Institute For Reference Materials And Measurements Research Articles

Development of technology for high-purity [formula omitted] production by method of electromagnetic separation

The IAEA needs plutonium isotopic reference materials and spikes certified to an accuracy of 0.05% or better for the verification of large throughputs and inventories of plutonium under IAEA safeguards and for the isotopic analysis of traces of plutonium in environmental samples taken to confirm state declarations. At the request of the IAEA the Russian Federal Nuclear Center (RFNC) has defined a plan to produce highly enriched plutonium isotopes necessary for the preparation of the required reference materials and spikes. The objective is to produce about 260 mg of 99.74% enriched 242 Pu and up to 100 mg of 99.56% enriched 244 Pu by electromagnetic separation starting from 5 g of a feed material of US origin containing about 16% of 244 Pu . A second enrichment cycle is foreseen to produce about 1 mg of 99.99% enriched 244 Pu . In view of the limited amount of feed material, RFNC will upgrade its technologies and procedures for the preparation of high-purity plutonium chloride, the processes of ionisation, the radiochemical recovery of the material deposited on the collectors of the mass separator or scattered in the machine and the regeneration of the latter, before proceeding with the production of the isotopes requested by the IAEA. To cover the cost of this development RFNC has applied to the International Science and Technology Center for a grant which is presently under evaluation. The project described in this paper is undertaken with the close support and collaboration of the IAEA, Los Alamos National Laboratory (LANL), New Brunswick Laboratory (NBL) and the Institute for Reference Materials and Measurements (IRMM).

Measurement of low-level radioactivity in bone ash

Bone is a critical organ for the accumulation of many radionuclides including 90Sr and the actinides. The National Institute of Standards and Technology (0NIST) has prepared bone ash samples with a view to producing a standard reference material. The Institute for Reference Materials and Measurements (IRMM) participated in the analysis for the certification of the radionuclide concentrations in the bone ash. This article describes the assaying of the actinides, 90Sr, 210Pb and 226Ra activity concentrations. A radiochemical procedure based on extraction chromatography has been developed to separate these radionuclides from the bone ash. The activity concentrations of the actinides, 210Pb and 226Ra have been measured using gamma-ray spectrometry and alpha-particle spectrometry and that of 90Sr using low-level liquid scintillation counting.

Calibration procedures for a multicollector mass spectrometer for cup efficiency, detector amplifier linearity, and isotope fractionation to evaluate the accuracy in the total evaporation method

The procedure used for the evaluation of the cup efficiency factors of a multicollector mass spectrometer is described and results are given that were obtained with three different isotopes ( 187Re, 238U, and 239Pu). A check of the linearity of the detector amplifier system including the Faraday cup itself is described using the uranium reference material of IRMM (Institute for Reference Materials and Measurements) series 072. These reference materials allow the determination of the mass fractionation on the 235U/ 238U ratio to correct the 233U/ 235U ratio which is used to check the linearity of the whole system at different ion intensities. The correction factors determined through these procedures were applied to the results of isotope analyses obtained by total evaporation in order to evaluate the magnitude of residual biases. The mass spectrometer used for these tests is a 12 year old Finnigan MAT 261 with nine fixed Faraday collectors in a configuration allowing simultaneous measurement of all uranium and plutonium isotopes.

CCQM-1 interlaboratory study, measurement of lead amount content in water by a primary method of measurement: direct isotope dilution

The first interlaboratory study of the Consultative Committee for Amount of Substance (CCQM) focused on the determination of lead concentration in a synthetic water sample. In the framework of the CCQM activities, only leading metrology institutes participated in the study. The prescribed analytical method was double isotope dilution mass spectrometry (IDMS) as a primary method of measurement (PMM). At the Institute for Reference Materials and Measurements (IRMM) the material was additionally analysed by direct IDMS as a primary method of measurement using, completely independently, a certified spike reference material. The work described in this paper concerns direct IDMS. Conclusions are drawn on the use of IDMS as a PMM, on the comparison of the results with those of double IDMS, on the use of a certified spike reference material and on the calculation of uncertainty.

Quantitative determination of cadmium in polyethylene using total reflection X-ray fluorescence (TXRF) spectroscopy

A new application of total reflection X-ray fluorescence (TXRF) spectroscopy was tested for its use in the quantitative determination of element mass fractions (Z ≥ 12) in solid polyethylene samples. The experiments were conducted with four polyethylene reference materials from the Institute for Reference Materials and Measurements (IRMM) with cadmium mass fractions in the range from 40 to 400 mg/kg (VDA 001–004). Samples from each reference material were transferred as thin films straight onto quartz glass discs commonly used for TXRF analysis. Precision, accuracy and capability of the method are discussed on the basis of the current results and recent experiences with real samples. The method appears to be suitable for tasks in forensic science and polymer analysis.

The ultra-clean chemical laboratory (UCCL) at the Institute for Reference Materials and Measurements (IRMM)

An Ultra-Clean Chemical Laboratory (UCCL) has been built at IRMM to allow reliable, contamination-free chemical treatment of samples prior to inorganic elemental or isotopic analysis. The concept is intended to guarantee a dust-free environment as well as resistance to corrosion even if hot concentrated mixtures of acids are continuously used, thus establishing not a clean or dust-free room but a clean laboratory. The excellent air quality is demonstrated both by particle measurements and the analysis of acids purified by subboiling distillation in the UCCL.