Event Notification Report for May 05, 2000

REACTOR SCRAM DURING PLANNED INSTRUMENT MAINTENANCE

"At 0940 hours on 5-5-00, Unit 2 scrammed while performing a scheduled Instrument Maintenance surveillance that resulted in a Group 1 isolation. The Unit 2 Emergency Diesel Generator received a spurious Auto Start signal during the Auxiliary Power transfer. During the transient reactor water level reached +8 inches and all Group 2 actuations occurred as expected. Unit 2 is now in Mode 3 with reactor water level within its normal band."

All rods fully inserted with the reactor scram and the plant is now stable in normal plant configuration for Mode 3. Preliminary investigation determined that a technician valved out one instrument then tripped a different instrument causing the reactor scram. Investigation is still on going and startup will not proceed until complete.

The licensee notified the NRC Resident Inspector.

POTENTIAL FOR RESIDUAL HEAT REMOVAL SYSTEM NOT ABLE TO PERFORM SAFETY FUNCTION

"During the performance of the cold shutdown surveillance N1-ST-V 14 (SERVICE WATER CHECK VALVE AND EMERGENCY SERVICE WATER PUMP AND CHECK VALVE TEST) it was determined that ESW (EMERGENCY SERVICE WATER) check valves 72-21 and 72-22 failed to isolate. The failure of these valves to close may have resulted in ESW not being able to perform its safety function to support residual heat removal (RHR)."

The two check valves serve to isolate the non-safety loads of ESW. The valves were serviced and the test was performed again successfully. It was on 5/7/00 about 1230 CDT that the licensee recognized that a four hour notification should have been made on 5/5/00.

The licensee notified the NRC Resident Inspector.

SAFETY EQUIPMENT FAILURE (CELL 2)

At 2130 CDT on 5/05/2000, the C-337 Unit 3 Cell 2 Freezer/Sublimer A-valve failed to open while in TSR mode F/S 3 which requires operability of the A-valve in order for the valve to open if required to do so upon actuation of the Freezer/Sublimer High-High Weight Trip System. An operator was attempting to place the Freezer/Sublimer into mode F/S 2 which does not require operability of the High-High Weight Trip System. The Freezer/Sublimer was unable to enter Mode F/S 2 due to inability to open A-valve because of mechanical failure. Actuation of High- High Weight Trip system did not occur. However, had it been required to do so while in mode F/S 3, there is potential that the A-valve would not have opened as required if actuation of system occurred. Upon discovery of valve failure, Freezer/Sublimer was placed in mode F/S 4 which does not require operability of the High-High Weight Trip system. The valve failure was caused by a failure of the motor operator in this six inch valve.

The NRC Senior Resident Inspector has been notified of this event. See related event 36985.

* * * RETRACTION 1718 5/19/2000 FROM MIKE UNDERWOOD TAKEN BY BOB STRANSKY * * *

"On May 18, 2000, troubleshooting and functional testing of the F/S in the failed condition determined that the valve was opening in response to DPCS demands, but the limit switches were not correctly communicating the valve position to the DPCS. This caused the DPCS to indicate a mode equipment state failure on May 5, 2000. In addition the F/S was subjected to the high-high weight trip safety system functional test while in cold standby and with the system engineer visually monitoring the A-valve. The valve operated as designed, but due to the failed limit switches, the DPCS tripped the unit into hot standby, recreating the events of May 5, 2000. Thus, the A-valve was capable of performing its intended function if required, and the reporting requirements of 10CFR76.120(c) (2) were not met.

"Based on this evaluation, this event has been retracted."

The NRC resident inspector has been informed of this retraction. Notified R3DO (Madera).

FAILURE OF A SAFETY SYSTEM (CELL 8)

At 2130 CDT on 5/05/2000, the C-337 Unit 3 Cell 8 Freezer/Sublimer A-valve failed to open while in TSR mode F/S 3 which requires operability of the A-valve in order for the valve to open if required to do so upon actuation of the Freezer/Sublimer High-High Weight Trip System. An operator was attempting to place the Freezer/Sublimer into mode F/S 2 which does not require operability of the High-High Weight Trip System. The Freezer/Sublimer was unable to enter Mode F/S 2 due to inability to open A-valve because of mechanical failure. Actuation of High-High Weight Trip system did not occur. However, had it been required to do so while in mode F/S 3, there is potential that the A-valve would not have opened as required if actuation of system occurred. Upon discovery of valve failure, Freezer/Sublimer was placed in mode F/S 4 which does not require operability of the High-High Weight Trip system.

The valve failure was caused by a failure of limit switch on the valve.

The NRC Senior Resident Inspector has been notified of this event. See related event 36984.

POSSIBLE LOSS OF A TRITIATED EXIT SIGN

During final walkthrough for renovation of the Waring Chemistry Building, one tritiated exit sign appears to be missing. Eleven signs were collected, but there appeared to be a "spot" on the wall at one exit where it appears a sign had hung. A search was conducted of the building without finding any indication of the sign. There is no inventory of the signs so there is no positive way of determining that a sign is actually missing. The sign would by a model 101 by Shield Source Incorporated if it matches the rest of the signs. The sign contained 7 curies of tritium on 1/93 and would contain about 5 curies now. The university plans to send out a flyer looking for the sign and provide warning of the hazards involved.