Calculations and measurements of 154Eu and 155Eu in ‘fuel-like’ hot particles from Chernobyl fallout

Calculations of 154 Eu and 155 Eu activities in the Chernobyl Unit IV reactor are given, together with a discussion of the uncertainties involved and comparison with results of other authors. The measurements of activities of the Chernobyl-origin ‘fuel-like’ hot particles (fuel fragments) and analysis of the radionuclide fractionation reveal a common behaviour of 154 Eu, 155 Eu and 144 Ce radioisotopes as regards non-volatility, similar to 95 Zr and 95 Nb in hot particles.