the fire would rot affect redundant I
j safe shutdown trains.
i The two hatches closest to each other are located within Units 1 and 2.
They 3re separated by more than 20 feet of space free of intervening combustibles, j
Some piping penetrations of 1-inch annular space are separated by lets than 20 feet. Since the general area in the refuel floor is free of intervening J
s
, combustibles, these small openings are not significant paths for fire propagation. Therefore, it would be unlikely for fire to propagate from one reactor building to an sdjacent reactor building via the refuel floor, or for fire originating in the refuel floor to propagate dcwn into more than one reactor building.
For a fire in the turbine building to propagate to the refuel floor area, it would have to destroy the main exhaust duct from the turbine building and pass through the metcl panel walls of the ventilation tower.
It is not expected that a fire would accomplish this, but if it did, no severe consequences would result because there are no combustibles within the refuel floor area and no safe shutdown system components located therein.
The staff finds that the installation of complete 3-hour fire rated barriers or automatic fire detection and fire suppression systems would not significantly increase the level of fire protection in the refuel area.
Based on the above evaluation, the staff concludes that the existing fire prntection and proposed modifications for the refuel floor area provide a level of fire protection equivalent to the technical requirements of Section III.G.2 of Appendix R.
Therefore, no exemption is necessary in accordance with the provisions of Generic Letter 86-10. The staff will, however, review controls on transient combustibles on the refuel floor during the Appendix R audit.
3.3.0 Turbine and Reactor Building Interface Wall Fire Dampers 3.3.1 Exemption Recuested An exemption was requested from Section III.G.2 of Appendix R to the er. tent that 3-hour fire rated HVAC dampers are not installed in 3-hour fire rated barriers that separate the turbine building and each unit's reactor building and the reactor buildings from each other.
3.3.2. Discussion There are two separate sets of unprotected HVAC ducts. One set is located in the main steam and feedwater piping tunnel.
The second set is associated with i
the standby gas treatment system. These ducts are in fire rated walls between the reactor buildings.
The walls, floor, and ceiling of the main steam and feedwater piping tunnels have a 3-hour fire rating.
This area has been previously discussed in Section 4.2.1 of this report. The walls that separate the teactor building from each other are 3-hour fire rated. The reactor building fire area has been previously discussed in Sections 4.2.2 and 5.0 of this report.
The standby gas treatment system (SBGT) has ducts of spiral-welded ASTM-A211 pipe, a black steel pipe with a wall thickness of 0.375 inches.
During plant operation the SBGT is shut down.
There are charcoal filters with a fire load / severity equivalent to 24 minutes within the SRGT buildings.
i
3.3.3 Evaluation The fire protection in the affected plant areas does not comply with the technical requirements of Section III.G.2 of Appendix R because fire rated dampers have not been installed in HVAC ducts that penetrate 3-hour fire rated walls separating the turbine building from the reactor building and the reactor buildings from each other.
An evaluation of these areas has been performed in Sections 4.3, 5.3 and 7.3.
It was found that a fire would develop slowly and remain small. A fire within the SBGT charcoal filters would safely ventilate through the system and not infiltrate the reactor buildings.
A fire in the reactor buildings would not damage the SBGT duct and would only generate warm air within the idle ducts.
The staff finds that the installation of 3-hour fire rated dampers would not significantly increase the level of fire protection.
3.3.4 Conclusion Based on the above evaluation, the staff concludes that the existing fire protection features provide a level of protection equivalent to the technical requirements of Section III.G.2 of Appendix R.
Therefore, no exemption is necessary in accordance with the provisions of Generic letter 86-10.
3.4.0 Exemption for Use of Water Curtains in Reactor Buildings 3.4.1 Exemption Required An exemption was requested from Section III.G.2 of Appendix R to the extent that redundant safe shutdown circuits are not separated by 3-hour fire rated barriers or 1-hour fire rated barriers with automatic fire detection and suppression provided.
3.4.2 Discussion Each Reactor Building is a designated Fire Area and each is separated from other fire areas by barriers with minimum 3-hour fire rating.
Each Reector Building is further subdivided into fire zones by reinforced concrete floor slabs at the 593, 621 and 639 foot elevations.
The floor slabs have a minimum 3-hour fire rating and all piping and electrical penetrations are or will be closed with slabs having minimum 1-hour fire rating.
HVAC ducts will be provided where reauired with dampers having minimum 1-hour fire rating, i
However, unprotected openings through the reinforced concrete floor slabs exist in the form of open stairways, equipment hatches and RHR heat exchanger room openings.
Equivalent 1-hour protection is required for some of these openings to satisfy separation requirements of Section III.G.2 of Appendix R.
Since it is not practical to install 1-hour fire rated enclosures for these f
openinos, the licensee has installed draft stops and close spiced automatic sprinklers to forri a water curtain around each opening that is required to be protected.
The purpose of the draft stop around the opening is to bank heat near the ceiling from any postulated fire and cause rapid operation of the
, close spaced sprinklers around the opening.
This will create a water curtain around the opening and cool the hot gases from the fire before they force tnrough the opening to fire zones above.
This arrangement of draft stops and close spaced automatic sprinklers is in accordance with Section 4-4.8.2.3 of NFPA-13, standard for the installation of sprinkler systems,1985 Edition.
3.3.3 Evaluation Fire protection featutes in the affected plant areas de not meet the specific requirements of Section III.G.2 of Appendix R for either 1-hour or 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> fire rated barriers separating redundant trains of safe-shutdown equipment in that reinforced concrete floor slabs have unprotected openings in the form of stairways, equipment hatches and RHR heat exchanger rooms openings.
The licensee has, however, installed draft stops and close spaced automatic sprinklers to provide ' water curtains" around these openings. The installation of the draft stops and close spaced sprinklers is in accordance with the provisions of Section 4-4.8.2.3 of NFPA-13, a standard for the installation of sprinkler systems, 1985 Edition, and is an acceptable method of protecting openings through floor-ceiling fire barriers. The staff finds that this method of protection for the floor openings is acceptable in conjunction with the fire protection features provided for safe shutdown components located in the areas of concern.
Therefora, the inullation of 1-hour or 3-hour fire rated enclosures around these openings would not significantly increase the level of fire protection in the Reactor Buildings.
3.4.4 Conclusion Based on the above evaluation, the staff concludes that existing and proposed fire protection features will provide a level of fire protection that satisfies the technical requirements of Section III.G.2 of Appendix R.
Therefore, no exemption is necessary in accordance with the provisions of Generic letter 06-10.
4.0
SUMMARY
Based on this evaluation, it is found that the level of fire safety in the areas listed below is equivalent to that achieved by compliance with the technical requirements of Appendix R and therefore, the request for exerrptions in these areas should be granted:
1.
Core Uncovery to the extent that alternative shutdown capability is not able to maintain reactor coolant inventory above the core in a BWR as required by Section III.L of Appendix R.
See Section 2.1 for detailt.
2.
The Main Control Room to the extent that a fixed suppression system is not provided throughout the area as required by Section 1:1.G of Appendix R. See Section 2.2 for details.
j l
l
. 3.
RHR Pump Rooms and Heat Exchanger Rooms to the extent that an automatic fire suppression system is not provided as required by Section III.G of Appendix R.
See Section 2.3 for details.
4.
The Reactor Buildings to the extent that Section III.G of Appendix R requires that there be no intervening combustibles within a 20 foot separation space between redundant safe shutdown system components.
See Section 2.4 for details.
5.
The Control Building to the exter.t that Section III.G.3 requires installation of fire detection and fixed fire suppression in the fire areas for which an alternative shutdown capability has been provided.
See Section 2.5 for details.
In addition to the above listed exemptions, the staff has also approved the licensee's analysis in regard to the fire area boundary deviations as per Generic Letter 86-10.
These deviations are es follows:
1.
Reactor Buildings on elevations $65, 541, and 519 feet to the extent that 3-hour fire rated doors are not provided for certain fire rated barriers. See Section 3.1 for details.
2.
Reactor Building Refuel floors to the extent that 3-hour barriers are not provided betwetn redundant safe shutdown equipment and circuits.
See Section 3.2 for details.
3.
Turbine and Reactor Building Interface Wall Firt dampers to the extent that 3-hour fire rated dampers are not provided for certain locations. See Section 3.3 for details.
4.
Water Curtains in Reactor Buildings to the extent that redundant safe shutdown circuits are not separated by 3-hour fire rated barriers.
See Section 3.4 for details.
5.0 PRINCIPAL CONTRIBUTORS This Safety Evaluation was prepared by John Stang, Rex Wescott, and James Watt and was partly based on a technical evaluation report prepared by Franklin i
Research Center (FRC) under a contract with U.S. Nuclear Regulatory Conmission l
(NRC).
Principal Contributors:
R. Wescott and J. Watt Dated: October 21, 1988 i
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