Event Notification Report for March 27, 1999

BOTH UNIT 1 SOURCE RANGE NUCLEAR INSTRUMENTS (NI-31 & NI-32) WERE DECLARED INOPERABLE AT 1028 ON 03/27/99 BASED ON UNSAT CHECK PERFORMED DURING THE SHUTDOWN OF THE UNIT FOR REFUELING.

This event was reported per paragraph 2.G of South Texas Project Operating License

During review of source range discriminator bias curve procedures for resolution of the channel check discrepancy, it was discovered that the bias curves in the procedure used to satisfy the Technical Specification surveillance were the same for both channels 31 and 32. Technical Specifications for channel calibration require that the curves be taken and compared with the initial curves. Each channel in each unit should be different and unique which would make four separate curves (N-31 & 32 for Unit 1 and N-31 & 32 for Unit 2). Further investigation showed that the curves for Unit 1 and Unit 2 are not the initial curves as required by the Technical Specification surveillance.

Since the same procedures and curves have been used to meet refueling frequency (last refueling for Unit 1 was 3/98 and last refueling for Unit 2 was 10/98) surveillance requirements in the past (since 1995 when the Source Range Channel instruments were replaced), it was determined that those past surveillance tests had not complied with the Technical Specification requirements to compare with the initial curves. Consequently, the past surveillance tests are considered inadequate and to have resulted in a condition prohibited by Technical Specifications.

The curves for both Unit 1 source range instruments have been satisfactorily compared to the initial curves in accordance with Technical Specifications. The unsatisfactory channel check has been resolved and the instruments restored to operability. Unit 2 is in Mode 1, and operability of the source range instruments is not required. However, the most recent bias curves for Unit 2 instruments were satisfactorily compared to the initial curves for the instruments, as required by the Technical Specification surveillance.

The NRC Resident Inspector was notified of this event by the licensee.

RHR PUMP FAILS TO START

While attempting to place the unit onto RHR shutdown cooling, the 'A' RHR pump failed to start. The unit is currently in Condition 3 at 227°F, and the main condenser is being used to remove decay heat. The licensee suspects that the failure of the pump to start may be due to a problem with a pump interlock. The licensee is currently troubleshooting the pump.

The licensee entered Technical Specification Action Statement 3.0.3 due to the unavailability of shutdown cooling loop 'A'. The unit was shut down overnight in order to commence a refueling outage. The licensee will inform the NRC resident inspector of this report.

***RETRACTION ON 03/29/99 AT 1603 ET BY S. SANFORD TAKEN BY MACKINNON***

At 0704, an entry was made into Technical Specification 3.0.3 due to the 1 hour action of not verifying that a second alternate decay heat removal system was available within the 1 hour. A 1 hour non-emergency report was made to the NRC under 50.72 (b)(1)(I)(A), Tech Spec shutdown. The reactor was already shutdown, and this event is not reportable under this criterion. This is in accordance with the guidance in NUREG 1022, Event Reporting Guidelines 10 CFR 50.72 and 50.73.

The Technical Specification bases states that "it is also required to reduce reactor temperature to the point where mode 4 is entered." This statement was incorrectly determined to apply to the requirements of a Decay Heat Removal system. The "it" in this case refers to the requirement of the required action A.3 to be in mode 4 within 24 hours.

Therefore, the action requirement to have TWO Alternate Decay Heat Removal methods to maintain or reduce temperature was met within the required time limit of 1 hour. The entry into Technical Specification 3.0.3 was not required.

The failure of RHR "A" to start was determined to be a faulty optical isolator in the suction path logic, which was replaced. The RHR "A" subsystem was restarted in the Shutdown Cooling mode, and Mode 4 was reached at 1148 hours. R3DO (Mark Ring) notified.

The NRC Resident Inspector was notified of this retraction by the licensee.

POTENTIAL RADIATION EXPOSURE TO UNMONITORED PERSONNEL

A potential overexposure condition was discovered when a shredder line at the site was being put back in service. When the level detector was energized the expected alarm was not received. Investigation found that the shutter on a KayRay Model 7062-BP sealed source (serial number 26139-D) was stuck open. The source contains 50 millicuries of Cs-137. A survey of the area measured 150-200 mR/Hr at 2-4 inches and about 20 mR/Hr at 1 meter. The radiation officer initial investigation has identified three potential unmonitored exposures with the following estimations of time and field for each:

1. For 30 minutes with a whole body exposure rate of 50 mR/Hr and up to 200 mR/Hr to extremities (hands),
2. For 5-10 minutes to the lower body an exposure rate of 5-10 mR/Hr, and
3. For 5-10 minutes at 10 mR/Hr and 20 minutes at 50 mR/Hr to the whole body, 20 minutes at 150-200 mR/Hr to the upper extremities, and another 10 minutes at 150-200 mR/Hr to the lower body and lower extremities.

Further investigation will be carried out to determine if others may have been exposed. The line was shut down on 3/12/99 and the shutter was closed, this was the last known time it was closed. The licensee has yet to determine when the shutter may have been opened.

The licensee will submit a written report within 30 days.

Refer to HOO Log for contact numbers.

* * * UPDATE 1747EST ON 3/28/99 FROM RON FRICK TO S.SANDIN * * *

Gamma Corporation acting as physics consultants for Honolulu Resource Recovery Venure contacted the NRC requesting instructions for moving the device to a storage area. Established conference call with R4DO(Cain) and NMSS EO(Pierson).