05000245/LER-1979-036, Forwards LER 79-036/03L-0

Forwards LER 79-036/03L-0

ML20148B996
Person / Time
Site:	Millstone
Issue date:	01/18/1980
From:	Opeka J NORTHEAST UTILITIES
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20148C000	List: 05000245/LER-1979-036, Forwards LER 79-036/03L-0 05000245/LER-1979-036-03, /03L-0:on 791219,during Shutdown Following Reactor Scram,Water hammer-type Movement Detected in Isolation Condenser Piping.Caused by Introduction of Water Into Isolation Condenser Steam Supply Line.Instructions Revised
References
MP-1-1398, NUDOCS 8001240441
Download: ML20148B996 (2)

LER-1979-036, Forwards LER 79-036/03L-0

Event date:
Report date:
2451979036R00 - NRC Website

text

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t January 18, 1980 MP-1-l~398

!!r. Boyce H. Grier Director, Region I Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 j

Reference:

Provisional License DPR-21 Docket No. 50-245 Reportable Occiarrence R0-79-36/3L i

Dear !!r. Grier:

This letter forwards the Licensee Event Report for Reportable Occurrence R0-79-36/3L required to be submitted within 30 days pursuant to the requirements of the liillstone Unit 1 Technical Specifications, Section 6.9.1.

An additional three copies of the report are enclosed.

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Yours truly, a

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. F. Opeka j

Station Superintendent liillstone fluclear Power Station JF0/RHY/lls 1

Attachnent:

(LERR0-79-36/3L) cc:

Director, Office of Inspection and Enforcement, Washington, D.C.(30)

Director, Office of fianagement Infonnation and Progrca Control, Washington, D.C. (3) 90030261

ATTACNMENT TO LER 79-36/3L i

NORTilEAST NUCLEAR ENERGY COMPANY

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. MILLSTONE NUCLEAR POWER STATION - UtlIT 1 l

PROVISIONAL LICEllSE flVMBER - DPR-21 DOCKET NUMBER 50-245 i

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IDENTIFICATION OF OCCURRENCE Operation in a degraded mode permitted by a limiting condition for operation occurred when the Isolation Condenser System was removed from service.

CONDITI0flS PRIOR TO OCCURREi!CE i

i Prior to the occurrence, the unit was in the process of shutting down following a turbine trip induced reactor scram.

l DESCRIPTION OF OCCURRENCE On December 19,1979, at 1635 hours0.0189 days <br />0.454 hours <br />0.0027 weeks <br />6.221175e-4 months <br />, during a shutdown following a reactor scram, water hammer type movement was detected in the isolation condenser piping.

The Control Room Operator isolated the f

isolation condenser and the pipe motion terminated.

At that time system pressure was approximately 1010 psig.

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DESIGtlATI0fl 0F APPARENT CAUSE I

After investigation, it was detemined that the water hammer was caused from the introduction of water into the isolation condenser steam supply line. This was due to the fact that reactor vessel water level was maximized, as instructed, in order to minimize l

thermal cycling to the feedwater nozzles and to naintain naximum vessel water inventory based on TMI experience.

ANALYSIS OF OCCURRENCE The isolation condenser is provided for core decay heat removal following reactor isolation and scram.

Removing the isolation condenser from service at this time did not create a condition which had not been previously analyzed since the main steam isolation valves were reopened prior to the isolation condenser going out of service. Because of this, the main condenser was available and was used to control the unit cooldown.

An alter-nate method of cooling the core was available and could have been used had it been required.

CORRECTIVE ACTI0t{

The instruction to operations personnel regarding maintenance of maximum reactor vessel water level on a transient has been revised.

This occurrence is similar in nature to R0-78-7/3L.

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