A medical and industrial isotope production factory in Belgium has been shut down after an unusual release of one of its products, iodine-131, through its chimney stack.
The emission began during the weekend 23-24 August and the factory's operator, the Institute of Radioelements (IRE), informed safety regulators at 5.30pm on 25 August. An official from the Federal Agency for Nuclear Control (Fanc) travelled immediately to the plant, at Fleurus about 40 km south of Brussels, and ascertained that 40 GBq of radiation had passed through the chimney. It was then decided that the factory should be shut down.
Iodine-131 is a product the plant produces for medical diagnosis and therapy applications. It also manufactures the radioactive elements xenon-133, yttrium-90 and rhenium-188 for similar uses as well as molybdenum-99/technetium-99m for cancer treatment.
Fanc's French counterpart was informed of the incident on 27 August, while an alert via the Europe's Ecurie system was sent very early this morning. Sharing information from the alert, Spanish authorities said a person who remained at the facility's perimeter fence would receive a maximum radiation dose of 0.10 mSv - one tenth of the standard regulatory annual dose limit for a member of the public. For comparison, the typical limit for workers in a nuclear plant is around 20 mSv, with up to 50 mSv in a single year. Workers at IRE received no additional exposure.
Despite the low levels of radiation involved, Fanc discovered some elevated readings on grass near the plant and advised nearby residents not to eat leafy vegetables or use rainwater from their gardens. Drinking fresh milk from the area was discouraged. Iodine-131 has a half life of eight days.
Not far from the Belgian border, France's Chooz nuclear power plant has heightened its environmental monitoring but has not detected anything abnormal.
Because the incident involved a release of radiation beyond a plant boundary it has been given a preliminary rating on the International Nuclear Events Scale of 3, a 'major incident'. This could be subject to revision, however, as that rating would normally require greater potential radiation exposure.
The cause of the release is as yet unknown.