ML20210U183

Revises 980202 Commitment Re GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design- Basis Accident Conditions

ML20210U183
Person / Time
Site:	Monticello
Issue date:	08/12/1999
From:	Day B NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-06, TAC-M96835, NUDOCS 9908200029
Download: ML20210U183 (3)

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Northern States Power Company Monticello Nuclear Generatng Plant

.807 West County Road 75 Monticello, MN 55362 August 12,1999 US Nuclear Regulatory Commission Generic Letter 96-06 Attn: Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22

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Generic Lette 96-06 Commitment Revision (TAC NO. M96835)

References:

1. Letter from M. F. Hammer, NSP, to US Nuclear Regulatory Commission Document Control Desk, " Revised Response to Generic Letter 96-06 (TAC NO. M96835)," February 2,1998

2. Letter from M. F. Hammer, NSP, to US Nuclear Regulatory Commission Document Control Desk, " Post Refueling Outage Update to NRC Generic Letter 96-06 (TAC NO. M96835)," May 6,1998

3. Letter from C. A. Schibonski, NSP, to US Nyclear Regulatory Commission Document Control Desk, " Response to Request for Additional Information Dated September 16,1997 Related to the Monticello Response to Generic Letter 96-06 (TAC NO. M96835)," October 30,1997 The purpose of this letter is to revise our February 2,1998 commitment regarding g Generic Letter 96-06, " Assurance of Equipment Operability and Containment Integrity 1 During Design-Basis Accident Conditions." In Reference 1, NSP made the following j commitment: I "Monticsflo willinstallpressure relieving devices or other equivalent means to resolve the overpressure conditions identified by NSP's January 28,1997 submittal prior to startup from the 1998 refueling outage with the exception of the RHR ,

l Shutdown cooling line and the instrument air /altemato N2 system which will be resolved during the 1999 refueling outage. The 1998 refueling outage is currently scheduled for March 1998 and the 1999 outage for November 1999."

In Reference 2, NSP informed the NRC that Monticello did install pressure relieving devices during the 1998 refueling outage and reaffirmed our commitment to complete GL-

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• August 12,1999 Page 2

- 96 06 modifications during the 1999 refueling outage (RFO). Please note that the 1999 RFO has been delayed until January 2000.

In an April 8,1999 conference call with the NRC staff, NSP expressed safety concerns with installing the proposed design fix to the RHR shutdown cooling line during the upcoming 2000 refueling outage, and requested an extension to the 2001 refueling outage. The shutdown cooling line connects directly with the recirculation line upstream of the recirculation pump. System isolation between shutdown cooling inboard isolation valve MO-2029 and the reactor vessel would consist of a single manual valve. Waiting until the 2001 RFO for installation results in lower overall modification risk because a full core offload is planned for the 2001 refueling outage. Continued operation of the shutdown cooling line in its current configuration until the 2001 refueling outage is considered acceptable because the RHR Shutdown cooling line meets ASME Section lil, Appendix F operability criteria as allowed by GL 96-06 and GL 91-18. Reference 3 describes NSP's application of the Appendix F methodology and gives values for design pressure, calculated maximum expected pressure, and maximum allowable Appendix F pressure.

During the 2001 refueling outage, a modification will replace the existing shutdown cooling inboard isolation valve MO-2029 with a new double disc gate valve that will self relieve. Should pressure build up between the two isolation valves, the inboard valve will self relieve through a hole in the vessel side valve disc, thus precluding a potential overpressure condition.

Although GL 96-06 only required licensees to review water filled lines, NSP also reviewed gas filled lines (Ref. 3) and found some components in the instrument air / alternate N2 system to be inadequate. NSP intends to replace components in these lines with higher pressure rated components, or upgrade existing components through vendor certification.

Our February 2,1998, commitment is therefore being modified to the following:

"Monticello willinstall higher pressure rated devices or upP,ade certification of existing devices to resolve the margin concem identified oy NSP's January 28,1997 submittal for the instrument air / alternate N2 system prict to startup from the 2000 refueling outage. During the 2001 refueling outage, the RHR Shutdown cooling inboard isolation valve will be replaced with a new double disc gate valve that self relieves. The 2000 refueling outage is currently scheduled forJanuary 2000 and the 2001 outage for May 2001.'

Please contact Sam Shirey, Sr. Licensing Engineer, at (612) 295-1449 if you require additional information related to this request.

By 'k!/h ])A

[pyron D. Day I Plant Manager v Monticello Nuclear Generating Plant Page 2

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,, a August 12,1999-Page 2 On this 12% ay of Awu-r d 1999 before me a notary public in and for said County, personalIy'alfdeared Byron D. Day, Plant Manager, Monticello Nuclear Generating Plant, and being first duty swom acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay.

$anYuel1. Shirey "

Notary Public - Minnesota [ ]:

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c: Regional Administrator-111, hPC NRR Project Manager, NRC Sr. Resident inspector, NRC State of Minnesota Attn: Steve Minn J. Silberg Page 3

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