ML20141C144

Submits New NRC Commitment to Perform Plant Mods to Address Postulated RWCU Line Breaks

ML20141C144
Person / Time
Site:	Monticello
Issue date:	06/10/1997
From:	Hill W NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9706250008
Download: ML20141C144 (2)

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Northem States Power Company MonticeHo Nuclear Generating Plant 2807 West Hwy 75 Monticello, Minnesota 55362 9637 l l l l

June 10,1997 l

US Nuclear Regulatory Commission l Attn: Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Commitment to Perform Plant Modifications to Address Postulated RWCU Line Breaks

Reference:

1) Letter from W.J. Hill, NSP, to USNRC Document Control Desk, "LER 96-008 Reactor Water Clean Up Line Break Reanalysis Due to an Error Discovered During Re-evaluation," September 16,1996 By letter dated September 16,1996 (Ref.1), NSP committed to investigate the feasibility of modifying the plant to provide additional automatic isolations for the RWCU system. This investigation has determined that a modification to the RWCU system to provide automatic system isolation in order to more directly mitigate a RWCU line break is prudent and feasible.

The proposed plant modification willlikely include automatic isolation of RWCU System isolation valves MO-2397 (RWCU Inlet Inboard Isolation), MO-2398 (RWCU Inlet Outboard Isolation),

and MO-2399 (RWCU Return isolation) to mitigate RWCU line breaks. The proposed new l isolation signals to these valves are: 1) High RWCU room temperature and 2) High RWCU l system flow.

NSP intends to install this modification during the 1998 refueling outage in accordance with the requirements of 10 CFR 50.59. A separate license amendment request will be submitted to revise the MNGP Technical Specifications to include the additional isolation functions for the RWCU system primary containment isolation valves. l This letter contains the following new NRC commitment:

The RWCU system will be modified to provide an appropriate automatic system isolation j to mitigate the consequences of a postulated high energy line break in the RWCU piping.

l This action will be performed prior to the end of the 1998 refueling outage.

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Please contact Joel Beres, Licensing Engineer, at (612) 295-1436 if you require further

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!ld$ f f William J. Hill-

! Plant Manager .

l Monticello Nuclear Generating Plant c: Regional Administrator- 111, NRC NRR Project Manager, NRC  ;

Sr Resident inspector, NRC i State of Minnesota, Attn: Kris Sanda l

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