ML20215E638
| ML20215E638 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/02/1986 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | YANKEE ATOMIC ELECTRIC CO. |
| Shared Package | |
| ML20215E571 | List: |
| References | |
| NUDOCS 8610150415 | |
| Download: ML20215E638 (19) | |
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7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of )
) Docket No.50-029 YANKEE ATOMIC ELECTRIC COMPANY (Yankee Nuclear Power Station) )
EXEMPTION I.
The Yankee Atomic Electric Company (YAEC, the licensee) is the holder of Facility Operating License No. DPR-3 which authorizes operation of the Yankee Nuclear Power Station (the facility) at a steady-state power level not in excess of 600 megawatts thermal. The facility is a pressurized water reactor (PWR) located at the licensee's site in Rowe, Massachusetts. This license provides, among other things, that the facility is subject to all rules, regulations, and orders of the Commission now or hereafter in effect.
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 effective 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. Portions of III.G applicable to these requests are presented below.
8610150415 861002 PDR F ADOCK 05000029 PDR
7590-01 Subsection 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:
- c. Enclosure of cables and equipment and associated non-safety 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.
Inside noninerted containments one of the fire protection means specified above or one of the following fire protection means shall be provided:
- d. Separation of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening combustibles or fire hazards.
Subsection III.G.3 of Appendix R requires that for areas where alternative or dedicated shutdown is provided, fire detection and a fixed fire suppression system also shall be installed in the area, room, or zone under consideration. '
III.
By lette,r dated December 28, 1984, the licensee requested thirteen exemptions from Section III.G of Appendix R in six areas of the plant. By letter dated
7590-01 April 30, 1985, the licensee withdrew exemption requests 1, 2, 3, and 6 and added exemption requests 14 through 17. By letter dated November 7, 1985, the licensee withdrew exemption requests 4, 5, 11, 15, 16, and 17, leaving seven requests in four plant areas (exemption requests 7,8,9,10,12,13,14).
By letter dated August 22, 1986, the licensee provided information relevant tothe"specialcircumstances"findingrequiredbyrevised10CFR50.12(a)(See 50 FR 50764). The licensee stated that the existing fire protection features and the modifications that have been implemented at the Yankee Nuclear Power Station accomplish the underlying purpose of the rule. For each requested exemption, the licensee discussed why compliance with either Section III.G.2 cr III.G.3 of Appendix R in the particular circumstances is not necessary to achieve the underlying purpose of the rule. For example, when less than 20 feet separation between redundant trains exists, the licensee notes that the combustible loading in the vicinity is too small to cause damage to both trains. Similarly, for locations without fixed fire detection and suppression throughout the building, the licensee states that no significant combustibles or hot shutdown equipment are present in those areas so a fire cannot spread and cause damage. Thus, implementing further modifications to provide additional fire suppression, fire detection and fire barriers or greater horizontal separation would require the expenditure of engineering and construction resources as well as the associated capital costs which would represent an unwarranted burden on
7590-01 the licensee's resources. The staff, therefore, concludes that "special circumstances" exist for the licensee's requested 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. See 10 CFR 50.12(a)(2)(ii).
The acceptability of each exemption request is addressed below. Further i
details are contained in the staff's related Safety Evaluation. NRR and contractor fire protection engineers visited the site to walk down the fire protection modifications made by the licensee to comply with Appendix R and review the above areas where exemptions from Appendix R had been requested.
Exemption Requested for Primary Auxiliary Building (Section III.G.3)
An exemption was requested from Section III.G.3 to the extent that it requires installation of fire detection and fixed fire suppression throughout an area i
requiring alternative shutdown capability.
Evaluation The primary auxiliary building (PAB) is an L-shaped building located south of the vapor container and the safety injection accumulator room and east of the diesel generator building (DGB) and the gas storage building. The walls between the PAB and the DGB (including the door) and the accumulator room wall that abuts the PAB provide a 3-hour barrier between the PAB and the DGB.
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7590-01 Safe shutdown systems in the PAB include the two motor-driven emergency feedwater pumps; the three charging pumps; and the associated valves for each. Both motor-driven emergency feedwater pumps are located on the west side of the PAB, along with the component cooling water pumps and several other systems. A steam-driven emergency feedwater pump which is located in the turbine building provides the redundant train for the motor-driven pumps. Each charging pump is located in a separate cubicle on the east side of the PAB. The safety injection pumps in the DGB provide a redundant shutdown train for the charging pumps.
The concern was that without fire detection and suppression in the PAB, a fire might spread to the DGB and affect the alternate shutdown capability.
Because of the light fuel load in adjacent portions of the PAB and DGB, the staff does not expect a fire of significant magnitude or duration to occur. The limited intervening combustibles in the PAB do not provide a path for the spread of fire between redundant charging pamps because the cables are either mineral-insulated or routed in conduit, and because the pumps are in pits in separate cubicles.
Should a fire occur in one of the charging pump cubicles, it should not spread because the pumps are in pits. A fire would be detected by installed fire detectors which will alert the plant fire brigade. Upon arrival, the fire brigade will extinguish the fire. Should the fire
7590-01 continue, it will not spread to the safety injection pumps in the DGB because the fire ratings of barriers and of doors between the PAB and DGB (including the safety injection accumulator room) exceed the estimated fire severity.
Because of the light fuel load in the PAB, there is reasonab'le assurance that a fire in the PAB will not result in the loss of safe shutdown capability.
Therefore, the staff finds installation of fixed fire suppression and fire detection throughout the PAB would not significantly improve the level of fire protection.
Conclusion Based on the above evaluation, the staff concludes that the existing fire protection provides a level of protection equivalent to the technical requirements of Appendix R. Therefore, the exemption is hereby granted.
Exemption Requested for the Diesel Generator Building (Section III.G.2.c)
An exemption was requested from Section III.G.2.c to the extent that it requires enclosure of cables and equipment and associated non-safety circuits of one redundant train in a fire barrier having a 1-hour rating.
Evaluation The diesel generator building (DGB) is an L-shaped building located south of the vapor container and attached to the PAB. The three diesel generator
7590-01 rooms in the DGB are separated from each other and from the rest of the DGB by 8-inch concrete block walls (estimated 3-hour fire resistance). Doorways between diesel generator rooms are protected with 3-hour fire rated doors; doorways between the diesel generator rooms and the rest of the building are protected by li-hour fire rated doors. The south portion of the DGB is not subdivided except that below grade Manhole No. 3, which is located in the southeast portion of the DGB, is provided with a 1/2-inch thick steel plate at floor level and a 3/8-inch thick steel manhole cover approximately one foot below floor level.
Safe shutdown equipment in the DGB includes three diesel generators, the high and low pressure safety injection pumps (three of each), associated cables and switchgear including containment isolation system (CIS) Train A power and control cables, and CIS Train B power cables (which are routed through Manhole No. 3 to the PAB).
Dedicated shutdown capability is provided for the safe shutdown equipment in the DGB and Manhole No. 3 by the safe shutdown system (SSS) located in other plant areas, except for CIS Train B power cables in Manhole No. 3 (CIS Train A is in the DGB). The requirement to have a 1-hour barrier betweer, redundant trains in Manhole No. 3 and in the DGB is the subject of this exemption request.
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7590-01 A concern existed in that the lack of 1-hour fire rated barrier between Manhole No. 3 and the remainder of the DGB would provide a path for the spread of fire between associated circuits. The CIS is needed to isolate the solenoid-controlled air-operated valve in the bleed line. The concern was that a fire affecting both trains of the CIS might cause this valve to inadvertently reoper.
The diesel generator rooms are separated from the rest of the DGB by rated fire barriers, and are provided with automatic detection and manual fixed fire suppression systems. The fire detection systems would alert the plant fire brigade to a fire in one of these rooms. Upon arrival, the fire brigade will extinguish the fire. Should the fire continue, it is not expected to spread beyond the fire rated barriers of the diesel generator room in which it starts. In the unlikely event that it does spread into the DGB, th,e CIS Train B power cables in Manhole No. 3 should be adequately protected by their location and by the barriers between the manhole and the room. Because of the light fuel load in the south portion of the DGB, the staff does not expect a fire of significant duration or magnitude to occur. The generally limited combustible contents of this zone do not provide a path for the spread of fire to or from Manhole No.
3; there are no intervening combustibles.
Should a fire start outside Manhole No. 3, it will be detected by the installed fire detectors which will alert the plant fire brigade. Upon
7590-01
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arrival, the fire brigade will extinguish the fire. Should the fire continue, it will not spread to Manhole No. 3 because of the latter's location below the fire and because the two steel plates separated by over one foot provide an effective fire barrier in this situation.
Diesel fuel oil will not spread to the manhole because a spill will be confined by the splash shield and curb.
Should a fire start in Manhole No. 3, it will be detected by installed fire detectcrs which will alert the plant fire brigade and actuate the total flooding carbon dioxide extinguishing system. If the extinguishing system fails to operate properly, the fire brigade will extinguish the fire. The fire is not expected to continue because of the limited combustible loading in the manhole and the ease with which a fire in such a confined space can be extinguished.
Dedicated shutdown capability is provided in the event of a fire in the DGB or in Manhole No. 3. The associated circuit valve of concern requires air to reopen; thus, removal of the supply of air is a backup to the redundant trains of CIS. One of the immediate operator actions as part of using the SSS is to bleed off the air system in the turbine building. This would be accomplished ',
within 30 minutes. The staff believes at least 30 minutes would be available to j complete this action, considering the fire detection and suppression capabilities in the DGB and in Manhole No. 3 as discussed above.
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4 7590-01 Despite the presence of a non-standard fire barrier between Manhole No. 3 and the remainder of the DGB, a fire in either locatior. will not result in the loss of safe shutdown capability. Therefore, the staff finds that providing a 1-hour rated fire barrier over the access cover to Manhole No. 3 would not significantly increase the level of fire protection in this fire area.
Conclusion Based on the above evaluation, the staff concludes that the existing fire protection provides a level of protection equivalent to the technical requirements of Appendix R. Therefore, the exemption is hereby granted.
Exemptions Requested for the Vapor Container (Section III.G.2.d)
Exemptions were requested from Section III.G.2.d to the extent that it requires the separation of cables and equipment and associated non-safety circuits of redundant trains in containment by a horizontal distance of more than 20 feet free of intervening combustibles for fire hazards.
Exemptions were requested for:
- 1. The separation between the electrical blisters containing the power cables to the pressurizer solenoid-operated relief valve PR-50V-90 l and its motor-operated block valve PR-MOV-512.
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- 2. The separation between the electrical cables and the actuators for valves PR-S0V-90 and PR-M0V-512 in the pressurizer cubicle.
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- 3. The separation between the electrical cables and transmitters for both pressurizer level instrumentation channels in the pressurizer cubicle, l
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7590-01 Evaluation The vapor container (VC) surrounds the reactor vessel, steam generators, and associated equipment, and encloses all pressurized parts of the main coolant system. It is a freestanding structure, which abuts no other building and is connected by a concrete pipe tunnel to the PAB and by the spent fuel chute to the spent fuel building.
1 A cor.cern existed in that the lack of 20 feet of separation free of intervening combustibles between redundant circuits of the pressurizer valves and of the pressurizer level transmitters could provide a path for the spread of fire which could result in a loss of safe shutdown capability.
PR-S0V-90 is normally closed and fails closed on loss of power. A hot short to the power cable for its solenoid actuator could, however, cause the valve to open. The block valve, PR-MOV-512 is in series in the piping with l PR-50V-90. This valve is manually closed to isolate the line should PR-50V-90 l
l fail open. A hot short of the solenoid for PR-S0V-90 causing the valve to 1
open and damage to the cable for the block valve would result in a small loss-of-coolant accident. A fire in the VC would not present successful operation of the emergency core cooling systems relied upon to mitigate this event.
The power cables to PR-S0V-90 and PR-MOV-512 enter the VC through l
blisters. The cables to these two valves enter containment through separate 1
blisters separated by a horizontal distance of approximately 12 feet. The 12-foot horizontal area between these two blisters is completely empty.
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7590-01 From the blisters, the conduits are routed away from each other so that adequate separation is maintained until the conduit approaches the pressurizer cubicle. The licensee has rerouted the conduit containing the PR-50V-90 power cable to provide this separation. Inside the top of the pressurizer cubicle, the two valves are in the same pipe line where 20-foot separation is not possible.
Two channels of pressurizer level indication are provided. If both channels of level indication were damaged by a single fire, the operators would control primary water addition based on primary pressure indication. Multiple channels of primary pressure indication are available and would not be affected by a fire in the pressurizer cubicle.
The pressurizer level transmitters (PR-LT-705 and PR-LT-8) and cables are separated by approximately 4 feet in the bottom of the pressurizer cubicle.
The conduit routing provides up to 10 feet of separation inside this area.
The only combustible materials in this area are the signal cables to each of these level transmitters, and the power cables to the pressurizer motor-operated l drain valve. All of this cable is in conduit and is, therefore, not considered to be an intervening combustible, with the exception of the last few feet at the j transmitters and motor operator. This area is accessible only from a 40-foot ladder from the top of the pressurizer cubicle, or a 10-foot ladder from the l bottom of the loop area. Thus, transient combustible materials are not likely I
to be brought into this area.
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7590-01 Because of the light combustible load in the VC, the staff does not expect a fire of significant duration or magnitude to occur.
The only significant intervening combustibles are the control rod drive and position indication cables which are routed in a cable tray from the top of the reactor head up and out of the reactor cavity onto the charging floor. This cable tray runs above the neutron source range detector signal cables and is not near any other safe shutdown system of concern. Should a fire occur in the cable tray, it will be detected by the installed linear thermal detector which will alert the plant fire brigade. Upon arrival, the fire brigade will extinguish the fire. In the staff's judgment, at no time will redundant safe shutdown systems be damaged by this fire.
Should a fire occur elsewhere in the VC, it is not expected to cause any damage to the redundant safe shutdown systems because of the light combustible load in their locations. The cables are run in conduit or are mineral insulated and, therefore, present an insignificant fire hazard to their redundant counterparts. Horizontal separation distances between redundant cables are generally ten feet or more, and instrumentation is separated by at least four feet.
In spite of the separation distances of as little as four feet, a fire in any location in the VC will not result in the loss of safe shutdown capability because of the absence of intervening combustibles.
7590-01 Therefore, the staff finds that providing a 20-foot separation free of intervening combustibles would not significantly improve the level of fire protection in the VC.
Conclusion Based on the above evaluation, the staff concludes that the existing fire protection combined with the modifications made by the licensee provide a level of fire protection equivalent to the technical requirements of Appendix R. Therefore, the exemptions are hereby granted.
Exemption Requested for the Turbine Buildino (Section III.G.3)
An exemption was requested from Section III.G.3 to the extent that it requires the installation of fire detection and fixed fire suppression systems in an area for which an alternative or dedicated shutdown capability is provided.
Evaluation The turbine building is a rectangular structure with three operating levels. It abuts the Service Building on the east wall and an office on the northwest corner. The ground level includes the heating boiler room, lube oil room and water treatment room. The mezzanine level is comprised of the enclosed switchgear room, the ventilating fan room and an open area. The operating floor level consists of the enclosed control room and an open area.
7590-01 Safe shutdown systems in the turbine building include power, control, and instrument indication for the emergency power system, charging and emergency feedwater systems, and secondary systems. Portions of these and other safe shutdown systems are also located in the main control room, switchgear room, and cable spreading room. No safe shutdown systems are located in the water treatment room or on the operating level of the turbine building.
A concern existed in which the lack of fire detection and fixed fire suppression systems in the water treatment room and on the operating level of the turbine building could permit a fire to cause the loss of safe shutdown capability.
The water treatment room has a light combustible load and is separated from the rest of the turbine building by a minimum 8-inch concrete block wall and nonrated doors. In addition, there is no safe shutdown equipment in this room. Because of the light fuel load here, the staff does not expect a fire of significant duration or magnitude to occur.
Should a fire occur, it will be detected by plant personnel or by fire detectors or waterflow devices in adjacent areas, which will alert the plant fire brigade. Upon arrival, the fire brigade will extinguish the fire. Should the fire continue, it will not cause the loss of safe shutdown capability because dedicated shutdown capability is provided independent of the turbine building.
7590-01 Because of the light fuel load on the operating level of the turbine building, the staff does not expect a fire of significant duration or magnitude to occur there. Should the fire occur, it will be detected by operating equipment monitors which will alert the plant fire brigade. Upon arrival, the fire brigade will extinguish the fire. Should a fire continue, it will not cause the loss of safe shutdown capability because there is none on this level. The fire is not expected to affect the main control room because it is separated from the operating level by concrete walls and metal doors.
Despite the lack of fire detection and fixed fire suppression systems in these locations, a fire will not result in the loss of safe shutdown capability.
Therefore, the staff finds that providing fire detection and fixed fire suppression systems in these locations would not significantly increase the level of fire protection.
Conclusion Based on the above evaluation, the staff concludes that the existing fire protection provides a level of protection equivalent to the technical requirements of Appendix R. Therefore, the exemption is hereby granted.
Exemption Requested for the Diesel Generator Building (Section III.G.3)
An exemption was requested from the Section III.G.3 to the extent that it requires installation of a fixed fire suppression system in an area, room, or zone for which an alternative or dedicated shutdown system is provided.
7590-01 Evaluation The fire protection in the DGB does not comply with the technical requirements of Section III.G.3 of Appendix R because a fixed fire suppression system is not installed in an area for which dedicated shutdown capability is provided.
A concern existed in that the lack of a fixed fire suppression system in the DGB could permit a fire to cause the loss of safe shutdown capability.
The diesel generator rooms are separated from the rest of the DGB by rated fire barriers, and are provided with automatic detection and manual fixed fire suppression systems. The fire detection systems would alert the plant fire brigade to a fire in one of these rooms. Upon arrival, the fire brigade will extinguish the fire. Should the fire continue, it is not expected to spread beyond the fire-rated barriers of the diesel generator room in which it starts. In the unlikely event that it does spread, the CIS Train B power cables in Manhole No. 3 should be adequately protected by their location and by the barriers between the manhole and the room as discussed previously.
Thus, despite the lack of a fixed fire suppression system in the south portion of the DGB, a fire in this building will not result in the loss of safe shutdown capability. Therefore, the staff finds that providing a fixed fire suppression system would not significantly increase the level of fire protection in this fire area.
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7590-01 Conclusion Based on the above evaluation, the staff concludes that the existing fire protection provides a level of protection equivalent to the technical requirements of Appendix R. Therefore, the exemption is hereby granted.
IV.
Accordingly, the Commission has determined that, pursuant to 10 CFR ,
50.12(a)(1), the requested exemptions are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense and security. In addition, the Commission has determined that, pursuant to 10 CFR 50.12(a)(2)(ii), special circumstances are present for those exemption requests in that application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purposes of Appendix R to 10 CFR Part 50. Therefore, the Commission hereby grants the exemptions from the requirements of Section III.G of Appendix R to 10 CFR Part 50 to the extent l
j discussed in Section III above.
Pursuant to 10 CFR 51.32, the Commission has determined that the granting of these exemptions will have no significant impact on the environment (January 29, 1986, 51 FR 3708).
The Safety Evaluation dated OCT02 1986, related to this l action and the above referenced submittals by the licensee are available for l
public inspection at the Commission's Public Document Room, 1717 H Street I
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7590-01 N.W., Washington, D.C. 20555, and at the Greenfield Comunity College Library, 1 College Drive, Greenfield, Massachusetts 01301.
This Exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Thomas M. Novak, Acting Director Division of PWR Licensing-A Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 00T 0 2 986 i
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