ML20112C741
| ML20112C741 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/18/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20112C735 | List: |
| References | |
| NUDOCS 8501110366 | |
| Download: ML20112C741 (7) | |
Text
V
.hf" p?g UNITEN S,TATES g
NUCLEAR RECULATORY COMMISSION j;;
\\...../gC
. WASHINGTON. D. C. 20555 E!! CLOSURE 2 SAFETY EVALUATI0ft BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATIVE TO APPEl! DIX R EXEMPTIONS RE00ESTED FOR PILGRIM HUCLEAR POWEP, STATION DOCKET NO. 50-293
1.0 INTRODUCTION
By letter dated liay 17, 1983, as amended by letter dated April 2, 1984, the Boston Edison Company (BECo/the licensee) requested exemptions from Section III.G of Appendix R to 10 CFR Part 50.
Section III.G.2 of Appendix R reovires that one train of cables and equipment necessary to achieve and maintain safe shutdown be maintained free of. fire danage by one of the following means:
1.
Separation of cables and equipment and associated nonsafety circuits 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 required of the barrier.
2.
Separation of cables and equipment and associated nonsafety circuits of redundant trains by a horizontal distance of more than 20 feet with nn intervening combustibles or_ fire hazards.
In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
3.
Enclosure of cable and equipment and associated nonsafety circuits of one redundant train in a fire barrier having a 1-hour rating.
In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
If the above conditiom are not net, Srction III.G.3 requirre + bat there be i.,...'.crnative shuta..;. mLil:!.y independuit of the fire una of concern.
It also requires that a fixtc' suppression system be installed in tLe fire area e' concern if it contains a large concentratior of cables or cther conbustibles. These alternative requirements are rot decred to be Wti"nlent; hrwever, thrv rrovide ocuivalent pretection for %o e tions in e o" 4j m cerep+cd.
A 0
3 F
?
?
e !
Because it is not possible to predict the specific conditions under which fires may occur and propagate, the design-basis protective features rather than the design-basis fire are specified in the rule.
Plant-specific features may require protection different from the measures specified in Section III.G.
In such a case, the licensee must demonstrate, by neans of a detailed fire hazards analysis, that existing protection or existing protection in conjunction with proposed modifications will provide a level of safety equivalent to the technical requirenents of Section III.G of Appendix R.
In summary,Section III.G is related to fire protection features for ensuring that systems and associated circuits used to achieve and maintain safe shutdown are free of damage.
Either fire protection configurations must meet the specific requirements of Section III.G or an alternative fire protection configuration must be justified by a fire hazard analysis.
Generally, the staff will accept an alternative fire protection configuration if:
1.
The alternative ensures that one train of equipnent necessary to achieve hot shutdown from either the control room or emergency control stations is free of fire damage.
2.
The alternative ensures that fire damage to at least one train of 4
equipment necessary to achieve cold shutdown is limited so that it can be repaired within a reasonable time (miner repairs using. components stored on the site).
3.
Fire-retardant coatings are not used as fire barriers.
4 Itodifications required to meet Section III.G would not enhance fire protection safety levels above that provided by either existing or proposed alternatives.
5.
Modifications required to meet Section III.G would be detrimental to overall facility safety.
2.0 REACTOR BUILDING ELEVATION 23'-0" AND ELEVATION 51'-0" (FIRE ZONES 1.9, 1.10, 1.11 AND 1.12 2.1 _ Exemptions Recue_sted T' - licensee requt:tcd excr;ticrs frcn Ecctions !".r.2 c.nd ';*.C 3 cf Appendix R to the extent they rcquire the installation of a total trea covercqe automatic fire suppression system on Elevatiers 23'-0" and 51'-0" of the Reactor Building, 20 feet of separation (free of intervening co*stibles) between redundant trains of safe shutdown conf runt and q, ed. fi md (i n o m,,bn
~tm i, h
t o
e n e
- i edown capabili ty.
.W 3-t 2.2 Discussion Elevations 23'-0" and 51'-0" of the Reactor Building constitute a single fire area because of the unprotected openings in the floor / ceiling assembly separating the elevations (i.e., open hatch and open stairwell). Each elevation has been divided into two fire zones as follows:
Fire Zone 1.9 - East Side. Reactor Building Elevation 23'-0" Fire Zone 1.10 - West Side Reactor Building Elevation 23'-0" Fire Zone 1.11 - East Side Reactor Building Elevation 51'-0" Fire Zone 1.12 - West Side Reactor Building Elevation 51'-0" a.
Elevation 23'-0" (Fire Zones 1.9 and 1.10)
Specific safe shutdown equipnent and cabling associated with the automatic depressurization system, core spray system, residual heat removal system and instrumentation are located on Elevation 23'-0".
Fire Zone 1.9 contains Division A, and Fire Zone 1.10 contains Division B equipment and cables.
Fire Zone 1.9 is separated from Fire Zone 1.10 by a 3-hour fire roted wall along their common boundary except for an area apprcximately 30 feet wide on the north side of the Reactor Building. Alternative shutdown capability has been provided for certain redundant cables installed in these fire zones.
The in-situ ccrbustibles en Elevation 23'-0" are cable insulation. The insulation is either IEEE Standard 383 qualified cable or the cables have been coated with an approved fire retardant material.
Existing fire protection includes early warning fire detection which alarms in the control room, standpipe hose stations and portable fire extinguishers.
The licensce proposes to install a " water curtain" systen at the interface area of Fire Zones 1.9 and 1.10. The system will be designed to discharge water in a " curtain" pattern completely across the open portion of the common zone boundary.
b.
Elevation 51'-0" (Fire Zones 1.11 and 1.1?)
Specific safe shutdown equipnent and cabling associcted with the residual mt irrnval systen and instn.rentation are located r,n Firvatien 51'-0".
R nc 1.11 cent + r*c der A, and fire 7e c 1.12 conta:r Diviticn P.
"r i
eceipment and cables.
Fire 70ne 1.11 is separated from Fire Zone 1.12 by a 3-hour fire rated wall along their corrron boundary except in the following areas:
(a) an area approximately 40 feet wie along the common boundery on the north side, and (b) an area approximately 11 for' wide cruth sit'.
e rm m tw.e ut a
.n
.+
lility I.as been pr cs MN for er ria in redunm
- cahlri n 'tailtd in a,_ic f i n ; c r e r,.
V i
4-The in-situ combustibles on Elevation 51'-0" are cable insulation. The insulation is either IEEE Standard 383 qualified cable or the cables have been coated with an approved fire retardant material.
Existing fire protection includes early warning fire detection which alarms in the control room, standpipe hose stations, and portable fire extinguishers.
The licensee proposes to install " water curtain" systems at each of the two open interface areas of Fire Zones 1.11 and 1.12 described above.
The systems will be designed to discharge water in a " curtain" pattern completely across open portions of the common zone boundary.
2.3 Evaluation The fire protection in fire zones 1.9, 1.10, 1.11 and 1.12 does not conply with the technical requirements of Section III.G of Appendix R because an automatic fire suppression system is not installed in the area and the
' redundant trains are not separated by 20 feet free of intervening combustibles.
We were concerned that, because each half of the reactor building was open to the other, a fire occurring on one side could spread to the other and damage' systems associated with the redundant shutdown division.
The licensee has proposed to install a water curtain system which consists of automatic sprinkler systems at the conrion boundary between the fire zones on elevations 23'-0" and 51'-0" of the reactor building where no physical barrier exists. The sprinkler systems, consisting of close-spaced, thermally activated sprinkler heads, are expected to discharge water in a
" curtain" fashion to prevent significant horizontal fire propagation.
Such systems have been used successfully to protect conveyor openings in fire walls and escalator openings in buildings.
Because there are water barriers rather than continuous nasonry walls, we expect a small quantity of smoke and heat to pass through the water curtain. However, the smoke and hot gases would be cooled and dispersed throughout the large open areas of the reactor building so as to pose no credible threat to the redundant
- hutdown division.
The existing fire detecticn systems ord the proposed " water curtain" systert will assure tMt. a firr would be detected in itt initial starcs N ' rc sigr.ifictrt d ra:c cccurs. The O rc would % n La m pece.cd narually by the plant fire brigade before it represents a serious threat to shutdown systers. The water curtains in the large cpen areas of the reactor building, and the existing spatial separation between redundant divisions provW reae,nnable assurance that one division will remin free o
!ir-. mqe to w a o r, ',o a i n u,<
'io-e +w.
N 2.4 Conclusion Based on our evaluation, we conclude that the existing fire protection with the proposed modifications will achieve an acceptable level of safety.
equivalent to that provided by complying with Sections III.G.2 and III.G.3.
Therefore, the licensee's request for exemptions in Fire Zones 1.9,1.10,1.11 and 1.12 should be granted.
3.0 TORUS COMPARTMENT (FIRE 20'NE 1.30A) 3.1 Exemption Requested The licensee requested an exemption from Section III.G.2 of Appendix R to the extent it requires the installation of a total area coverage automatic fire detection and suppression system.
3.2 Discussion The area is located at the -17'-6" elevation of the Reactor Building.
The area is scparated frcn other plant areas by fire barriers reviewed and approved by the Safety Evaluation (Section 4.13) for Pilgrim License Amendment Number 35. The ceiling height is approximately 35 feet.
Fire protection for the area consists of manual hose stations and portable fire extinguishers located on Elevation 23'-0".
The safe shutdown equipment in the area consists of instrumentation for measuring the water temperature and level in the torus. The redundant trains are separated by 30 feet free of intervening combustibles. By letter dated April 2,1984, the licensee connitted to enclose one train of redundant cables in a 1-hour fire rated barrier.
The in-situ fuel load in the area is very low, consisting of one horizontal cable tray.
3.3 Evaluation The fire protection in this area does not comply with the technical requirerents of Section III.G.? of Apperdix R because an automatic supprossion and detection system is not installed in the area.
% licensee justif4- % exemption bc W cr the followhm:
c)) The in-situ fuel load is very low, b
The arca has linited access during norral operation, c) Tbc redundant trains cf shutdown equipment are horizontally separated by 30 feet free of intervening combustibles.
r-, fr:.:n of r.
+.4h i
"E 1*"
t c wric.
L
r
. Because of the negligible in-situ fuel load in the Torus Area, and because
.of the limited access to the area, the anticipated fires involving
' transient and in-situ combustibles would be limited in size and duration.
The proposed 1-hour fire rated barrier would provide adequate protection for one train of safe shutdown cables.
Because of the configuration, full area fire detection and automatic suppression would not provide a significant increase in fire safety.
3.4 Conclusion Based on our evaluation, we conclude that the existing fire protection with the proposed modification in the Torus Compartment (Fire Zone 1.30A) provides a level of protection equivalent to Section III.G.2. Therefore, the exemption should be granted.
4.0 VITAL M.G. SET ROOM (FIRE ZONE 3.5) 4.1 Exemption Requested An exemption was requested from Section III.G.3 to the extent it requires a fixed fire suppression system in an area for which alternate shutdown capability is provided.
4.2 Discussion The Vital M.G. Set Room is located on Elevation 23'-0" of the Reactor Building.
It is separated from other areas of the plant by 3-hour rated fire barriers. The ccmbustible loading in the area is moderate. A fire detection system and manual suppression equipment are provided in the area. There is alternate shutdown capability, independent of this area.
4.3 Evaluation The fire protection in this area does not comply with the technical requirements of Section III.G.3 of Appendix P. because a fixed fire suppression system has not been installed in the area.
There is reasonable assurance that a fire in this area would be prcmptly detected and extinpuished. The moderate ccmbustible loading in this aroc ensurcs that safety related equipment in ad,iacent areas will not be
'hn:ctered.
The irs tillet Ln of a fi>ed 'irc suppression systm could not e i< r'ficantly tu rc~ tN 'evel of fire ;"mtutice in this ucc.
4.4 Conclusion l
Based on our evt,1pation, we find that the existico fire protection in l
t i n
- 1. i t t
'1-
'm*r a - u.-
t il t
.Et u
f
+ t c,1 provides e l m l of fire prctectiu',Cr/Jival""
- c tne techtiirr)
' tin %
q 1..
t
. l'
-requirements of'3ection III.G.3 of Appendix R.
Therefore, the exemption
.should be granted.
5.0
SUMMARY
Based on our evaluation, we-conclude that the existing fire protection,
.with the proposed modifications, provides a level of safety in Fire Zones 1.9, 1.10,' 1.11, 1.12, 1.30A an,d 3.5 equivalent to compliance with Section III.G of Appendix R. - Therefore.. the licensee's request for exemptions should be granted.
Principal Contributor: -J. Stang Dated:' December 18, 1984 D
e
- s f