LfE Database

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LFE ID Facility Type Description of Event Criticality Safety Parameters Affected Immediate Actions Taken Method of Resolution Apparent Cause(s) Root Cause Lessons Learnt Type of Operation Keyword(s)
001 Fuel Cycle Facility Uranium Accumulation in Casting Furnace Mass Material was cleaned out & whole set of Corrective Actions Natural build-up over time Assumptions about uranium accumulations in the casting process did not align with operations in the field Need to understand process you are assessing - view it in action Operations Furnace, accumulation, hidden
002 Storage/ Waste/ Repository Storage of Materials Above Height of CAAS Analysis Assumptions (On Top of a Cabinet) CWS/ CAAS Material immediately relocated Human Error Unknown - possibly lack of awareness of CAAS assumptions ? None given - but presumably lessons for (i) training / briefing, and (ii) investigate whether height restriction is required Emergency Planning/ Recovery Storage, CAAS, stacking
004 Fuel Cycle Facility Samples inputted on the wrong inventory system Mass Operations stopped to rectify issue Human Error Unknown - but believed to be different parts of the same Inventory sheet Unknown Operations Inventory, software
005 Fuel Cycle Facility Over pressurisation of domestic water supply resulting in multiple facility leaks Moderator Unknown Human Error Isolation activities in a different facility knocked onto main facility Many creative ways that water can leak from systems Operations Water, leak, over pressurisation
006 Storage/ Waste/ Repository Non-conservative assumption about concentration of product solution entering steam condensate isolation unit Concentration/ Density Unit taken out of service & will not be operated until issue has been resolved Incorrect assumption Lack of understanding of process None given - but presume lessons regarding a full understanding of the process Operations Response, steam, dissolver
007 Storage/ Waste/ Repository Erroneous storage of contaminated exhaust pipes without spacing requirement Mass, Spacing Erroneous items were removed and compliantly stored in a separate storage area Human Error Lack of understanding of requirements None given - but presume lessons for training Decommissioning Spacing ; contamination
008 Storage/ Waste/ Repository Erroneous opening of transport container in a CSI array Transport None required as operation already completed - discovered during final moves Human Error Believed to be the right course of action on shielding grounds None given Operations Transport container, array, shielding
009 Fuel Cycle Facility Simultaneous loading of drop box with twice the permitted amount of material Mass Transferred material back to original location Human Error Simultaneous moves by two independent organisations None given Operations Mass, Drop Box, Simultaneous
010 Fuel Cycle Facility Transfer of erroneous concentrated liquor heel to a downstream process during flushing Concentration/ Density Unknown Equipment Failure Level indication anomaly didn't reveal the erroneous heel which was subsequently transferred downstream during flushing None given Major Maintenance/Facility Modification/Shutdown Heel, Level Indication, Downstream transfer
011 Fuel Cycle Facility A portion of the ventilation system associated with a scrubber was found to have exceeded the criticality safety mass limit Mass The operation was shutdown and the ventilation system was opened and cleaned out; the extent of condition was evaluated for other scrubber systems in the facility The inspection and cleanout frequency was increased for this scrubber Incorrect Assumption Slow accumulations of material downstream of scrubbers occur at different rates, the ventilation system had not had an extensive cleanout for many years. The accumulation rates of material should be checked on a regular frequency. The estimated accumulation rate for one location should not be applied to many locations. Ventilation systems will accumulate material over time and need to be evaluated. Operations scrubbers, mass accumulations, ventilation system
012 Reactor A duty holder derived safety limits using random distributions of fuels rods in moderator. Ths came to light after the plant was running. Other The plant was shutdown until the dutyholder produced an adequate safety case. This safety case needed to address (a) the criticality code had not been validated (b) normal operations were assessed using a probabilistic approach. Human Error Use of unvalidated criticality safety assessment method. None given but lessons on use of a validated code and adequate safety cases. Operations Unvalidated code, probabilistic
013 Fuel Cycle Facility During an inspection, when asked about the fisile content of a mobile filtration unit, the plant manager was not certain about the quantity. Mass A safety case was created to support a mobile filtration unit. Although isolated and not in operational use, the organisation did not have a safety case for a mobile filtration unit. As a result of the error a safety case was created. Human Error Uncertain Fissile content in mobile filtration unit None given but lessons on ensuring items on plant have a safety case Operations mobile filtration unit, safety case, undertain mass
014 Fuel Cycle Facility HEPA filter was found to have exceeded mass limits, while still having an acceptable delta pressure Mass Operation was shutdown; evaluate similar HEPA filters and replace as needed; Increase monitoring of HEPA filters Replace the HEPA design with one that did not need mass a control; develop a crititeria for using delta-P as a primary control Incorrect Assumption The delta-P limit was developed for UO2 powder with known particle size distribution; a new oxidation process produced U3O8 powders with different particle size distribution that did not correlate with the former UO2 delta-p behavior for primary HEPA filters. Staff should question the basis of a criticality limit on a regular basis. Accumulation locations should be monitored to verify compliance with the limits; new or changed operations should be monitored more frequently. Operations HEPA filters, mass accumulations, ventilation system

Database

Developed by: M. Savage, G. Willock, B. Philpotts, D.A.Hill, M. Erlund, A. Till, A. Brown.

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