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

{{Adams
| number = ML20148B996
| issue date = 01/18/1980
| title = Forwards LER 79-036/03L-0
| author name = Opeka J
| author affiliation = NORTHEAST UTILITIES
| addressee name = Grier B
| addressee affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION I)
| docket = 05000245
| license number = 
| contact person = 
| document report number = MP-1-1398, NUDOCS 8001240441
| package number = ML20148C000
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 2
}}
{{LER
| Title = Forwards LER 79-036/03L-0
| Plant = 
| Reporting criterion = 
| Power level = 
| Mode = 
| Docket = 05000245
| LER year = 2079
| LER number = 36
| LER revision = 
| Event date = 
| Report date = 
| ENS = 
| abstract = 
}}

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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.                                                                       j l
Yours truly,                                 a j
h     -~
                                                                . F. Opeka k
j Station Superintendent liillstone fluclear Power Station JF0/RHY/lls 1
Attachnent:          (LERR0-79-36/3L)                                                        l 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                                    {
                                                   . MILLSTONE NUCLEAR POWER STATION - UtlIT 1                                l PROVISIONAL LICEllSE flVMBER - DPR-21                                 ;
DOCKET NUMBER 50-245                                        i IDENTIFICATION OF OCCURRENCE                                                                              [
Operation in a degraded mode permitted by a limiting condition for operation occurred when the Isolation Condenser System was removed                                          .
l 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 hours, 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.                                                              P I
DESIGtlATI0fl 0F APPARENT CAUSE After investigation, it was detemined that the water hammer was                                          I 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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