A new Certified Reference Material for radionuclides in Irish sea sediment (IAEA-385).

A new Certified Reference Material (CRM) for radionuclides in sediment (IAEA-385) is described and the results of the certification process are presented. Eleven radionuclides ((40)K, (137)Cs, (226)Ra, (228)Ra, (230)Th, (232)Th, (234)U, (238)U, (238)Pu, (239+240)Pu and (241)Am) have been certified and information mass activities with 95% confidence intervals are given for seven other radionuclides ((90)Sr, (210)Pb((210)Po), (235)U, (239)Pu, (240)Pu and (241)Pu). Results for less frequently reported radionuclides ((60)Co, (99)Tc, (134)Cs, (155)Eu, (224)Ra and (239)Np) and information on some activity and mass ratios are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in sediment samples, for the development and validation of analytical methods and for training purposes.

Radiochemistry: inconvenient but indispensable

Radiochemistry has always been and still is a crucial tool in the field of radionuclide determination, both for high and low level works; this holds particularly in the case of alpha and beta emitters. Requests to the analyst are increasingly demanding in terms of performance (detection limit, reliability, accuracy, precision,...), but also of economy (cost, time,...) and of flexibility with respect to sample types. In general, chemical and radiochemical analyses consist of four main steps: sample pre-treatment including pre-concentration, dissolution and/or digestion, separation of analytes from the matrix and from each other, transformation of the separated fraction into a source suited for measurement, determination of the amount or the activity of the analytes. The required combination of sub-procedures is determined by the analytes under investigation, their absolute and relative amounts, the matrix composition and by the performance required. IRMM's Analytical Chemistry Unit started several years ago to develop, adapt and/or validate various radiochemical methods and procedures, and apply these to different measurement tasks. This paper gives an overview on recent and ongoing activities.

Determination of thorium in environmental and workplace materials by ICP-MS.

The paper outlines the advantages of the use of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) over radiometric techniques to measure natural thorium, 232Th. Experimental parameters that must be taken into account in the sample digestion, preparation and ICP-MS analysis of environmental (soils, rocks, sediments) or workplace (thorium oxide, reference solutions) materials are described. The methods presented are applied to various reference materials, with the aim of providing suitable procedures to be useful for other important thorium containing materials (such as monazite sands or welding electrodes). The participation in a European Commission intercomparison exercise is detailed and a comparison with alpha spectrometry is made.

Actinoid separations by extraction chromatography

Two separation methods based on extraction chromatography are presented: the first for the determination of Pu and Am, and the second for U and Th. These two methods are applied to (i) the determination of Pu and Am in diluted MOX samples and (ii) the analyses of Th from four standard solutions. Both of the methods gave high recoveries and showed good reproducibility for Th, Pu and Am. Special requirements for the determination of Th are discussed.

Pre-concentration of actinoids from waters: a comparison of various sorbents

The first part of comparison study was based on the properties of different sorbents. These included different forms of manganese oxides, and specific organic ion-exchangers: HYPHAN and POLYORGS. In order to provide reproducible samples with moderate presence of possible interferences, spiked tap water was used for this first set of experiments. Results indicate that the sorption of Th, U, Pu and Am varies for different forms of manganese oxides. These variations are attributed to different physico-chemical properties of the oxides. HYPHAN was limited in its sorption to Th and U. The manganese oxide dissolved rapidly and the radiochemical separation procedure was quick and simple using extraction chromatography techniques. The radionuclides in the water samples were determined by ICP-MS and/or alpha spectrometry.