ML20202B721
| ML20202B721 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 11/25/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20202B713 | List: |
| References | |
| NUDOCS 9712030164 | |
| Download: ML20202B721 (3) | |
Text
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((
- t UNITED STATES g
y NUCLEAR REGULATORY COMMISSION t
WASHtNGTON, D.C. 30666-0001
.....,6 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION I
RELATED TO AMENDMENT NOS.134 AND126TO FACIUTY OPERATING LICENSE NOS. DPR-42 AND DPR-60 NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT. UNIT NOS.1 AND 2 DOCKET NOS. 50-282 AND 50-306
1.0 INTRODUCTION
Sy letter dated September 26,1997, the Northem States Power Company (NSP or the licensee) requested amendments to the Technical Specifications (TS) appended to Facility Operating License Nos. DPR42 and DPR-60 for the Prairie Island Nuclear Generating Plant (PINGP), Unit Nos.1 and 2. The proposed amendments would rense TS 3.4.B," Auxiliary Feedwater System," to provide specific guidance for conducting post-maintenance operational testing of the turbine-driven auxiliary feedwater (TDAFW) pump and associated system valves to meet operability and limitirg conditions for operation during unit startup. An additional change is proposed to revise Table TS.3.5.28 to permit during Mode 2 bypassing one of the auto-start features of the auxiliary feedwater (AFW) pi cps. The bypassed auto-start feature starts the AFW pumps when both main feedwater pumps trip. During startup (Mode 2), feedwater is initially supplied with the AFW pumps and the main feedwater pumps are not operating. This submittal partially addresses issues raised in the NRC's letter dated October 16,1997, that reviewed TS interpretations for the AFW and safety injection systems at PINGP.
2.0 EVALUATION The proposed amendments affect the TDAFW pumps and associated valves that supply water to the steam generators during startup and shutdown when use of the main feedwater pumps could overcool the reactor coolant system (RCS) and during accident scenarios when operation of the main feedwater pumps cannot be assumed and AFW system supplies emergency shutdown cooling. The AFW system at Prairie Island has four AFW pumps, one TDAFW pump associated with each unit, and two sha od motor driven AFW (MDAFW) pumps. The proposed amendments clarify the limiting conditions for operation (LCO) of the TDAFW pumps and the associated flowpaths and allow bypassing of the start sig1al for the AFW pumps on loss of the main feedwater pumps during the time that the main feedwater pumps are not operating.
Current TS 3.4.B. " Auxiliary Feedwater System," requires that a reactor shall not be made or maintained critical nor shall RCS average temperature exceed 350 *F unless the fo: lowing conditions are satisfied:
9712030164 971125 PDR ADOCK 05000282 P
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e i 1.a.
For single unit operation, the turbine-driven pump associated with that reactor plus one motor-driven pump are OPERABLE.
b.
For two-unit operation, all four auxiliary feedwater pumps are OPERABLE.
c.
Valves and piping associated with the above components are operable except that during STARTUP OPERATION nt.cessary changes may be made ir.
motor-operated valve position. All such changes shall be under direct administrative control.
TS 3.4.B.1.e, f, and g ensure that valves in the flowpath are properly aligned for emergency shutdown cooling unless the valves are under direct administrative control TS 3.4.B.2 allows any one of five conditions to exist for each unit during STARTUP OPERATION or POYER OPERATION provided STARTUP OPERATION is discontinued until OPERABILITY is restored. If OPERABILIT( is not restored within the time specified, the affected unit shall be placed in at least HOT SHUTDOWN within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and RCS average temperature shall be below 350 *F within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Currently, one cf the conditions, TS 3.4.B.2.a, allows 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> during which the TDAFW pump, system valves, and piping may be inoperable. However, there is no exception to the required discontinuation of STARTUP OPERATION.
The prcposed change would add a parenthetical clarification, "(except as noted in 3.4.B.2.a),"
to e rrent TS 3.4.B.2. The proposed change to TS 3.4.B.2.a would allow STARTUP OPERATION to continue with a TDAFW pump and/or associated system valves inoperable based solely on the need to complete the inservice testing requirements of TS 4.2.A.2 and AFW flow verification, i.e., alignment of valves, provided all other requirements for operability are satisfied. The pump and/or associated system valves must be tested and operable prior to exceeding 10% reactor power or 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from the time RCS temperature is increased above 350 'F. The limit of 10% reactor power is the maximum power level that the AFW can supply normal cooling. The 72-hour limit provides a specific duration based on the time when testing can be started, i.e., RCS temperature > 350 'F.
The current limiting conditione 'or operation do not provide the flexibility during unit startup to perform post-maintenance, surveillance, and inservice testing of the TDAFW pump and assoe'ated system flowpaths, i.e., assuring valves are aligned to verify design flowrates.
Since sufficient steam pressure is needed to perform testing of the TDAFW pump, plant conditions are not adequate to perform testing before exceeding an RCS temperature of 350 'F. The proposed changes would modify the TS to allow testing the TDAFW pumps and tssociated system valves without having to terminate STARTUP OPERATION. Sufficient limits are specified for performing the required testing to prove the TDAFW pump and associated system valves are OPERABLE. The staff finds the proposed changes acceptable.
The amendment request includes a proposed change to Table TS.3.5-28, item 7, " Auxiliary Feedwater," subitem d," Trip of Both Main Feedwater Pumps." During Mods ? 1 a.d 2, the current TS requires the actuation instrumentation that starts the TDAFW and MDAFW pumps when both main feedwater pumps trip to be OPERABLE. The proposed change to item 7.d adds an asterisk to Mode 2 that allows the AFW pump auto-start actuation instrumentation to
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E.
be bypassed during startup and shutdown operations when the main feedwater pumps are not required to supply feedwater to the steam generators. As discussed in the NRC's October 16,1997 letter to NSP, without the proposed change, compliance with the current TS would not allow placing an AFW pump selector switch in the shutdown-auto or manual positions. The staff agrees that use of the AFW system during startup and shutdown to avoid main feedwater pump damage is required at PINGP. Therefore, the proposed changes are acceptable.
3.0 STATE CONSULTATION
L In accordance with the Commission's regulations, the Minnesota State off'cial was noufied of the proposed issuance of the amendments. The State official had no commants.
4.0 ENVIRONMEN(AL CONSIDERATION The amendments change a requirement with respect to 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 public comment on such finding (62 FR 54874).
Accordingly, the amendments meet the eligibility enteria for categodcal exclusion set forth in
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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 common defense and security or to the health and safety of the public.
Principal Contributors:
W. LeFave R Giardina L. Gundrum Date: November 25, 1997
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