ML20079K886
| ML20079K886 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 01/07/1983 |
| From: | James Smith LONG ISLAND LIGHTING CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.16, TASK-TM SNRC-816, NUDOCS 8301100203 | |
| Download: ML20079K886 (3) | |
Text
I.
LONG ISLAND LIGHTING COM PANY FAnr SHOREHAM NUCLEAR POWER STATION P.O. BOX 618, NORTH COUNTRY ROAD e WADING RIVER, N.Y.11792 January 7, 1983 SNRC-816 Mr. Harold R.
Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 SER Open Issue II.K.3.16 MSIV Setpoint Changes Shoreham Nuclear Power Station - Unit 1 Docket No. 50-322
Reference:
(1)
LILCO letter, SNRC-563, (J. P. Novarro) to the NRC (H.
R.
Denton), dated 5/15/82
Dear Mr. Denton:
As a member of the BWR Owners Group, LILCO participated in the evaluation of NUREG-0737, Item II.K.3.16 " Reduction of Challenges to the SRVs" (Reference 1).
The shoreham Nuclear Power Station incorporated several of the recommended modifications to reduce the number of challenges to the safety / relief valves.
These modifications, in conjunction with the use of the two stage Target Rock SRVs, result in an estimated stuck open relief valve (SORV) frequency which is approximately an order of magnitude less than the BWR 4 benchmark plant.
The present Shoreham design there-fore meets the intent of NUREG-0737, II.K.3.16.
During the ASLB hearing litigation on SC Contention 28a (vi), LILCO indicated that it was investigating the feasibility of another modification which would further reduce the number of SRV challenges; i.e.,
changing the MSIV isolation setpoint from the present low reactor water level (L2) to the low-low level (L1).
This investi-gation, which is complete, has determined that it is feasible for Shoreham to modify the setpoint so that isolation occurs at level 1, without impacting the safe operation of the unit.
pl C301100203 030107 PDR ADOCK 05000322 E
January 7, 1983 Mr. Denton Page 2 As previously stated, Shoreham has already incorporated several design changes which have reduced the SORV frequency by an order of magnitude and, as shown in reference 1, the incremental benefit of the proposed MSIV isolation setpoint chcnge will result in a minor improvement to the total SORV event frequency.
This small incremental benefit is due to the fact that the previous modifica-tions have already remedied common SORV initiators that were factored into the estimate of the benefits of the proposed mod-ification taken singly.
The benefits are not additive; each subsequent modification results in a smaller incremental improve-ment to the predicted SORV event frequency.
Not withstanding this small incremental reduction in total SORV event frequency resulting from the incorporation of this change, LILCO commits to its implementation.
The aforementioned investigation, detc rmined that several actions are necessary to support the actual physical incorporation of the hardware to implement the MSIV logic setpoint revision.
Although the feasibility investigation determined that the FSAR Chapter 15 bounding analyses remain unaffected, two of the less critical transients will require revision.
Specifically, the loss of offsite power and the loss of feedwater transients must be reanalyzed to reflect the lowered isolation setpoint.
The engineering revisions involve several organizations.
The NSSS vendor must revise all related documentation such as elementary and one line drawings, logic diagrams, and the master parts list and provide formal permission to revise the MSIV isolation logic setpoint.
Upon receipt of the formal approval and the technical details of the revision, LILCO's architect / engineer will revise the applic-able plant drawings and authorize the change.
The Start-Up or the Plant Maintenance group will then implement the actual hard-ware modification.
To support the modified MSIV isolation set-point logic, the Plant Staff must revise the applicable station procedures.
In addition, the operators must be trained using these procedures to ensure familiarity with the modified plant parameters resulting from the change.
In view of the efforts involved in this modification, the implementation of the MSIV logic setpoint revision can not support the start-up testing schedule.
In summary, the Shoreham design already meets the intent of NUREG-0737.
Previous modifications have reduced the predicted SORV frequency by an order of magnitude vis-a-vis the benchmark BWR-4 plant.
The modification of the isolation logic requires hardware
January 7, 1982 Mr. Denton Page 3 modifications to systems that will not be an extended chutdown when access is permissible and the MSIVs are not required to perform a safety function.
In light of the above, and since the proposed MSIV isolation setpoint revision does not provide a significant contribution to the overall plant safety, LILCO intends to incorporate this plant modification during the first refueling outage.
In the course of the ASLB hearing litigation, LILCO committed to complete a feasibility evaluation for this modification.
LILCO believes the information stated herein and the commitment to modify the MSIV isolation setpoint logic adequately fulfills this commitment.
Very truly yours, m
J.
L.
Smith Manager, Special Projects Shoreham Nuclear Power Station RJT/jm cc:
J.
Higgins All Parties
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