COMPUCEA 2nd generation performance evaluation

COMPUCEA (Combined Procedure for Uranium Concentration and Enrichment Assay) is used for on-site analytical measurements in support of joint Euratom-IAEA inspections during physical inventory verification (PIV) campaigns in European Low-Enriched Uranium (LEU) fuel fabrication plants. The analyses provided on site during the PIV involve the accurate determination of the uranium element content and of the U-235 enrichment in verification samples (uranium product samples of solid form , i.e. powders, pellets) selected by the Safeguards inspectors. These samples are dissolved and then measured by energy-dispersive X-ray absorption edge spectrometry (L-edge densitometry) to obtain the uranium elemental content and gamma spectrometry with a Lanthanum-bromide detector for the U-235 abundance determination. The second generation of COMPUCEA equipment is compact, rugged and ready-to use directly after transport, no cooling of the detectors with liquid nitrogen is required. A software package for comfortable instrument control and data handling has been implemented. The paper describes the technique, setup and calibration procedure of the instrument. Results from PIV campaigns and comparisons between COMPUCEA results with data obtained by remote analysis with a qualified primary analytical method are presented, which demonstrate the performance of the technique. The achieved uncertainties are well within the international target values. First results obtained with a sandwich detector configuration for enhanced detection efficiency of the passive gamma spectrometry and a small separate X-ray fluorescence unit for the pre-screening of the samples for their Gd content are discussed.JRC.E.7-Nuclear Safeguards and Forensic

The Euratom Safeguards On-site Laboratories at the Reprocessing Plants of La Hague and Sellafield

In the European Union, nuclear material is reprocessed from irradiated power reactor fuel at two sites ¿ La Hague in France and Sellafield in the United Kingdom. These are the largest nuclear sites within the EU, processing many hundreds of tons of nuclear material in a year. Under the Euratom Treaty, the European Commission has the duty to assure that the nuclear material is only used for declared purposes. The Directorate General for Energy (DG ENER), acting for the Commission, assures itself that the terms of Article 77 of Chapter VII of the Treaty have been complied with. In contrast to the Non Proliferation Treaty, the Euratom Treaty requires to safeguard all civil nuclear material in all EU member states ¿ including the nuclear weapons states. The considerable amount of fissile material separated per year (several tonnes) calls for a stringent system of safeguards measures. The aim of safeguards is to deter diversion of nuclear material from peaceful use by maximizing the chance of early detection. At a broader level, it provides assurance to the public that the European nuclear industry, the EU member states and the European Union honour their legal duties under the Euratom Treaty and their commitments to the Non-Proliferation Treaty. Efficient and effective safeguards measures are essential for the public acceptance of nuclear activities.JRC.E.7-Nuclear Safeguards and Forensic

Production of powder targets for neutron-induced cross section measurements

Nuclear powder targets for neutron-induced cross section measurements were prepared by pressing. The choice of the production technique was related to the type of nuclear experiment and the quality of the powder. This paper describes the production process of unsintered compacts of 94Mo, 95Mo, 96Mo metal powders and 239PuO2 powder with a thickness as low as possible by uniaxial pressing of powders. Special attention goes to the difficulties encountered during the preparation process of 239PuO2 pellets. Investigation on the presence of impurities and so the quality of the PuO2 material was performed by scanning electron microscopy with energy dispersive X-ray spectroscopy, by inductively coupled plasma mass spectrometry, X-ray diffraction and by thermal analysis

Uranium Enrichment Assay with a LaBr3(Ce) Scintillation Detector: A Promising Option for the 2nd Generation of COMPUCEA

A careful evaluation of uranium enrichment measurements with a 2¿ x 2¿ LaBr3(Ce) scintillation detector has been carried out in order to test this new type of detector as a room-temperature detector option for future use in the in-field analyses made with COMPUCEA. Spectrum analysis has been made with an adapted version of the NaIGEM analysis code. Comparative performance data obtained from measurements with HPGe, NaI(Tl) and LaBr3(Ce) detectors on low-enriched uranium reference samples are presented.JRC.E.8-Nuclear safeguards and Securit

Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets

The development of tailored targets for the production of radioactive isotopes represents an active field in nuclear research. Radioactive beams find applications in nuclear medicine, in astrophysics, matter physics and materials science. In this work, we study the use of graphene both as carbon source for UO2 carbothermal reduction to produce UCx targets, and also as functional properties booster. At fixed composition, the UCx target grain size, porosity and thermal conductivity represent the three main points that affect the target production efficiency. UCx was synthesized using both graphite and graphene as the source of carbon and the target properties in terms of composition, grain size, porosity, thermal diffusivity and thermal conductivity were studied. The main output of this work is related to the remarkable enhancement achieved in thermal conductivity, which can profitably improve thermal dissipation during operational stages of UCx targets.JRC.G.I.5-Advanced Nuclear Knowledg

Thermal Expansion of the Heavy-fermion Superconductor PuCoGa5

We have performed high-resolution powder x-ray-diffraction measurements on a sample of 242PuCoGa5, the heavy-fermion superconductor with the highest critical temperature of Tc=18.7K. The results show that the tetragonal symmetry of its crystallographic lattice is preserved down to 2 K. Marginal evidence is obtained for an anomalous behavior below Tc of the a and c lattice parameters. The observed thermal expansion is isotropic down to 150 K and becomes anisotropic for lower temperatures. This gives a c/a ratio that decreases with increasing temperature to become almost constant above ∼150K. The volume thermal expansion coefficient αV has a jump at Tc, a factor ∼20 larger than the change predicted by the Ehrenfest relation for a second-order phase transition. The volume expansion deviates from the curve expected for the conventional anharmonic behavior described by a simple Grüneisen-Einstein model. The observed differences are about ten times larger than the statistical error bars but are too small to be taken as an indication for the proximity of the system to a valence instability that is avoided by the superconducting state.JRC.G.I.5-Advanced Nuclear Knowledg

COMPUCEA: A High-performance Analysis Procedure for Timely On-Site Uranium Accountancy Verification in LEU Fuel Fabrication Plants

COMPUCEA is a transportable system for accurate on-site analytical measurements of uranium elemental assay and enrichment during the physical inventory verification (PIV) in European Low-Enriched Uranium (LEU) fuel fabrication plants. The paper describes the main procedural steps, instrument calibration and performance of the COMPUCEA system, which presently consist of a compact L-edge densitometer and Ge well detectors for 235U enrichment measurements. The performance of room-temperature scintillation detectors, NaI and LaBr3(Ce) has recently been evaluated.JRC.E.8-Nuclear safeguards and Securit

COMPUCEA: a high-performance analysis procedure for timely on-site uranium accountancy verification in LEU fuel fabrication plants

COMPUCEA (Combined Procedure for Uranium Concentration and Enrichment Assay) is used for on-site analytical measurements in support of joint Euratom- IAEA inspections during physical inventory verification (PIV) campaigns in European Low-Enriched Uranium (LEU) fuel fabrication plants. The analytical technique involves the accurate determination of the uranium element content by energy-dispersive X-ray absorption edge spectrometry ( L-edge densitometry) and of the 235U enrichment by gamma spectrometry with a LaBr3(Ce) detector. For evaluation of the LaBr3 spectra a modified version of the NaIGEM code is used, which has recently been adapted to handle the presence of reprocessed uranium. This paper describes the technique, setup and calibration procedure of the instrument. Results from PIV campaigns in 2007 and 2008 are presented, which demonstrate the performance of the technique. First results obtained with a sandwich detector configuration for enhanced detection efficiency of the passive gamma spectrometry are discussed.JRC.E.7-Nuclear Safeguards and Forensic

COMPUCEA 2nd Generation Performance Evaluation

COMPUCEA (Combined Procedure for Uranium Concentration and Enrichment Assay) is used for on-site analytical measurements in support of joint Euratom-IAEA inspections during physical inventory verification (PIV) campaigns in European Low-Enriched Uranium (LEU) fuel fabrication plants. The analytical technique involves the accurate determination of the uranium element content by energy-dispersive X-ray absorption edge spectrometry (L-edge densitometry) and of the 235U enrichment by gamma spectrometry with a LaBr3(Ce) detector. For evaluation of the LaBr3 spectra a modified version of the NaIGEM code is used, which has recently been adapted to handle the presence of reprocessed uranium. This paper describes the technique, setup and calibration procedure of the instrument. Results from PIV campaigns in 2007 and 2008 are presented, which demonstrate the performance of the technique. First results obtained with a sandwich detector configuration for enhanced detection efficiency of the passive gamma spectrometry are discussed.JRC.E.8-Nuclear safeguards and Securit