ML20151B442
| ML20151B442 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 04/01/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20151B423 | List: |
| References | |
| NUDOCS 8804080234 | |
| Download: ML20151B442 (3) | |
Text
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NUCLEAP. REGULATORY COMMISSION
- . j WASHINGTON, D. C. 20555 g
,p SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACT 0P REGULATION SUPPORTING AMENDMENT NO.146 TO FACII.ITY OPERATING LICENSE NO. OPR-62 CAROLINA POWFR A LIGHT COMPANY, et al.
BRUNSWICK STEAM ELECTRIC PLANT, UNIT 2 DOCKET NO. 50-324
1.0 INTRODUCTION
By letter dated Septenber 29, 1987, as supplemented on November 24, 1987, the Carolina Power & Light Company submitted a request for changes to the Brunswick Stean Electric Plan +, Unit 2. Technical Specifications (TS).
The anendment revises Section 3/4.3.? by changing the reactor water level setpoint for the isolation of the Group 1 primary containment isolation valves from Low Level 2 to Low level 3.
The revisions also correct the existing naster trip unit numbars to make them agree with current plant ennvention.
By their letters, the licensee states that the following benefits will be 1
realized as a result of the main steam isolation valve (MSIV) setpoint change:
1.
Reduction in the probability of MSIV closure (reactor isolation).
2.
Reduction in Safety / Relief Valve (S/RV1 challenges.
3.
Prevention of unnecessary use of the suppression pool as a heat sink.
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Possible increase in the life expectancy of the feedwater sparger.
2.0 EVALUATION NUREG-0737. Item II.K 3.16 "Reduction of Challenges and Failures of Relief Valves--Feasibility Study and System Modification," required the licensee to investigate the feasibility and contraindications of reducing challenges to the relief valves by the use of the given sung hted changes /nethods or the use of other methods developed by the licensee. Tha changes should not compromise 1
the performance of the valves or other systems.
The licensee was reauired to document the proposed system changes for staff approval before implementation.
1 By letter dated September 29, 1987, as supplemented on November 24, 1987, the licensee provided the required documentation. The documents were Technical Specification changes that lower the MSIV setpoint from Low level 2 (LL?.)
i
( + 112 inches) to Low Level 3 (LL3) ( + ?.5 inches). This was an NRC kg40gD 4
P
p Staff recommendation to meet NUREG-0737, Item II.K.3.16 recuirements relating to safety / relief valve (S/RV) challenges. Thic chance has also been recomended by the General Electric BWR Owners' Group and has been inplemented at the other BWRs to which it applies.
In addition, the licensee providnd their contractor's safety evaluation of the setpoint changes.
The setpoint change was evaluated with respect to several operating parameters, including the nininum critical power ratio (MCPR), peak vessel pressure, radiation release, and shutdown capability during abnormal operating transients.
Fuel cladding integrity during a loss-of-ccolant accident (LOCA) and the reactor responsa during an ATWS event were also evaluated. Results of this evaluation are provided in the GE Topical Report NEDC-30601-P, "Safety Review of Water level Setpoint Chance for Brunswick Stean Flectric Plant, Units 1 and ?" (proprietary).
As stated in Section 4.2.3 and 4.2.4 of that raport, the change will not cause a reduction in MCPR, an increase in the peak pressure, an increase in radiation release, causa equipment damage, a reduction in plant shutdown capability, i
or a decrease in core cooling capability.
The PSIV level setpoint change has no impact on LOCA events previously evaluated, nor does it cause consequences of accidents previcusly evaluated to be increased.
Fuel cledding integrity during a LOCA and reactor response during in ATWS event were also evaluated, and the results provided in the report.
None of these evalua-tions indicated that any new or different type of accident would be created by the change.
In addition, the present function and structure of the Group 1 isolation valves remains unchanged, thereby eliminating possible operator confusion and training problems that could lead to a new or di#ferent type of eccident.
The effects of the setpoint change for LOCA events has been reviawed, and it has beer determined that the change has no inpact. As stated in NEDC-30601-P, large and intemediate LOCA events will not be effected because the rapid depressurization and rapid inventory loss wi11 rause tha MSIV to close almost imediately after the accident, be' ore any fuel failure could occur. Thus, the lower MSIV trip will not increase inventory loss from the reactor core or radiation release to the environment.
For a small break LOCA, the highest peak cladding temperature for the worst case single feilure (i.e., failure of the HPCI system) is considerably less than the 2200 F peak clad temperature limit.
Therefore, the setpoint change will have no effect on the limiting naximum average planar linear hear generation rate (MAPLHGR).
For a loss of feedwater flow event the reactor would not be isolated while HPCI and RDIC are operating.
Reactor core isolation cooling system flow would compensate for steam flow through the turbine control valves to the main condenser, thereby maintaining water level above Low level 3, keeping the MSIVs i
open, and preventing the safety / relief valves from opening. Thus, the MSIV l
setroint change will not compromise core cooling capability for the loss of feedwater flow event. Furthermore, it reduces suppression pool heatup for j
this event because the main condenser is available for a longer time, j
The Low Level 3 reartor water level setpoint for the Group 1 primary containment isolation systen valves still "ensures the effectiveness of the instrumentation i
used to mitigate the consequences of accidents" as demonstrated by the evaluation i
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1 5
3 Thus, for the reasons Ascribed above, in Sections 4 and 5 of NEDC-30601-P.
the margin of safety is not reduced and may actually be increased.
This was an The licensee also revised certain master trip unit numoers.
administrative change to make the TS agree with plant numbers.
3.0
SUMMARY
The contractor's conclusion from their analysis is that implementation of the MS!V setpoint change from low level 2 to low level 3 will not resuli in any unacceptable safety results for any transients during accident events.
The benefit of the lower MSIV water level trip is that it enhances the plant It will reduce the possibility of spurious MSIV availability and safety.
closure due to water level variation during nortnal operation and it will maintain the availability of the main condenser which limits heat up of the suppression pool and reduces S/RV challenges.
The staff has reviewed the contractor's analyses and conclusions contained in report NEDE-30601-P and agrees with the above conclusions.
4.0 ENVIRONMENTAL CONSIDERATION
S This amendment changes a requirement with respect to installation or use of a facility component located within the restricted crea as defined in 10 CFR The staff has determined that the amendment involves no significant Part 20.
increase in the amounts, and no significant change in the type of any effluents that may be released off site; and there should be no significant j
The increase in individual or cumulative occupational radiation exposure.
Connission has previously issued a proposed finding that this amendment involves no significant haz3rds consideration, and there has been no public coment on such finding. Accordingly, this amendment meets the eli ibility criterh for categcrical exclusion set forth in 10 CFR 151.22(c)(9)g Pursuant to 10 CFR 951.22(b), no environmental impact statement or environm1ntal assessment need be prepared in connection with the issuance of tha amendment.
5.0 CONCLUSION
The Comnission made a proposed determination that this amendment involves no significant hazards consideration which was publithed in the FEDERAL REGISTER and consulted w.h the State of i
(52 FR 47778) on December 16, 1987, j
No public coments or requests for hearing were received, and the State of North Carolina did not have any coments.
The staff has cuncluded, 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, and (2) such activities will be conducted in compliance with the Comission's regulations, and the issuance of the amendment will not be inimical to the comon defanse and security or to the health and safety of the public.
Principal Contributor:
G. Requa Dated: April 1, 1988
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