[en] Preliminary predictions of the ¹³⁷Cs contamination of upland lambs in west Cumbria resulting from the Windscale and Chernobyl accident are presented. The predictions are made using the RUINS model and are tentative, particularly for the Windscale accident given the paucity of data available with which the model can be tested. In west Cumbria in the first year after each accident the Windscale fire is concluded to have resulted in higher ¹³⁷Cs activity concentrations of upland sheep for human consumption than the Chernobyl accident. This was principally due to the timing of the accidents, but could have been exacerbated significantly by differences in farming practice. However, deposition from the Chernobyl accident was more widespread therefore affecting a greater number of sheep. (author)

[en] An experiment was carried out to provide a data set specifically designed to allow the development of a model to describe the dynamic behaviour of radiocaesium in sheep tissue. A single intraruminal dose of ¹³⁴CsCl was given to each of 15 Scottish Blackface ewes, aged 1-2 years. Radiocaesium activity concentrations were measured at various time intervals after dosing in blood, faeces and urine and, after slaughter, in a range of tissues and digestive tract contents. A first order compartment model was developed comprising nine compartments representing various organs and tissues in the body. Rate constants for the model were obtained by optimisation to the experimental results. A limited validation of the model was carried out by using it to calculate tissue transfer coefficients (F_f and biological half-lives (T_0.5) of radiocaesium in sheep. The values generated compare favourably with published figures. Applications for the model and constraints on its usage are examined along with possibilities for further development. (Author)