Uncontrolled entry into room under reactor vessel during refuelling outage

During the scheduled refuelling outage on unit 2, a worker received an external whole body dose of 32 milli-Sieverts (3.2 rem) during entry into a normally locked room inside the reactor containment building. The worker had a key to another room nearby, but mistakenly opened the wrong door. On entering the room he realised his mistake and exited.
The use of the key, and entry into the room were not performed according to existing authorised procedures.
The whole body dose received by the worker was within the annual legal limit of 50 milli-Sieverts (5 rem) for a radiation worker.
Justifications of the rating:
According to section C3.4, safety layer approach, in the addendum to the 1992 INES Manual. The actual dose was below site limits, however the only safety layer to prevent potential further dose was the individual's knowledge of the plant, resulting in him leaving the room quickly.

Location: KOEBERG-2
Event date: Tue, 11-03-1997
Nuclear event report
Legenda & explanation