Understanding the structural relationships within the Th(SO4)2‧xH2O system by hydration and dehydration

National audienc

Investigation of thorium salts behavior on hydration/dehydration

International audienc

Influence de l’hydratation et la déshydratation sur la structure des composés Th(SO4)2xH2O

National audienc

Etude de nouveaux systèmes pour le stockage de la chaleur par voie thermochimique

National audienc

Opportunities for the Multi Recycling of Used MOX Fuel in the US -12122

ABSTRACT Over the last 50 years the US has accumulated an inventory of used nuclear fuel (UNF) in the region of 64,000 metric tons in 2010, and adds an additional 2,200 metric tons each year from the current fleet of 104 Light Water Reactors. This paper considers a fuel cycle option that would be available for a future pilot U.S. recycling plant that could take advantage of the unique opportunities offered by the age and size of the large U.S. UNF inventory. For the purpose of this scenario, recycling of UNF must use the available reactor infrastructure, currently LWR's, and the main product of recycling is considered to be plutonium (Pu), recycled into MOX fuel for use in these reactors. Use of MOX fuels must provide the service (burn-up) expected by the reactor operator, with the required level of safety. To do so, the fissile material concentration (Pu-239, Pu-241) in the MOX must be high enough to maintain criticality, while, in current recycle facilities, the Pu-238 content has to be kept low enough to prevent excessive heat load, neutron emission, and neutron capture during recycle operations. In most countries, used MOX fuel (MOX UNF) is typically stored after one irradiation in an LWR, pending the development of the GEN IV reactors, since it is considered difficult to directly reuse the recycled MOX fuel in LWRs due to the degraded Pu fissile isotopic composition. In the US, it is possible to blend MOX UNF with LEUOx UNF from the large inventory, using the oldest UNF first. Blending at the ratio of about one MOX UNF assembly with 15 LEUOx UNF assemblies, would achieve a fissile plutonium concentration sufficient for reirradiation in new MOX fuel. The Pu-238 yield in the new fuel will be sufficiently low to meet current fuel fabrication standards. Therefore, it should be possible in the context of the US, for discharged MOX fuel to be recycled back into LWR's, using only technologies already industrially deployed worldwide. Building on that possibility, two scenarios are assessed where current US inventory is treated; Pu recycled in LWR MOX fuels, and used MOX fuels themselves are treated in a continuous partitioning-transmutation mode (case 2a) or until the whole current UNF inventory (64,000 MT in 2010) has been treated followed by disposal of the MOX UNF to a geologic repository (case 2b). In the recycling scenario, two cases (2a and 2b) are considered. Benefits achieved are compared with the once through scenario (case 1) where UNF in the current US inventory are disposed directly to a geologic repository. For each scenario, the heat load and radioactivity of the high activity wastes disposed to a geologic repository are calculated and the savings in natural resources quantified, and compared with the once-through fuel cycle

Étude du potentiel pour le stockage de la chaleur de l’oxy-hydroxyde d’uranyle [(UO2)4O(OH)6].5H2O : Influence des cycles d’hydratation/déshydratation sur les propriétés physico-chimiques

National audienc

Influence of humidity on the stability of metaschoepite

National audienc

Production of nanometric PuO2 by hydrothermal decomposition of Pu(IV) oxalate

International audienc

Americium transmutation in a scenario of progressive SFR deployment

International audienceAfter the studies carried out in the frame of the 2006 French act for waste management, the CEA, EDF and AREVA decided to work together on potential progressive transition scenarios from the current French nuclear fleet to a SFR fleet which does not require natural uranium to operate. This paper describes one of these scenarios.The first part of the paper focuses on the presentation and results of this transition scenario, with no minor actinides (MA) transmutation taken into account. The scenario starts with the current French fleet and its replacement by an EPR reactor fleet in which plutonium keeps on being monorecycled. MOX PWR spent fuel (SF) reprocessing begins in 2040 in order to feed three breakeven SFR, commissioned between 2050 and 2059. To prepare for a larger SFR deployment, three more SFRs are commissioned between 2075 and 2085 and small-scale SFR SF reprocessing starts in 2060. In 2090, additional SFR are deployed in order to stabilize total plutonium and used fuels inventories, with a fleet composed of 16 breeder SFR and 22 EPR reactors. Finally, between 2150 and 2185, this EPR/SFR reactor fleet is progressively renewed by a new one composed of 41 breakeven SFR. At the end of the scenario, the total Pu inventory is stabilized at 1260t (mostly present in SF and reactor cores) but the MA inventory in the waste is still increasing at a rate of 2.5tHM/y.The following parts of the paper focus on the impact of americium (Am) transmutation in Am bearing blankets (AmBB) loaded in the SFR commissioned in the scenario. Two cases are described, one considering the Am transmutation in the fleet ultimately composed only of SFR, and the other one considering the Am transmutation starting with the mixed SFR/EPR fleet. Finally, one row of AmBB containing 10wt% of Am is enough to stabilize the Am inventory (in both cycle and waste) if the fleet is only composed only of SFR. In the case of a mixed fleet composed of 16 SFRs and 22 moxed EPRs, two rows of AmBB containing 15wt% of Am are required in each SFR core in order to recycle all of the separated Am. However, in that case the total Am inventory is not stabilized as it is still increasing in the spent fuel and blankets. It is noteworthy that, compared to a scenario with Pu multirecycling but without transmutation, Am transmutation in AmBB can lead to a 30% reduction of the radiotoxicity of the waste accumulated all over the scenario

Radioactive waste inventories in the case of different nuclearoptions for the French reactor fleet

International audienc