05000219/LER-1982-016, Forwards LER 82-016/03L-0.Detailed Event Analysis Encl

Forwards LER 82-016/03L-0.Detailed Event Analysis Encl

ML20062D101
Person / Time
Site:	Oyster Creek
Issue date:	07/14/1982
From:	Fiedler P GENERAL PUBLIC UTILITIES CORP.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20062D103	List: 05000219/LER-1982-016, Forwards LER 82-016/03L-0.Detailed Event Analysis Encl 05000219/LER-1982-016-03, /03L-0:on 820611,during Transfer of Spent Resin, Svc Air Piping Became Cross Contaminated W/Water,Resulting in Three Leaks to Environ.Caused by Blocked Vent Lines on Tank.Affected Sys Isolated
References
NUDOCS 8208050453
Download: ML20062D101 (5)

LER-1982-016, Forwards LER 82-016/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2191982016R00 - NRC Website

text

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,#1 GPU Nuclear g

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

July 14, 1982 Mr. Ronald C. Haynes, Administrator 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. 50-219/82-16/03L This letter forwards three copies of a Licensee Event Repert to report Reportable Occurrence No. 50-219/82-16/03L in compliance with paragraph 6.9 2.b.4 of the Technical Specifications.

Very truly yours, MM Peter B. Fiedler Vice President and Director Oyster Creek PBP: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 huclear Generating Station Forked River, NJ 08731 GPU Nuclear is a part of the General Pubhc Uhhties System

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OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/82-16/03L Report Date July 14, 1982 Occurrence Date June 11,1982 Identification of Occurrence An unmonitored release of radioactive water occurred due to contamination of service air piping in the New Radwaste Building. In one instance the leakage j

was to the discharge canal via the drainage system, and in two other instances, the leakage was to the soil.

This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9.2.b 4.

Conditions Prior to Occurrence 1

The plant was at s teady s tate operation.

Power Levels:

Reactor 1621 MWt Generator 540 MWe Mode Switch Run Description of Occurrence On Friday, June 11, 1982 at approximately 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, New Radwaste Operations personnel were preparing to transfer spent resins from the storage tank into a shipping cask.

Prior to the actual resin transfer operation, the tank was filled with condensate water to create a slurry and was then mixed using air at approximately 30 psig. With the air still mixing the tank contents, condensate water was used to backflush the resin transfer line into the tank.

It was during this backflush that the vent line became plugged, (attributed to a blinded resin screen on the vent) which resulted in pressurizing the tank from the condensate transfer system. Water was forced back into the air line, through the pressure regulator and the in-line check valve (condensate water pressure at the tank is greater than air system pressure).

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Licensee Event Report Page 2 Reportable Occurrence No. 50-219/82-16 /03L The first evidence of a problem was when the backflush line pressure did not decrease as expected. Further indications received later were an area high radiation alarm near the air receiver tank, and the discovery of radioactive fluid leaking from a moisture trap in the air line.

The resin tank was isolated and all necessary safety and radiological concerns were promptly addressed.

During the investigation into the extent of the problem, a leaking hose connection in an air line outside of the New Radwaste Building was d iscovered. Total leakage to the soil was estimated at approximately 10 m1, with a gross radioactivity of 0.62 microcuries.

The air system geometry is such that most of the contaminated water remained in the bottom of the air receiver tank (thus preventing the accumulation in the air compressor and after cooler from becoming contaminated). The air receiver

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is automatically blown down through a drain line which has a filter and a trap l

in the line. The available data suggests this feature was inoperable at the time of this event.

During the primary decontamination of the air receiver, it was flushed with water several times via an alternate route utilizing a bypass around the filter / trap assembly.

. It was realized on June 21, 1982, that the drain line from the air receiver leads to the storm drain which discharges directly to the discharge canal.

It was estimated that a total of approximately 300 gallons.was discharged, with gro:: radioactivity of 6.21 E-2 microcuries/ml. This correlates to a total of 0.0705 curies.

Upon discovery of this event, the affected catch baains, storm drains, and the air receiver drain line were isolated.

During the secondary decontamination of the air receiver using a hydrolazer, l

water (less than 5 gallons) leaked to the soil outside the building.

l Approximately 30 ft of soil (3 f t. x 10 f t. x 1 f t. deep) was collected and sampled; based on the sample results, all of the soil was returned to the original area.

Apparent Cause of Occurrence The cause of the event was attributed to a blocked vent line from the spent resin tank.

Since the resin-water mixture level in the tank was above the level of the screen on the vent line, the air pressure in the tank apparently trapped enough resins against the screen to prevent the venting of the tank.

The vent valve in the line was checked af ter the event, and both the remote valve indication and valve operation checked out satisfactorily.

In addition, the check valve in the air system did not provide effective isolation of the spent resin tank from the Service Air System.

Analysis of Occurrence The first of the three interrelated events was the leak from the hose connection. All surveys taken of the soil from this leak (estimated at 10 ml) showed no appreciable readings above background levels.

Licensee Event Report Page 3 Reportable Occurence No. 50-219/82-16 /03L The second of these events was the leakage from the building to the soil.

Several soil samples were examined before returning the soil back to its

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location.

The maximum concentrations of the two detetable isotopes, Mn 54 and Co 60, were 7.09 E-5 and 3.71 E-4 microcuries/gm, respectively. Both of these values are within the limits set forth in 10 CFR 20 and 10 CFR 30 (10 CFR 30 is used to determine concentrations in the soil based on 1 gram.) Total volume leakage was estimated at approximately five (5) gallons.

The third of these events is the drainage to the discharge canal. Total volume leakage was estimated at 300 gallons. The isotopic analysis showed the following maximum concentrations:

Mn 54 9.46 E-3 microcuries/ml Co 60 5.26 E-2 microcuries/ml Although these releases occurred during 3 separate flushes of the air receiver, the following analysis assumes that all 300 gallons were released in 15 minute s.

It also assumes a minimum dilution flow of 460,000 gpm, even though actual dilution flow was higher.

Based on this, the concentrations of each isotope in the discharge are as follows, with their associated 10 CFR 20 limit:

Mn 54 4.11 x 10-7 microcuries/m1, limit 1.0 E-4 meirocuries/ml Co 60 2.29 x 10-6 microcuries/ml, limit 5.0 E-5 microcuries/mi

Corrective Action

The immediate corrective actions were to first isolate the affected spent resin tank and then prevent as much of the air system as possible from becoming contaminated. The air compressor was kept in operation, in order to prevent the syphoning of water into unaffected piping. A direct frisk was made of the ground under the total length of hose outside the building, and all readings 3 of soil outside the were at or below background levels.

Approximately 30 f t building, affected by the leak during flushing, was collected, sampled, and then returned once sample results were analyzed and it was determined that no 10 CFR 20 or 10 CFR 30 limits were exceeded.

The check valve in the air line to the spent resin tank was examined and no failures were detected. The affected storm drains and catch basins in the drainage system were decontaminated and the radiation levels in the air receiver have been reduced to background levels.

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Licensee Event Report Page 4 Reportable Occurrence No. 50-219/82-16/03L In addition to these efforts, the procedure for the transfer of spent resins has been reviewed, and has been changed to reflect two (2) important concepts:

1) dhe air mixing operation will be halted prior to starting the backflushing operation, so that air and condensate water are not being forced into the tank at the same time; 2) prior to transferring resins from the tank, the level in the tank will be lowered to insure that the resin slurry is below the screen on the vent line (i.e., prever; inadvertant vent line blockage).

An evaluation will be concucted to determine what constitutes acceptable isolation of noncontaminatad systems from contaminated systems. Based on the results of this determination, modification of existing systems will be considered to prevent future incidents of contamination entering " clean" systems through designed interconnections.

Additionally, procedural controls will be established to assure that in all nonroutine draining evolutions, the discharge point of the drain path will be verified prior to commencing the evolution. As an aid to implementing this requirement, a system of unique definition of noncontaminated drains will be evaluated.

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