Determination of ⁷⁵Se, ⁹⁵Zr, ²³⁷Np and ²⁴¹Am activities in Boom Clay samples from laboratory migration experiments using γ-ray spectrometry

Percolation tests (i.e. routine laboratory migration experiments) have been performed to evaluate the diffusion behaviour of a number of long-lived radionuclides in Boom Clay, a candidate geological host formation for high level radioactive waste (HLW) in Belgium. Among the many potentially hazardous radionuclides under investigation are ⁷⁹Se, ⁹³Zr, ²³⁷Np, ²⁴¹Am and ²⁴³Am. Actinide migration experiments have been carried out with ²³⁷Np and ²⁴¹Am, while for the studies with Se and Zr the radioisotopes ⁷⁵Se and ⁹⁵Zr were used. Their transport patterns in the Boom Clay were examined using a combination of a NaI(Tl) detector and High- Purity Ge detectors either on the dissolved matrix (²³⁷Np, ²⁴¹Am) or directly on the clay (⁷⁵Se, ⁹⁵Zr). (C) 2000 Elsevier Science Ltd.