ML20196H162
| ML20196H162 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/29/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20196H161 | List: |
| References | |
| NUDOCS 9907060103 | |
| Download: ML20196H162 (4) | |
Text
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- c UNITED ' STATES 5
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NUCLEAR REGULATORY COMMISSION o1 WASHINGTON, D.c. 20555 6 1
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a SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 236 l
70 FACILITY OPERATING LICENSE NO. DPR-GE NORTHEAST NUCLEAR ENERGY COMPANY THE CONNECTICUT LIGHT AND POWER COMPANY l
l THE WESTERN MASSACHUSETTS ELECTRIC COMPANY i
MILLSTONE NUCLEAR POWER STATION.' UNIT NO. 2 DOCKET NO. 50-336 L
l
1.0 INTRODUCTION
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By letter dated January 4,1999, as supplemented April 7,1999, the Northeast Nuclear Energy j
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- Company, et al. (the licensee), submitted a request for changes to the M;llstone Nuclear Power Station, Unit No. 2 Technical Specifications (TS). The requested amendment would change TS 3.5.2, " Emergency Core Cooling Systems - ECCS Subsystems.Tavg ;t 300 *F;" TS 3.6.2.1, " Containment Systems - Depressurization and Cooling Systems - Containment Spray and Cooling Systems;" TS 3.7.1.2, " Plant Systems - Auxiliary Feedwater Pumps;" TS 3.7.3.1, L
" Plant Systems - Reactor Building Closed Cooling Water System;" and TS 3.7.4.1, " Plant Systems - Service Water System." The Bases of the associated TS would be modified to address the proposed changes. The proposed changes to each of the surveillance requirement acceptance criteria are consistent with revised hydraulic and accioent analyses performed by the licensee. Also, changes are proposed to measure pump performance in terms of differential pressure instead of discharge pressure.' The April 7,1999, supplemental letter did not change the staff's original proposed no significant hazards consideration determination.
,2.0 EVALUATION Each change proposed by the licensee is discussed in the following paragraphs along with the staff's corresponding evaluation.
I i-2.1 TS 3.5.2 uThe licensee is proposing to revise surveillance requirement 4.5.2a.1.b to change the
, acceptance criterion from 21231 pounds per square irich (psi) to 21193 pounds per square inch I
differential (psid). This changes the minimum acceptable value for the recirculation flow test of the high-pressure safety injection pump (HMI). The revised value is based on the manufacturer's curves, v!ith a 5 percent degradation. The associated accident analyses have b
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, also been revised to reflect a HPSI flow that assumes 5 percent degradation. The instrument inaccuracies will be accounted for in the hydraulic analysis and the surveillance procedure acceptance criteria.
i Tho licensee's proposed revision is acceptable because the revised acceptance criterion is consistent with the value assumed in the accident analyses. Therefore, the surveillance testing will ensure that the accident analyses assumptions will continue to be met.
Additionally, the licensee is proposing to revise surveillance requirement 4.5.2a.2.b to change j
the acceptance criterion from 2157 psi to 2163 psid. This changes the minimum acceptable value for the recirculation flow test of the low-pressure safety injection pump (LPSI). The revised value is based on the manufacturer's curves and miriimum recirculation flow test results that showed pump developed heads less than the manufaciurer's curves. The accident analysis values are not changed by the licensee's proposal due to the delayed start of the LPSI pump during a design basis accident. The licensee has determined that pressure instrument inaccuracies are not required to be addressed since the accident analyses do not credit LPSI flow at recirculation flow conditions. Pressure measurement instrument inaccuracy will be epplied and controlled by the surveillance procedures when verifying pump performance in the flow ranges credited in the accident analyses. Flow measurement instrument inaccuracy has been accounted for in the hydraulic analysis.
The licensee's proposed revision is acceptable because it provides a corrected value for the pump acceptance criterion that will allow future testing to detect pump degradation.
2.2 TS 3.6.2.1 The licensee is proposing to revise surveillance requirement 4.6.2.1.1a.2 to change the acceptance criterion from a discharge pressure of 2254 p::a (pounds per square inch gauge) to a differential pressure of 2232 psid. This changes the minimum acceptable value for the recirculation flow test of the containment spray pumps. The revised value is based on a minimum flow curve developed from field test data, with a 5 percent degradation. This flow value is consistent with the revised hydraulic and accident analyses. Flow and pressure measurement instrument inaccuracies are already reflected in the TS acceptance criteria.
The licensee's proposed revision is acceptable because the revised acceptance criterion still bounds the design basis accident assumptions. Additionally, changing the measurement from psig to a differential pressure will compensate for possible differences in suction pressure.
2.3 TS 3.7.1.2 The licensou is proposing to revise surveillance requirement 4.7.1.2a.2.a to change the acceptance criterion from a discharge pressure of 2107'O psig to a differential pressure of 21144 psid. This changes the minimum acceptable value for the recirculation flov, iest of the motor driven auxiliary feedwater pumps. The revised value is based on pump curves, with a 5 percent degradation. This flow value is consistent with the revised hydraulic and accident analyses. Pressure and flow measurement instrument inaccuracies will be applied to test data when verifying pump performance in the flow ranges credited in the accident analyses.
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! The licensee's proposed revision is acceptable because the revised acceptance criterion bounde the design basis accident assumptions. Additionally, changing the measurement from
- psig to a differential pressure will compensate for possible differences in suction pressure.
The licensee is proposing to revise surveillance requirement 4.7.1.2a.2.b to change the acceptance criterion from a discharge pressure of 21080 psig to a differential pressure of 21113 paid, corrected to rated pump speed. This changes the minimum acceptable value for the recirculation flow test cf the turbine driven auxiliary feedwater pump. This value is different
- from the value preposed in the licensee's submittal of January 4,1999.
1The licensee amended their submittal in a letter dated April 7,1999, because it was determined through testing that the pump could not meet the previously proposed criterion of 21134 psid.
The licensee stated in this submittal that the new proposed acceptance criterion is based on high-flow test data extrapolated to minimum recirculation flow. The staff questioned this methodology because it is highly unlikely that the hydraulic performance of a centrifugal pump operating at recirculation flow rates can accurately be extrapolated from high-flow performance data unless the extrapolation is bounded by test data, in a phone conversation with the licensee on April 14,1999, the licensee stated that they had performance data at several points in the low-flow region which differed from the original manufacturer's pump curve, in addition,
' the accident analysis does not credit the auxiliary feedwater pump system below flow rates of 300 gpm.- The turbine driven auxiliary feedwater pump does not st trt automatically at Millstone 2, but is initiated manually by procedure. Therefore, there ~do not appee r be any concerns about this pump operating for extended periods of time at low-flow conditions other than for testing.
The licensee's proposed revision is acceptable because the revised acceptance criterion has been derived from actual test data. Additionally, changing the measurement from psig to a
' differential pressure'will compensate for possible differences in suction pressure. The addition of the phrase " corrected to rated pump spe6d" allows the licensee to correct the test results for variations in the speed of the turbine driven pump during the test.
2.4 TS 3.7.3.1 The licensee is proposing to revise surveillance requirement 4.7.3.1a.2 to change the acceptance criterion from a discharge pressure verification to a differential pressure verifica%n for the reactor building closed cooling water pumps. As with the above examples, this provides
' for a more meaningful measure of the pump's performance because variations in suction pressure will no longer affect the test.
2.5' TS 3.7.4.1
.The licensee is proposing to revise surveillance requirement 4.7.4.1a.2 to change the
' acceptance criterion from a discharga pressure verification to a differential pressure verification for the service water pumps. As with the above examples, this provides for a more meaningful measure of the pump's performance because variations in suction pressure will no longer affect y
the test.-
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,.4 2.6 TS Bases Changes
. The licensee also proposed changes to the corresponding TS Bases to reflect the above changes to the TS. The staff found that the licensee's TS Bases changes provided appropriate amplifying information for the plant operators.
2.7 Evaluation Summary-The licensee proposed several changes to the TS as a result of revised hydraulic analyses and
- related accident analyses. The licensee also changed the acceptance criteria from pump
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discharge pressure to pump differential pressure to eliminate the pump suction pressure variability from affecting the test. The licensee further stated that the proposed changes will ensure that pump degradation that could adversely impact the accident analyses will be
- detected. As discussed above, the staff reviewed the information provided by the licensee and determined that the licensee's proposed changes were acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes surveillance requirements. 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 indMdual or cumulative oc.cupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazardt: consideration, i
- and there has been no public comment on such finding (64 FR 2523, January 14,1999).
b.cordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in i
10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in conne etion with the issuance of the amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there l
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 complia.c.;e 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.
j Principal' Contributor: S. Dembek Date: June 29','1999