ML20126C208

Requests Technical Assistance Re Util Proposed Change to TS to Permit Permit Installation of New Containment Isolation Valve as Part of Proposed Nitrogen Recirculation Sys

ML20126C208
Person / Time
Site:	Monticello
Issue date:	03/17/1976
From:	Ziemann D Office of Nuclear Reactor Regulation
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
NUDOCS 9212220421
Download: ML20126C208 (2)

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MAR 17 B76

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! D. G. Eisenhut, Assistant Director for Operational Technology, DOR I

TECHNICAL ASSISTANCE REQUEST NO. ORB-2-220 Your assistance is requested in the following:

PLANT NAME: Monticcl(o DOCKET NO.: 50-263 BRANCH CODE: ORB-2

\ PROJECT MANAGER: R. P. Snaider (ext. 27403)

\ OPERATIONAL TEGINOLOGY BRANOI: Plant Systens Branch REQUESTED COMPLETION DATE: March 29, 1976 BACKGROUND: By letter dated March 1, 1976, Northern States Power Company (NSP) agreed to initiate measures to maintain a 1 psi drywell-torus differential pressure as an interim means of regaining torus safety margins. Such measures, commenced after plant startup and presently in effect, incorporate the intermittent discharge of nitrogen into the drywell, and i the venting of the torus, as necessary to maintain the required Ap, to the Standby l

Gas Treatment System to remove nitrogen which l

' has bled through vacuum breakers into the torus. This procedure, although effective,

' requires excessive usage of nitrogen and places an additional burden upon the !! EPA filters and charcoal adsorbers of the Standby Gas Treatment System.

DESCRIPTION OF REQUEST: By letter dated March 11, 1976, a copy of which is attached, NSP has proposed a change to the Technical Specifications to permit the installation of a new containment isolation valve as part of their proposed nitrogen recirculation system. This system will return nitrogen from the torus to the drywell, minimizing nitrogen usage and enhancing the capability to maintain a differential pressure. The submittal nust be reviewed to determine systen safety, isolability, and ability to function without affecting the operation of safety-related I systems.

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MAR 171976 D. G. Eisenhut . The March 11,-1976 NSP submittal contains revised pages to replace those of the January 30, 1976 initial Appendix J submittal

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(refer to TAR' ORB-2-213). These revised

, pages reflect the addition of the No recirculs-l tion system. _These need not be revlewed as part of this request, but they should be included in the review associated with TAR ORB-2-213.

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Requested Action

1. Review the NSP March 11, 1976 submittal

, and determine mechanical adequacy, noting that the containment penetrations

already exist, and using the information

, of the Safety Evaluation' on pages 2 and ,

{ j 3 of Exhibit A. ,

i 2. Determine adequacy of the electrical y isolability of the new valve, referring to page 5 of dxhibit A.

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3. Incorporate review of revised pages 153, IS4H, and 154J into the review

! of TAR ORB-2-213, i

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4. Provide a written safety evaluation report concerning items 1 and 2 above.

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! Prompt review of this matter is requested consistent with Mr. Rusche's letter of February'27, 1976 to NSP.

Mip6a1 signed by Dennis L 7.iethnnn -

' Dennis L. Ziemann,_ Chief Operating Reactors Branch 82 Division of Operating Renetors i

Enclosure:

DISTRIBUTION:

NSP 3/11/76 Submittal Docket ORB-2 Reading cc: V. Stello DLZiemann K. R. Goller R. P. Snaider-R. Diggs ,

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