Event Notification Report for April 01, 2001
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
03/31/2001 - 04/01/2001
EVENT NUMBERS
37879
Fuel Cycle Facility
Event Number: 37879
Facility: PADUCAH GASEOUS DIFFUSION PLANT
Region: 3 State: KY
Unit: [] [] []
RX Type: URANIUM ENRICHMENT FACILITY
Comments: 2 DEMOCRACY CENTER
6903 ROCKLEDGE DRIVE
BETHESDA, MD 20817 (301)564-3200
NRC Notified By: W. F. CAGE
HQ OPS Officer: JOHN MacKINNON
Region: 3 State: KY
Unit: [] [] []
RX Type: URANIUM ENRICHMENT FACILITY
Comments: 2 DEMOCRACY CENTER
6903 ROCKLEDGE DRIVE
BETHESDA, MD 20817 (301)564-3200
NRC Notified By: W. F. CAGE
HQ OPS Officer: JOHN MacKINNON
Notification Date: 04/02/2001
Notification Time: 03:42 [ET]
Event Date: 04/01/2001
Event Time: 01:45 [CST]
Last Update Date: 04/02/2001
Notification Time: 03:42 [ET]
Event Date: 04/01/2001
Event Time: 01:45 [CST]
Last Update Date: 04/02/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
10 CFR Section:
Person (Organization):
MICHAEL JORDAN (R3)
PATRICIA HOLAHAN (NMSS)
MICHAEL JORDAN (R3)
PATRICIA HOLAHAN (NMSS)
NRC BULLETIN 91-01, 24 HOUR NOTIFICATION INVOLVING REFRIGERANT-114 (R-114) NOT IMMEDIATELY SAMPLED TO DETERMINE MOISTURE CONTENT
On 03/31/01, R-114 was transferred from a rail car to the C-335 R-114 drain tank. Following the transfer from the rail car it was determined that the C-335 R-114 drain tank was over the desired fill level and the decision was made to transfer the R-114 from the drain tank to C-335 Unit 4 Cell 9 R-114 system. The R-114 transfer to C-335 Unit 4 Cell 9 from the C-335 drain tank was completed at 1740 CST on 03/31/01. Following the 1900 shift change on 03/31/01 the C-335 building personnel questioned if the R-114 in C-335 Unit 4 Cell 9 should be sampled for moisture. A review of the independent assay verification for C-335 Unit 4 Cell 9 revealed the assay was greater than 1 wt% U235 assay and at 0145 CST on 04/01/01 it was determined that moisture sampling was required and the Plant Shift Superintendent was notified. NCSA CAS-011 requires that if R-114 is transferred to a cell that is above 1wt%U235 assay, the R-114 in the cell must be immediately sampled to determine the moisture content. Since the time between the transfer of the R-114 to the cell and the actual sampling was determined to not meet the NCSA requirement of immediate sampling and is therefore an NCS violation.
SAFETY SIGNIFICANCE OF THE EVENT:
Although a time limit to determine moisture is not possible, the control requires sampling to start immediately as defined in the TSR. Sampling was delayed in violation of the control procedure.
POTENTIAL CRITICALITY PATHWAYS INVOLVED:
In order for criticality to be possible, the following sequence must occur: Wet R-114 must leak into the process gas portion of the system which contains a larger that critical mass fissile deposit. Sufficient time to enable the hydrogen of the deposit must pass and the deposit must be in a critical geometry for criticality to be possible.
CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.):
Double contingency for this scenario is established by implementing two controls on moderation.
ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS AND % CASE CRITICAL MASS):
1.5185 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 immediately sampling of R-114 for water content. Actual moisture content was within acceptable specifications but the sample was not taken in accordance with the time requirement for control. Specifically the control requires immediate sampling upon completion of the addition of R-114.
CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:
The R-114 was sampled at 0300 on 04/1/01 with the moisture level determined to be within specifications.
The NRC Resident Inspector was notified of this event by the Certificate Holder.
On 03/31/01, R-114 was transferred from a rail car to the C-335 R-114 drain tank. Following the transfer from the rail car it was determined that the C-335 R-114 drain tank was over the desired fill level and the decision was made to transfer the R-114 from the drain tank to C-335 Unit 4 Cell 9 R-114 system. The R-114 transfer to C-335 Unit 4 Cell 9 from the C-335 drain tank was completed at 1740 CST on 03/31/01. Following the 1900 shift change on 03/31/01 the C-335 building personnel questioned if the R-114 in C-335 Unit 4 Cell 9 should be sampled for moisture. A review of the independent assay verification for C-335 Unit 4 Cell 9 revealed the assay was greater than 1 wt% U235 assay and at 0145 CST on 04/01/01 it was determined that moisture sampling was required and the Plant Shift Superintendent was notified. NCSA CAS-011 requires that if R-114 is transferred to a cell that is above 1wt%U235 assay, the R-114 in the cell must be immediately sampled to determine the moisture content. Since the time between the transfer of the R-114 to the cell and the actual sampling was determined to not meet the NCSA requirement of immediate sampling and is therefore an NCS violation.
SAFETY SIGNIFICANCE OF THE EVENT:
Although a time limit to determine moisture is not possible, the control requires sampling to start immediately as defined in the TSR. Sampling was delayed in violation of the control procedure.
POTENTIAL CRITICALITY PATHWAYS INVOLVED:
In order for criticality to be possible, the following sequence must occur: Wet R-114 must leak into the process gas portion of the system which contains a larger that critical mass fissile deposit. Sufficient time to enable the hydrogen of the deposit must pass and the deposit must be in a critical geometry for criticality to be possible.
CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.):
Double contingency for this scenario is established by implementing two controls on moderation.
ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS AND % CASE CRITICAL MASS):
1.5185 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 immediately sampling of R-114 for water content. Actual moisture content was within acceptable specifications but the sample was not taken in accordance with the time requirement for control. Specifically the control requires immediate sampling upon completion of the addition of R-114.
CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:
The R-114 was sampled at 0300 on 04/1/01 with the moisture level determined to be within specifications.
The NRC Resident Inspector was notified of this event by the Certificate Holder.