ML20099C194

Ro:On 840614,due to Series of Extremely Heavy Rains in Areas Upstream of Plant,Flood Control Actions Initiated Per Emergency Procedure 5.1.3.Deescalation from Unusual Event Classification Ordered on 840621

ML20099C194
Person / Time
Site:	Cooper
Issue date:	06/22/1984
From:	Thomason P NEBRASKA PUBLIC POWER DISTRICT
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
CNSS840269, NUDOCS 8411190430
Download: ML20099C194 (2)

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COOPER NUCLEAR STATION Nebraska Public Power District "" " * "A"E,

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JN2SEM J N Mr. John T. Collins, Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Dear Mr. Collins:

This event summary is submitted in accordance with NUREG 0654, Appendix 1 and CNS Emergency Plan Implementing Procedure (EPIP) 5.7.2 to close out the Notification of Unusual Event declared at 0618, June 15, 1984.

Due to a series of extremely heavy rains in the areas upstream of Cooper Nuclear Station (CNS), the Missouri River started to rise. At approximately 0300, June 14, 1984, the river level reached 895' (MSL) at the Intake Structure. Flood control actions were initiated in accordance with CNS Emergency Procedure 5.1.3. Hourly river level measurements were also initiated at this time. River level measurements were increased to twice hourly at 1215. Primary flood barrier installation was completed at 1945, June 14, 1984.

At approximately 0615, June 15, 1984, the Missouri River level at the Intake Structure had risen to 897' (MSL). A Notification of Unusual Event was declared at 0618 based on Initiating Condition 12.1 of CNS EPIP 5.7.1.

Appropriate notifications were initiated in accordance with EPIP 5.7.6 and were completed by 0634. Installation of secondary flood barriers commenced at this time also and was completed at 2100, June 15, 1984.

Contact with the National Weather Service Bureau was maintained on a four hour frequency in order to keep abreast of flood conditions upstream and projected crest heights. The river continued to rise throughout the day with a crest height of 897'11" (MSL) marked at 2315, June 15, 1984.

Although the river level did drop below the 897' (MSL) mark at 0800, June 17, 1984, deescalation was not initiated due to the National Weather Service Bureau forecast that called for the river level to rise again. The river did indeed rise, reaching a crest height of 897'6" (MSL) at 1730, June 19, 1984. j 8411190430 840622 / 0 ( pl/

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.3 '*~ *Mr. Jchn T. Collins Junn 22, 1984

. Page 2 On June 21, 1984 the river level dropped below the 897' (MSL) mark at 0500.

Forecasts from the National Weather Service Bureau later that morning indicated the river would continue to drop. Deescalation from the Notification of Unusual Event classification was ordered by the Emergency Director at 1300 June 21,1984. Closeout notifications were initiated in accordance with CNS EPIP 5.7.2 and 5.7.6. .These notifications were completed by 1318.

CNS,0perations personnel will continue to monitor the^ river level at the Intake Structure on a four hour frequency. This action will remain in effect until the river level drops below 895' (MSL).

Sincerely, W

P. V. Thomason Division Manager of Nuclear Operations ,

PVT:PRW:lb cc: L. G. Kuncl 1

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