A procedure has been developed for the determination of uranium and thorium in geological samples using extraction chromatography. Following sample preparation, uranium and thorium are pre-concentrated by precipitation with iron(iii) hydroxide and then separated using UTEVA resin. The separated uranium and thorium are electrodeposited onto stainless-steel discs and then measured by alpha spectrometry. The procedure was evaluated using uraninite ore, coral and granite reference materials. The uranium and thorium concentrations and the 234 U/ 238 U and 230 Th/ 234 U activity ratio values determined for the reference materials were in good agreement with the certified values. The presence of plutonium was found to interfere with the separation, but the inclusion of a reduction step using iron(ii) sulfamate eliminated the problem. Chemical recoveries for the procedure are similar to those for an anion-exchange procedure, but the extraction-chromatography procedure provides a more rapid separation using less reagents.

A method has been developed for the measurement of chlorine and iodine radionuclides in concrete wastes generated from the decommissioning of nuclear power stations. Sequential oxidation of 129 I and 36 Cl from samples of concrete takes less than 7 h and the method is relatively simple and can be used to reliably determine low levels of 129 I and 36 Cl. Generally, recoveries for the procedure are high (in excess of 70%) and large sample sizes can be tolerated ( ~1-10 g). This paper describes the development of the method and demonstrates a relatively simple, repeatable process for the measurement of 129 I and 36 Cl in concrete wastes. The equipment and the methods used should be available at most reactor sites or nuclear plants.

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