ML20238E707
| ML20238E707 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 12/29/1987 |
| From: | Bailey J WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| ET-87-0377, ET-87-377, NUDOCS 8801050302 | |
| Download: ML20238E707 (2) | |
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W4$LF CREEK NUCLEAR OPERATING CORPORATION John A. Bailey.
Vice President Engmeering and lischnical Services December 29, 1987 ET 87-0377 U. S.
Nuclear Regulatory Commission ATTN: ' Document Control Desk Washington, D.C.
20555
Subject:
Docket No. 50-482:
Diesel Generator Output Breaker Gentlemen The purpose of this letter is to document commitments made by Wolf Creek Nuclear Operating Corporation (WCNOC) concerning modifications' to the Standby Diesel Generator output breaker control circuitry. As a result of.a teleconference on December 8, 1987 and a meeting with members of the NRC-Staff on December 16, 1987 concerning the Standby Diesel Generator output
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breaker, WCNOC concurs that a design modification can be made to enhance the operation of the output breaker. As discussed during the December 16, 1987 meeting, WCNOC will have a preliminary design available for,NRC Staff review in January 1988.
The design will be finalized and any necessary equipment' procured by March 31, 1988.
Implementation of the design change will.be completed after March 31, 1988 as soon as-plant conditions permit, but no
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later than, STARTUP from the third refueling outage for Wolf Creek-Generating Station (WCGS).
Additional discussions with the Staff, i
concerning implementation of the design change, will occur after the j
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preliminary design is completed.
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This implementation schedule allows adequate time to complete a thorough j
design review and provide the required assurance that the design change will I
not adversely effect other safety, design, or regulatory requirements.
The existing design of WCNOC'S Standby Diesel Generator output breakers conforms with the present regulatory requirements, however, WCNOC has agreed with the Staff that a design enhancement would be beneficial to allow closure of the output breaker from the control room under the circumstances that occurred on October 14, 1987 and rimilar scenarios described by the Staff..
This design change would not bypass features necessary to protect the output breaker, or other associated equipment.
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8801050302 871229 l
DR p
AD0CN O5000482 x 411/ Burhngt n, KS 66839 / Phone: (316) 364 8831 j
DCD An Equal opporturwy Ernployer MF/HCNET
l Page 2 of 2 ET 87-0377 December 29, 1987 i
i Information has been provided to the licensed operators relative to the control circuitry of the Standby Diesel Generator output breaker.
This information included instructions on the actions necessary to re-close the J
breaker in the unlikely event the operator has had to open the breaker from j
the control room when a valid safety signal, which had closed the breaker, i
was present.
These operator actions require less than five minutes to accomplish.
l This tim:
frame is deemed acceptable since situations that would preclude closure of both breakers from the control room would result from an unusual set of circumstances in which the operator had intentionally deenergized both safety related busses.
Situations other than intentional operator override of a safety signal, preventing subsequent closure of the breaker, would have to involve multiple failures in both safety trains.
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The safety analyses presented in the Updated Safety Analyses Report for all Design Basis events still remain valid.
In addition, the increased cognizance of the licensed operators with regard to the output breaker control circuitry minimizes unnecessary delays in restoring electrical power if a similar event occurred at WCGS prior to implementation of the proposed design modification.
Therefore, the current output breaker design provides adequate protection of the health and safety of the public until the design enhancements are implemented.
j If you have any questions concerning this matter, please contact me or Mr. O. L. Maynard.
Very truly yours, j
- 0. Q 0
l John A. Bailey j
Vice President l
Engineering and Technical Services I
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JAB /skw cc:
J. E. Cummins (NRC)
R. D. Martin (NRC) i P. W. O'Connor (NRC), 2 I
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