ML20247D361
| ML20247D361 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 03/22/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20247D353 | List: |
| References | |
| NUDOCS 8903310054 | |
| Download: ML20247D361 (3) | |
Text
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SAFETY EVAlllATION BY THE OFFICE-0F NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.
17 TO FACILITY OPERATING LICENSE NO. NPF-39 PHILADELPHIA ELECTRIC COMPANY LIMERICK GENERATING STATION, UNIT 1 DOCKET NO. 50-352
1.0 INTRODUCTION
Py letter dated December 14, 1988, Philadelphia Electric Company.(the licensee) requested an amendment to Facility Operating License No. NPF-39 for the Limerick Generating Station, Unit 1.
The proposed amendment would change the Technical Specifications (TSs) to permit removal of the Rod Sequence Control System (RSCS) and to reduce the Rod Worth Minimizer (RWM) low power setpoint.
2.0 DISCUSSIO_N The Rod Sequence Control System restricts rod movement to minimize the individual worth of control rods to lessen the consequences of a Rod Drop l
Accident (RDA). Control rod movement is restricted throuch the use of rod select, insert, and withdrawal blocks. The Rod Sequence Control System is a hardwired (as opposed to a computer controlled), redundant backup to the Rod Worth Minimizer.
It is independent of the Rod Worth Minimizer in terms of inputs and outputs but the two systems are compatible. The RSCS is designed to monitor and block when necessary operator control rod selection, withdrawal and insertion actions, and thus assist in preventing significant control rod pattern errors which could lead to a control rod with a high reactivity worth (if dropped). A significant pattern error is one of several abnormal events all of which must occur to have a RDA which might exceed fuel energy density limit criteria for the event.
It was designed only for possible mitigation of the-RDA and is active only during low power operation (currently generally less than 20 percent power) when a RDA might be significant.
It provides rod blocks on detection of a significant pattern error.
It does not prevent a RDA. A similar pattern control function is also perfonned by the RWM, a computer controlled system. All reactors having a RSCS also have a RWM.
In response to a topical report submitted by the BWR Owner's Group, on December 27, 1987 the NRC staff issued a letter with a supporting safety evaluation approving 1) elimination of the RSCS while retaining the RWM to provide backup to the operator for control rod pattern control and 2) lowering the setpoint for turnoff of RWM to 10% of rated thermal power from its current 20% level.
(Letter, A. C. Thadani, NRC to J. S.
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i Charnley,GE,
Subject:
Acceptance for Referencing of Licensing Topical l
Report NEDE-24011-P-A, " General Electric Standard Application for Reactor Fuel," Revision 8, Amendment 17).
3.0 EVALUATION The letter of December 27, 1987 and supporting safety evaluation approving the topical report concluded that the modifications proposed by PECo were acceptable provided:
1)
The Technical Specifications (TS) should require provisions for minimizing operations without the RWM system operable.
2)
The occasional necessary use of a second operator replacement should be strengthened by a utility review of relevant procedures, related forms and quality control to assure that the second operator provides an effective and truly independent monitoring process. A discussion of this review should accompany the request for RSCS removal.
3)
Rod patterns used should be at least equivalent to Banked Position Withdrawal Sequence (BPWS) patterns.
With respect to item 1) above, the proposed TSs submitted with this amendment application allow only one reactor startup per calendar year with the RWM unavailable prior to or during the withdrawal of the first 12 control rods. We conclude that item 1) is adequately satisfied.
With regard to item 2) above, PEco described the programs and procedures that would be provided during instances when the RWM is not available to independently verify the correctness of the first operator's actions during rod movements.
The procedure for " Bypassing the Rod Worth Minimizer," procedure S73.0.D, Rev. 7 dated October 31, 1988 has been reviewed by the resident inspectors and the NRR Project Manager and it provides acceptable controls when used in conjunction with the specific procedural restrictions listed in the December 14, 1988 submittal.
During the January 11, 1989 shutdown of Unit 1 for the second refueling outage, the resident inspectors observed inanagement's attention to the procedures. We conclude that the procedural controls are acceptable.
The RWM at Limerick Unit 1 utilizes the BPWS patterns recommended in the staff's December 27, 1987 letter.
This satisfies item 3) above.
PECo's proposal to remove the RSCS and to lower the RWM low power setpoint from 20 to 10 percent at Limerick Unit 1 meets the requirements detailed in the staff's letter of December 27, 1987 approving the topical report on these modifications. Accordingly, the modifications proposed in PECo's letter of November 9, 1988 are found to be acceptable and are approved. We have also reviewed the proposed changes to the TSs and find
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-3 them to be consistent with the intent of the staff's afety evaluation approving the topical report and finT the changes ac dptable.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has detemined 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 signifi-cant increase in individual or cumulative occupational radiation exposure.
The Comnission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility l
criteria for categorical exclusion set forth in 10 CFR 51.2?(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental.
assessment need be prepared in connection with the issuance of this amendment.
5.0 CONCLUSION
The Commission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Recister (54 FR 5172) on February 1,1989 and consulted with the State of Pennsylvania.
No public comments were received and the State of Pennsylvania did not have any comments.
The staff 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and the security nor to the health and safety of the public.
Principal Contributor:
Dick Clark Dated: March 22, 1989 i
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