ML20010H735

Forwards LER 81-039/03L-0.Detailed Event Analysis Encl

ML20010H735
Person / Time
Site:	Oyster Creek
Issue date:	09/18/1981
From:	Carroll J JERSEY CENTRAL POWER & LIGHT CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010H736	List: ML20010H735 ML20010H737
References
NUDOCS 8109290245
Download: ML20010H735 (3)

Text

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OYSTER CREEK 07 NUCLEAR GENERATING STATION L)$ {{-- [[,y , (609)693-6000 P O. BOX 388

• FORKED RIVER e NEW JERSEY
• 08731 Septmber 18, 1981

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Q;)' i{flfh%g Mr. Ronald Haynes, Director [[' y( Office of Inspection and Enforcemnt /S ,/ (U( y Region I

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United States Nuclear Regulatory Cannission SEP*>O /Sg 4 631 Park Avenue gy i g ' % gWg g King of Prussia, Pennsylvania, 19406 Q 9[A

Dear Mr. Haynes:

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SUBJECT:

Oyster Creek Nuclear Generating Station Docket No. 50-219 Licensee Event Report Reportable Occurrence No. 50-219/81-39/3L This letter forwards three copies of a Licensee Event Report to report Reportable Occurrence No. 50-219/81-39/3L in empliance with paragraIt 6.9.2.b.4 of the Technical Specifications. Very truly yours, bJ

                                                    . T. Carroll, J ff[.

l cting Director ter Creek JIC:dh Enclosures cc: Director (40 copies) Office of Inspection and Enforcment United States Nuclear Regulatory Camiission Wash W _on, D.C. 20555 Director (3) Office of Managemnt Informaticn and Program Control United States Nuclear Regulatory Comtission Washington, D. C. 20555 NRC Resident Inspector (1) Oyster Creek Nuclear Generating Station Forked River, N. J. [// 8109290245 81091g gDRADOCK 05000219 PDR

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                                                      . REEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/81-39/3L Report Date Septeuber 18, 1981 Occurrence Date August 19,1981 (Discovery of occurrence)

Identification of Occurrence An unmonitored release of radioactive water due to Reactor Building Closed Cooling Water Heat Exchanger failure. This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9.2.b.4. Conditions Prior to Occ.urrence The plant operated.throtx3h a full range of operating conditions during the occurrence. Just prior to discovery of the occurrence the plant was in a i shutdown condition. Description of Occurren On August 11, 1981 a flow integrator was installed on the autcrnatic demineralized water makeup systen to che Reactor Anilding Closed Cooling Water (RBOCW) Surge Tank. After installation and calibration it was discovered that a 4.3 gpn leak existed scrnewhere in the RBCCN systen. Due to heat load on the RBOCW systen two punp and two heat exchanger operation was necessary and no atterpt was made to isolate the heat exchangers. I On August 14, 1981 a plant shutdown was ccmunenccd and on August 19 with the l plant in the cold ccodition (<2120 ) and F decay heat diminished, the West RBOCW heat exchanger was isolated. Upon isolation the RBCCN makeup rate was reduced fran 4.3 gpn to .5 gallons per hour indicating that the leak was stopped. l The heat exchanger reaimv1 isolated arx1 the systen was in a two ptunp and one l heat exchanger mode until approximately 4:00 A.M. on August 23, 1981. At this ( time an attenpt was made to operate in the one ptmp one heat exchanger mode. When an RBCCW punp was renoved fran service, discharge pressure on the other ptmp dropped to less than 90 psig, the minimum required by procedure. %e second ptmp was restarted with its discharge valve open and the heat exchanger i flow bypass valve essent ially closed. We starting of the second prnp caused i tube vibration in the east heat exchanger that was heard by th operaor. Shortly after restarting the second ptmp the RBOCW surge tank low level alarm was annunciated, indicating a larger leak in the east heat exchanger to the service water systen. The west RBOCW heat exchanger was placed in service and the east isolated. The west heat exchanger renained in service until approxi-mately 1320 on August 26 until the east heat exchanger was repaired by tube plugging and placed in service.

o Reportable Occurrence Page 2 Report No. 50-219/81-39/3L Apparent Cause of Occurrence The cause of the tube leaks appears to be tube vibration resulting from inadegaate procedures. Analysis of Occurrence In January 1981 in response to a 'IMI Iessons Learned requirenent the danineral-ized water makeup to the RBOCW Surge Tank was placed in autanatic operation. This mode of operation had not been used for many years of plant operation. When placed in autanatic operation there was no indication of heat exchanger tube leakage, however, for the purpcse of analysis it is assumed that the 4.3 gpn leak rate existed fran January 1,1981 to August 26, 1981.

   .Fran weekly analyses of the RBCCW Systen minimum, maximum and average isotopic concentrations were developed.

Time Period Mininun Average Maximum Concentration Concentration Concentration 12-26-80 to 4.35E-6 pCi/ml 1.15E-4 pCi/ml 1.34E-3 pCi/ml 9-10-81 With a 4 gpn leak into a mininun of 6000 gpn service water flow a dilution factor of 7.0E-4 is applied to the average to give a concentrat%n of 8.05E-8pci/ml at the point of discharge. An additional circulating water flow of 460,000 gpn gives a concentration of 1.8E-13pci/ml in the discnarge canal which is well below the allowable concentration for radioactive effloent discharge. Based on the above, the consequence of this event is considered minimal. O rrective Action Inmediate corrective action consisted of isolating the heat exchanger with major leakage and after its repair isolating the heat exhanger with the smaller leak. Both heat exchangers were repured by plugging leaking tubes and those inmediately surrounding the leaking tubes. In order to prevent recurrence the procedures governing RBCCW and Service Water System operation are being reviewed and revised as ne'ssary to ensure future tube bundle vibration does not occur. To prevent any possible long term un-detected leakage the newly installed integrator is being used. In addition, an engineering evaluation regarding tube replacement is being conducted to determine if and when the tube bundles should possibly be replaced.}}