05000312/LER-1981-020, Forwards LER 81-020/04T-0 & Submits Detailed Event Analysis

Forwards LER 81-020/04T-0 & Submits Detailed Event Analysis

ML20003F791
Person / Time
Site:	Rancho Seco
Issue date:	04/14/1981
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20003F792	List: 05000312/LER-1981-020, Forwards LER 81-020/04T-0 & Submits Detailed Event Analysis 05000312/LER-1981-020-04, /04T-0:on 810326,liquid Effluent Ph Exceeded 8.5 Tech Spec Limit for Approx 15 Minutes.Caused by Retention Basin Being Released Prior to Increasing Dilution Water Flow.Effluent Ph Instrumentation Calibr & Monitored
References
NUDOCS 8104230600
Download: ML20003F791 (2)

LER-1981-020, Forwards LER 81-020/04T-0 & Submits Detailed Event Analysis

Event date:
Report date:
3121981020R00 - NRC Website

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$SMUD SACRAMENTO VUNIC: PAL UTILITY DISTRICT C' 62:1 S Street. Bem !!a30. Sacran ento. Cahf:rnia 98.J13. 016)

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OPERATING LICENSE OPR-54 DOCKET NO. 50-312 REPORTABLE OCCURRENCE 81-20 In accordance with Technical Scecifications for Rancho Seco Nuclear Generating Station, Appendix B, Section 5.6.2c, the Sacramento Municipal Utility District hereby submits the following written report concerning an unusual Event which was reported to Mr. H. Canter, resident NRC Inspector, on Acril 7, 1981.

A monthly review of plant effluent charts indicated that on March 26, 1981, the Technical Specifications limit for plant effluent pH was exceeded.

Technical Specifications, Appendix B, Section 2.4 limits the effluent pH to a minimum 6.5 and maximum 3.5 On the date of the occurrence the effluent chart indicated a momentary increase to 8.7 Within 15 minutes the effluent pH had again dropped to below 3.5 The momentary rise in effluent pH occurred simultaneously with the initiation of a retention basin release. No rma l l y, to preclude a momen-tary pH spike, the dilution water flow rate is set prior to initiating the basin release.

Discussions with cperations cersonnel revealed that en tnis particular occassion the release was initiated prior to increasing the dilution water flow. This operational error centributed, in part, to possibly having exceeded the Technical Specification limits.

Whether or not the limit was actually exceeded is questionable.

The pH of the retention basin prior to release was easured at 3.55 Even without any dilut*cn water the maximum effluent pH would not have reached the recorded value of 3.7 Additionally, nine days after this occurrence the effluent pH monitor started to record cutlet pH values ranging from 3.6 to 9.0.

At the same time local meters indicated pH values in the 3.1 to S.3 range, and a grab sample indicated a pH value of S.2.

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R. H. Engelken April 14, 1981 calibration of the pH instrumentation revealed.that the outlet pH was

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recording between 0.3 and 0.4 pH units high.

this time the occurrence has been attributed to a combination of Atoperator error and instrumentation error. The Operations Supervisor is informing all operating personnel of this occurrence and emphasizing the necessity of establishing dilution water flow prior to initiating a retention basin release. The effluent pH instrumentation has been calibrated and is presently being closely monitored to determine the-error band and amount of instrument drift associated with the equipment.

There were no plant transients nor power reductions associated with this event.

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John

. Mattimoe

[ OAssistant General Manager d Chief Eng8 neer ISE Washington (30) cc:

MIPC (3)

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