ML20237E088

Clarifies Info Provided Re Containment Ventilation Sys & Use of Mixing Factor of 0.5,in Response to NRC Request Made During Telcon

ML20237E088
Person / Time
Site:	Kewaunee
Issue date:	08/24/1998
From:	Marchi M WISCONSIN PUBLIC SERVICE CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-98-91 NUDOCS 9808280244
Download: ML20237E088 (2)

Text

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. teum hear Puer ut es 'YW 4)3 H y Am 4) e Me/me W1542169511 920 ;8S 2%C August 24,1998 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Ladies / Gentlemen:

Docket 50-305 Operating License DPR-43 Kewaunee Nuclear Power Plant Amendment 132 to Kewaunee_ Plant Ooenting License - Clarification of Supplemental Information

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Reference:

Letter from M. L. Marchi (WPSC) to the Document Control Desk (NRC) dated August 13, 1998.

In the Reference, Wisconsin Public Service Corporation (WPSC) provided supplemental information to the Nuclear Regulatory Commission (NRC) to resolve concerns with Amendment 132 to the Kewaunee Plant Operating License. In a subsequent telecon, the NRC has requested that WPSC clarify the information provided regarding the Kewaunee containment ventilation system and the use of a mixing factor of 0.5.

Attachment 1 of the Reference provided a dose analysis for a fuel handling accident within the containment. The analysis states, " Mixing and dilution within the containment building will reduce the total release activity by at least a factor of two even with the conservative assumption of a continuous rekase flow at approximately 6000 scfm." The discussion continues by identifying that the basis for this assumption was developed and accepted by the NRC in a Prairie Island license action. WPSC's intent with this information was to indicate that WPSC followed the same methodology for establishing a mixing factor. While the containment free volumes are comparable for both Prairie Island and Kewaunee (i.e.,1.32E6 cubic feet), the Kewaunee containment ventilation system designs are not the same. During refueling operations, the Kewaunee containment ventilation system is generally operated in the vent mode with a supply and discharge of approximately 33,000 scfm. Unlike the Prairie Island design, both the supply and discharge lines have redundant containment isolation valves. The redundant valves are actuated by a Train A or B containment vent isolation signal initiated by a high radiation signal from the Tmin A or B mdiation monitor mspectively. Therefore following the postulated activity micase from a fuel handling accident, the ventilation system isolates and provides no motive force for a release through an open personnel airlock. Since the isolation is redundant and therefore satisfying single failure criterion, WPSC concluded it was not reasonable to assume a continued ,

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Document Control Desk s August 24,1998

. Page 2 release at this large value through this ventilation pathway. However to provide an assessment, WPSC assumed a rather ubitrary and conservative release rate of 6000 scfm. In addition, only lE6 cubic feet was credited for mixing in the containment. Using the previously accepted NRC methodology, this results in a mixing factor of 0.5 for a two hour release.

If you have any questions concerning this information, please contact me or a member of my staff.

Sincerely,

>1t M Mark L. Marchi Site Vice President-Kewaunee Plant RPP cc - US NRC Region III US NRC Senior Resident Inspector Ob%l Cl % >APPN llMAILil% BOY kPL 1.H*.RMPtAMD'I t rh WPD

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