An incident involving a shipment of iridium-192 produced at Studsvik research reactor has been rated level 3. The package containing 366TBq of the isotope had been discovered to have radiation levels of 4mSv/h at 25m on one side, and 0.01mSv/h at 5m on the other side.

The package left Sweden for the USA on 27 December. Radiation levels were measured as “normal” when leaving Studsvik. It was transported in a type B container to Paris and then to New Orleans. On arrival in the USA, a radiation inspection was carried out, but the man who monitored the package thought the detection instrument was “stuck”. He drove the container 1-2 miles to its final destination. On arrival, he noted the dosimeter showed an unusually high reading of 1.6mSv. It was calculated that he had received about 3.4mSv during the short journey.

The Swedish radiation protection authority will analyse the container’s transport route, and carry out an inspection of the Studsvik facility. All isotope transports from Studsvik have been temporarily stopped.

• An incident at Ringhals 2 in June 2001 has been re-rated from level 2 to level 1. It had been initially rated level 1, but later changed because it involved a common cause failure (CCF). The incident, where a redundant transformer tripped after 32 minutes at 60% load, was re-rated because officials established that the CCF was “counted twice”.