Steam leak at Sosnovyi Bor on 18.12.: STUK’s control measurements did not detect abnormal radioactivity in Finland
A steam leak from unit two of the Sosnovyi Bor nuclear power plant on 18 December 2015 was not seen as abnormal radioactivity in Finland. Air samples collected in Kotka and Imatra were analysed during the weekend by the Radiation and Nuclear Safety Authority, Finland (STUK). Even extremely accurate and lengthy laboratory measurements did not indicate signs of radioactive substances possibly originating from Sosnovyi Bor.
A tiny amount (0.8-millionth becquerel per cubic metre of air) of cesium-137, which is regularly detected in air samples, was observed in the sample collected in Kotka. Its origin is in the disaster at the Chernobyl nuclear power plant in 1986. Wind and air streams can lift a small amount of fallout particles to the surface air, thereby becoming visible in air samples. The quantities are so low that they are insignificant in terms of radiation protection.
During the day on Friday after the steam leak, air streams were flowing from Sosnovyi Bor in the direction of Eastern Finland. STUK checked the situation at the Imatra measurement station already on Friday, and no abnormal radioactivity was detected.
After the steam leak had occurred, STUK was in contact with the Russian safety authorities and the power plant. The steam leak was caused by a pipe fracture in the turbine hall, and the reactor was shut down as a normal precautionary measure. The steam leak was stopped on Friday evening. The plant unit is still out of use.
Measurement data on STUK website
STUK monitors radioactivity with air collectors in eight locations: Helsinki, Imatra, Ivalo, Kajaani, Kotka, Kuopio, Rovaniemi and Sodankylä. The air collectors absorb large amounts of air through a filter, with airborne particles separated on the filters. Lengthy laboratory measurements that take several days can detect radioactive substances almost at the level of number of atoms from the filters. Gaseous iodine from a nuclear power plant would also be visible in the measurement data if it existed in the air. Measurement data are published on the STUK website once the analysis has been completed.
The level of ambient radiation is also monitored with an external radiation monitoring network consisting of 255 measurement stations around Finland. The measurement data are automatically updated on the STUK website.
Measurement data on external radiation and radioactivity in outdoor air are also available as open data via the STUK website (Finnish pages)
Director Tarja K. Ikäheimonen, tel. +358 9 759 88 596
Information Officer Riikka Laitinen-Sorvari, tel. +358 9 759 88 210