ML17158A866
| ML17158A866 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 08/31/1995 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17158A865 | List: |
| References | |
| NUDOCS 9509060125 | |
| Download: ML17158A866 (4) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&4001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.153TO FACILITY OPERATING LICENSE NO'.
NPF-14 PENNSYLVANIA POWER AND LIGHT COMPANY ALLEGHENY ELECTRIC COOPERATIVE INC.
SUS UEHANNA STEAM ELECTRIC STATION UNIT 1
DOCKET NO. 50-354
- 1. 0 INTRODUCTION By.letter dated April ll, 1995, the Pennsylvania Power and Light Company (the licensee) submitted a request for changes to the Susquehanna Steam Electric
- Station, Unit 1, Technical Specifications (TS).
The requested changes would extend on a one-time basis the allowed outage time in the Susquehanna Steam Electric Station (SSES)
Technical Specification (TS) 3.8. 1. 1 from 3 to 7 days for one offsite circuit being out of service.
This change will provide additional time if needed for the licensee to complete planned modifications to an offsite circuit.
2.0 BACKGROUND
The power supply to the T-10 start-up transformer is currently tapped directly off the Montour-Mountain 230 kV line.
This arrangement exposes the T-10 to interruptions for a disturbance anywhere along the Montour-Mountain line.
The licensee is proposing to modify the power supply to improve its reliability.
The modification to be installed includes three elements.
The first element consists of segmenting the existing Montour-Mountain line into two new lines.
This arrangement will allow T-10 to remain in service following the loss of either line.
The second element consists of constructing a T-10 tap switchyard with a one and one-half breaker arrangement.
The design and layout should result in minimum outage duration for the T-10.
The third element is the separation of the relaying and the control circuits for both the T-10 and T-20 start-up transformer.
Currently, the relaying and control equipment is in the same panel in the control room.
This equipment will be relocated to the switchgear rooms in the turbine building.
This relocation will provide physical separation of the T-10 and T-20 relaying and control equipment and will eliminate exposure to the loss of both the T-10 and T-20 during periodic testing of relaying components.
- Together, these modifications will result in a significant improvement in the reliability of the T-10 and reduce the common cause outage of both the T-10 and T-20.
The licensee states that the core damage frequency for the Susquehanna plant will decrease by about 30X for LOOP events.
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The licensee estimates that the construction and installation of these modifications may require T-10 to be out of service for up to 7 days.
Current plant Technical Specifications only allow the T-10 to be out of service for up to 3 days.
Therefore, in order to avoid a dual-unit shutdown the licensee has proposed a one-time extension to allow the T-10 to be modified.
- 3. 0 EVALUATION The proposed change adds a footnote to Action a.3 of Specification 3.8. 1. 1 to
- allow, on a one-time basis, one offsite power source to be out of service for up to 7 days during the construction and installation of the T-10 tap 230 kV switchyard during the Unit 2 7th outage.
This change is applicable to Unit 1
only since Unit 2 will be in an outage and will not require two offsite power sources to be available.
The licensee states that its analysis showed that increasing the AOT from 3 to 7 days does not increase the consequences of a LOOP event nor change the consequences of a station blackout if mitigating measures are taken.
The licensee also concluded that the core damage frequency during the modification is within the risk envelope allowed by the existing TS with appropriate specified mitigative measures taken.
The licensee's conclusion was based upon in part information included in the Susquehanna Steam Electric Station Independent Plant Evaluation (IPE).
This IPE is still under review by the Office of Research and therefore the staff has chosen to evaluate this TS change deterministically.
The mitigating measures proposed by the licensee include the following:
1.
prohibiting high-risk activities within the confines of the plant or the grid system that may result in a loss of the T-20 during the T-10 outage, 2.
performing the modification during the fall season when the frequency of grid and weather-related LOOPs is reduced, 3.
requiring that if the high-pressure coolant injection (HPCI) system is declared inoperable during the T-10 work window, the HPCI system shall be returned to operable status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or the plant will be brought to at least hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to at least cold shutdown within the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, 4.
requiring that if the standby liquid control (SLC) system is declared inoperable during the T-10 work window, the SLC system shall be returned to operable status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or the plant will be brought to at least hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to at least cold shutdown within the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, 5.
requiring that within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before taking the T-10 out of service, Surveillance 4.8. 1. 1.2.a.4 be successfully completed on the aligned diesel generators, 6.
maintaining certain equipment and systems (important for safe shutdown) operable during the T-10 work window and restoring any failed equipment to operable status as soon as possible (The failed equipment shall be worked around the clock.),
The equipment that will be maintained operable include:
both control rod drive pumps, the diesel fire pump, yard fire hydrant (1FH122) and the associated hydrant hose station, the residual heat removal (RHR) system, the RHR service water and emergency service water systems for suppression pool cooling, the RHR and RHR service water cross tie valves, the reactor core isolation cooling system, the containment instrument gas 150 psig header and bottles, the turbine building closed cooling water system (one pump and one heat exchanger),
the portable diesel'generator,and the HV-141-F019 valve.
7.
placing restrictions upon diesel maintenance to ensure that the "E"
- diesel, an additional diesel generator, is available to substitute for any diesel that might fail during a loss of offsite power event.
The staff has evaluated the licensee's submittal and concludes that although the one-time increase in AOT for the T-10 start-up transformer may result in a slight decrease in safety, by implementing the measures described
- above, there is assurance that any slight decrease will be adequately mitigated during the extended AOT.
Based on its evaluation, the staff has concluded that the compensatory measures taken by the licensee will minimize the potential impact 'of extending the outage time and, therefore, the change to extend on a one-time basis the AOT from 3 to 7 days for one offsite power source is acceptable.
The approval of this amendment is predicated on the licensees implementation of each of the mitigative measures committed to in the April ll, 1995 request for amendment listed above as ite'ms 1-7.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State official was notified of, the proposed issuance of the amendment.
The State official had no comments.
- 4. 0 ENVIRONMENTAL CONSIDERATION The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendment involves 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 amendment involves no significant hazards consideration, and there has been no
public comment on such finding (60 FR 29886).
Accordingly, the amendment meets 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 amendment.
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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
N. Trehan August 31, 1995