ML20107C038
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.ersey Central Power & Light Company MADISON AVENUE AT PUNCH BOWL ROAD
- MORRISTOWN, N.J.07960
- 2015394111 asmane or rus General Public Utilities Corporation i
June 7, 1974 Mr. A. Giambusso Deputy Director for Reactor Projects Directorate of Licensing United States Atomic Energy Commission Washington, D. C. 20545
Dear Mr. Giambusso:
Subject:
Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/74/34 The purpose of this letter is to fom ard to you the attached Abnormal Occurrence Report in compliance with paragraph 6.6.2.a of the Technical Specifications.
Enclosed are forty copies of this submittal.
Very truly yours, L
D / E.L ^
Donald A. Ross Manager, Nuclear Generating Stations cs Enclosures cc:
Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I
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4 OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/34 Report Date June 7, 1974 Occurrence Date May 29, 1974 Identification of Occurrence Indications of coolant leakage existing in the area of an incore flux monitor reactor vessel housing located at core coordinate 28-05.
This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15E.
Conditions Prior to Occurrence The plant was shut down for refueling. The reactor was in the REFUEL mode during a hydrostatic test at 850 psig pressure and with coolant temperature approximately 155'F.
l Description of Occurrence On Tuesday, May 28, 1974, during a scheduled reactor vessel hydrostatic test to inspect the pressure boundary following refueling maintenance activities, leakage was observed in the vicinity of an incore flux monitor tube located at the bottom of the reactor vessel.
Further investigation conducted on Wednesday, May 29, 1974, showed evidence of possible leakage in the area of an incore flux monitor housing penetration located in the reactor vessel bottom head.
A second hydro-static test was conducted at a pressure of 850 psig at approximately 7:00 p.m.
on bby 29, 1974, whereupon, water was observed leaking between the monitor housing and the reactor vessel. The leakage was measured under the conditions of 850 psig with a temperature of 164*F, and calculated to be on the order of approximately 0.02 gallons per hour.
Apparent Cause of Occurrence The cause of this event has yet to be determined.
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Abnormal Occurrence No. 50-219/74/34 Page 2 Analysis of Occurrence As stated in FDSAR Amendment No. 37, a postulated failure of the flux monitor tube would result in vessel leakage at a rate which would not cause excessive cladding temperatures and for which core reflooding is possible by engineered safety features. This situation is less severe than the design basis accident.
To determine the consequences of a weld failure at a housing for an incore monitor tube, it is assumed that the weld. between the housing and the reactor vessel bottom head fails, allowing the housing and the incore monitor tube to be ejected from the vessel. The hole provided in the bottom head for the housing has a diameter of two inches.
This is the asrumed break size.
The hole has a break area of.0218 ft2 Assuming worst conditions, this results in peak clad temperatures less than 1000*F, as updated in FDSAR Amendment No. 67. This value is well within acceptable limits of the applicable ECCS criteria.
gprrective~ Action An inspection progran was developed by the plant staff and ^ Jersey Central i )wer 5 Light Company management and concurred with by the nuclear steam supply system vendor, the resctor vessel manufacturer, and an engineering consulting firm.
The program 1.o examine the incore flux monitor tube from below the reactor vessel is as follows:
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Visual inspection with a borescope j
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Leak test with helium using a mass-spectrometer 3.
UT inspection 4.
Pressure test of the reactor vessel 5.
Chemical and physical analyses of the water in the tube, the crud in the tube, and the buildup around the tube.
In addition, an eddy current inspection was later added to this program to be performed following the UT inspection.
Recommendations for repair will be forthcoming pending a complete review and evaluation of the results of this program by the Plant Operations Review Committee.
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