Développements analytiques en spectrométrie de masse à thermo-ionisation pour l'analyse isotopique de faibles quantités

Dans le cadre d'un axe d'orientation de la loi Bataille sur la gestion des déchets nucléaires, des expériences ont été menées dans le réacteur à neutrons rapides Phénix. Certaines d'entre elles ont consisté en l'irradiation de plusieurs poudres enrichies en un isotope. Ces irradiations vont permettre, par détermination de la composition élémentaire et isotopique de ces échantillons, d'obtenir des données nucléaires de base afin d'étudier la faisabilité de la transmutation. Un des enjeux du projet provient du fait que de faibles quantités de poudres ont été initialement introduites et en conséquence certains produits issus de l'irradiation sont présents en très faibles quantités (nanogramme). L'objectif de cette étude est le développement de méthodes analytiques innovantes pour l'analyse de ces faibles quantités par spectrométrie de masse à thermo-ionisation, technique dans laquelle l'échantillon est déposé sur un filament métallique en vue de son évaporation, son ionisation et sa séparation en masse. Quatre grands axes d'étude ont ainsi été explorés : i) le développement de méthode d'analyse en consommation totale avec traitement des données obtenues, ii) l'étude des potentialités pour la mesure isotopique de nouveaux systèmes de détecteurs, iii) l'étude des techniques de dépôt de l'échantillon sur le filament afin d'améliorer la robustesse de la technique, et iv) enfin la comparaison des données obtenues avec d'autres techniques de spectrométrie de masse. Ces développements ont permis d'analyser des quantités de l'ordre du nanogramme sur des échantillons issus des expériences d'irradiation avec des incertitudes en adéquation avec les attentes des neutroniciens. Au-delà de l'atteinte des objectifs analytiques, cette étude a permis de proposer une technique de dépôt homogène de l'échantillon sur le filament et qui améliore la robustesse de la méthode pour des quantités déposées de l'ordre du nanogramme. De plus, des premières mesures sur des multiplicateurs d'électrons en consommation totale ont été réalisées et ont permis de mesurer des quantités allant jusqu'à quelques centaines de femtogrammes. Plusieurs échantillons irradiés mais aussi des échantillons naturels d'eaux de rivières ont pu être analysés en utilisant les procédures analytiques mises en place et ont fait l'objet d'une comparaison avec une autre technique analytique la spectrométrie de masse à source plasma et système multicollection.In the framework of the French transmutation project of nuclear wastes, experiments consisted in the irradiation in a fast neutron reactor of few milligrams of isotopically enriched powders. Hence, the isotopic analysis of very small amount of irradiation products is one of the main issues. The aim of this study was to achieve analytical developments in thermal ionization mass spectrometry in order to accurately analyze these samples. Several axes were studied including the new total evaporation method, deposition techniques, electron multiplier potentialities and comparison between different isotope measurement techniques. Results showed that it was possible to drastically decrease the amounts needed for analysis, especially with Eu and Nd, while maintaining an uncertainty level in agreement with the project requirements

NUSIMEP-7: Uranium isotope amount ratios in uranium particles

The Additional Protocol (AP) authorizes safeguards authorities to verify the absence of undeclared nuclear activities in all parts of a state’s nuclear fuel cycle as well as any other location where nuclear material is or may be present. As part of the Additional Protocol, environmental sampling has become an important tool for the detection of non-declared nuclear activities. In environmental sampling micrometer-sized uranium particles with an isotopic composition characteristic for the processes at the inspected facility need to be collected, identified and analysed. Considering the potential consequences of the analyses, these measurements need to be subjected to a rigorous quality management system. NUSIMEP-7 focused on measurements of uranium isotope amount ratios in uranium particles aiming to support laboratories involved in uranium particle analysis. It was the second NUSIMEP on particle analysis coordinated by IRMM. NUSIMEP-7 was open for participation to all laboratories in the field of particle analysis, particularly also to the IAEA network of analytical laboratories for environmental sampling (NWAL). The NUSIMEP test samples were prepared by controlled hydrolysis of well certified uranium hexafluoride. Participating laboratories in NUSIMEP-7 received the test samples of uranium particles on two graphite disks with undisclosed isotope amount ratio values n(234U)/n(238U), n(235U)/n(238U) and n(236U)/n(238U). The uranium isotope amount ratios had to be measured using their routine analytical procedures. Measurement of the major ratio n(235U)/n(238U) was obligatory; measurement of the minor ratios n(234U)/n(238U) and n(236U)/n(238U) were optional. 24 institutes registered for NUSIMEP-7, whereof 17 have reported measurement results using different analytical methods, among those were 7 NWAL laboratories. The participants’ measurement results have been evaluated against the certified reference values in compliance with ISO 13528:2005. The results of NUSIMEP-7 confirm the capability of laboratories in measuring n(234U)/n(238U), n(235U)/n(238U) and n(236U)/n(238U) in uranium particles of <1 µm. Furthermore they underpin the recent advances in instrumental techniques in the field of particle analysis. In addition feedback from the measurement communities from nuclear safeguards, nuclear security and earth sciences was collected in view of identifying future needs for NUSIMEP interlaboratory comparisons.JRC.D.2-Reference material

Certification of the uranium hexafluoride (UF6) isotopic composition: The IRMM-019 to IRMM-029 series

This report describes the re-determination and certification of the IRMM-019 to IRMM-029 series of uranium hexafluoride (UF6) reference materials certified for the uranium isotopic composition. The values were assigned following ISO Guide 34:2009. The IRMM-019 to IRMM-029 series was originally produced and certified in the 1980's-1990's. Since, the materials are stored in monel ampoules. Upon customer request, UF6 gas is distilled from a mother ampoule into a daughter ampoule, the isotopic composition is verified by Gas Source Mass Spectrometry (GSMS) and the daughter ampoule is sent to the customer. For the purpose of this project, the UF6 materials were converted into uranium nitrate solutions to perform the homogeneity and characterisation studies. Between-unit homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The materials were characterised by Thermal Ionisation Mass Spectrometry (TIMS) using newly established measurement procedures such as the Modified Total Evaporation (MTE) and Double Spike (DS) methods, and with a new set of certified uranium isotope reference materials, which were prepared by gravimetrical mixing of highly enriched 233U, 235U, 236U and 238U oxides or solutions. The results of the characterisation measurements were also confirmed by GSMS measurements using the original UF6 gases. 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 the characterisation measurements and the homogeneity study. The materials are intended for the calibration of methods, quality control purposes, and the assessment of method performance for isotope mass spectrometry. As with any certified reference material, they can also be used for validation studies. The CRMs are available in monel ampoules. Based on physical reasons, there is no minimum sample intake to be taken into account.JRC.D.2-Standards for Innovation and sustainable Developmen

Preparation and certification of Large-Sized Dried (LSD) Spike - IRMM-1027p

IRMM Large-Sized Dried (LSD) Spikes are widely used as a fundamental part of the fissile material control of irradiated nuclear fuel and have been provided on a regular basis to safeguards authorities and industry for more than 10 years. This report describes the preparation and certification of a new batch of LSD Spikes. IRMM-1027p is a dried nitrate material in cellulose acetate butyrate (CAB), certified for the mass of uranium and plutonium and isotope amount ratios per unit. The material was produced following ISO Guide 34:2009. The certified reference materials uranium metal EC NRM 101, enriched uranium metal NBL CRM-116 and plutonium metal CETAMA MP2 were used as starting materials to prepare the mother solution. This solution was dispensed by means of an automated robot system into individual units and dried down. A solution of an organic substance, cellulose acetate butyrate (CAB), was dried on the spike material as a stabiliser to retain the dried material at the bottom of the vial. Between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The certified values were obtained from the gravimetric preparation of the mother solution, taking into account the mass, purity and isotopic abundances of the starting materials, the mass of the mother solution, and the mass of an aliquot in each individual unit. The certified values were confirmed by isotope dilution thermal ionisation mass spectrometry (ID-TIMS) and thermal ionisation mass spectrometry (TIMS) as independent confirmation methods. 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 and to characterisation. This spike CRM is applied as a calibrant to measure the uranium and plutonium amount content of dissolved spent nuclear fuel solutions using isotope dilution mass spectrometry (IDMS). Each unit contains about 50 mg of uranium with a relative mass fraction m(235U)/m(U) of 17.4 % and 1.8 mg of plutonium with a relative mass fraction m(239Pu)/m(Pu) of 97.8 % as dried nitrates in CAB. The whole amount of sample per unit has to be used for analysis.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Développements analytiques en spectrométrie de masse à thermo-ionisation pour l'analyse isotopique de faibles quantités

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Comparaison de deux méthodes de séparation chromatographique pour la séparation U-Pu pour des analyses isotopiques par spectrométrie de masse à système multi-collection

International audienceLa mesure des compositions isotopiques en U et en Pu est essentielle dans le domaine du nucléaire et plus particulièrement dans le cadre de la non-prolifération nucléaire. Le LANIE (Laboratoire de développement Analytique Nucléaire Isotopique et Elémentaire) participe à de nombreux circuits d'intercomparaisons sur différents types d'échantillons à base d'U et de Pu dont notamment le circuit EQRAIN (Evaluation de la Qualité du Résultat d'Analyse dans l'Industrie Nucléaire) organisé par la CETAMA (Commission d'ETAblissement des Méthodes d'Analyse). Ils permettent au LANIE d'évaluer ses performances pour la détermination des compositions isotopiques et élémentaires par spectrométrie de masse à Thermo-ionisation (TIMS) ou par spectrométrie de masse à source plasma multicollection (ICPMS MC). Pour atteindre les meilleures précisions possibles des étapes de séparations sont nécessaires pour se départir des principales interférences isobariques (238U-238Pu, 241Pu-241Am).Dans le cadre d'un circuit de validation de méthode mené par la CETAMA, les performances de la séparation U-Pu via 2 supports chromatographiques différents ont été évaluées. Les deux supports chromatographiques testés sont la résine UTEVA (Triskem) et la résine anionique AG 1X4 (BioRad). La comparaison a été faite sur deux solutions, un échantillon de Pu seul avec des traces d'238U et d'241Am issus de la décroissance respective du 238Pu et du 241Pu et un mélange avec un rapport U/Pu de l'ordre de 20. Deux purifications successives ont été réalisées et les rendements de séparations ont été évalués. Après chacune des étapes de purification des mesures isotopiques ont été effectuées à la fois par TIMS et par ICPMS MC sur la base des méthodes du laboratoire et en utilisant en particulier une résistance 1013 pour la détermination du Pu 238.Cette étude nous a permis tout d'abord de démontrer l'importance du conditionnement des résines et le rôle majeur du cycle d'oxydo-réduction afin de mettre le Plutonium sous une seule et même valence lors de son introduction sur la résine. Nous avons également démontré que la résine UTEVA avait un plus fort pouvoir de décontamination de l'Uranium dans la fraction Plutonium que l'AG1X4. Des différences ont été observées avec les deux protocoles au cours de l'étape de dépôt sur filament pour les mesures TIMS. Cette étude s'est aussi accompagnée d'une intercomparaison des performances de la mesure isotopique du Pu en TIMS et ICPMS MC

Standardization of Nuclear Mass Spectrometry Methods for Nuclear Safeguards

A standardized new version of the "modified total evaporation" (MTE) method for isotopic analysis of uranium samples by multi-collector thermal ionization mass spectrometry (TIMS) with high analytical performance is described. The development of the MTE method was organized as a collaboration of several nuclear mass spectrometry laboratories, namely the New Brunswick Laboratory (NBL, U.S.DOE), the Safeguards Analytical Laboratory (SAL, now SGAS-Safeguards Analytical Services) of the International Atomic Energy Agency (IAEA), the Institute for Transuranium Elements (JRC-ITU), and the Institute for Reference Materials and Measurements (JRC-IRMM). Due to the use of the “total evaporation” (TE) principle measurements of the "major" ratio 235U/238U is routinely being performed with an accuracy of 0.02%. But the most significant improvement using the MTE method is in the measurement performance achieved for the "minor" ratios 234U/238U and 236U/238U. The MTE method provides a measurement performance which, depending on the ratio, is several orders of magnitude superior compared to the IAEA requirement and to the TE method. For routine MTE measurements a detection limit of 3×10-9 for the 236U/238U ratio is achieved using an SEM detector combined with an energy filter for detecting the isotope 236U. The MTE method has proven to be a significant improvement for measuring in particular the "minor" isotope ratios 234U/238U and 236U/238U in the frame of performing reference measurements for development and production of certified reference materials at NBL and JRC-IRMM as well as for nuclear safeguards measurements at the IAEA and JRC-ITU. The collaboration between JRC-IRMM and ASTM-International started with the invitation to develop an ASTM standard document for the MTE method in 2013. The recently released new MTE standard ASTM C1832-16 document does not only provide a detailed description and instructions for users, it also provides information about the typical analytical performance to be expected. This is beneficial to the user in conformity assessment with the deployed quality system, as well as to organizers of interlaboratory comparisons (ILCs), such as JRC-IRMM, NBL, IAEA or others.JRC.G.2-Standards for Nuclear Safety, Security and Safeguar

Development of a microfluidic device for the analysis of nuclear samples

International audienceThe miniaturization and integration of analytical tools in microfluidic devices, in the form of labs-on-chip or micro total analysis systems (µ-TAS), currently offer several advantages: the opportunity to analyze rare samples with limited quantities available, to better control parameters that influence reactions, and to develop portable systems for on-site analyses. In the nuclear field, an additional advantage consists in reducing the volume of samples to handle and the corresponding doses, the amount of reagents, as well as the amount of produced waste and the necessary costs for their specific management. Indeed, in order to characterize the elemental and isotopic composition of samples for the management of effluents from nuclear facilities, of those resulting from processing steps or of spent fuels, various purification steps by solid phase extraction are necessary, upstream of mass spectrometry measurements (ICP-MS, TIMS). While there are established protocols to perform radionuclides separation such as U and Pu from commercial resins (e.g. UTEVA™, TBP™, TRU™), those are time-consuming and require large volumes of resins and eluents. This work aims to develop a separative microsystem including a monolithic support in order to reduce the scale of nuclear samples purification protocols.First, different materials (e.g. glass, thermoplastics) for the microsystem conception were evaluated in order to find the best compromise in relation to the targeted application. These were compared in terms of resistance to concentrated acids which are associated with the sample matrices and the radiochemical separation conditions; in terms of ease and repeatability of monolith anchoring process in the microsystem channels; and of cost and ease of shaping. To date, most monoliths described in literature are synthesized and anchored in silica capillaries or glass chips, materials that are easily functionalized unlike thermoplastic polymers such as cyclic olefin copolymer (COC) or polytetrafluoroethylene (PTFE), which are known to be chemically inert but easily shaped. Organic monoliths bearing phosphate monomers with a good affinity for actinides have been synthesized by photopolymerization in commercial microsystem channels or internally fabricated by micromilling. Particular attention was paid to limit diffusion effects during monoliths synthesis.The different functionalized microsystems were characterized in terms of morphology and permeability before developing their coupling with an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Dedicated quantification methods have been developed to determine on-line their selectivity towards simulants (U, Th, and Eu as simulants for radionuclides U, Pu, and Am) in different media as well as their loading capacity. The development of these different steps in a conventional laboratory is essential to validate the downscaling of the separation protocol before applying it to the purification of radioactive samples, requiring a transposition in a glove box in a controlled area

Certification of the uranium hexafluoride reference materials for isotopic composition

The IRMM-019 to IRMM-029 series of uranium hexafluoride materials is certified for the isotopic composition. After conversion into uranyl nitrate solution, certification and homogeneity measurements were performed by Thermal Ionization Mass Spectrometry. Analyses were performed by Modified Total Evaporation and for some materials the major isotope amount ratio n(235U)/n(238U) was measured using a n(233U)/n(236U) double spike. Measurements were confirmed by UF6 Gas Source Mass Spectrometry. Major isotope amount ratios were certified with relative expanded uncertainties (k=2) from 0.015 % to 0.030 %, minor isotope amount ratios n(234U)/n(238U) and n(236U)/n(238U) with relative expanded uncertainties ranging from 0.02 % to 3 %.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Standards for uranium hexafluoride (UF6) mass spectrometry

For UF6 mass spectrometry two types of "standards" are equally important: firstly "documentary standards" which describe specific measurement techniques and associated calculations, and secondly "material standards" which are preferentially SItraceable certified isotopic reference materials, as e.g. provided by the European Commission's Institute for Reference Materials and Measurements (IRMM). Recently the IRMM has upgraded its facilities for uranium isotopic measurements using uranium hexafluoride (UF6) gas by the acquisition of a new gas source mass spectrometer (GSMS), the "URANUS" from Thermo Fisher. By that IRMM has expanded its UF6 mass spectrometry capability from measurements of only the "major" isotope ratio n(235U)/n(238U) towards the so-called "minor" isotope ratios n(234U)/n(238U) and n(236U)/n(238U). The minor ratios contain increasingly valuable information about the source of the original ("feed") material used for the commercial or possibly clandestine isotopic enrichment of UF6 and have therefore reached a high level of attention for safeguards authorities. "Documentary standards": within the recent few years new measurement techniques for UF6-GSMS have been developed at IRMM, e.g. the "memory corrected double standard" (MCDS) technique which shows an improved measurement performance for both the "major" n(235U)/n(238U) isotope ratio as well as the "minor" isotope ratios n(234U)/n(238U) and n(236U)/n(238U). A careful revision of some of the documentary standards for UF6 GSMS measurements (e.g. ASTM C1429-99) is now strongly suggested by IRMM. This will be an important contribution to improve the overall performance of UF6 GSMS measurements. It is a good example of the JRC’s expertise contributing to standardization and innovation by further developing material standards and reference methods but also documentary standards to the benefit of the safeguards community and industry. "Material standards": IRMM has just started a comprehensive project for a new certification of the worldwide most widely used and well-known IRMM-019 to IRMM-029 series of 12 UF6 reference materials. Special emphasis will be given on achieving lower uncertainties particularly for the "minor" isotope ratios using previously established high performance TIMS instrumentation and techniques. This new certification is a prerequisite for achieving accurate results for UF6 GSMS measurements also for the minor ratios to be used for nuclear safeguards investigations.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard