ML20112C075
| ML20112C075 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 05/21/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20112C073 | List: |
| References | |
| NUDOCS 9605240158 | |
| Download: ML20112C075 (5) | |
Text
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aretuqk UNITED STATES y*
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NUCLEAR REGULATORY COMMISSION 2
WASHINGTON, D.C. 20066 4001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 119 TO FACILITY OPERATING LICENSE NO. NPF-2 AND AMENDMENT NO.111 TO FACILITY OPERATING LICENSE NO. NPF-Q SOUTHERN NUCLEAR OPERATING COMPANY. INC.
JOSEPH M. FARLEY NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-348 AND 50-364
1.0 INTRODUCTION
By letter dated December 19, 1995, as supplemented January 5,1996 and May 3, 1996, the Southern Nuclear Operating Company, Inc., et al. (the licensee),
submitted a request for changes to the Joseph M. Farley Nuclear Plant, Units 1 and 2, Technical Specifications (TS). The requested changes would replace the requirements associated with the control room emergency ventilation system with requirements related to the operation of the control room emergency filtration / pressurization systems (CREFS) and control room air conditioning system (CRACS).
In addition to the permanent TS change, the licensee
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requested a one-time extension to the allowable outage time (A0T) for the control room recirculation filtration system to facilitate implementation of design modifications for the CRACS.
The January 5, 1996 and May 3, 1996, letters provided clarifying information that did not change the scope of the December 19, 1995, application and the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
The Farley plant has a common control room designed for both units with an independent air conditioning system, a recirculation filtration system, and an-emergency pressurization system.
Each system consists of two fully redundant trains and each train is capable of performing 100 percent of the control room heating, ventilation, and air conditioning (HVAC) functions for both units with the loss of the other train. The control room emergency ventilation system, referred to as the control room emergency air cleanup systems in the current TS, is required to be operable during all modes of operation.
Upon receiving a containment isolation signal, the control room HVAC system will automatically switch from normal to emergency mode of operation.
The CRACS presently includes two cooling trains, each having a 100-percent capacity cooling unit. The licensee proposes to replace the existing cooling unit on each train with two 100-percent cooling units by the Spring of 1997.
The installation of the air conditioning cooling units would require the existing duct work of the ventilation system to be modified.
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. During the CRACS modification, one train of the recirculation filtration system will be inoperable. Therefore, the licensee requested to extend the 7-day outage time allowed by the TS to 30 days on a one-time basis for each train of the recirculation filtration function of the CREFS to facilitate the
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i CRACS design changes.
i The licensee's proposed revisions to TS 3/4.7.7, " Control Room Emergency Ventilation System" are as follows:
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Replace the limiting condition for operation (LCO) in TS 3.7.7 for control room emergency air cleanup systems with TS 3.7.7.1 for control room emergency filtration / pressurization system and add TS 3.7.7.2 for the control room air conditioning system. The l
proposed TS 3/4.7.7.1 will address the filtration / pressurization aspects of the control room emergency air cleanup system.
Change the A0T of the CRACS to 30 days from 7 days during Modes 1 through 6 in the proposed TS 3.7.7.2.
Add an action statement in l
Modes 5 and 6 to state that, with one CRACS train inoperable, immediately suspend movement of irradiated fuel assemblies and movement of loads over irradiated fuel.
Delete the statement "the provisions of Specification 3.0.3 are j
not applicable in Mode 6" from the current TS 3.7.7(c).
j Add a note in TS 3.7.7.1 with asterisk on the A0T of the CREFS to state "a one-time extension to 30 days for each train of the i
recirculation filtration function of the CREFS is granted for implementation of control room cooling design changes."
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3.0 EVALUATION f
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-3.1 Permanent Control Room Emergency Ventilation System TS Changes The staff has reviewed the proposed TS changes associated with the control j
room emergency ventilation system and concluded the following:
The proposed TS for the control room emergency ventilation system are i
divided into two specifications based on the overall system functions.
The changes reorganize the requirements of the control room emergency air cleanup system based on function rather than unit operation mode and l
are technically consistent with the requirements of the Westinghouse Standard Technical Specifications (STS), issued on April 7,1995. The staff finds that the proposed TS format provides an improvement and is, a
therefore, acceptable.
1 The proposed TS allow one train of the CRACS to be inoperable for 30 days during Modes 1 through 4 rather than 7 days as it is allowed by the 4
1 current TS for the control room emergency air cleanup system. The q
licensee states that the current LC0 allowed outage time of 7 days is d
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- not consistent with the low probability of loss of all control room cooling, because following a loss of the CRACS, temperature changes are gradual, dependent upon outside temperature, and time is available for manual actions that can alleviate the loss of CRACS.
The licensee has performed a sensitivity analysis which has determined that various operator actions can be taken which would extend the time to reach the control room component qualification temperature limit of 120*F.
Since 1
the change conforms to the STS and the licensee has provided adequate justification for increasing the inoperability time for CRACS, the staff finds the proposed TS change acceptable.
The action statement for Modes 5 and 6 alsc changes the A0T with one CRACS train inoperable from 7 days to 30 days and adds an alternative action to immediately suspend movement of irradiated fuel assemblies and movement of loads over irradiated fuel. The added alternative action, to suspend core alterations and the movement of spent fuel assemblies, limits fission product releases. The change is consistent with the STS and the staff finds the proposed change acceptable.
The licensee's removal of the statement "the provisions of Specification 3.0.3 are not applicable in Mode 6" is found to be acceptable because 2
the plant is already in the most restrictive condition required by LC0 3.0.3 when Mode 5 or 6 is reached.
The proposed TS did not specify that the plant must enter LCO 3.0.3 immediately during Modes 1 through 4 when both trains of CREFS or CRACS are inoperable. The staff finds this acceptable because if both trains of CREFS or CRACS are inoperable, in accordance with the TS, the licensee is required to enter LC0 3.0.3.
Nevertheless, the' licensee in its improved STS conversion, should include this. action statement to be consistent with the improved STS.
3.2 One-Time Extension of A0T for CREFS j
The staff also reviewed the licensee's proposed TS change related to the one-time A0T extension of 30 days for each train of the CREFS.
The licensee stated in its submittal that measures will be taken to limit the l
unavailability of the recirculation filtration system during the modification, which includes detailed planning of the work sequence, prefabrication of components and staging of parts.
In addition, the control room operators will be briefed on sitigative actions that may be taken in the unlikely event of an accident involving a release and the accompanying failure of the available train of the recirculation filtration system. These compensatory measures include donning of filter masks (respiratory protection) and the use of portable recirculation filtration units that are available on site.
Although the'CREFS will not meet the single failure criterion during the extended A0T period, the capability to maintain a positive pressure in the.
control room will not be affected by the A0T extension of CREFS because the control room pressurization system has separate intake air filtration and is therefore, independent of the CRACS and the recirculation filtration system.
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1 4 In addition, the licensee also provided a probabilistic risk assessment based on the Farley Individual Plant Evaluation (IPE) and the EPRI Probabilistic Safety Assessment (PSA) Application Guide (EPRI TR-105396, August 1995). The Farley IPE, identifies early containment airborne release categories, which would not allow time for compensatory measures in the event of a random failure of the operable filtration system. The total early release frequency from these categories is 5.19E-07 per reactor-year.
For the planned CRACS replacement evolution of 60 days, this represents a conditional probability of a core damage event occurring at 8.53E-08 per unit or 1.71E-07 overall since the recirculation filter units are shared between both units.
In accordance
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with the EPRI PSA Application Guide criteria, a temporary increase in containment large early release probability (LERP) risk of less than 1.0E-07 or a core damage probability (CDP) risk of less than 1.0E-06 would be considered non risk-significant. With the LERP between 1.0E-07 and 1.0E-06, 1
other non-quantitative arguments may apply, which could still justify the increase as non-risk significant. The licensee has stated that if a conservative failure probability of 0.5 for the operable control room air filuation system is taken, in combination with a large early release, the actual LERP would be less than 1.0E-07 which, according to the EPRI guidelines, is non-risk significant.
A policy and acceptance criteria for risk-based TS are currently under j
development by the staff.
In addition, although the staff agrees with the high level concepts proposed.in the EPRI PSA Application Guide, it has not as yet endorsed the methodological details or decision criteria contained in the guide. Nevertheless, the licensee's risk assessment summarized above, in combination with the compensatory measures to be taken by the licensee, further supports the conclusion that the extension of the A0T is non-risk significant.
j The licensee has also stated that this case docs not represent an increase in release probability but a potential increase in dose to the control room operators following an event during which the control room filtration system failed.
The staff has reviewed the information provided by the licensee and concludes that the A0T extension for the CREFS is acceptable based on the following:
The licensee is providing detailed work planning to minimize the unavailability of the CREFS.
The licensee has planned compensatory measures in the event of an accident and failure of the operating CREFS train to limit exposurc of control room operators.
The licensee has evaluated the LERP based on its IPE and EPRI PSA guidelines and determined that the probability of an accident in combination with the failure of the operating train of CREFS is non-risk significant.
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a 1 Since the control room pressurization system, including the intake air
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filtration system, is independent of the CRACS and the recirculation filtration system the capability to maintain a positive pressure in the control room and to filter outside air will not be affected during the extended A0T.
Although the one-time A0T extension for the recirculation filtration system increases the system unavailability during the planned CRACS design changes, the net effect represents a benefit to plant safety due to the enhancement to control room cooling capability and reliability.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the State of Alabama official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change the surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (61 FR 1637 dated January 22,1996). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the ccamon defense and security or to the health and safety of the public.
Principal Contributor: J. S. Guo Date:
May 21, 1996 i
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