ML20072S883

Forwards PRA-2/3-94-012, PRA Evaluation of Population Dose Risk... & PRA-2/3-94-013, PRA Evaluation of Risk Impact of Proposed One-Time Exemption from Requirements of 10CFR50, in Support of 940817 Application for Amends

ML20072S883
Person / Time
Site:	San Onofre
Issue date:	09/02/1994
From:	Marsh W SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20072S884	List: ML20072S883 ML20072S893 ML20072S935
References
NUDOCS 9409140280
Download: ML20072S883 (2)

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Southem Califomia Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 m,.mn $^I5".n $71*1 m.,n. September 2, 1994 j,",i""",,

U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

Docket Nos. 50-361 and 50-362 Additional Infomation Supporting the {

One-time Exemption from 10CFR50, Appendix J Amendment Application Nos. 143 and 127 San Onofre Nuclear Generating Station Units 2 and 3

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Reference:

August 17, 1994, letter from R. M. Rosenblum (Edison) to Document Control Desk (NRC),

Subject:

"One-time Exemption from 10CFR50, Appendix J Amendment Application Nos. 143 and 127 Change to Technical Specification 3/4.6.1.2, " Containment Leakage" San Onofre Nuclear Generating Station, Units 2 and 3."

On August 17, 1994, Southern California Edison (Edison) submitted Amendment Application Nos. 143 and 127 to Facility Operating Licenses NPF-10 and NPF-15, respectively, for the San Onofre Nuclear Generating Station, Units 2 and 3 (Referenced above). -These Amendment Applications consisted of Proposed Change Number (PCN) 438. PCN 438 is a request to revise- Technical Specification (TS) 3/4.6.1.2, " Containment Leakage," to extend-the interval between Integrated Leak Rate Tests (ILRTs) from 40 i 10 months to 60 i 10 months on'a one-time basis.

PCN 438 is a Cost Beneficial Licensing Action. NRC approval of this change would save approximately 110 critical path hours per unit during the Cycle 8 refueling outages. At an estimated power replacement cost of approximately

$16,000 per hour (according to the Units 2 and 3 Cycle 7 optimization estimates) this results in approximate savings of $1,760,000 per unit. Other

savings would be approximately 2800 hours0.0324 days <br />0.778 hours <br />0.00463 weeks <br />0.00107 months <br /> of labor (a) proximately $124,000) and'approximately $50,000 for special equipment, whic1, when added to the replacement power cost savings, result in a total savings of approximately

$1.9 million. In addition, a savings of 2000 mrem of occupational exposure i

L l per unit will also be realized.

Edison committed to submit a Level 3 Probabilistic Risk Assessment (PRA) in support of this proposed TS change. This PRA is provided as Enclosure 1.

The PRA determined the increase in population dose risk from severe accidents initiated by internal events at San Onofre Units 2 and 3 attributable to the proposed increase in the ILRT interval requested in PCN 438. The result is a L

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Document Control Desk population dose increase of 0.095 person-rem /yr over a base case risk of 18.6 person-rem /yr.

The small increase in risk is the basis for our request for ILRT deferral. It should be noted that, using the NRC guidance of $1000 per person-rem, the risk-reduction benefit from performing an ILRT during the Cycle 8 refueling outage instead of deferring it roughly 20 months to the Cycle 9 refueling outage approximately $160 per unit. This is a negligible benefit when compared with the approximately $1.9 million cost per unit currently estimated for performing each ILRT.

If you would like additional information regarding these exemption and Technical Specification change requests, please let me know.

Sincerely, h0 1

cc: L. J. Callan, Regional Administrator, NRC Region IV A. B. Beach, Director, Division of Reactor Projects, Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 1, 2, and 3  ;

M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 l H. Kocol, California Department of Health Services {

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