ML20154Q255
| ML20154Q255 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/24/1988 |
| From: | Allen C COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20154Q258 | List: |
| References | |
| 4679K, NUDOCS 8806060231 | |
| Download: ML20154Q255 (2) | |
Text
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Comm:nw alth Edison
].
One First National Plaza, Chicaco, Illinois V
Address Reply to: Post Office Box 767 Chicago, Illinos 60690 0767 4
May 24, 1988 U.S. Nuclear Regulatory Commission Attn: Document Control Desk washington, DC 20555
Subject:
LaSalle County Station Units 1 and 2 Proposed Technical Specification for Diesel Generator "0" NRC Docket Nos. 50-373 and 50-374 References (a): January 19,.1987 letter from C.M. Allen proposing amendment to NPF-ll and NPF-18 to allow D/G "0" out-of-Service for up to 7 days for Preplanned Preventative Maintenance Activities (b): February 24, 1987 letter from C.M. Allen documenting Commitments made in a Telecon held February 4, 1987.
(c): No Significant Hazards Determination published in Federal Register, Vol. 52, No. 106 dated June 3, 1987.
Dear Sir:
This letter is in response to a request by a member of the NRC Staff for a Probabilistic Risk Assessment (PRA) of the Technical Specification amendment proposed in Reference (a). The requested PRA is attached.
Ccanonwealth Edison (CECO) originally proposed that LaSalle County Station (LSCS) Units 1 and 2 Technical Specifications be amended to allow Diesel Generator "0" (D/G "0") out-of-service for up to seven days for performance of specific preplanned maintenance activities. Together with that request CECO made certain commitments which would further reduce the risk associated with having D/G "0" out-of-service during that period. During the evaluation of that proposal the reviewer requested in a teleconference in February, 1987 that certain additional commitments be made.
These additional commitments were made by CECO and documented in Reference (b).
In another teleconference held in March 1987, the reviewer requested that a formal PRA be done to demonstrate that no significant additional risk would be incurred by f
the approval of this proposed amendment.
That PRA has been completed and concludes that the increase in risk is insignificant.
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8806060231 880M4 PDR ADOCK 05000373 k
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US NRC May 24, 1988 l
l Attached is the requested pRA which was performed by IT-Delian Corporation. The pRA specifically addresses the risk implication of amending the Technical Specifications for LSCS to allow continued operation of one unit 1
for seven days while the shared D/G "0" is out-of-service to satisfy mainten-ance requirements. The report concludes that the extension of the allowable out-of-service time results in an increase risk of approximately 88-09.
"When compared to the annual core damage frequency estimate for a similar plant, such an increase (approximately 0.01 percent) is considered to be insignificant." and "As a result, when economic and operational beneifts are considered the proposed Technical Specification change represents a net benefit..."
The attached pRA was technically evaluated by CECO personnel and
)
found to use high estimates for failure frequency which results in a higher predicted core damage frequency.
This is conservative since a model that over predicts core damage frequency will also over predict the consequences of extending the allowed outage. The Delian conservatively high results still show a negligible increase in core damage frequency.
Based on that review, che results of the pRA were found acceptable and nothing has been identified to require change to the original No Significant Hazards Consideration Determination (Reference (c)).
If you have any additional questions regarding this matter, please contact this office.
Ve y truly yours,
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C. M. Allen Nuclear Licensing Administrator 1m Attachment cc: