05000219/LER-2002-001

LER-2002-001,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)
2192002001R00 - NRC Website

FACILITY NAME (1) DOCKET (2) LER NUMBER 6) PAGE (3) 05000 -219 2 � of � 4 02 � -- � 01 � -- � 00

DATE OF DISCOVERY

On April 25, 2002, a review of system performance determined the Technical Specification Limit for the Offgas Radiation Monitor Out of Service time had been exceeded on March 26, 2002.

IDENTIFICATION OF OCCURRENCE

At approximately 7:00 AM on March 26, 2002, a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Technical Specification out of service allowance expired but a reactor shutdown was not commenced. This occurrence is considered reportable under 10 CFR 50.73(a)(2)(i).

CONDITIONS PRIOR TO DISCOVERY

The plant was operating at 100% power with all temperatures and pressures normal for full power operation.

DESCRIPTION OF OCCURRENCE

Before main condenser (EIIC - COND) air ejector offgas is discharged to the environment, a sample stream is passed through a six-foot section of four inch, internally polished, stainless steel pipe. Two ion chamber radiation detectors (EIIS - IL) monitor this sample chamber. At 7:00 AM on March 23, 2002, a sufficient volume of water had condensed in the Offgas Radiation Monitor sample chamber to cause the monitor to read unacceptably low. Although both detectors passed all Technical Specification required surveillances, the water resulted in the monitor being incapable of performing its intended function of isolating the offgas line if the Technical Specification release limits were exceeded. On April 7, 2002, the operators questioned the lower than normal Offgas Radiation Monitor readings and a Corrective Action Program document was issued. An inspection of the Air Ejector Offgas Sample Line for air leaks (which were thought to be the cause of the indications) was conducted. No air leaks were discovered. The downward trend continued and on April 9, 2002, at 1:28 PM, the Shift Manager declared the system inoperable, entered a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Technical Specification out of service allowance, and documented the abnormal radiation trend in a maintenance request.

FACILITY NAME (1) DOCKET (2) LER NUMBER (6) PAGE (3) 05000 YEAR SEQUENTIAL NUMBER REV Oyster Creek, Unit 1 -219 02 � -- � 001 � -- � 00 3 � of � 4 DESCRIPTION OF OCCURRENCE (Cont.) The system engineer, in response to the maintenance request, developed a troubleshooting plan which included a procedure to remove moisture from the sample chamber and initiated an Action Request to check the sample chamber heat trace (EIIC - EHTR). On April 9, 2002, at 5:49 PM, draining was commenced on the sample chamber. Indications returned to normal and the system was declared operable at 7:25 PM.

Subsequently, on April 25, 2002, an evaluation of monitor performance was completed and it was concluded that the monitor had become inoperable on March 23, 2002 at 7:00AM and continued in excess of the Technical Specification out of service allowance.

FAILURE DATA

General Electric; electrical heat trace.

APPARENT CAUSE

The failure of the sample chamber heat trace in the Air Ejector Off Gas sample system resulted in moisture collecting in the sample chamber. As water collected in the chamber, a decrease in offgas radiation indications occurred due to the displacement of the monitored gas away from the detectors.

A contributing cause was determined to be insufficient administrative controls to evaluate component degradation.

ANALYSIS OF OCCURRENCE AND SAFETY ASSESSMENT

The safety significance of this occurrence was minimal. Although the Air Ejector Offgas Radiation Detectors were inoperable, the Stack Radioactive Gaseous Effluent Monitoring System was in operation. No unexpected activity was noted. Weekly samples performed by the chemistry department of air ejector offgas did not show an increase in offgas activity. Additionally the main steam line radiation detectors were in operation and did not indicate any fuel element failure. The plant remained within the Technical Specification Release Limits at all times. There was no unexpected radioactive release and thus there was no effect on the health and safety of the public.

FACILITY NAME (1) DOCKET (2) LER NUMBER (6) PAGE (3) 05000 YEAR SEQUENTIAL NUMBER REV

CORRECTIVE ACTIONS

Immediate Corrective Actions

Upon recognizing that the detection system was degraded, the sample chamber was drained and enhanced monitoring was commenced.

Short Term Corrective Actions It was determined that the cause of the water buildup was a failure of the sample chamber heat trace.

New administrative controls have been initiated to evaluate detection system performance. If monitoring of these additional parameters indicates that the detection system performance has degraded, the sample chamber will be drained.

The heat trace was replaced and the radiation monitoring system restored to full operability on May 8, 2002.