 INES 1 |
FUEL BUNDLE DAMAGE DURING TRANSFER TO SPENT FUEL BAY |
During a fuel transfer operation using fuelling grapples, an irradiated fuel bundle was damaged at the outlet of the discharge port and a broken fuel element fell on the floor of the spent fuel bay room. The emergency sprinklers were activated in the room and a sectorial alert was initiated in the reactor building and the fuel bay areas. The broken element was recovered within hours and was deposited in the bay. The ambient irradation levels fell to normal after decontamination of the room. No fuel escaped from the element and atomspheric contamination remained below detection levels. No personnel exposure resulted except for the worker that removed the broken element to the bay who received less than 1 MSv. (The residual heat of the fuel was very low as the unit had been shutdown for 17 days and the fuel was from a peripheral channel.)
BASIS FOR RATING: Actual initiator: Damage to irradiated fuel
Safety function Availability: Full
Reference Table A2 in Manual: INES severity = 1
DIFFICULTIES IN RATING: Referring to the list of initiators for CANDU, the "Possible" initiator"damage to irradiated fuel" was chosen even though this event could beconsidered a "Minor Fuel Handling Incident" (Expected), as the consequencewas minor. However, the potential existed for a limited release under lessfavourable conditions.
The safety functions of cooling sprays and the fuel bay ventillationfilters were fully functional.
Event date: Thu, 19-09-1991
