Radiological inventory of irradiated graphite samples

International audienceIn France, graphite is present as reflector, moderator or structural element in 9 Gas Cooled Reactors which are now in decommissioning phase. The creation of storage, whose characteristics have to be determined, dedicated to irradiated graphite is planned in France for 2010. Consequently, the radiological inventory of the graphite has to be done. Measurement campaigns already organised on different graphite samples showed discrepancies for the computed calculation-measurement ratio and the necessity to acquire more experimental results was stressed. The ability to realise an experimental radiological inventory, with particular attention to 3H, 14C, 36Cl and 63Ni, was studied. A new mineralization was developed based on an acid attack (iodic+sulfuric acid). This process causes a high gaseous emission and can not be applied to analyses of volatile elements such as 14C, 3H and 36Cl. The routine pyrolysis protocol used to measure these elements in other matrices, was specially adapted to the graphite samples. After these mineralizations, radiochemical steps were conducted in order to separate the different requested radionuclides. The mean yield of the complete separation process was evaluated for each of them and the detection limits were evaluate

Improvement of a radiochemical separation for selenium 79 applications to effluents and nuclear wastes.

International audienceSelenium 79 is a beta emitter produced from 235U fission and is one of the long half-life radionuclides of interest in nuclear waste disposal problematic because of its potential migration capacity to the surface environment. Measurement of 79Se is particularly difficult due to its low activity in waste matrices (about 10-3 Bq g-1). A radiochemical procedure based on ion exchange separations was already described in a previous paper. This work presents different applications of the radiochemical separation to waste samples and an improvement of this procedure, including a selective extraction of selenium as diethylselenium in an organic solvent followed by a re-extraction in aqueous medium. This additional step allows the decontamination factor to be increased with the aim of counting 79Se by liquid scintillation counting

I and

129I, is a natural long-lived isotope, with a half-life of 15.7 million years, also artificially produced in nuclear power plant and released in liquid and gaseous effluents of nuclear fuel reprocessing plants. Due to the lack of environmental international reference material for 129I, interlaboratory comparison exercises are very rare and validation of new measurement techniques is very difficult to achieve. This study presents three intercomparison exercises on the 129I and 129I/127I measurements using three different techniques: Radiochemical Neutron Activation Analysis, Accelerator Mass Spectrometry and direct γ-X spectrometry associated with Ionic Chromatography. The first intercomparison was performed on a Fucus serratus sample, leading to propose it as a reference material. The others intercomparison exercises were performed on samples of different biological matrices, marine and terrestrial, presenting various 129I activity levels. The different intercomparison exercises results showed a good agreement between the three techniques on the considered environmental matrices, for samples with 129I activity comprised between 0.2 and 200 Bq.kg-1 dry weight

International comparison of activity measurements of radon 222: EURAMET Project n°1475 – EURAMET.RI(II)-S8.Rn-222

International audienceAn international comparison of activity per unit volume of 222Rn (EURAMET project N° 1475, registered in KCDB as supplementary comparison EURAMET.RI(II)-S8.Rn-222) was organised in 2019 within the framework of the European project MetroRADON. The LNE-LNHB is the pilot of the comparison. Samples of 222Rn gas provided by the LNE-LNHB were sent to the participants and were measured using various techniques. The reference value is the power moderated mean (PMM) (Pommé, 2013) of the seven submitted results

Results of the EURAMET.RI(II)- S7.Sm-151 supplementary comparison (EURAMET Project 1292)

An international comparison of the activity standardisation of the relatively long-lived gamma-ray emitter 151Sm has been recently completed. A total of six laboratories measured a solution prepared by CEA/LNHB and CEA/LANIE. Aliquots of the master solution were standardized in terms of activity per mass unit by participant laboratories using 2 different techniques. The results of the comparison can be used as the basis for establishing equivalence among the laboratories. The activity measurements of this comparison are part of the joint research project “Metrology for Radioactive Waste Management” of the European Metrology Research Programme (EMRP). One aim of this project is a new determination of the 151Sm half-life.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Results of an international comparison for the determination of radionuclide activity in bilberry material

Radioactivity found in wild food products has assumed greater importance when assessing the total exposure of the population. For this reason, IRMM has been developing a candidate reference material for the activity concentration of 40K and the anthropogenic radionuclides 90Sr and 137Cs in bilberry samples collected in the Chernobyl region. In order to characterise this new material, which had been processed into a homogeneous powder, a CCRI(II) supplementary comparison was organised, piloted by the IRMM. The results for the gamma-ray emitters, 40K and 137Cs, are treated in this paper. The difficulties encountered in this comparison are discussed, in particular the preparation of reproducible volume sources and the efficiency transfer from SI-traceable standard sources to the measurement parameters of the test samples. Comparison reference values for 137Cs and 40K were calculated with coefficients of variation of 4 % and 7 %, respectively. These relatively high uncertainties can probably be attributed to the use of a secondary method and the mentioned difficulties.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Activity concentration measurements of 137Cs, 90Sr and 40K in a wild food matrix reference material (Wild Berries) CCRI(II)-S8

In 2009, the CCRI approved a supplementary comparison to be organised by the IRMM as pilot laboratory for the activity concentrations of 137Cs, 90Sr and 40K in a matrix material of dried bilberries. The organisation of this comparison and the material and measurement methods used are described. The supplementary comparison reference value (SCRV) for each of the three radionuclides are given together with the degrees of equivalence of each participating laboratory with the SCRV for the specific radionuclide. The results of this supplementary comparison allow the participating NMIs/designated institutes to declare calibration and measurement capabilities (CMCs) for the given radionuclides in a similar type of food matrix, an important aspect seen the relatively few supplementary comparisons for activity in matrix materials organised so far.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

The CCRI(II)-K2.Fe-55.2019 key comparison of activity concentration measurements of a 55^{55}Fe solution

International audienceA comparison of the activity concentration of an 55 Fe solution was organized by the POLATOM under the auspices of the CCRI(II). The solution was sent to thirteen laboratories; ready-to-measure sources were also prepared using the same 55 Fe solution in diffusive (polyethylene) vials and sent to twelve laboratories. Twelve measurement reports were received. The results, as well as relevant information on the measurement techniques, are presented and analysed in this paper. The differences in the results obtained from measurements in non-diffusive (glass) and diffusive vials are indicated. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/ . The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA)