Cyclotron operated with an open bunker door

On the 12th of October 2016 the Swedish Radiation Safety Authority was informed about an event that occurred on the 7th of October where a cyclotron was operated with an open bunker door. The licensee is authorised to produce short lived isotopes used for medical
diagnostics. The bunker is supposed to be sealed with interlocks preventing operation of the cyclotron with an open door. At the time of the event a study visit was performed at the facility by hospital personnel from the whole of Sweden lead by a representative from
the facility. Another chemist entered the facility and started to operate the cyclotron, assuming the door to the bunker was closed since the cyclotron started. After 8 minutes the chemist identifies an alarm and realises that the cyclotron is operated with an open bunker door. The cyclotron is then turned off immediately. By the time of reporting this
event it is unclear for how long or why the interlock had been turned off. Though it is possible that the interlock system has been turned off since 2012 which is the only time the interlock system has knowingly been turned off. The visitors had been standing at the location for 4 minutes during operation of the cyclotron at a 5 m distance. A simulation shows that the total effective dose to individuals
is judged to be below 300 μSv/h. The affected individuals have been informed about the dose received. The dose rate in the cyclotron bunker is not yet confirmed though judged to
be approximately 10 Sv / h.

Corrective actions were performed at the facility, for example the interlock system is now restored. The authority has performed an investigation on site.

Location: University Hospital of UmeƄ
Event date: Fri, 07-10-2016
Nuclear event report
Legenda & explanation