ML20149D355

Informs NRC That SCE Will Not Complete All Upgrades Required to Support IPEEE According to Schedule

ML20149D355
Person / Time
Site:	San Onofre
Issue date:	07/15/1997
From:	Rainsberry J SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-88-20, NUDOCS 9707170108
Download: ML20149D355 (2)

Text

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h h 500lHf RN CAtif ORNIA E, DISON Manager. Plant Licensing An I(MON l4TIRNATIONAL" Gmnany i

July 15, 1997 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D. C. 20555 Gentlemen:

Subject:

Docket Nos.'50-361'and 50-362 Individual Plant Examination of External Events Commitments San Onofre Nuclear Generating Station, Units 2 and 3

References:

1) March 24,1995 Letter from Walter C. Marsh (Edison) to the Document Control Desk (NRC),

Subject:

Response to Generic Letter 88-20, Supplement 4. " Individual Plant Examination of External' Events (IPEEE)," San Onofre Nuclear Generating Station, Units 2 and 3'

2) December 31, 1996 Letter from J. L. Rainsberry (Edison) to the Document Control Desk (NRC),

Subject:

Inter-Unit 4.16 kV Bus Cross-Tie, San Onofre Nuclear Generating Station, Units 2 and 3 ThisletteristoinformtheNRCthatSouthernCaliforniaEdison(Edison)will not complete all upgrades that are required to support the Individual Plant Examination of External Events'(IPEEE) according to the original schedule.

i Reference 1 submitted the IPEEE for San Onofre Units 2 and 3.

In this submittal Edison committed to complete all upgrades required to support the assumptions of the IPEEE before close of breakers on the Unit 3 Cycle 9 Refueling Outage.

Unit 3 is currently scheduled to close breakers on July 16, 1997.- Two of the actions committed te in Reference 1 will not be completed by this date.

The first action was to install and:have an operational electrical Cross-Tie i

between Units 2 and 3 such that one Unit could receive power at the 4.16 kV

{)h, bus.from the. opposite Units' Diesel Generator. The cross-tie has been installed in both Units _2 and 3 but has been disabled with jumpers installed I

and leads lifted to the. cross-ti permissive switches. As detailed in i O Reference 2. "Because the use u.his modification in a beyond design basis i

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Document Control Desk event is not allowed by 10CFR50.59," Edison requested NRC approval for the design of the cross tie and performance of the preoperational testing and final turnover.

NRC approval has not yet been received. Therefore, the final turnover of this modification has not been completed and the original schedule

'for completion will not be met.

With the expectation that NRC approval will be received, Edison intends to perform the final turnover of the cross-tie modification by the end of the Unit 3 Cycle 9 Mid-Cycle Outage.

The second remaining action from the IPEEE was to revise an emergency operating procedure dealing with plant shutdown from outside the control room in the event of a control room area fire.

The procedure currently requires the transfer of electrical loads from the offsite grid to the emergency diesel generators whenever the control room is evacuated regardless of whether a loss of offsite power has occured. The IPEEE action was to preclude unnecesshry challenges to safety equipment such as diesels and circuit breakers.

Because more recent data indicate diesel generator reliability is higher than j

that assumed in the IPEEE, the risk significance improvement of the proposed

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procedure change is now believed to be small.

Nevertheless, Edison intends to proceed with revising the procedure to simplify it and enhance its usability.

Because the procedure change requires consideration of Appendix R requirements and therefore has become more complex than anticipated, Edison plans to complete revision of the procedure by the end of the Unit 3 Cycle 9 Mid-Cycle Outage.

If you have any questions on this information, please let me know.

Sincerely, N

c ~--

cc:

E. W. Herschoff, Regional Administrator, NRC Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV

_J. A. Sloan, NRC Senior. Resident Inspector, San Onofre Units 2 & 3

M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 ww w

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