ML20197A486

Provides Supplemental Response to NRC Final Rept of Spent Fuel Storage Pool Safety Issues Lasalle,Units 1 & 2.Rev 1 to Calculation L-001378, Calculated Probability for Sustained Boiling in LaSalle Fuel Pools, Encl

ML20197A486
Person / Time
Site:	LaSalle
Issue date:	12/16/1997
From:	Subalusky W COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20197A489	List: ML20197A486 ML20197A499
References
NUDOCS 9712230070
Download: ML20197A486 (2)

Text

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• ' mmm u nmwr Irl hl' M* F61 r December 16,1997 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555

Subject:

Supplemental Response to NRC Final Repor1 on Spent Fuel Storage Pool Safety Issues LaSalle County Station, Units 1 and 2 Facility Operating License NPF 11 and NPF 18 NRC Docket Nos. 50 373 and 50 374

References:

1. James M. Taylor (NRC) Memorandum to Chairman Jackson (NRC), et. al., ' Resolution of Spent Fuel Storage Pool Action Plan issues,"

dated July 26,1996

2. Donna M. Skay (NRC) letter to Irene Johnson (Comed)," Resolution of Spent Fuel Storage Pool Safety issues: Issuance of Final Staff Report and Notification of Staff Plans to Perform Plant.

Specific Safety Enhancement Backfit Analyses -

LaSalle Count Station (TAC No M88094)," dated September 25,1996

3. John B. Hosmer (Comed) letter to NRC Document Control Desk, ' Response to NRC Final Report on Spent Fuel Storage Pool Safety issues," dated November 18,1996 In Referonco (2) the United States Nuclear Regulatory Commission (NRC)

Informed Commonwealth Edison Company (Comed) of its concems rogarding spent fuel storage pool safety issues at LaSalle County Nuclear

.Tj u ,A ~ ~ Power Station, Units 1 and 2 (LaSalle). The NRC Staff identitled that issue 6, ' Shared Systems and Structures at Multi Unit Sites," and issue 10,

'Limitod instrumentation for Loss of Coo!!ng Events," as discussed in '

Referenco (1) were of concern at LaSalle Comed responded to those g concoms in Reference (3). f 9712230070 971214 gm Am s ga llpgj%i,((,[ll 1

In reviewing issue 6. LaSalle identified a vulnerability !n the design of the <

spent fuel pool cooling systems. The control power for both Unit 1 and l Unit 2 spent fuel storage pool cooling system flow control valves is l dependent upon a single source of Unit I normal 6.9 kilovolt (kV) offsite  ;

power. LaSalle committed to enhance system reliability by either proceduralizing a method to restore control power following a Unit 1 loss of 1 offsite power (LOOP) or installing a modification to provide control power  !

from either unit's normal 6.9 kV offsite power supply. This commitment was l' included in Reference (3). Subsequently, LaSalle has decided to pursue the.

modification. This modification will be installed prior to the next refuel outage on either unit.

i During recent conversations with the NRC Staff a question was raised regarding how LaSalle would respond to a dual unit loss of offsite power (DLOOP). As shown in the attached calculation, the probability of a DLOOP of sufficient duration to allow sustained bolling in either unit's spent fuel storage pool is 2E 07 when the spent fuel storage pools are not connected and 8E 08 when the spent fuel storage pools are connected. Although the probability of a DLOOP is not risk significant, LaSalle will revise its procedures to provide sufficient guidance to align and operate either unit's spent fuel storage pool cooling system without reliance on offsite power.

These procedwe revisions will be completed prior to the next refuel outage on either unit.

If there are any questions or comments concerning this letter, please refer them to Perry Barnes, Regulatory Assurance Supervisor, at (815) 357 6761, extension 3600.

Respectfully, f .

W. T. Subalusky /

Site Vice Presideht LaSalle County Station Attachment cc: A; B. Beach, NRC Region lll Administrator M. P. Huber, NRC Senior Resident inspector LaSalle D. M. Skay, Project Manager NRR - LaSalle F. Niziolek, Office of Nuclear Facility Safety IDNS

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