Event Notification Report for July 17, 2010
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
07/16/2010 - 07/17/2010
EVENT NUMBERS
46105
Fuel Cycle Facility
Event Number: 46105
Facility: PADUCAH GASEOUS DIFFUSION PLANT
Region: 2 State: KY
Unit: [] [] []
RX Type: URANIUM ENRICHMENT FACILITY
Comments: 2 DEMOCRACY CENTER
6903 ROCKLEDGE DRIVE
BETHESDA, MD 20817 (301)564-3200
NRC Notified By: KEVIN BEASLEY
HQ OPS Officer: BILL HUFFMAN
Region: 2 State: KY
Unit: [] [] []
RX Type: URANIUM ENRICHMENT FACILITY
Comments: 2 DEMOCRACY CENTER
6903 ROCKLEDGE DRIVE
BETHESDA, MD 20817 (301)564-3200
NRC Notified By: KEVIN BEASLEY
HQ OPS Officer: BILL HUFFMAN
Notification Date: 07/18/2010
Notification Time: 14:06 [ET]
Event Date: 07/17/2010
Event Time: 14:07 [CDT]
Last Update Date: 07/18/2010
Notification Time: 14:06 [ET]
Event Date: 07/17/2010
Event Time: 14:07 [CDT]
Last Update Date: 07/18/2010
Emergency Class: NON EMERGENCY
10 CFR Section:
10 CFR Section:
Person (Organization):
DEBORAH SEYMOUR (R2DO)
PETER HABIGHORST (NMSS)
DEBORAH SEYMOUR (R2DO)
PETER HABIGHORST (NMSS)
24 HOUR 91-01 BULLETIN REPORT ON LOSS OF ONE OF TWO CRITICALITY CONTROL CONTINGENCIES
"At 1407 CDT, on 07/17/2010 the Plant Shift Superintendent was notified that cracks had been discovered in the C-400 Spray Booth containment pan by Quality Control Inspectors. The floor pan for the spray booth storage tanks, near the hand tables, was found to be inadequate and would allow solution to leak directly onto the concrete floor, in violation of NCSE (Nuclear Criticality Safety Evaluation) 015. The floor pan is a Safety Related Item that is intended to prevent solution from leaking to the concrete floor beneath the floor pan and accumulating in or creating an unsafe geometry/volume.
"Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC Bulletin 91-01 Supplement 1.
"The process conditions relied upon for double contingency for this scenario are mass and geometry. The first leg of double contingency is based on the mass of uranium in solution form that leaks out of the system. The analysis credits both the integrity of the Spray Booth system and the fact that the tanks and piping are inspected for leakage. Small leaks will be identified and fixed before they have leaked enough uranium mass, in solution form, to be a concern. This control was not violated.
"The second leg of double contingency relies on the integrity of the floor pan to prevent accumulated liquids from leaking to the underlying concrete floor and accumulating in unfavorable geometries that may be present or created under the containment pan. Because a portion of the floor pan was discovered to have a hole, the Safety Related Item was violated; therefore, this control was violated. Pressure was placed on the Spray Booth floor pan in the area around the crack. Based on this inspection, there are no indication of unsafe geometry voids being present or having been created under the floor pan. Because the integrity of the floor pan was not maintained, this leg of double contingency is conservatively being considered as having been lost.
Double contingency is conservatively considered to have been lost since the integrity of the spray booth storage tank floor pan was lost.
"In order for a criticality to be possible, greater than a safe mass of fissile material, in solution form, would have to leak out of the system undetected, leak under the floor pan, dissolve the concrete floor, and accumulate in an unsafe geometry.
"While the intended safety function of the Safety Related Item was violated, there was no significant uranium solution leak from the Spray Booth system. Additionally, there are no indications of unsafe geometry voids under the floor pan.
"The NRC Senior Resident Inspector has been notified of this event."
The crack was characterized as through-wall and approximately 9 inches long. Since the pan is flush to the concrete floor it is mounted on, the licensee does not believe that any material has accumulated under the pan. A preliminary inspection of the pan did not reveal any indication of voiding under the pan. The licensee still has not determined if the pan will be lifted to inspect underneath. The crack was found during an annual inspection of the pan. The cause of the cracking is still under investigation.
"At 1407 CDT, on 07/17/2010 the Plant Shift Superintendent was notified that cracks had been discovered in the C-400 Spray Booth containment pan by Quality Control Inspectors. The floor pan for the spray booth storage tanks, near the hand tables, was found to be inadequate and would allow solution to leak directly onto the concrete floor, in violation of NCSE (Nuclear Criticality Safety Evaluation) 015. The floor pan is a Safety Related Item that is intended to prevent solution from leaking to the concrete floor beneath the floor pan and accumulating in or creating an unsafe geometry/volume.
"Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC Bulletin 91-01 Supplement 1.
"The process conditions relied upon for double contingency for this scenario are mass and geometry. The first leg of double contingency is based on the mass of uranium in solution form that leaks out of the system. The analysis credits both the integrity of the Spray Booth system and the fact that the tanks and piping are inspected for leakage. Small leaks will be identified and fixed before they have leaked enough uranium mass, in solution form, to be a concern. This control was not violated.
"The second leg of double contingency relies on the integrity of the floor pan to prevent accumulated liquids from leaking to the underlying concrete floor and accumulating in unfavorable geometries that may be present or created under the containment pan. Because a portion of the floor pan was discovered to have a hole, the Safety Related Item was violated; therefore, this control was violated. Pressure was placed on the Spray Booth floor pan in the area around the crack. Based on this inspection, there are no indication of unsafe geometry voids being present or having been created under the floor pan. Because the integrity of the floor pan was not maintained, this leg of double contingency is conservatively being considered as having been lost.
Double contingency is conservatively considered to have been lost since the integrity of the spray booth storage tank floor pan was lost.
"In order for a criticality to be possible, greater than a safe mass of fissile material, in solution form, would have to leak out of the system undetected, leak under the floor pan, dissolve the concrete floor, and accumulate in an unsafe geometry.
"While the intended safety function of the Safety Related Item was violated, there was no significant uranium solution leak from the Spray Booth system. Additionally, there are no indications of unsafe geometry voids under the floor pan.
"The NRC Senior Resident Inspector has been notified of this event."
The crack was characterized as through-wall and approximately 9 inches long. Since the pan is flush to the concrete floor it is mounted on, the licensee does not believe that any material has accumulated under the pan. A preliminary inspection of the pan did not reveal any indication of voiding under the pan. The licensee still has not determined if the pan will be lifted to inspect underneath. The crack was found during an annual inspection of the pan. The cause of the cracking is still under investigation.