ML20085N732
| ML20085N732 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/22/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20085N715 | List: |
| References | |
| NUDOCS 9506300300 | |
| Download: ML20085N732 (5) | |
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NUCLEAR REGULATORY COMMISSION f
f WASHINGTON, D.C. 2000H001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 94 AND 58 TO FACILITY OPERATING LICENSE NOS. NPF-39 AND NPF-85 PHILADELPHIA ELECTRIC COMPANY LIMERICK GENERATING STATION. UNITS 1 AND 2 1
DOCKET NOS. 50-352 AND 50-353
1.0 INTRODUCTION
By letter dated August 12, 1994, as supplemented by letter dated March 29,.
I 1995, the Philadelphia Electric Company (the licensee) submitted a request for changes to the Limerick Generating Station (LGS), Units 1 and 2, Technical Specifications (TS). The requested changes would involve a revision to the action statements regarding the emergency core cooling systems (ECCS) to allow continued operation in the event that the high pressure coolant injection
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(HPCI) system, one core spray subsystem and/or one low pressure coolant
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injection (LPCI) subsystem are inoperable. The March 29, 1995, letter provided clarifying information and an updated TS page that did not change the initial proposed no significant hazards consideration determination.
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2.0 EVALUATION The licensee proposed revisions to the limiting conditions for operation of the ECCS Section 3.5.1 and the associated Bases Sections 3/4.5.1 and 3/4.5.2.
Specifically, Action statement "c" will be added to TS Section 3.5.1 to allow continued operation in the event that the HPCI system,-and one core spray subsystem, and/or one LPCI subsystem are inoperable. The current TS do not address this particular situation. Therefore TS Section 3.0.3 is currently applied, requiring plant shutdown if the HPCI system, and one core spray subsystem and/or one LPCI subsystem are inoperable.
ECCS consists of HPCI, LPCI, the core spray system (CSS), and the automatic depressurization system (ADS). ECCS is designed to furnish core cooling in the case of a postulated loss-of-coolant accidcnt (LOCA) caused by the rupture of primary coolant piping. The LGS, Units 1 and 2, TS allow HPCI to be inoperable for up to 14 days provided that ADS, CS, LPCI, and the reactor core isolation cooling (RCIC) systems are operable. The proposed revision would obviate the need for immediate plant shutdown in the event HPCI, and one of the other ECCS systems or RCIC are inoperable. Under the revision to TS 3.5.1, Action statement "c" will permit HPCI to be inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> with one CSS subsystem and/or one LPCI subsystem also inoper able.
c?herwise the plant is required to be in hot shutdown in the following 12 w Jrs and cold shutdown in the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
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. 2.1 ECCS Operating Requirement ECCS is designed to protect against the effects of a postulated LOCA in compliance with the requirements of 10 CFR 50.46, " Acceptable Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors." The systems comprising ECCS are described in Section 6.3 of the LGS Updated Final Safety Analysis Report (UFSAR). Normally, the ECCS has built-in redundancy so i
that adequate core cooling will be available even in the event of the failures specified in the LGS-UFSAR. An operable ECCS requires HPCI, ADS, two CSS subsystems, and four LPCI subsystems, per TS Section 3.5.1.
The action statements in TS Section 3.5.1 allow interim operation for a number of situations where ECCS components are inoperable. Action statement "a" covers various cases of CSS inoperability. Action statement "b" addresses the LPCI system, and Action statement "c" addresses HPCI inoperability. Adequate core i
cooling is assured for the different scenarios associated with the above stated action statements by the operability of the remaining ECCS systems and RCIC, a system for which no credit is taken in the safety analyses.
ECCS is also designed so that a single active or passive component failure, including power supplies and electrical and mechanical components, cannot prevent actuation and successful operation of the minimum complement of equipment. All of the combinations of ECCS equipment remaining after the various postulated failures are identified in Section 6.3.1.1.2 of the LGS-UFSAR.
For these combinations, the minimum complement is three LPCI pumps and ADS. The minimum complement could result from an ECCS system pipe break accompanied by another single failure. However, the proposed TS change retains ECCS capabilities in excess of the minimum equipment complement discussed in LGS-UFSAR Section 6.3.1.1.2.
As part of the single failure analysis for ECCS, the effect of the loss of division 2 safeguard DC power has been evaluated and discussed in Section 6.3.2.5 of the LGS-UFSAR and the General Electric (GE) topical report on SAFER /GESTR LOCA analysis (Reference 1). The loss of division 2 safeguard DC power results in the loss of the HPCI system, one CSS subsystem and one LPCI subsystem. The loss of power also prevents manual starting of these systems.
The analysis concludes that despite the reduction in ECCS capability presented by this situation, the peak cladding temperature will not reach the licensing basis limit. Although the loss of division 2 DC power specifically impacts the "B" LPCI and "C" CS subsystems, the SAFER /GESTR LOCA analyses addresses the loss of any division or subsystem of LPCI and CSS. Thus, the loss of 1
HPCI, one CS and/or one LPCI is considered an analyzed condition. Therefore, since actions associated with TS Section 3.0.3 are related to circumstances not covered in other Specifications or unanalyzed conditions, the requirements of TS Section 3.0.3 do not apply to this situation.
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The current TS action statements related to electrical power systems specify that with any of the safeguard DC batteries or_ chargers inoperable, component operability will be= restored within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or the plant shall be shut down.
The A0T and shutdown requirements of the proposed TS revision correspond with
' the action statements of TS 3.8.2.1 and 3.8.3.1, which apply to the loss of safeguard DC power.
Certain TS limiting conditions for operation are based on analyses presented R
in NED0-24708A (Reference 2), which is incorporated into the LGS, Units 1 and
- 2. UFSAR by reference.. The generic analysis of the design basis accident (DBA) suction line breaks shows that one low pressure ECCS along with ADS is adequate to reflood the vessel and maintain core cooling and preclude fuel damage. The UFSAR discusses the outcome of LOCA studies documented in NEDO-30936P (Reference 3) that were performed to establish success criteria for l
ECCS injection functions. Table 3-7 of Reference 3 shows the minimum combination of systems required to successfully respond to large, i
intermediate, and small break LOCAs for BWR4 plants. The most restrictive combination shown is ADS and low pressure injection by either LPCI or CSS.
This condition is exceeded by the ECCS capability retained by the proposed change. However, the report stipulates that in the event that only the l
minimum ECCS equipment is available, an alternate cooling path may be needed for long-tern LOCA cooling. For the alternate path condition, LPCI injects i
directly into the core shroud, and maintains a substantial subcooling margin in the water around the core, thereby quenching any steam cooling effects.
Also, the availability of the core spray provides another means of long-term l
cooling.
i 2.2 ECCS Shutdown and Decay Heat Removal Impact TS 3.5.2 requires that when the plant is shut down (Cold Shutdown and Refueling), two ECCS subsystems composed of a combination of CSS and/or LPCI subsystems be operable. Two loops of shutdown cooling are required to be operable in accordance with TS Sections 3.4.9.1 (for hot shutdown) and TS 3.4.9.2 and 3.9.11.2 (for cold shutdown and refueling). Otherwise, an alternate method of decay heat removal is required.
In case the plant is shut down after operating under the requirements of this proposed revision, the proposed change provides ECCS equipment sufficient to meet these requirements.
2.3 Conclusion The staff has evaluated the safety implications of the proposed TS revision for ECCS operability when HPCI, one CSS and/or one LPCI subsystem are inoperable. The proposed change will leave ADS, one CSS subsystem, and three LPCI subsystems available. This complement of equipment exceeds the ECCS complement required by ECCS performance analyses (Reference 1).
Further, the proposed change is consistent with the associated TS requirements for electric power system operability.
The staff has determined that based on the generic l
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. analyses (Reference 2) and the licensee's evaluation, the minimum required complement of ECCS equipment is sufficient to furnish core cooling in the event of a postulated LOCA, and therefore the staff concludes that the proposed TS change is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State 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. 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 pubile comment on such finding (59 FR 51623). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR
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51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or
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environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
1 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, i
and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
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6.0 REFERENCES
1.
NEDC-32170P, " Limerick Generating Station Units 1 and 2 SAFER /GESTR-LOCA Loss-of-Coolant Accident Analysis," General Electric Report, Rev.1, June 1993, Proprietary Information.
2.
NED0-24708A, " Additional Information Required for NRC Staff Generic Report on Boiling Water Reactors," General Electric Report, Rev.1, December 1980.
3.
NEDC-30936P, "BWR Owners' Group Technical Specification Improvement Methodology (With Demonstration for BWR ECCS Actuation Instrumentation),"
Part 1, General Electric Report, November 1985, Proprietary Information.
Principal Contributors:
J. Donoghue F. Rinaldi Date: June 22, 1995 i
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