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FRINATEK-Fri prosj.st. mat.,naturv.,tek

CHARACTERISATION OF PARTICLES FROM NUCLEAR WEAPONS FALLOUT OVER NORWEGIAN TERRITORIES

Tildelt: kr 4,0 mill.

A significant fraction of actinides released by nuclear weapons tests is associated with radioactive particles. For particle contaminated areas, radiological impact assessments will suffer from large uncertainties unless particle characteristics, weatheri ng and mobiisation of associated actinides are taken into account. Atmospheric tests represent the largest source of actinide contamination to the environment. In total, 543 atmospheric nuclear tests have been performed mainly by the US and the former USS R, with a total yield of 440 Mt. A total of about 0.33 PBq 238Pu, 6.5 PBq 239Pu, 4.3 PBq 240Pu and 142 PBq 241Pu have been released by past atmospheric nuclear tests. The global fallout Pu in Northern Hemisphere is characterised by a Pu-240/Pu-239 atom ra tio of 0.175 - 0.19. In air filter samples collected at Værnes, Skattøra and in Vadsø, Norway, during a period of intense atmospheric nuclear testing and a few days after the worlds largest nuclear detonation ever, hot spots have been identified. This imp lies that radioactive particles in fallout from nuclear weapon tests at Novaya Zemlya deposited on Norwegian territories. Plutonium-239,240 have been analysed in Canadian Arctic ice cores identifying the Nagasaki A-bomb in 1945 and global fallout is recor ded in ice cores from Siberian Altai. However, information on the Pu-240/Pu-239 and U-235/U-238 atom ratios localised to individual radioactive particles would provide unique information, linking specific particle characteristics to specific sources/deton ations. This project aims to provide information on source related characteristics of radioactive particles from atmospheric nuclear fallout, in Svalbard (dated ice cores) and Norway (archived air filter samples from 1950-1960s) to estimate the atmospheri c transport, the inventory of actinides associated with particles, weathering rates and ecosystem transfer of associated actinides. Thus, advanced technologies available abroad (AMS, SR) will be utilized.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek