Detection limits for 90Sr, Pu, Am and Cm in soil and pasture vegetation shortly after a nuclear accident.

This work estimates the critical activity concentrations of 90Sr and the alpha-emitting isotopes of Pu, Am and Cm in soil and pasture vegetation that would be required to exceed the action levels for foodstuffs recommended by the IAEA. The results show that the common detection limits for environmental analysis of these nuclides may be increased by orders of magnitude if the aim of the analysis is to determine whether or not the action levels will be exceeded. This information is useful in the development of more simple and rapid analytical methods to be used shortly after a nuclear accident. In addition to activity concentrations, the critical deposition densities on soil and grazing areas are estimated. Critical limits are also derived for 137Cs and 131I.