ML20127G425

Ro:On 730525,low Boron Concentration in Standby Liquid Control Sys Found to Be Below That Required by TS 3.4.C. Chemicals Added to Bring Tank Solution Concentration within Ts.Listed Procedural Changes Being Implemented

ML20127G425
Person / Time
Site:	Monticello
Issue date:	06/04/1973
From:	Mayer L NORTHERN STATES POWER CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9211160595
Download: ML20127G425 (2)

Text

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%g he Tebhat0G NORTHERN N S1p 5 TATE 8 POWER COMPANY f44 M I N N E A Po t.i t, M I N N E s oT A 58401

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k;9ff({({, [ s Mr. J F O' Leary, Director ro Directorate of Licensing g

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United States Atomic Energy Commission ,<b p $ g /S/k ~h SE e Washington, D C 20545 N ( $

Dear Mr. O' Leary:

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MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Low Boron Concentration in Standby Liquid Control System A condition occurred at Monticello Nuclear Generating Plant which we are reporting to your office in accordance with Section 6.7.B.1, Abnormal Occur-rence Reports, of the Technical Specifications, of Provisional Operating License DPR-22.

At 0030 on May 25, 1973, the Standby Liquid Control System sodium pentaborate concentration was measured following an addition of water to the tank. The concentration was found to be below tht: required by Technical Specification 3.4.C.

On May 24, 1973 an addition of water to the liquid poison tank was authorized without an addition of boron chemicals. The liquid poison concentration in the tank was not verified by measurement prior to the authorized addition of water.

This addition of water was based on a liquid poison concentration which had been measured on May 12, 1973 prior to, o an addition of water to the tank on that day instead of the measurement subsequent n the May 12, 1973 water addition.

As a result, the sodium pentaborate concentration dropped to 11.1% on May 25 for a tank volume of 2820 gallons. This concentration was below the minimum concentration allowed by Technical Specification 3.4.C.

Chemicals were added to bring the tank solution concentration within Technical Specification 3.4.C. The resultant concentration was 11.7% at a volume of 2820 gallons.

The following procedural changes are being impicmented:

1. The liquid poison tank concentration will be measured within a twelve hour period prior to the addition of chemicals and/or water. (the tank concentration will continue to be determined following the addi-tion of chemicals or water.)

9211160595 730604 PDR ADOCK 05000263 dnGy S PDR

NOR'. ERN CTATED POWER CO 'ANY Mr. J F O' Leary June 4, 1973

2. Additions to the poison tank will be made with the approval of the Operations Supervisor and the Plant Chemist.

3. All additions to the liquid poison tank will be specified and documented on a written form.

The above mentioned procedural changes will eliminate occurrences of this nature in the future. The cause of this occurrence is not related to any previous malfunction. There are no similar systems which could be affected by a si2ailar occurrence.

Yours very truly,

. O.

L 0 Mayer, PE Director of Nuclear Support Services LOM/br cc: B H Grier o Charnoff Minnesota Pollution Control Agency Attn. Ken Dzugan i

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