ML17054B438

Advises That Util Conceptual Design for Manual Inhibit Switch for Automatic Depressurization Sys Logic (Identified as Part of Review of TMI Item II.K.3.18) Acceptable

ML17054B438
Person / Time
Site:	Nine Mile Point
Issue date:	02/13/1985
From:	Vassallo D Office of Nuclear Reactor Regulation
To:	Hooten B NIAGARA MOHAWK POWER CORP.
References
TASK-2.K.3.18, TASK-TM NUDOCS 8503050063
Download: ML17054B438 (4)

Text

Docket No. 50-220

Dear Mr. Hooten:

February'3, '1985 J

Mr. B. G. Hooten Executive Director, Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 I;

2 y

-t j'UBJECT:

SAFETY EVALUATION, ADS INHIBIT SWITCH Re:

Nine Mile Point Nuclear Station, Unit No.

1 As a part of the review of TMI Item II.K.3.18, an adjunctive issue regarding the need for a manual inhibit switch for the Automatic Depressurization System logic was identified.

In a letter dated November 27, 1984, you indicated your intent to install a manually operated inhibit switch in the Automatic Depressurization System (ADS) logic circuitry.

The purpose of the switch is to facilitate operator response in accordance with the BWR Emergency Procedures Guidelines during various events.

For certain LOCA or ATWS conditions it is advisable or necessary to maintain water level below the ADS initiation level but above the top of the active fuel while the vessel is at high pressure.

With the current logic design (i.e.,

no manual inhibit) it is necessary for the operator to reset the ADS logic every two minutes to avoid system blowdown.

Incorporation of the inhibit switch will permit the operator to block premature blowdown with a single action.

We have reviewed your conceptual design and conclude it is acceptable.

Sincerely, Original signed by/

cc:

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Mr. B. G. Hooten Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station, Unit No.

1 CC:

Troy B. Conner, Jr., Esquire Conner 5 Wetterhahn Suite 1050 1747 Pennsylvania

Avenue, N.

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Washington, D. C.

20006 Frank R. Church, Supervisor Town of Scriba R.

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Oswego, New York 13126 Niagara Mohawk Power Corporation ATTN:

Mr. Thomas Perkins Plant Superintendent Nine Mile Point Nuclear Station Post Office Box 32

Lycoming, New York 13093 Resident Inspector U. S. Nuclear Regulatory Commission Post Office Box 126

Lycoming, New York 13093 John W. Keib, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 Thomas A. Murley Regional Administrator Region I Office U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 Mr. Jay Dunkleberger Division of Policy Analysis and Planning New York State Energy Office Agency Building 2 Empire State Plaza

Albany, New York 12223