ML20077B679
| ML20077B679 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 07/14/1983 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8307250372 | |
| Download: ML20077B679 (2) | |
Text
e DUKE POWER GOMPANY P.O. Box 33180 011ARLOTTE, N.O. 28242 HALB. TUCKER TELEPHONE r
vice rammeneur (704) 3TJ-4531 July 14, 1983
.mu...om.ono, Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414
Dear Mr. Denton:
Elinor G. Adensam's letter of June 21, 1983 transmitted the Staff's licensing position on Catawba Safety Evaluation Report Open Item 10, Lockout of Manual Control by the Load Sequencer. Attached is Duke's proposed resolution for this item.
Very truly yours, dbY 1 B. Tucker 4
ROS/php Attachment cc:
Mr. James P. O'Reilly Mr. Jesse L. Riley Regional Administrator Carolina Environmental Study Group U. S. Nuclear Regulatory Commission 854 Henley Place Region II Charlotte, North Carolina 28207 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Palmetto Alliance 2135 Devine Street hTC Resident Inspector Columbia, South Carolina 29205 Catawba Nuclear Station Mr. Henry A. Presler, Chairman Mr. Robert Guild, Esq.
Charlotte-Mecklenburg Environmental Attorney-at-Law Coalition P. O. Box 12097 945 Henley Place Charleston, South Carolina 29412 Charlotte, North Carolina 28207 1
8307250372 830714 PDR ADOCK 05000413 E
CATAWBA NUCLEAR STATION LOCK 0UT OF MANUAL CONTROL BY THE LOAD SEQUENCER (OPEN ITEM NO.10)
As previously discussed with the staff, the present design of the Catawba Diesel Generator Load Sequencer has many positive advantages.
The design does not introduce a new manual control lockout until after re-set philosophy but merely endorses and extends the design philosophy of the Solid State Protection System (SSPS).
The precluding of manual actions until after SSPS reset is typical for Westinghouse plants. Since this philosophy is employed for air operated valves, motor operated valves and 600 volt motors which have no sequencer interface, it is good human factors practice to provide consistency by extending this re-set philosophy to sequencer controlled loads.
This practice includes a "stop and think" feature (resetting of the SSPS) which helps to insure that assumption of manual control by the operator is a planned, conscious, deliLerate action. This reduces the ootential for inadvertent or erroneous actions especially in the first few critical minutes of an accident.
The staff has expressed concern that a failure could occur which would prevent the resetting of a sequencer and thus inhibit subsequent manual control by the opera tor.
(Note that such a postulated failure would only affect one of the redundant sequencers thus the remaining train would be fully capable of fulfilling all safety functions).
In the unlikely event of such a failure, the operator can regain manual control of sequencer loads by simply tripping a single breaker to remove control power from the sequencer. The appropriate station procedures will be revised to provide the operator with the specific guidance as to when and how this action should be ta ken.
By implementing this resolution the positive aspects of the present sequencer design can be preserved while also providing a simple, straightforward recovery method for the operators should a failure to reset occur.