CBRN event in Italy on Mon 29th September 1997

On the evening of 29 September 1997 two workers from a subcontractor were asked by the contracting company to perform a non-destructive test with a Co-60 source of 1221 GBq (33Ci). The irradiation was expected to last for 7 hours. Owing to a misconnection between the remote control cable and the source holder (due to a human error in following the written procedure), the source was left in the exposure head at the end of the irradiation. In addition, the two workers did not switch on their radiation monitors. The next morning (30 September) a worker of the contracting company was charged to collect all the instruments and apparatuses. He noticed that he was irradiated by the overflow of his fountain pen dosimeter (no alarm), and received the following doses.
a) whole body equivalent dose 0.89 Sv (statutory annual limit: 0.05 Sv); b) hand equivalent dose 3.56 Sv; c) eye lens equivalent dose 0.89 Sv
The two workers from the subcontractor, who performed the irradiation on Sept. 29, received only very low doses, as they were shielded by the thick irradiated specimen.
Basis for rating:
The event had no off-site impact. it was rated at level 3 under the on-site impact criterion (see Section II-2.2),as the dose received was more than ten times the annual statutory limit, and it was received in about 15 minutes. Deficiencies in Safety Culture have obviously been noted, but not considered, such as to warrant an upgrading of the already high basic level.