Environmental radioactivity surveillance programme: results for the UK for 1981

The 1981 results of a NRPB report on a UK environmental radioactivity surveillance programme are presented. The concentrations in air of long-lived radionuclides produced by weapons testing were higher than those observed in 1980 due to the intermediate level atmospheric nuclear weapon explosion in Central Asia in October 1980. The concentrations of fission products were the highest observed since 1978; the annual average caesium-137 concentration was three times the value for 1980. The average depositions of strontium-90 and caesium-137 in the UK were also elevated above those in recent years. An average effective dose equivalent commitment of 2 μSv from external irradiation by radionuclides deposited in 1981 added less than 1% to that accumulated from atmospheric nuclear explosions in earlier years. The concentrations of strontium-90 and caesium-137 in milk were higher than that reported for 1980. For a typical adult, the average committed effective dose equivalent attributable to contamination of diet with these radionuclides is estimated to be 4 μSv. The estimate for caesium is consistent with that obtained from direct measurement of this radionuclide in the body. The average annual effective dose equivalent from fallout is evaluated and compared with that from natural background radiation. (author)