ML20039B740
| ML20039B740 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 11/30/1981 |
| From: | Cohn B GAGE-BABCOCK ASSOCIATES, INC. |
| To: | Benaroya V Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8112230503 | |
| Download: ML20039B740 (4) | |
Text
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@CPA G-fb GAGE-BABCOCK & ASSOCIATES, INC.-
CHICAGO OFFICE
- 135 ADDISON AVENUE, ELMHURST, IL 60126 * (312) 530-1494 PAUL D. SMITH. P E., Prescent BERT M COHN. P E, Sener Vee Prescent 9
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4 nECENED DEC22198 7 E November 30, 1981
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U.S.
Nuclear Regulatory Commission Chemical Engineering Branch, NRR Washington, D.C.
20555 Attn:
Mr. V. Benaroya Gentlemen:
Pilgrim Station Unit'#1 Appendix R Exemption Request By letter dated March 18, 1981, Boston Edison Company submitted their interpretation and evaluation for an exemption of Section III, G, 2 for the Vital M.G.
Set Room based on the assertion that the existing fire protection features in the form of equip-ment, structures and procedures would assure that the intent of Section III, G,
1 of Appendix R to 10 CFR 50 is satisfied.
Enclosed is our review and evaluation of the licensee's submittal for the requested exemption item using 10 CFR'Part 50, Appendix'R and the guidelines contained in the Standard Review Plan', Section 9.5.1,
" Fire Protection System," and Appendix A.
Very truly yours, B rt M. Cohn Project Director Encl.
cc:
C.
Poslusny
. cob W. Johnston J
E.
E. Grenier B.
L. Grenier
/f Contracting Officer I
8112230503 811130 PDR ADOCK 05000293 F
PDR IERS AND CONSULTANTS IN FIRE PROTECTION, SAFETY AND SECURITY LOS ANGELES NEW YORK WASHINGTON CHICAGO '
- ' SAN FRANCISCO e
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Enclosure;I Pilgrim I Exemption Request
1.0 INTRODUCTION
By letter dated March 18,1981 the licensee requested an exemption for the Vital Motor Generator Set Room from Section III, G, 2 of Appendix R to 10 CFR Part 50 on the " Fire Protection For Safe Shutdown Capability" based on the assertion that the existing fire protection features in the form of equipment, structures and procedures would assure the intent of Section III, G,1 of Appendix R.
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- 2. 0 DISCUSSION In-situ combustibles for this fire zone-consist of a minimal amount of lubricants -
- for the M.G. sets as well as 1,385 lbs. of cable insulation producing a combus-tible loading of 4.9 lbs/sq.ft. (of equivalent wood). All cables-routed within the M.G. set room deemed incapable of meeting the IEEE 383 will be covered with a suitable fire retardant coating in accordance with the guidelines of Appendix -
A to BTP-APCSB 9.5-1 except for where cables are installed in enclosed trays.
Non-safety cable trays of which -20% of the cables are deemed incapable of meet-ing the IEEE-383 requirement will be covered with solid steel tray covers.
All of the walls of this zone are' fire rated for 3 hrs. with a lh ' fire door being provided for access to the stairwell in the south wall.
The licensee has provided the following fire protection features for protection of fire zone 3.5 - vital M.G. set room:
1.
Both ionization and photoelectric smoke detectors are installed with alarm and annunciation in the Control room.
2.
A lh in. hose station with 75 ft. of. hose is provided outside the door to this zone in the stairwell.
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The majority of cable trays has been sprayed with Flamemastic 77.
Boston Edison Company submitted an " Analysis of Effects of a Postulated Fire Involving Both Redundant Divisions of Shutdown Systems" dated January 1980 for the entire plant. The Safe Shutdown Analysis was performed for the Radwaste and Control Building, elevation 23 ft., Vital Motor Generator Set Room (Fire Zone-3.5).
Fire Zone 3.5 contains division A safety-related system panel and conduits serving the'RCIC, SSW and RBBCW systems, the MCR and diesel generator H&V and.the torus level and temperature instrumentation. Cable trays'containing' safety-related train B circuits are.also routed through this room. The train B safety-related cable trays are approximately 6 ft. horizontal distance from the train A safety-related panel and are installed in accordance with the separation criteria as described in the FSAR Amendment response submittal 7.1.4.
The vertical separation of the train B cable trays from the M.G. sets is approximately 4 ft.
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.. 4 Safety-related train B cable trays run west-east in the northern part of this fire zone and then turn and run north-south ~in the eastern part. There are redundant division A and X conduits in the same area.
3.0 EVALUATION The Safety Shutdown Analysis that was performed for this area identified RHR inboard isolation valve 1001-50 as requiring protection from a postulated fire involving division B. raceways. Structures, systems and components of both division A & B were evaluated to determine if one train of systems neces ary to achieve and maintain hot shutdown conditions from either the control room or emergency control station is free of fire damage. A fire in fire zone 3.5 in-volving more-than one safety division raceway cannot be tolerated because safe shutdown would be jeopardized, The only safe shutdown system needed is the RHR which is supplied from the 120 volt A.C., division A-panel Y3.
Marinite boards are installed between division B trays BF and BE and between BR and KG.
Cable trays BF and BE are sprayed with Flamemastic 77 throughout their east-west routing.
It should be noted that Flamemastic and Marinite board give little or no protection against a' postulated exposure fire located on the floor.
The steel enclosed cable trays are provided with fire breaks every 20 ft.
Safety-related panel Y3 is supplied from 480 volt MCCB17 which is located in the Reactor Building at elevation 23 ft.
Panel Y3 provides control feeds for panels CI, C903, C904, C89 and C220. The #1 breaker of this panel feeds systems which are not essential for safe shutdown.
The #2 breaker provides the feed to panel C904 for isolation system for:
(1) Steam line inboard valves.
(2) RHR inboard isolation valves 1001-50,1001-63 and 1001-32.
(3) Reactor water cleanup system inboard valve 12-1-2.
Isolation valves will fail close on loss of offsite power. Valve 1001-50 is required for shutdown cooling mode which has been addressed in the-shutdown analysis.
Interactions exist as the division A conduits pass over and/or under division B cable trays; division A distribution panel Y3 is in the immediate area of train B cable trays. A postulated exposure fire on -the floor may jeopardize safe plant shutdown since damage to redundant divisions can result. The fire protec-tion being provided by the licensee places total reliance on manual extinguish-ment by the plant's fire brigade and is -inadequate to prevent damage to circuit integrity of redundant safety systems should a fire develop.
The' licensee has not demonstrated that for a postulated exposure fire in fire zone 3.5, adequate protection has been provided to mitigate the consequences of loss of equipment and conduit needed for safe plant shutdown.
4.0 CONCLUSION
S Section III, G,1 of Appendix R to 10 CFR Part 50 states that " Fire Protection features shall be provided for structures, systems, and components important to safe shutdown. These features shall be capable-of limiting fire damage so that:
a.
One train of systems necessary to achieve and maintain hot shutdown conditions from either the control room or emergency control station (s) is free of fire damage; and...."
As stated in the preceding Section 3.0 EVALUATION, damage may result to systems necessary for hot shutdown; hence Section III, G, 2 also applies.
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the criteria which should be applied to prevent damage to safety-related systems.
Based on our evaluation, we conclude that the fire protection being provided for the Pilgrim #1 Vital M.G. set room (fire zone 3.5) ~1ocated on elevation 23 ;ft.
of the Radwaste and Control Building is unacceptable, and the exemption request from Section III, G, 2 of Appendix R to 10 CFR Part 50 should be denied.
To meet Section III, G, 2 of Appendix R-to 10 CFR Part 50, the licensee should provide one of the following:
1.
Alternative shutdown capability independent of cables, systems or components in fire zone 3.5.
2.
Relocate the necessary panels and conduit of train A to another fire zone. This will result in separation of cables and equipment of redundant trains by a fire barrier having a 3 hr. fire rating.
If this option is used, the new fire zone that the train A system is relocated to'should be re-evaluated in the Safe Shutdown Analysis.
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