ML20085K993
| ML20085K993 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/15/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20085K981 | List: |
| References | |
| NUDOCS 9506280221 | |
| Download: ML20085K993 (3) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.164 TO FACILITY OPERATING LICENSE NO. DPR-35 BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DOCKET NO. 50-293
1.0 INTRODUCTION
By letter dated February 9, 1995, the Boston Edison Company (BEco or the u
licensee) submitted a request for changes to the Pilgrim Nuclear Power Station Technical Specifications (TSs). The requested changes would increase the reactor high water level trip level setting for the Group 1 isolation. This
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change will allow an increase to the main steam isolation valve (MSIV) high water level isolation setpoint.
j 2.0 EVALUATION f
The purpose of the' change is to increase the operating margin associated with the MSIV isolation. The increased operating margin will allow the operator to control the reactor water level and pressure more effectively during a i
controlled shutdown.
It will'also reduce the likelihood of spurious isolations.
The proposed change will increase the reactor water level at which the MSIV l
isolation signal occurs. The isolation signal is provided to minimize reactor vessel inventory loss in the event of a pressure regulator failure and to prevent gross moisture carryover.
General Electric analyzed a rapid depressurization caused by a pressure regulator malfunction at low reactor power. MSIV closure was' initiated by low reactor pressure approximately 30 seconds into the event. No credit is taken for MSIV closure on high level. The resulting reactor water level swell was not sufficient to reach the main steam lines. The revised analytical limit is 52 inches below the bottom elevation of the main steam lines.
i The proposed change will increase the reactor high water level trip level setting for the Group 1 isolation. The change will allow the licensee to increase the MSIV high water level isolation setpoint. The remaining high water level trip signals (high-pressure coolant injection, reactor core i
isolation coolant, etc.) will not be changed. The MSIV high water level isolation parameters are summarized below:
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PDR ADOCK 05000293
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Existing Values Proposed Values l
Analytical-Limit:
+48 inches indicated
+60 inches indicated i
Trip Level Setting:
+48 inches indicated
+55.4 inches indicated-(TS allowatne value) l l
Setpoint:
+45 inches indicated
+55 inches indicated This change will also result in a new calibration range for the fo11owin.1 instruments:
LT263-57A and B LS263-57A-1 and B-1 LT263-58A and B LS263-58A-1 and B-1 LIS263-57A and B LS263-57A-2 and B-2 LIS263-58A and B LS263-58A-2 and B-2 The~ calibration range will be increased from "-50 to + 50 inches indicated" I
to "-50 to + 60 inches indicated".
This, in turn, will result in a change in the TS allowable value-for the -
reactor low level trip level setting. The allowable value will. change from l
">= 11.7 inches" to ">- 11.6 inches.".The increase in the calibration range will also result in a change in the TS allowable value for the reactor low low water level trip level setting. The allowable value will change from f
">= -46.3 inches indicated level" to ">- -46.4 ' inches indicated level."' These changes will not impact plant safety.
The changes were evaluated in accordance with the guidance provided in i
Regulatory Guide 1.105 and Generic Letter 91-04, " Change in Technical l
Specification Surveillance Intervals to Accommodate a 24 Month Fuel Cycle."
l Operation of the station in-accordance with the proposed trip level setting
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will not sianificantly increase the probability or consequences of an accident previously evaluated. The MSIV high water level isolation signal is provided to protect against rapid depressurization due to a pressure regulator.
I malfunctior, during plant startup. The high water level isolation signal is not functional when the mode switch is in the RUN position. A high water level in the reactor vessel indicates that fuel is covered.
Increasing the trip level setting will have minimal effect on moisture l
carryover in the event of a pressure regulator failure at low reactor power.
MSIV closure (Group 1) is initiated by low reactor pressure (810 psig) approximately 30 seconds into the event. The resulting reactor water level i
swell is not sufficient to reach the bottom elevation of the main steam lines.
l The proposed TS allow'able value for the reactor low level trip level setting and the reactor low low water. level trip level setting does not-involve a significant increase in the probability or consequences of an accident.
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The proposed change does not affect the Group 1 isolation safety function.
The proposed change is consistent with the Final Safety Analysis Report and TS
-basis associated with reactor vessel inventory control ard main steam line r
flooding.
The proposed change to the instrument calibration range does not affect the margin of safety for systems or components affected by the ch M:e. Operating Pilgrim in accordance with the proposed trip level setting does not involve a significant reduction in the margin of safety.
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3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Massachusetts State official was notified of the proposed issuance of the amendment. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a f
facility component located within the restricted area as defined in 10 CFR
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Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types.
l 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
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amendment involves no significant hazards consideration, and there has been no public comment on such finding (60 FR 14017). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR f
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 i
the amendment.
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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 i
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 F
defense and security or to the health and safety of the public.
Principal Contributor:
K. Cotton Date: June 15,1995 q
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