Monitoring error on a vitrified waste canister

Incident report

January 31, 2005

On Friday, January 28, surface monitoring performed on a canister of vitrified waste during its transfer from the T7 vitrification facility(1) at the UP3 plant to the storage building proved to be defective.
The results of a prior swab test were assigned to the canister when the swab got stuck in the equipment used to verify the absence of contamination.

The maintenance department intervened and returned the monitoring equipment to normal service. A new test confirmed the radiological cleanliness of the canister.

This event was without impact on personnel or the environment. Nonetheless, it resulted in non-compliance with authorized operating parameters.
A proposal was therefore made to the nuclear safety authority to classify this as a level 1 event on the 7-level international scale of nuclear events (INES).

(1) The vitrification process immobilizes the most radioactive radioelements (fission products) in a safe and stable glass matrix, which is poured into stainless steel canisters. This is called a vitrified waste canister.