Cesium 137 now traced back to the property’s garage and parts of its basement premises
The radioactive cesium 137 detected by the Radiation and Nuclear Safety Authority (STUK) on the 3rd and 4th of March has now been traced back to the garage and parts of the basement of the building in which STUK operates. The same property complex also houses a company that treats small radioactive waste. The premises in question have been isolated and the measurements continue. Areas in the immediate vicinity of the property will be examined on Wednesday morning by STUK’s own measurements.
“The investigation concerning the source of the radiation is still ongoing. The concentrations measured have been very low and do not pose a threat to health. The staff and people who’ve visited STUK’s premises are not in any danger,” says STUK’s director Tarja K. Ikäheimonen.
Cesium 137 is used as a radiation source by the industrial sector in, for instance, measuring the thickness of materials and in radiotherapy in hospitals.
The particle sampler on the roof of STUK’s building in Roihupelto, Helsinki, collected an exceptionally high amount of radioactive cesium 137 on the 3rd and 4th of March. While the measurement data—4,000 microbecquerels per square metre of air—is about a thousand-fold compared to normal, it is nevertheless only a millionth of a concentration that would require people to shield themselves from it. The amount detected does not pose a threat to health.
“After the observation, we continued our investigations by measuring the filters of the air samplers at five other localities and looking at the concentrations of radioactivity recorded by the sampler in Helsinki on the 4th and 5th of March. Nothing out of the ordinary was detected in the data from the air samplers in Imatra, Kuopio, Loviisa, Olkiluoto and Rovaniemi. On the 4th and 5th of March, the cesium 137 concentration of the sampler in Helsinki was 12 microbecquerels per square metre of air. This means that the radiation level has dropped back to normal,” says STUK’s director Tarja K. Ikäheimonen.
STUK also monitors outdoor radiation in Finland with the help of an automated radiation monitoring network composed of 255 monitoring stations. Rather than collecting samples from the air, these monitoring stations measure real-time environmental radiation directly. The monitoring stations give an immediate warning if the radiation level rises above the level of normal background radiation, which is 0.05–0.3 microsieverts per hour. The concentrations now detected by the particle sampler are so low that they are not observable even as a slight rise in normal background radiation in the outdoor air, due to which the automated monitoring network does not detect them.
For further information, please contact:
Director Tarja K. Ikäheimonen, tel. +358 9 759 88 596
Head of Public Affairs Kaisa Raitio, tel. +358 9 759 88 795