ML20214V784
| ML20214V784 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 12/01/1986 |
| From: | Bernero R Office of Nuclear Reactor Regulation |
| To: | VERMONT YANKEE NUCLEAR POWER CORP. |
| Shared Package | |
| ML20214E708 | List: |
| References | |
| NUDOCS 8612090830 | |
| Download: ML20214V784 (15) | |
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7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of VERMONT YANKEE NUCLEAR POWER CORPORATION Docket No. 50-271 Vermont Yankee Nuclear Power Station EXEMPTION I.
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The Vermont Yankee Nuclear Power Corporation (VYNPC, the licensee) is the
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holder of Facility Operating License No. DPR-28 which authorizes operation of Vermont Yankee Nuclear Power Station. This license provides, among other things, that Vermont Yankee Nuclear Power Station is subject to all rules, regulations, and Orders of the Commission now or hereafter in effect.
The station is a boiling water reactor located at the licensee's site in Windham County, Vermont.
II.
On November 19, 1980, the Commission published a revised Section 50.48 and a new Appendix R to 10 CFR Part 50 regarding fire protection features of nuclear power plants. The revised Section 50.48 and Appendix R became effec-tive on February 17, 1981.Section III of Appendix R contains 15 subsections, lettered A through 0, each of which specified requirements for a particular aspect of the fire protection features at a nuclear power plant. One of these subsections, III.G, is the subject of the licensee's exemption requests.
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.Section III.G.2 of Appendix R requires that one train of cables and equipment necessary to achieve and maintain safe shutdown be maintained free of fire damage by one of the following means:
a.
Separation of cables and equipment and associated nonsafety circuits of redundant trains by a fire barrier having a 3-hour rating. Structural l
steel forming a part of or supporting such fire barriers shall be protected to provide fire resistance equivalent to that required of the barrier.
b.
Separation of cables and equipment and associated nonsafety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening combustibles or fire hazards.
In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
c.
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 autcmatic fire suppression system shall be installed in the fire area.
In addition,Section III.G.I.a of Appendix R requires that one train of cables and equipment necessary to achieve and maintain hot shutdown conditions from either the control room or emergency control stations (s) be free of fire damage.
III.
By letter dated April 24, 1985, the licensee requested exemptions from III.G.2 of Appendix R in 11 areas of the plant.
On July 16, 1985, the licensee met with the NRC in Bethesda and a request was made of the licensee to provide additional information.
By letters dated July 26, 1985, August 2, 1985, and August 16, 1985, the licensee provided additional information and/or revisions to its submitted exemption requests.
By letters dated August 2 and August 16, 1985, the licensee subsequently
. withdrew four exemption requests identified as numbers 3, 9,10, and 11 and also withdrew exemption number item 8 after incorporating it into exemption number 7.
The following list of exemption requests, therefore, reflects the latest status of the exemption request from Appendix R Section III.G.2 resulting from the original April 24, 1985 letter:
1.
Reactor Building, Torus Area Elevations 213 feet 9 inches, and 232 feet 6 inches (Zones RB-1 and RB-2).
Exemptions were requested from the specific requirements of Section III.G.2.b to the extent that an automatic fire suppression system is not installed in these zones.
2.
RCIC Room Elevation 213 feet 9 inches (RCIC Room Fire Area).
Exemptions were requested from the specific requirement of Section III.G.2.a to the extent that this area is not separated by 3-hour fire rated barriers from the areas containing redundant shutdown systems, cables, and associated circuits.
Note: This exemption is a revised version. The original exemption request in the April 24, 1985 submittal was from the provisions of III.G.2.c.
3.
Reactor Building Northeast and Southeast Corner Rooms Elevation 213 feet 9 inches to 252 feet (Zones RB-1 and RB-2).
Exemptions were requested from the specific requirements of Section III.G.2.b to the extent that automatic fire suppression is not provided in the corner rooms and within the area between these rooms and the stairs at elevation 252 feet.
4.
Reactor Building Northeast Corner Vital MCCs Elevation 252 feet (Zones RB-3 and RB-4).
Exemptions were requested from the specific requirement of III.G.2.b to the extent that automatic fire suppression is not installed
. within the vital Motor Control Center (MCC) area and to the extent that
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20 feet of separation without intervening combustible or fire hazard is not provided between redundant safe shutdown systems.
5.
ReactorBuildingNorthwestCornerElevation252 feet (ZoneRB-3).
Exemptions were requested from the specific requirement of III.G.2.b to the extent that redundant trains of cables and equipment are not separated by a horizontal distance of more than 20 feet free of combustibles or fire hazards.
6.
Reactor Building East Side Instrument Racks Elevation 280 feet (Zones RB-5 and RB-6).
Exemptions were requested from the specific requirement of III.G.2.b to the extent that automatic fire suppression systems are not installed throughout the area.
In addition, by letter dated October 31, 1985, the licensee requested two exemptions from III.G.I.a of Appendix R.
Because Section II G.1.a does not allow for repairs in order to achieve and maintain hot shutdown, the exemption request involved allowing the operators to perform the following repairs:
1.
Rearranging electrical leads to connect 'a back-up battery charger in the event a fire in the cable vault disables the operating battery charger; and 2.
Replacing fuses that could be blown due to a fire in the cable spreading i
area.
By letter dated August 15, 1986, the licensee provided information rele-i vant to the "special circumstances" finding required by revised 10 CFR 50.12(a)
(50 FR 50764) for the licensee's April 24, 1985 request. The licensee stated that existing and proposed fire protection features at Vermont Yankee accom-plish the underlying purpose of the rule.
Implementing additional modifications
. to provide additional suppression systems, detection systems, and fire barriers would require the expenditure of engineering and construction resources as well as the associated capital costs which would represent an unwarranted burden on the licensee's resources. The licensee stated that the costs to be incurred are as follows:
o Engineering and installation of additional piping, sprinkler heads, and supporting structures.
o Engineering and installation of fire barriers, supports, support protec-tion, and ongoing maintenance.
o Rerouting of power and control cables, and associated conduits, and supports.
o Increased surveillance on new or extended fire suppression and fire detection systems.
o Increased congestion in numerous plant locations complicating future plant modifications / operation.
Also by letter dated June 10, 1986, the licensee provided information relevant to the "special circumstances" finding required by revised 10 CFR 50.12(a) (50 FR 50764) for the licensee's October 31, 1985 request. The licensee stated that existing and proposed fire protection features at Vermont Yankee accomplish the underlying purpose of the rule.
Implementing additional modifications to provide additional suppression systems, detection systems, and fire barriers would require the expenditure of engineering and construction resources as well as the associated capital costs which would represent an unwarranted burden on the licensee's resources. The licensee stated that the costs to be incurred are a: follows Engineering of additional power and control circuits and the analysis and o
design of associated equipment supports.
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o Significant additions and routing of power and control cables, associated conduits, and supports.
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. o Increased congestion in numerous plant locations complicating plant modifications and operation.
The licensee stated that in both instances the costs are significantly in excess of those required to meet the underlying purpose of the rule. The staff concludes that "special circumstances" exist for the licensee's requested exemptions in that application of the regulation in these particular circum-stances is not necessary to achieve the underlying purpose of Appendix R to CFR Part 50. See 10 CFR 50.12(a)(2)(ii).
The licensee requested an exemption from Section III.G.2.b to the extent that it requires installation of an automatic fire suppression system in Fire Zones RB-1 and RB-2 (Reactor Building, Torus Area Elevation 213 feet 9 inches),
Fire Zones RB-1 and RB-2 (Reactor Building Northeast and Southeast Corner Rooms Elevation 213 feet 9 inches to 252 feet), and Fire Zones RB-5 and RB-6 (Reactor Building East and West Side Instrument Racks Elevation 280 feet).
For Fire Zone RB-1 and RB-2, the existing fire protection includes smoke detection, fire extinguishers, and manual hose stations. All redundant safe shutdown systems are separated by 20 feet with no intervening combustibles located within the spatial separation. The licensee proposes to provide fire stopping for the cable trays to create a 20-foot separation zone in the north-west quadrant and providing the de power feed from the alternative shutdown battery with a 3-hour fire barrier. This fire-stopped separation zone pre-cludes the direct propagation of a fire from zone RB-1 to RB-2 and vice versa.
The licensee committed to provide fire detections on elevation 252 feet for both zones.
The existing fire protection for fire zones RB-5 and RB-6 is in the form of fire extinguishers, fire detection in the MG set area, manual hose stations,
. and an automatic foam fire. suppression system for the Motor Generator (MG) set.
The separation between the racks is 30 feet with a low fire load (6,100 Btu per square. feet excluding the MG set area fire load). The licensee proposes to create 20-foot separation zones by fire stopping cable trays. These separ-ation zones will be from the concrete shield wall to the edge of the MG set area berm and from the concrete shield wall to the reactor building wall on the west side. The licensee has committed to install early warning fire detectors on the ceiling within the 20-foot separation zones just described.
The staff's principal concern with the level of fire protection in these locations was that because of the absence of an area-wide automatic fire suppression system, a fire of significant magnitude could develop and damage redundant shutdown-related systems. However, the fire load in these locations is low.
If a fire were to occur, the staff anticipates that it would develop slowly, with initially low heat release and slow room temperature rise. The MG o
set fire hazard is protected by early warning fire detection and an automatic fire suppression system. Because of the presence of the early warning fire detection systems, the fire would be detected in its incipient stages. The alarms from these detectors are annunciated in the control room. The fire brigade would then be dispatched and would extinguish the fire manually. Until the fire was extinguished, the 20 feet of spatial separation between the redundant shutdown-related systems will provide sufficient passive protection to provide reasonable assurance that one shutdown division would remain free of fire damage.
Based on the above evaluation, the staff concludes that the existing fire protection combined with the proposed fire protection measures in the above zones provides a level of fire protection equivalent to the technical require-ments of Section III.G.2.b of Appendix R.
. The licensee also requested an exemption from Section III.G.2.a to the extent that it requires 3-hour fire rated barrier between redundant trains of safe shutdown equipment for the RCIC room fire area.
The RCIC room contains the Reactor Core Isolation Cooling System (RCIC) and the alternative safe shutdown panel. The RCIC room contains only division II shutdown cables. The room directly above is part of fire zone RB-1 and contains division I and II cables.
The existing fire protection in the RCIC room consists of 3-hour fire rated barriers forming the walls, floor, ceiling, and penetration seals. The exception to this is the steel plate stairway enclosure, equipment hatch, and the steel security door to the torus area.
Fire detection exists in the RCIC room and both fire detection and fire suppression systems exists in the torus area adjacent to the RCIC room. Manual hose stations and fire extinguishers are available to the area.
Finally, this room is accessible by the fire brigade from two separate access entry points. The licensee has committed to provide fire stopping in the torus area cable trays directly outside and near the steel security door to the RCIC room.
The staff's principal concern in the RCIC room was that because of the absence of a 3-hour fire rated barrier, a fire of significant magnitude could l
develop and damage safe shutdown cables. However, there is no significant fire load on the floor area and the cable fire load is low (less than 20-minute severity).
If a fire were to occur, then the staff anticipates that it would develop slowly, with initially a low heat release and slow area temperature rise. The floor, walls, ceiling, and penetrations are 3-hour fire rated barriers. However, the stairway enclosure, a hatch cover, and the security door to the torus area are constructed of steel. This steel construction is substantial since it was designed for a high energy steam line break. Because of the presence of the early warning fire detection system, the fire would be
. detected in its incipient stages. The alarms from these detectors are annunciated in the control room. The fire brigade would then be dispatched and would extinguish the fire. Until the fire was put out, the steel barriers between the RCIC room and the upper room / torus area would provide sufficient passive protection to provide reasonable assurance that one division would remain free of fire damage. The staff finds that the provision of a complete 3-hour fire rated barrier would not significantly increase the level of fire protection in this zone.
Based on the above evaluation, the staff concludes that the existing and the proposed fire protection measures in the area (cable tray fire stops) provide a level of fire protection equivalent to the technical requirements of Section III.G.2.a of Appendix R.
The licensee also requested an exemption from Section III.G.2.b to the extent that it requires the installation of an automatic fire suppression system in the area and to the extent that it requires 20 feet of separation free of intervening combustibles for fire zones RB-3 and RB-4 (Reactor Building northwest corner).
The existing fire protection in these zones is in the form of the fire extinguishers, manual hose stations, and a radiant energy heat shield installed between MCC 89A and MCC 89b. This noncombustible shield is 14 feet high and extends out from the wall by 4 feet. Also, fire stops have been installed in all conduits that span the separation zone between the redundant MCCs. The licensee comitted to install an early warning fire detection system in the separation zones and over the MCCs. Also, the licensee committed to install 20-foot-wide fire stops in all cable trays that cross from fire zones RB-3 and RB-4.
This separation zone would prevent fire propagation from one fire zone to the other.
Finally, in the northwest sector of RB-3, a partial area
. sprinkler system has been installed in the separation zone. The licensee also committed to install a 1-hour fire rated barrier for cables in raceways re-quired for safe shutdown that pass through any of the two separation zones.
Because the fire load in these locations is low, the staff expects that if a fire were to occur, then it would develop slowly, with initially low heat release and slow room temperature rise.
Because of the presence of the early warning fire detection systems, the fire would be detected in its incipient stages. The fire brigade would then be dispatched and would extinguish the fire manually. Until the fire was extinguished, the 20 feet of spatial separa-tion between the redundant shutdown-related systems would provide sufficient passive protection to provide reasonable assurance that one shutdown division would remain free of fire damage.
Where redundant safe shutdown cables are routed through separation zones, they will be provided with a 1-hour fire rated barrier. Finally, in the northwest corner of Fire Zone RB-3, there is a partial area sprinkler system.
The staff finds that the installation of an area wide automatic fire suppres-sion system would not significantly increase the level of fire protection in these zones.
Based on the above evaluation, the staff concludes that the existing fire protection combined with the proposed fire protection measures in Fire Zones RB-3 and RB-4 provides a level of fire protection equivalent to the technical requirements of Section III.G.2.b of Appendix R.
The licensee also requested an exemption from Section III.G.2.b to the extent that it requires 20 feet of separation free of intervening combustibles in Fire Zone RB-3 (Reactor Building Northwest Corner Elevation 252 feet).
The existing fire protection is in the form of fire extinguishers and manual hose stations on an area wide basis.
Fire stops have been installed on i
. all cable trays that span the separation zone in the northwest corner. The licensee has provided an early warning fire detection system in the separation zone containing the cables in question. Also, a preaction sprinkler system has been installed beneath the lowest level of cable trays and above the top trays throughout the corner area. The licensee has committed to provide a 1-hour fire rated barrier for cables in raceways required for safe shutdown that pass through the separation zone in the northwest corner of Fire Zone RB-3.
The safe shutdown systems that exist within Fire Zone RB-3 include MCCs and cables. The issue of redundant MCCs in the northeast corner is addressed above.
The staff's principal concern with the level of fire protection in the northwest corner of Fire Zone RB-3 was that because of the absence of a 20-foot separation free of intervening combustibles, a fire of significant magnitude could develop and damage redundant safe shutdown cables. However, there is no significant fire load on the floor area and the cable fire load is low.
If a fire were to occur, then the staff expects that it would develop slowly, with initially a low heat release and slow area temperature rise. Because of the presence of the early warning fire detection ' system, the fire would be detected in its incipient stages. The fire brigade would then be dispatched and would extinguish the fire. Until the fire is put out, the 18 feet of spatial separa-tion between the cable trays in question would provide sufficient passive l
protection to provide us with reasonable assurance that one division would remain free of fire damage. Another major factor that reduces the fire risk in this zone is that redundant cable trays are well separated after diverging from the one point where 18 feet of separation exists. The staff finds that the provision of 20-foot separation free of all intervening combustibles would not significantly increase the level of fire protection in this zone.
Based on the above evaluation, the staff concludes that the existing fire protection combined with the proposed fire protection measures in the above area of Fire Zone RB-3 provides a level of fire protection equivalent to the technical requirements of Section III.G.2.b of Appendix R.
The licensee also requested exemptions from Section III.G.I.a of Appendix R to allow operators to perform certain' repairs in order to achieve and main-tain hot shutdown. These exemption requests are to allow the operators to connect a spare battery charger to the batteries in the event of a fire in the cable vault, and to replace fuses following a fire in the ca$le spreading area.
The repairs are simple and can be completed quickly with materials that are readily available following acceptable procedures.
The batteries associated with the battery charger, which carry post-fire loads, would not be discharged before 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Since the battery charger is not required to be functional for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and the repairs involved in aligning the back-up battery charger are routine, the staff concludes that operator action to connect a back-up battery charger is acceptable.
The fuse replacement repair involves components in the Reactor Core Isolation Cooling System and the Residual Heat Removal System. The RCIC System is required to be operational within 43 minutes of reactor scram, and the'RHR System is required to be operational within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of reactor scram.
In either case it is unlikely that all fuses would be damaged, however, in either case, all fuses could be replaced in less than 20 minutes, two sets of spare fuses are readily available at the locations needed. Based on the proximity of the fuse replacement locations and the adequacy of licensee preparations for possible fuse replacement, the staff concludes that fuse replacement is an acceptable repair.
. A more detailed analysis of each exemption request is contained in the staff's concurrently issued Safety Evaluation.
IV.
Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12(a),(1)theseexemptionsasdescribedinSectionIIIareauthorizedby law and will not present an undue risk to the public health and safety, and are consistent with common defense and security and (2) special circumstances are present for the exemptions in that application of the regulation in these particular circumstances is not necessary to achieve the underlying purposes of Appendix R to 10 CFR Part 50.
Therefore, the Commission hereby grants the following exemptions from the requirements of Section III.G of Appendix R to 10 CFR Part 50:
1.
Reactor Building Torus Area Elevations 213 feet - 9 inches and 232 feet -
6 inches (fire zones RB-1 and RB-2) to the extent that an automatic fire suppression system is not installed in the zones pursuant to III.G.2.b.
2.
RCIC Room Elevations 213 feet - 9 inches (RCIC Room Fire Area) to the extent that this area is not separated by 3-hour fire rated barriers from the areas containing redundant shutdown' system equipment, cables, and associated circuits pursuant to III.G.2.0.-
3.
Reactor Building Northeast and Southog L dt a er Rooms Elevations 213 feet 9 inches through 252 feet (Fire Zones RB-1 and RB-2) to the extent that automatic fire suppression systems are not installed within the corner rooms and within the area between the stairs at Elevation 252 feet and the corner rooms pursuant to III.G.2.b.
4.
Reactor Building Northeast Corner Vital MCCs Elevations 252 feet (Fire Zones RB-3 and RB-4) to the extent that automatic fire suppression is not installed in the vital MCC area and to the extent that 20 feet of separation
' 4 without intervening combustibles is not provided between redundant safe shutdown systems pursuant to III.G.2.b.
5.
Reactor Building Northwest Corner Eievation 252 feet (Fire Zor.e RB-3) to the extent that 20 feet of separation is not provided between redundant safe shutdown systems pursuant to III.G.2.b.
6.
Reactor Building East Side Instrument Racks Elevation 280 feet (Fire Zeres RB-5 and RB-6) to the extent that an automatic fire suppression system is not installed in the zones pursuant to III.G.2.b.
7.
To the extent that rearranging electrical leads to connect a back-up battery charger in the event a fire in the cable vault disables the operating battery charger be permitted in order to achieve and to maintain hot shutdown conditions pursuant to III.G.I.a.
8.
To the extent that replacing fuses that could be blown due to a fire in 4
the cable spreading area be permitted in order to achieve and to maintain hot shutdown conditions pursuant to III.G.I.a.
Pursuant to 10 CFR 51.32, the Commission has determined that the granting of these exemptions will have no significant impact on the environment (51 FR 43254).
A copy of the concurrently issued Safety Evaluation related to this action is available for public inspection at the Comission's Public Document Room, 1717 !! Street, NW, Washington, D.C. and at the local public document room located at Brooks Memorial Library, 224 Main Street, Brattleboro, Vermont.
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. A copy may be obtained upon written request addressed to the U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Attention: Director, Division of BWR Licensing.
This Exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY COMMISSION s,---
Robert M. Bernero, Director Division of BWR Licensing Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 1st day of December 1986.
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