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

Structural investigation of uranium-neptunium mixed oxides using XRD, XANES, and 17O MAS NMR

Uranium−neptunium mixed dioxides are considered as fuels and targets for the transmutation of the minor actinides in fast neutron reactors. Hereafter, a local and atomic scale structural analysis was performed on a series of U1−xNpxO2 (x = 0.01; 0.05; 0.20; 0.50; 0.75; 0.85) synthesized by the sol−gel external gelation method, for which longer range structural analysis indicates that the process yields solid solutions. The oxidation state of IV for uranium and neptunium cations was confirmed using U LIII and Np LIII edge X-ray absorption near edge structure (XANES). The atomic scale structure was probed with 17O magic angle spinning nuclear magnetic resonance (MAS NMR) for the anion. Structural distortions due to the substitution of U by the smaller Np cation were detected by 17O MAS NMR.JRC.E.4-Nuclear Fuel Safet

Optimisation of uranium-doped americium oxide synthesis for space application

Americium 241 is a potential alternative to plutonium 238 as energy source for missions into deep space or to the dark side of planetary bodies. In order to use 241Am isotope for radioisotope thermoelectric generators (RTG) or heating units (RHU) production, americium materials need to be developed. This study focusses on the stabilisation of a cubic americium oxide phase using uranium as dopant. After optimisation of the material preparation, (Am0.80U0.12Np0.06Pu0.02)O1.8 has been successfully synthesized to prepare a 2.96 g pellet containing 2.13 g of 241Am for fabrication of a small scale RHU prototype. Compared to pure americium oxide, the use of uranium-doped americium oxide leads to a number of improvements from the material properties and the safety point of view, like a good behaviour under sintering conditions or under alpha self-irradiation. The mixed oxide is a good host for neptunium (i.e. the 241Am daughter element) and it has improved safety against radioactive material dispersion in case of accidental conditions.JRC.G.I.3-Nuclear Fuel Safet

A low-temperature synthesis method of AnO2 nanocrystals (An= Th, U, Np, Pu) and associate solid solutions

Production of actinide oxide powder via dry thermal decomposition of corresponding oxalates is currently used at industrial scale at temperatures exceeding 500 °C. Altough it is simple, this method presents some disadvantages such as high decomposition temperature with direct effect on the surface area, pre-organised morphology of the nanoparticles affecting the sintering behaviour, etc. We have recently proposed the hydrothermal decomposition of AnIV-oxalates as a simple way to produce reactive actinide oxide nanocrystals. The method could be easily applied at low temperature (95-250 °C) in order to generate highly crystalline nano-AnO2. We present here the formation conditions of AnO2 (An= Th, U, Np, and Pu) and some associated solid solutions, their stability, and grains growth during thermal treatment. The involvement of the water molecules in the oxalate hydrothermal decomposition mechanism has been demonstrated by the isotopic exchange reaction during the thermal decomposition of the hydrated oxalate in H217O through MAS NMR and Raman techniques.JRC.G.I.3-Nuclear Fuel Safet

The solidification behaviour of the UO2 – ThO2 system in a laser heating study

The high-temperature phase diagram of the UO2 – ThO2 system has been experimentally revisited in the present study for the first time since 1970, using a laser heating approach combined with fast pyrometry in a thermal arrest method. The melting / solidification temperature, which is of fundamental information for a reactor design was studied here. It was found that low addition of ThO2 to UO2 would result in a slight decrease of the solidification temperature. A minimum was found at 3098 K around a composition of 5 mol % ThO2. The solid / liquid transition temperature was then observed to increase again with increasing ThO2 fraction. The literature value of pure ThO2 (around 3630 K) was well reproduced here. Important experimental difficulties, stemming from the high temperatures reached during the measurements, as well as a completeinvestigation with electron microscopy, Raman spectroscopy and powder X-ray diffraction are extensively discussed. These results show the importance of the high-temperature oxygen chemistry also in this actinide oxide compound.JRC.E.3-Materials researc

Preparation and safety testing of Fast reactor Fuels and Targets

Fast reactor driver fuels are based on MOX with a high Pu content. They can be prepared by classical powder metallurgy, but suffer from potential heterogeneities in the Pu distribution, and significant quantities of dust have to be managed in the processing gloveboxes. In contrast, sol gel and infiltration routes offer appealing alternatives especially, if minor actinides are to be included for their transmutation in fast reactor systems. As the processes rely on well controlled liquid to solid conversion steps, resulting in particles in the 20-150 µm size range, dust is no longer an issue for their handling. Furthermore, excellent solid solutions can be obtained by such liquid processing routes. X –ray diffraction is a good means to check the longer range order, but the absolute quality can solely be provided by Magic Angle Spinning (MAS) NMR. A detailed study on the (U,Np)O2 system has shown that the metal atoms around the oxygen atoms are randomly distributed. Fast reactor fuels must fulfil a variety of specifications on pellet diameter, Pu homogeneity, and grain size. The oxygen to metal ration must be less than 2.00 to ensure that the oxygen potential is sufficiently low to avoid internal oxidation of the cladding. In addition, all fast reactor fuels must be compatible with the reactor coolant. The typical tests to ensure this criterion are usually achieved by heating the fuels in the appropriate coolant for 50 hours at pre-selected temperatures, usually the highest temperature in the core, or at higher temperatures to exacerbate any chemical interaction effects. We will report here on the results determined for MOX interaction with lead bismuth eutectic and with MOX fuels with Na at elevated temperatures.JRC.E.4-Nuclear Fuel Safet

Structural Investigation of Uranium–Neptunium Mixed Oxides Using XRD, XANES, and ¹⁷O MAS NMR

Uranium–neptunium mixed dioxides are considered as fuels and targets for the transmutation of the minor actinides in fast neutron reactors. Hereafter, a local and atomic scale structural analysis was performed on a series of U_1–<i>x</i>Np_<i>x</i>O₂ (<i>x</i> = 0.01; 0.05; 0.20; 0.50; 0.75; 0.85) synthesized by the sol–gel external gelation method, for which longer range structural analysis indicates that the process yields solid solutions. The oxidation state of IV for uranium and neptunium cations was confirmed using U L_III and Np L_III edge X-ray absorption near edge structure (XANES). The atomic scale structure was probed with ¹⁷O magic angle spinning nuclear magnetic resonance (MAS NMR) for the anion. Structural distortions due to the substitution of U by the smaller Np cation were detected by ¹⁷O MAS NMR

Optimization of Uranium-Doped Americium Oxide Synthesis for Space Application

Americium 241 is a potential alternative to plutonium 238 as an energy source for missions into deep space or to the dark side of planetary bodies. In order to use the ²⁴¹Am isotope for radioisotope thermoelectric generator or radioisotope heating unit (RHU) production, americium materials need to be developed. This study focuses on the stabilization of a cubic americium oxide phase using uranium as the dopant. After optimization of the material preparation, (Am_0.80U_0.12Np_0.06Pu_0.02)­O_1.8 has been successfully synthesized to prepare a 2.96 g pellet containing 2.13 g of ²⁴¹Am for fabrication of a small scale RHU prototype. Compared to the use of pure americium oxide, the use of uranium-doped americium oxide leads to a number of improvements from a material properties and safety point of view, such as good behavior under sintering conditions or under alpha self-irradiation. The mixed oxide is a good host for neptunium (i.e., the ²⁴¹Am daughter element), and it has improved safety against radioactive material dispersion in the case of accidental conditions

The Safeguards On-Site Laboratory at La Hague June 2000 - June 2005 - Experience over Five Years of Operation

see attachmentJRC.E.5-Nuclear chemistr

In-field Timely and Accurate Measurements - Fundamental to Minimising Safeguards Issues in Reprocessing Facilities

The two large reprocessing plants in Europe, located in Sellafield (UK) and La Hague (F) have a throughput of 800 t and 1600 t of spent fuel per year. In order to meet the safeguards criteria of quantity, timeliness and probability (QTP), these facilities deserve particular attention and appropriate safeguards measures have to be implemented. At either plant Euratom installed an on-site laboratory where the verification measurements are performed with minimal time delays and at highest possible accuracy.JRC.E-Institute for Transuranium Elements (Karlsruhe