INES-event
INES 3

High radiation levels measured on a package containing Iridium-192

The Swedish Radiation Protection Authority (SSI) was the 3 of January 2002 notifyed by the US Depatment of Transportation that a package containing 366 TBq of iridium-192 had been discovered with high radiation levels. The level of radiation on one side of the package is 4 mSv/h on 25 meters distance and on the other side 0,01 mSv/h on 5 meters distance. The iridium was produced at Studsvik research reactor and was transported in a certified Type-B container. The container was transported by airplane to Paris and from there to New Orleans USA. When the package was picked up in New Orleans a radiation survey was performed. The individual that performed the survey observed that his radiation detection instrument was "stuck". Believing that his survey instrument was malfunctioning the individual loaded the container in his vehicle and transported the package to the final destination located approximatly 1-2 miles from the pick up point. Upon arrival the individual observed that his pocket dosimeter read approximately 1,6 mSv ( it was later calculated that the driver had recieved approxamately 3,4 mSv during the 10 minute drive). Noting that this was an abnormally high reading more messurements was performed and the package were immediately secured in a hotcell for further investigations. All transports of isotopes from Studsvik were stopped by the SSI.

The investigations efter the incident showed that two of the three inner containers were unscrewed (probably during the transport) and several of the small Iridium discs were spread inside the package. Furthermore an inner plug in the package which should provide radiation protection did not perfecty fit. Consequently the Iridium discs could slip into the space left. This led to the high levels of irradiation on the outside of the package.
After the investigations SSI ordered Studsvik to carry out corrective action to prevent recurrence. Studsvik has performed corrective actions regarding instructions, responsibility clarifications and organizational changes.

Location: Studsvik Nuclear AB
Event date: Wed, 02-01-2002
Nuclear event report
Legenda & explanation