INES-event
INES 1

DROPPING OF A SPENT FUEL BUNDLE IN INSPECTION BAY

Unit was operating at 175 MWe and spent fuel discharge was in progress. First pair of spent fuel bundles were received at the Inspection bay in an open tray called the Insert (meant for receiving spent fuel bundles) attached to a Transfer Arm (T/A). The T/A was rotated and aligned to the spent fuel storage bay port in order to discharge the bundles to storage bay. When the T/A Ram was advanced to push the bundles, the front end bundle got stuck at the storage bay port entry and due to the Ram force, the rear end bundle got lifted and toppled out of the insert. The event was caused by the partial detachment of three pencils in the circumference at the storage bay port entry causing the above incident. Even though one bundle had fallen down and pencils were detached, there was no damage to the pencils and the fuel cladding was intact and there was no radioactivity release.
Dropping of a spent fuel assembly can be classified as a real, possible initiator. Safty function was fully available. Hence the event can be rated as Level-1 under A-2R category of Table-1 of user's manual.

Location: KALPAKKAM-2
Event date: Mon, 30-03-1992
Nuclear event report
Legenda & explanation