05000219/LER-1982-048, Forwards LER 82-048/03L-0.Detailed Event Analysis Encl

Forwards LER 82-048/03L-0.Detailed Event Analysis Encl

ML20063N805
Person / Time
Site:	Oyster Creek
Issue date:	09/27/1982
From:	Fiedler P GENERAL PUBLIC UTILITIES CORP.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20063N806	List: 05000219/LER-1982-048, Forwards LER 82-048/03L-0.Detailed Event Analysis Encl
References
NUDOCS 8210070238
Download: ML20063N805 (3)

LER-2082-048, Forwards LER 82-048/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2192082048R00 - NRC Website

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' g g{ P.O. Box 388 Forked River, New Jersey 08731 609-693-6000 Writer's Direct Dial Number.

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September 27, 1982 i

Mr. Ronald C, Haynes, Administrator l Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

Dear Mr. Haynes:

Subj ect: Oyster Creek Nuclear Generating Station Docket No. 50-219 Licensee Event Report Reportable Occurrence No. 50-219/82-48/03L This letter forwards three copies of a Licensee Event Report to report Reportable Occurrence No. 50-219/82-48/03L in compliance with paragraph 6 9 2.b(2) of the Technical Specifications.

Very truly yours, E

Peter B. Fiedler Vice President and Director Oyster Creek PBF:1se Enclosures cc: Director (40 copies)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Director (3)

Office of Management Information and Program Control

. U.S. Nuclear Regulatory Commission  :

Washington, D.C. 20555 NRC Resident Inspector .

Oyster Creek Nuclear Generating Station Forked River, NJ 08731

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OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occura nce No. 50-219/82-48/03L .

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Report Date -

Sept' ember 27, 1982 Occurnnce Date August 26, 1982 Identification of Occurrence Violation of Technical Specification 31. A, when the reactor water level instrumentation for one channel in each Reactor Protection System and one channel in each of several safety systems were rendered inoperable as a result of the loss of reference column head.

This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6 9 2.b(2).

Conditions Prior to Occurrence The plant was shutdown with the reactor vessel vented. Reactor coolant temperature was being maintained at less than 2120F.

Description of Occurrence On August 28,1982 at 4:30 AM, a ten inch reactor water level error was entered into the shutdown logs. Approximately four hours later, the instmment error increased another ten inches which represented 100% of full scale or vessel high water level. All other level instrumentation indicated normal reactor water level. At 2:30 PM, the instrument reference leg was back-filled to correct the level error. A close observation of four sensors was maintained for a day and one half with no evidence of level error. Valve alignment was checked with attention given to the bypass valves; local piping was also observed for leakage, but none was evident.

A calculation was performed to determine the leak rate required to reduce the reference leg by approximately twenty-one and three quarter inches (21-3/4") .

Assuming ten inches (10") or 27.7 cc of water was lost in four hours (taken from log readings) from the reference leg piping, the leak rate would be .12 cc/ min. The volume of the constant head chamber is 168 cc. To evacuate this chaniber at the constant rate of .12 cc/ min. or 2 3 drops / min would take 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 15 minutes. It would take 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to drain 20 inches of sreference leg piping and an additional 116 hours0.00134 days <br />0.0322 hours <br />1.917989e-4 weeks <br />4.4138e-5 months <br /> and 15 minutes to drain i:he constant head neerve chamber, for a total of 148 hours0.00171 days <br />0.0411 hours <br />2.44709e-4 weeks <br />5.6314e-5 months <br /> and 30 minutes to reach the as-found level. A review of various 1cge indicated that no maintenance or surveillance tests had been performed on the sensors or piping in question during this time. The last surveillance test was performed on August 6,1982, nine days prior to plant shutdown, and nineteen days prior to the error event.

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Licensee Event Report Page 2 Reportable Occurrence No. 50-219/82-48/03L It abould be noted that there are no piping connections with other,' systems and the ,affected water level reference leg. This was confirmed, at an' earlier date, by a hand over hand walkdown of the instrument sensor piping, Apparent Cause of Occurrence The cause of the erroneous vessel water level reading was a decrease in reference leg head.

Analysis of Occurrence The reactor water level instruments in question provide various reactor .

protection and safety system functions associated with nactor scram, core spray initiation, isolation condenser initiation and ATWS recirculation pump trip. Redundant instrumentation, which was operable, also provides these functions; and, since the Reactor was shutdown, vented and reactor coolant was less than 2120F, the safety significance of this event is considend minimal.

During power operation, steam condensing in the constant head chamber provides continuous make-up to the reference leg thereby preventing erroneous high readings. Additionally, it should be noted that no change in actual reactor ,

water level occurred as a result of this event.

Corrective Action The reference leg for the affected level instruments was backfilled which restored it to an operable condition. As stated above, in response to a similar incident, a hand over hand walkdown of the reference leg piping for ,'

proper configuration together with a check of the instrumentation connected to the reference leg was performed with no abnormalities noted. A program will be developed in an attempt to determine the cause for the loss of reference leg. >

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