Event Notification Report for April 06, 2001

AUTOMATIC REACTOR SCRAM DUE TO BLOWN FUSE IN FEEDWATER CONTROL SYSTEM

"This report is bring made per 10CFR50.72(b)(2)(iv)(B) RPS actuation, 4 hour notification for Unit 2 and 10CFR50.72(b)(3)(iv)(A) System Actuation not including RPS, 8 hour notification for Units 1 and 2.

"At 0909, Friday 4-6-01, U-2 automatically scrammed. Initial investigations indicate that a blown fuse in the Feedwater control system caused the reactor Recirculation pumps to downshift. The resultant level swell caused reactor water level to reach the level 8 trip setpoint (plus 55 inches). The main turbine tripped on the high reactor water level. The reactor scrammed due to the main turbine Stop Valves closure with reactor power above 25% power. All control rods fully inserted.

"The Turbine driven reactor feedwater pumps tripped as designed. The Motor Driven Reactor Feedwater pump feed regulating valve locked out, the cause is not known at this time. Reactor Core Isolation Cooling (RCIC) was initiated manually by the operators for reactor pressure and level control.

"A primary containment level 2 isolation (primary containment cooling, containment monitoring. process sample, Unit 1 and 2 Reactor Building Ventilation. Unit 1 and 2 Standby Gas treatment initiation, Reactor water cleanup, reactor Recirculation hydraulic power units and others) occurred at approximately minus 40 inches.

"The lowest Reactor water level reached was minus 44 inches and was recovered to normal level utilizing RCIC. RCIC was operated in manual mode following erratic operation in automatic, the cause is not known at this time. System isolations have been restored with exception of reactor water cleanup on U-2.

"The station is taking action to investigate the cause of the blown fuse and erratic RCIC operation."

The NRC resident inspector has been informed of this event by the licensee.

LOST MOISTURE/DENSITY GAUGE

The licensee reported that a Humboldt Model HS-EZ moisture/density gauge (serial #3310) fell from the bed of a pickup truck in Hazlewood, MO. The device was not stored in its case at the time of the loss. The unit contains one 11 millicurie Cs-137 source and one 44 millicurie Am-241/Be source.

The licensee was unable to locate the gauge after retracing the route of the vehicle. The licensee has contacted the local police department for assistance in recovering the gauge.

UNUSUAL EVENT DECLARED DUE TO FIRE IN EXHAUST HOOD DUCTING

A fire occurred in an exhaust hood duct in the Unit 2 chemistry sample room during the processing of an oil sample. The fire was located inside the ducting. Offsite departments responded to the site. An Unusual Event was declared at 1943 EDT. The fire was extinguished at 2022 EDT. The NRC resident inspector has been informed of this event by the licensee.

* * * UPDATE 0012EDT ON 4/7/01 FROM CARLOS CONTRERAS TO S. SANDIN * * *

The licensee terminated the Unusual Event at 2300EDT on 4/6/01 based on the fact that the fire had been extinguished, current stable plant conditions, and adequate support staff availability. The licensee informed state/local agencies and the NRC resident inspector. Notified R1DO(McFadden), EO(Grimes) and FEMA(Bardon).

AGREEMENT STATE REPORT REGARDING AN IODINE-131 SPILL IN A PROCESSING ROOM AT SYNCOR PHARMACEUTICALS IN DENVER, COLORADO

An iodine-131 spill occurred on the evening of 04/06/01 at Syncor Pharmaceuticals in Denver. Apparently, one of two pharmacists dropped a vial containing 250 millicuries of iodine-131. This occurred in a normal processing room where capsules are made. However, at the time of the incident, the fume hood was out of operation. As a result, the ventilation was not proper for the ongoing activities.

The two pharmacists involved took agents to block their thyroids and did their best to contain the spill. At this point in time, the thyroid bioassays indicate minimal uptake of radio-iodine, and the licensee has not identified any contamination outside the room. The processing room is not completely clean at this point. There are a few spots with absorbent material and shielding. The licensee plans to address this later today. The fume hood is operating at this time, and it does have charcoal filters in line with the exhaust. The licensee is taking actions to determine if there was any release of iodine outside the facility.

NRC BULLETIN 91-01 24 HOUR REPORT

The following is from a faxed report:

On 4/6/01, R-114 evacuation from C-337 Unit 1 Cell 8 was performed as a non-fissile operation without independent verification documentation that the cell was less than 1.0 wt. % U235 in violation of NCSA CAS.011. Since documentation to determine the assay was not reviewed prior to removing the R-114 vapor pressure, an NCS administrative requirement was not met.

SAFETY SIGNIFICANCE OF EVENTS:
Double contingency was not maintained. Although the required documentation was not verified at the time tile R-114 vapor pressure was removed from the cell, the assay of the cell was well known through historical process knowledge. Upon discovery, the historical cascade gradient was reviewed and it was determined that the cell was less than 1.0 wt. % U235.

POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR:
In order for criticality to be possible, the shutdown cell would need to have an unsafe mass of moderated uranium with an enrichment greater than 1.0 wt. % U235.

CONTROLLED PARAMETERS (MASS, MODERATION. GEOMETRY, CONCENTRATION, ETC.):
Double contingency for this scenario is established by implementing two controls on assay.

ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS):
0.7183 wt. % U235

NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:
The first leg of double contingency is based on verification that the equipment contains uranium enriched to less than 1.0 wt. %. The verification of assay was not performed. Therefore, the control was violated and the first leg of double contingency was lost.

The second leg of double contingency is based on independent verification that the equipment contains uranium enriched to less than 1.0 wt. % U235. This independent verification was not performed. Therefore, the control was violated and the second leg of double contingency was lost.

Since double contingency is based on two controls on assay, double contingency was not maintained.

CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:
An independent assay verification was performed and documented, which indicated that the assay was less than 1.0 wt. % U235.

Crew briefings have been held to remind them of the requirements of the NCSA.

The licensee notified the NRC Resident Inspector and intends to notify the DOE representative.