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International audience; Since 1987, the CEA's Committee for the Establishment of Analysis Methods (CETAMA) has regularly implemented interlaboratory comparisons, entitled Evaluation of the Quality Results of Analysis in the Nuclear Industry (EQRAIN). Notably, the EQRAIN U and EQRAIN Pu interlaboratory comparisons assess proficiency in measuring a mass content of uranium or plutonium in reference solutions. This presentation deals with the results of measurement uncertainty assessments from EQRAIN U and EQRAIN Pu comparisons over 20 years of exercises (1997 2016). The mathematical approach developed allows to estimate the impact of short-term systematic and random errors to the overall uncertainty of each analytical method used in the interlaboratory comparison program. This statistical analysis shows a good consistency between measurement uncertainty values from EQRAINs and the measurement uncertainty target values established by the International Atomic Energy Agency (IAEA) for nuclear material balances (ITVs-2010).

International audience; Following the expression of the need for an americium (Am) standard and particularly for one with a certified americium 243 (243Am) content in 2009 and thereafter by the International Atomic Energy Agency, the Commissariat a l'Energie Atomique (CEA) et aux Energies Alternatives/ Direction de l'Energie Nucleaire of Marcoule and the Joint Research Center in Geel carried out a collaborative project for the production of a certified reference material enriched in 243Am. CEA's Commission d'ETAblissement des Methodes d'Analyse organized an interlaboratory comparison on this material prior to the issuing of its certificate. The usefulness of an interlaboratory comparison to assess the measurement capabilities in the field and to confirm the provisional certified values for the amount contents of 243Am, 241Am, total Am, the isotopic composition and the molar mass of Am has been demonstrated. Further this interlaboratory comparison enabled to derive an indicative value for the n(242mAm)/n(243Am) isotope amount ratio.

International audience; The EURATOM work programme project INSIDER (Improved Nuclear Site Characterization for Waste minimization in Decommissioning under Constrained Environment) was launched June 2017. This 4 year project has 18 partners. It aims at improving the management of contaminated materials arising from Decommissioning and Dismantling (DetD) operations by proposing an integrated methodology for radiological characterization. This methodology is based on advanced statistical processing and modelling, coupled with adapted and innovative analytical and measurement methods, with respect to sustainability and economic objectives. In order to achieve these objectives, the approaches will be then applied to common case studies in the form of Inter-laboratory comparisons on matrix representative reference samples and benchmarking. Assessment of the outcomes will be used for providing recommendations and guidance resulting in pre-standardization texts.

International audience; The EURATOM workprogram project INSIDER (Improved Nuclear Site Characterization for Waste minimization in Decommissioning under Constrained Environment) was launched in June 2017. This 4 year project has 18 partners, and aims at improving the management of contaminated materials arising from Decommissioning and dismantling (DetD) operations by proposing an integrated methodology of characterization. This method-ology is based on advanced statistical processing and modelling, coupled with adapted and innovative analyti-cal and measurement methods, with respect to sustainability and economic objectives. In order to achieve these objectives, the approaches will be then applied to common case studies in the form of Inter-laboratory comparisons on matrix representative reference samples and benchmarking. Work Package 6 (WP6) Performance analysis and overall uncertainty' is in charge of the analysis of the benchmarking on real samples, the organisation of inter-laboratory comparison on synthetic certified reference materials and the establishment of overall uncertainty budget.Assessment of the outcome will be used for providing recommendations and guidance resulting in pre-standardization tests.

International audience; Since 1987, the CEA's Committee for the Establishment of Analysis Methods (CETAMA) has regularly implemented interlaboratory comparisons, entitled Evaluation of the Quality of Analysis Results in the Nuclear Industry (EQRAIN). Notably, the EQRAIN U and EQRAIN Pu interlaboratory comparisons assess the proficiency to measure mass content of uranium or plutonium in reference solutions.This paper presents the results of measurement uncertainty assesssment from EQRAIN U and EQRAIN Pu comparisons over 20 years exercices (1997 2016). The chosen mathematical approach allows to estimate contributions due to systematic and random errors in results uncertainty for each of the current analytical methods. This statistical analysis shows a good consistency between measurement uncertainties values from EQRAINs and the measurement uncertainty target values established by International Atomic Energy Agency (IAEA) for nuclear material balances (ITVs 2010).

International audience; The Commission d’Établissement des Méthodes d'Analyse (CETAMA) organises Inter-Laboratory Comparisonround robins entitled “Evaluation of the Quality of Analysis Results in the Nuclear Industry”,” (EQRAIN, “Evaluation de laQualité du Résultat d'Analyse dans l'Industrie Nucléaire”, in French). The “EQRAIN Trace Elements n° 21” inter-laboratorycomparison (ILC), which was launched in the first half of 2016, concerned the elemental chemical analysis of 15 elementswhose concentrations were between 0.2 and 15 mg/L. The main objective of this proficiency test was to check the quality ofmeasurement results for the concentrations of metallic elements in a solution. It enabled the participating laboratories toevaluate their performances in carrying out this type of analysis and if they wish, to compare different analytical techniques.After the measurement results had been returned, the reference values were sent to the laboratories which were then able toestimate the bias of their measurements and to check for the absence of drift, implementing corrective actions if necessary.Inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry(ICP-AES) are the best-adapted analytical techniques for this kind of exercise, leaving atomic absorption a complementaryrole and the use of colorimetry for certain special elements.

International audience; Controlled-potential coulometry is a method of choice for determining plutonium in solution because it is not related to chemical standards but only to physical parameters such as time and current which can be calibrated very accurately.The method is thus called a primary method and is of great interest for metrology laboratories providing certified reference materials of plutonium. Indeed, it allows to attain high trueness with bias close or below 0.1% on low sample amounts, typically a few milligrams of matter.But, coulometry of high degree of accuracy is still a difficult exercise because every step of the procedure, from sample preparation to the signal integration has to be carefully controlled and optimized.This paper describes the key points of the method and emphasizes on uncertainty budget calculations. This approach will allow us to think over the method and adapt the procedure in order to improve trueness and repeatability for plutonium alone but also to cope with measurement of plutonium in presence of uranium.

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This report describes the preparation and certification of IRMM-0243, a 243Am spike reference material. It is certified for the amount content of 243Am and the isotope amount ratios of n(241Am)/n(243Am) and n(242mAm)/n(243Am). Furthermore, the material is certified for the amount contents of 241Am and total Am, the mass fractions of 243Am, 241Am and total Am, the isotope amount and mass fractions (e.g. isotopic composition) and the molar mass of Am. The material was produced in compliance with ISO/IEC 17034:2016 and certified in accordance with ISO Guide 35:2006. The material was prepared by dilution of an americium starting solution in nitric acid and dispensing of the solution into glass ampoules. In total 587 units were produced. Between-unit homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The characterisation of the amount content of 243Am was performed by Isotope Dilution Mass Spectrometry (IDMS) using a 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios of n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by Thermal Ionisation Mass Spectrometry (TIMS). The certified values were verified by alpha particle spectrometry, alpha particle counting at a defined solid angle (DSA) and high-resolution gamma-ray spectrometry as independent verification methods. The uncertainties of the certified values were estimated in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM) [ ] and include uncertainties related to possible inhomogeneity, instability and characterisation. The main purpose of this material is for use as a spike isotopic reference material for the quantification of americium by IDMS in unknown samples. A unit of IRMM-0243 consists of a glass ampoule with a screw cap containing about 3.5 mL nitric acid solution (c = 1 mol/L) with an americium mass fraction of about 1.5 μg/g solution. The material is a true solution; therefore there is no recommended minimum sample intake to be taken into account., JRC.G.2-Standards for Nuclear Safety, Security and Safeguards

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International audience; CETAMA network is organized in 13 thematic working groups. The working group number 21 is dedicated to Electron Probe Micro Analysis (EPMA). Its main mission is to listen to participant needs about EPMA practical issues and to propose tools in order to improve the quality of measurement and analysis results.

International audience; The accuracy of analysis results at each step of the nuclear fuel cycle is of prime importance for nuclear material control and forensic investigations.The IAEA specifies several target values for measurement uncertainties in monitoring nuclear materials. Some of these represent serious challenges for industrial processes.To improve and guarantee accuracy and performance, analysis laboratories rely on certified reference materials (CRM) for measurement quality control, for the calibration of analytical instrumentation, and when spiking samples for elemental assay by isotope dilution analysis. Proficiency tests such as the CETAMA EQRAIN program are tailored for laboratory performance comparisons. In the future, the nuclear fuel cycle and in particular the reprocessing industry and RandD will require new standards and methods to comply with high-content plutonium fuel and new extraction solvents.Some recent involvements of the CETAMA concern-New high chemical purity CRM development or enlarged recertification for actinide analyses,-Enhanced certification methodology,- Feedback on performance assessment,-Support in uncertainty assessments and analytical method standardization.

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The option of direct disposal of spent nuclear fuel in a deep geological formation raises the need to investigate the long-term behavior of the UO2 matrix in aqueous media subjected to alpha-beta-gamma radiation. The beta-gamma emitters account for most of the activity of spent fuel at the moment it is removed from the reactor, but diminish within a millennial time frame by over three orders of magnitude to less than the long-term activity. The latter persists over much longer time periods and must therefore be taken into account over a geological disposal time scale. Leaching experiments with solution renewal were carried out on UO2 pellets doped with alpha emitters (Pu-238 and Pu-239) to quantify the impact of alpha irradiation on UO2 matrix alteration. Three batches of doped UO2 pellets with different alpha flux levels (3.30 x 10(4), 3.30 x 10(5), and 3.2 x 10(6) alphacm(-2) s(-1)) were studied. The results obtained in aerated and deaerated media immediately after sample annealing or interim storage in air provide a better understanding of the UO2 matrix alteration mechanisms under alpha irradiation. Interim storage in air Of UO2 pellets doped with alpha emitters results in variations of the UO2 surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO2 pellet batches and spent fuel. Oxygen diffusion enhanced by alpha irradiation of the extreme surface layer and/or radiolysis of the air could account for the oxidation of the surface UO2 to UO2+x. However, leaching experiments performed in deaerated media after annealing the samples and preleaching the surface suggest that alpha radiolysis does indeed affect the dissolution, which varies with the flux at the UO2/water interface

A device measures the propagation time for an acoustic wave in a continuous phase of a two-phase mix (28) comprising the continuous phase and a dispersed phase forming droplets (40) in the continuous phase. The device comprises an electro-acoustic transducer (12) capable of emitting acoustic waves (30) and outputting a reception signal of reflected acoustic waves, a signal pulse generator capable of determining a propagation time starting from signals output by the transducer, and an acoustic lens for focusing acoustic waves and the frequency of the acoustic waves being adjusted to cause reflection of the waves on the droplets of the dispersed phase, essentially located within a focusing area.