ML19224D805

Forwards LER 79-013/03L-0

ML19224D805
Person / Time
Site:	Cooper
Issue date:	05/30/1979
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19224D806	List: ML19224D805 ML19224D808
References
CNSS790271, NUDOCS 7907170063
Download: ML19224D805 (2)

Text

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COOPER NUCLE AR 5TATioN P.O. Box 98. B ROWNVf LLE, NEB R ASK/ 1321 Nebraska Publ.ic Power D.

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CNSS790271 May 30, 19/s Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1.000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Station and' discusses a reportable occurrence that was discovered on May 8, 1979. A licensee event report form is also enclosed.

Report No.: 50-298-79-13 Report Date: May 30, 1979 Occurrence Date: May 8, 1979 ,

Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Zdentificit;nn t' Occurrence:

A condition leading to operation in a degraded mode pernitted by a limiting condition for operation established in Section 3.7 E.1.a of the Technical Specificaticns.

Conditions Prior to Occurrence:

The reactor was in the "Run" mode at 672 MWt. '

Description of Occurrence:

Technical Specification Section 3.7.E.1.a was not met, in that differential pressure between the drywell and suppression chanber of

> 1.47 psid was established in 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> 52 minutes and not within the required 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> of achieving operating temperature and pressur2.

Designation of Apparent Cause of Occurrence:

Ihe cause of the failure to establish drywell to suppression chamber 2P 2 1.47 psid has been attributed a valve PC-236 AV, drywell inlet purge shutoff, leaking excessively.

15 l

3% 343 7907170063 S

Mr. K. V. Seyfrit May 30, 1979 Fage 2.

Analysis of Occurrence:

The maintenance of the drywell to suppression chamber AP of 1.47 psid with a suppression chamber water level corresponding to a downcomer submergence range of four to five feet will assure the integrity of the suppression chamber when subjected to post-LOCA suppression pool hydrodynamic forces.

The drywell to suppression chamber AP was > 1.15 psid within the 26 hour3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> period following achieving opet, ting temperature and pressure, and increasing. The leakage of nitrogea through PC-236 AV to the inlet purge line prevented the nitrcgen purge from preresurizing the drywell prior to establishing the AP.

This occurrence presented minimal potential consequences from the standpoint of public health and safety.

Corrective Action:

The valve lineup for purging the drywall and suppression chamber with nitrogen and establishing the required drywell to suppression chamber SP was temporarily changed to use the ACAD System.

PC-236 AV was removed, repaired, leak tested and reinstalled. The nitrogen purging and drywell to torus LP systems were returned to normal lineup.

This occurrence has been discussed with the personnel involved and a copy of the nonconformance report has been routed to all licensed personnel.

Sincerely, L. C. Lessor Station Superintendent Ccoper Nuclear Station LCL:cg Attach.

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