05000298/LER-1982-007, Forwards LER 82-007/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-007/03L-0.Detailed Event Analysis Submitted

ML20052B399
Person / Time
Site:	Cooper
Issue date:	04/22/1982
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20052B400	List: 05000298/LER-1982-007, Forwards LER 82-007/03L-0.Detailed Event Analysis Submitted 05000298/LER-1982-007-03, /03L-0:on 820324,differential Pressure Between Drywell & Suppression Chamber Reduced Below Tech Spec Limits During RHR Test Mode Operation.Caused by Nitrogen Flow from Drywell to Suppression Chamber.Return Piping to Be Modif
References
CNSS820211, NUDOCS 8204300376
Download: ML20052B399 (2)

LER-1982-007, Forwards LER 82-007/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2981982007R00 - NRC Website

text

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CooPE R NUCLEAft STATION Nebraska Public Power District

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CNSS820211 April 22, 1982 bh j

t APR 26122 Mr. John T. Collins, Regional Administrator U.S. Nuclear Regulatory Commission g\\-

y Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 3.7.E.1 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on March 24, 1982.

A lice event report form is also enclosed, o

Report No.:

50-298-82-07 8

Report Date:

April 22, 1982 "3CE 'iD Occurrence Date: March 24, 1982 t'

APR 2 91992w I Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 5 c ry gg.g.

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fsy Identification of Occurrence:

s Condition leading to operation in a degraded mode permitte /bfg g,j '

i limiting condition for operation as delineated in Section 3.. Lo'f' the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at a steady state power level of approx-imately 87% of rated thermal power.

Description of Occurrence:

l While performing routine Surveillance Test Procedure 6.3.5.1, Residual lleat Removal (RIIR) Test Mode Operation, differential pressure between the drywell and the suppression chamber was re-duced to a value less than allowed by Technical Specifications.

Designation of Apparent Cause of Occurrence:

The drywell downcomer was uncovered resulting in nitrogen flow from 1

i the drywell to the suppression chamber and reduced differential pressure.

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8204300 3%

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Mr. John T. Collins April 22, 1982 Page 2.

Analysis of Occurrence:

During the conduct of S.P. 6.3.5.1, full RHR flow returning to the suppression chamber through the flow test line induced jet vel-ocities along the torus axis. The resultant flow wave uncovered the downcomer(s) allowing drywell pressure to partially vent to the torus. The differential pressure was reduced from 1.18 PSID to 0.95 PSID at 1046 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.98003e-4 months <br /> on March 24, 1982. The Technical Spec-ification limit is >1.0 PSID.

Differential pressure was restored to 1.33 PSID at 1144 hours0.0132 days <br />0.318 hours <br />0.00189 weeks <br />4.35292e-4 months <br /> on March 24, 1982.

Technical Spec-ifications 3.7.E.2 permits operation with reduced differential pressure up to six hours.

This occurrence presented no adverse consequences from the stand-point of public health and safety.

Corrective Action

During the Fby 1982 outage, the RHR test line return piping to the suppression chamber will be modified. The discharge from the piping will be directed down the side of the torus and away from any downcomer.

In the interim, insuring an adequate water level exists in the suppression chamber prior to performance of S.P.

6.3.5.1 prevents uncovering any downcomers and loss of differential pressure. A copy of this LER will be routed to all licensed personnel.

Sincerely, 4%,

L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.

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