Event Notification Report for August 31, 2002
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
08/30/2002 - 08/31/2002
EVENT NUMBERS
39162
Fuel Cycle Facility
Event Number: 39162
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: K. A. BEASLEY
HQ OPS Officer: MIKE NORRIS
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: K. A. BEASLEY
HQ OPS Officer: MIKE NORRIS
Notification Date: 08/31/2002
Notification Time: 16:52 [ET]
Event Date: 08/31/2002
Event Time: 01:20 [CDT]
Last Update Date: 08/31/2002
Notification Time: 16:52 [ET]
Event Date: 08/31/2002
Event Time: 01:20 [CDT]
Last Update Date: 08/31/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
10 CFR Section:
Person (Organization):
RONALD GARDNER (R3)
E. WILLIAM BRACH (NMSS)
RONALD GARDNER (R3)
E. WILLIAM BRACH (NMSS)
NRC BULLETIN 91-01 24 HOUR REPORT - IMPROPER ISOLATION OF PUMP PRESSURE ALARMS
The following is taken from a facsimile report.
At 0120, on 8-31-02 the Plant Shift Superintendent (PSS) determined that a loss of double contingency had occurred in the C-337 process building. In preparation for maintenance work on the #2 dual Speed Purge and Evacuation (P&E) pump Instrument Maintenance had been requested to disable the two delta pressure alarms associated with this pump. The delta pressure alarms are safety related items (SRI). The SRI requires that both delta pressure alarms be functional while the P&E pump is isolated from the cascade. Building Operations personnel later discovered that one of the delta pressure alarms that had been disabled was an alarm for the #3 P&E pump which was not undergoing maintenance. Both delta-pressure alarms for the #3 P&E pump were required to be in service at the time. The C-337 Front Line Manager and Instrument Maintenance responded to the alarm panel and restored the alarm to the #3 P&E pump. At that time, double contingency was restored.
This event resulted in a loss of one leg of double contingency in which double contingency was restored within 4 hours.
The NRC Resident Inspector has been notified.
SAFETY SIGNIFICANCE OF EVENTS:
While the R-114 was demonstrated to be dry, an SRI for double contingency was rendered not functional without the knowledge of the operator.
POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR)
In order for a criticality to occur, an unsafe mass uranium deposit would have to be present in the process gas system, an R-114 leak to the process gas system would have to occur, the R-114 would have to contain an unacceptable amount of moisture and moderate the deposit.
CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY. CONCENTRATION, ETC
Double contingency is maintained by implementing two controls on moderation.
ESTIMATED AMOUNT, ENRICHMENT, FORMS OF LICENSED MATERIAL (INCLUDES PROCESS LIMIT AND % WORST CASE CRITICAL MASS):
No known mass of licensed material exists in the #3 Dual Speed P & E pump.
NUCLEAR CRITICALITY SAFETY CONTROL SYSTEM(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES
The first leg of double contingency is based on the delta pressure switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. This delta pressure alarm was maintained as operable, the SRI was maintained and the control was not violated.
The second leg of double contingency is based on the independent delta pressure switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. The independent delta pressure alarm was disconnected without first isolating the RCW system violating the SRI. The Independent delta pressure switch was reconnected immediately upon discovery. This re-established double contingency.
Since double contingency is based on two controls (i.e. SRIs) on one parameter, double contingency was not maintained.
CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:
1. Make the #3 dual speed P&E alarm operable.
2. Independently sample the #3 dual speed P&E R-114 system for moisture.
The following is taken from a facsimile report.
At 0120, on 8-31-02 the Plant Shift Superintendent (PSS) determined that a loss of double contingency had occurred in the C-337 process building. In preparation for maintenance work on the #2 dual Speed Purge and Evacuation (P&E) pump Instrument Maintenance had been requested to disable the two delta pressure alarms associated with this pump. The delta pressure alarms are safety related items (SRI). The SRI requires that both delta pressure alarms be functional while the P&E pump is isolated from the cascade. Building Operations personnel later discovered that one of the delta pressure alarms that had been disabled was an alarm for the #3 P&E pump which was not undergoing maintenance. Both delta-pressure alarms for the #3 P&E pump were required to be in service at the time. The C-337 Front Line Manager and Instrument Maintenance responded to the alarm panel and restored the alarm to the #3 P&E pump. At that time, double contingency was restored.
This event resulted in a loss of one leg of double contingency in which double contingency was restored within 4 hours.
The NRC Resident Inspector has been notified.
SAFETY SIGNIFICANCE OF EVENTS:
While the R-114 was demonstrated to be dry, an SRI for double contingency was rendered not functional without the knowledge of the operator.
POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR)
In order for a criticality to occur, an unsafe mass uranium deposit would have to be present in the process gas system, an R-114 leak to the process gas system would have to occur, the R-114 would have to contain an unacceptable amount of moisture and moderate the deposit.
CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY. CONCENTRATION, ETC
Double contingency is maintained by implementing two controls on moderation.
ESTIMATED AMOUNT, ENRICHMENT, FORMS OF LICENSED MATERIAL (INCLUDES PROCESS LIMIT AND % WORST CASE CRITICAL MASS):
No known mass of licensed material exists in the #3 Dual Speed P & E pump.
NUCLEAR CRITICALITY SAFETY CONTROL SYSTEM(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES
The first leg of double contingency is based on the delta pressure switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. This delta pressure alarm was maintained as operable, the SRI was maintained and the control was not violated.
The second leg of double contingency is based on the independent delta pressure switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. The independent delta pressure alarm was disconnected without first isolating the RCW system violating the SRI. The Independent delta pressure switch was reconnected immediately upon discovery. This re-established double contingency.
Since double contingency is based on two controls (i.e. SRIs) on one parameter, double contingency was not maintained.
CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:
1. Make the #3 dual speed P&E alarm operable.
2. Independently sample the #3 dual speed P&E R-114 system for moisture.