French transition scenarios toward a symbiotic nuclear fleet

International audienceScenario studies are performed in France to explore future options of nuclear energy development within the limits of conservative criteria defined by AREVA, EDF and CEA. These scenarios assume a constant electricity production. They ultimately lead to nuclear systems which do not need any natural uranium supply. Here a fleet composed of 10 MOX fueled EPRTM (European Pressurized water Reactor) and 28 breeder SFR (Sodium Fast Reactor) of 1.51 GWe is deployed it is symbiotic since plutonium production and consumption balance. SFR and EPR MOX fuels are reprocessed together at equilibrium.Two scenarios are presented the progressive transition to the symbiotic equilibrium begins from 2150 whereas the fast transition starts in 2090. When transitioning, 10 EPRTM are fed with MOX (to 30% at least) while a considerable number of SFR are deployed. Plutonium availability is therefore so critical that the fast transition is only possible at the price of a significant increase of the reprocessing capacity, over 1700 tHM/yr for near 30 years. Substantial natural uranium savings and spent fuel reduction are achieved in the 22nd century with respect to a one-through cycle. This study raises a new area of consideration for a sustainable development of nuclear energy in France

Effect and uncertainties of H in Ice thermal scattering laws on the neutron multiplication factor for PWR fuel criticality applications

International audienceIn the context of the IAEA recommendation to ensure the transportation of fuel assemblies between 233 K and 311 K, thermal scattering laws of hydrogen in iced water have been produced with the LEAPR module of the NJOY code and included in the JEFF-3.3 nuclear data evaluation. Following this work, a benchmark was launched by the OECD/NEA Working Party on Nuclear Criticality-Safety subgroup-3 to evaluate the effect of the temperature on a PWR assembly criticality. This paper first focuses on the results obtained on this benchmark by CEA with the TRIPOLI-4 ® Monte-Carlo code. They show that, in terms of criticality-safety, computations made at 293 K are conservative and that the impact of density on the k eff is much stronger than the nature of the hydrogen bound or the adjustment of nuclear data to temperature. To go further, the uncertainties associated with the thermal scattering laws of hydrogen in iced water have been evaluated and propagated on one of the benchmark cases. The reference method to do so consists in a direct propagation of the LEAPR model parameters uncertainties. Another method, based on covariance matrix of the hydrogen in iced water scattering cross section, was also used in order to evaluate its relevance. The direct propagation leads to an uncertainty of 111 pcm. The uncertainty evaluated with the second method is lower by around 50 pcm. Whatever the method considered, those uncertainties remain acceptable in the criticality-safety context especially as the effect of the temperature on the k eff and the impact of the hydrogen bound nature are both low regarding density effects

COSI6 : a Tool for Nuclear Transition Scenarios Studies

International audienceNuclear systems, composed of reactors with varied fuel and cycle facilities (enrichment plant, fabrication plant, reprocessing plant,) are complex and in constant evolution. Decision makers need to have all the technical elements, based on dynamic nuclear fleet transition scenarios studies. These scenarios are tools to compare different options of nuclear systems evolution, and identify strengths and drawbacks. To have a complete overview of nuclear systems, it is required to follow precisely material flows at each step of the fuel cycle front-end and back-end, and at each date of the operation period. The evolution in time and under flux of materials isotopic composition has also to be taken into account, which can give access to other interesting values (activity, decay heat, toxicity,).Since 1985, CEA has been developing the COSI software, simulating in detail the evolution in time of a nuclear reactors fleet and its associated fuel cycle facilities. It is designed to study different options for the introduction of various nuclear reactor types and the use of the associated nuclear materials.The general principle and the physical models of the current version in 2014 (COSI6 7.0) is described in the paper. The main physical models are the equivalence models in the fabrication plant, which determine the initial composition of mixed fuels in order to provide an equivalent efficiency whatever the isotopic composition of constitutive materials, and the depletion models for irradiated fuels in the core and cooling materials in storage the reference model is CESAR of which several versions are available. CESAR is the reference code at the AREVA NC La Hague reprocessing plant and is used to calculate the isotopic composition of spent fuel by solving Bateman equation, using one-group cross sections libraries coming from neutronic codes (APOLLO2 in thermal spectrum and ERANOS in fast spectrum). An exercise of validation of COSI6 previously carried out on the French PWR historic nuclear fleet until 2010 (and not presented in this paper) allows us to validate the essential phases of the fuel cycle computation and highlights the credibility of the results provided by the code. Otherwise, a methodology of propagation of inputs uncertainties on results has been developed and could be implemented to quantify the uncertainties associated to scenarios results.Finally, a methodology of optimization of scenarios is currently developed. It will consist in a module associated to COSI6, to find the appropriate input parameters defining the best scenarios for a given problem. Indeed COSI6 is a deterministic code in the sense that the scenario is simulated chronologically as function of the input parameters defined by the user, without any decision taken by the code. Nevertheless the user needs more and more often to identify solution scenarios to different problems (e.g. how to minimize natural resources consumption, waste production and toxicity) while respecting industrial constraints (maintaining the energy production, limiting the interim storages, stabilizing the plants capacities,...)

Sodium Fast Reactor: an Asset for a PWR UOX/MOX Fleet

International audienceThe industrial program on used fuel reprocessing was launched in France in order to close the cycle of plutonium. In the 90s, the stoppage of Fast Reactors programs led to recycle plutonium into LWR MOX fuels instead of FR MOX fuels. The first MOX fuel assemblies were introduced in a French LWR in 1987. Since, recycling has been continued in France as 24 out of 58 PWRs operated can be currently loaded with MOX fuels.Due to its low fissile content, Pu from spent MOX fuels is sometimes regarded as not recyclable in LWR. Based on the existing French nuclear infrastructure (La Hague reprocessing plant and MELOX MOX manufacturing plant), AREVA and the CEA have evaluated the conditions of Pu multirecycling in a 100% LWR fleet. As France is currently supporting a Fast Reactor prototype project, scenario studies have also been conducted to evaluate the contribution of a 600 MWe SFR in the LWR fleet.These scenario studies consider a nuclear fleet composed of 8 PWR 900MWe, with or without the contribution of a SFR, and aim at evaluating the following points- the feasibility of Pu multi-recycling in PWR;- the impact on the spent fuels storage;- the reduction of the stored separated Pu;- the impact on waste management and final disposal.The studies have been conducted with the COSI6 code, developed by the CEA Nuclear Energy Direction since 1985, that simulates the evolution over time of a nuclear power plants fleet and of its associated fuel cycle facilities and provides material flux and isotopic compositions at each point of the scenario.To multi-recycle Pu into LWR MOX and to ensure flexibility, different reprocessing strategies were evaluated by adjusting the reprocessing order, the choice of used fuel assemblies according to their burn-up and the UOX/MOX proportions.The improvement of the Pu fissile quality and the kinetic of Pu multi-recycling in SFR depending on the initial Pu quality were also evaluated and led to a reintroduction of Pu in PWR MOX after a single irradiation in SFR, still in dilution with Pu from UOX to maintain a sufficient fissile quality

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

Simulations of Progressive Potential Scenarios of Pu Multirecycling in SFR and Associated Phase-out in the French Nuclear Power Fleet

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 progressive potential scenarios of the French transition between the current nuclear fleet and a SFR fleet which does not require natural uranium to operate. To do so, several steps were defined, each of them having a different purpose and allowing a gain of experience to move on to the next one.In one of these scenarios, between 2030 and 2062 the current PWR fleet is renewed by an EPR reactor fleet in which plutonium keeps on being monorecycled. This EPR reactor fleet is loaded with about 10% of MOX fuel which enables to stabilize the UOX spent fuel inventory. Beginning from the 2040 decade, a few FR reactors and their associated cycle are progressively introduced MOX PWR spent fuels reprocessing begins in 2040 in order to feed three 1000 MWe breakeven SFR, commissioned between 2050 and 2059.This enables to test at an industrial scale the new Nuclear System and to stabilize used MOX fuel inventory. To prepare for a larger FR deployment, three 1450 MWe breakeven SFR are commissioned between 2075 and 2085. An SFR spent fuel reprocessing of 15 to 21 tHM/y starts in 2060 in order to feed the three 1450 MWe SFR. From 2090, thirteen additional 1450 MWe SFR are deployed in order to reach an equilibrium fleet composed of sixteen 1450 MWe breeder SFR and 22 EPR reactors (with an average MOX load of 39.5%). At this point of the scenario, the Pu global inventory is stabilized, and the energy production remains constant at 420TWhe. From 2150, this EPR/SFR reactor fleet is progressively renewed by a new one composed of 41 breakeven SFR, which does not require natural uranium to operate.SFR deployment in 2150 leads to a slight increase in the global plutonium inventory which stabilizes definitively in 2180. At the end of the scenario, the Pu inventory is reduced by 47% compared with a 100% UOX PWR fleet (open cycle scenario). The global minor actinides inventory is increasing at a rate that can be managed at the back end. Over the whole scenario, 1.01.106 tons of natural uranium have been used. This represents a 40% reduction compared with the open cycle scenario.A faster SFR deployment scenario was also studied, identical to the previous one up to 2090. From 2090, a 41 SFR fleet is deployed according to Pu availability. The equilibrium is reached in 2135 when the global Pu inventory is stabilized.Nuclear phase-outs have been studied at several dates in order to evaluate the impacts in terms of inventories at each step of the scenario. Studies of optimized phase-out, aiming at reducing the Pu global inventory, the spent fuel mass and the waste inventories, have also been carried out. They involve MOX EPR reactors with high moderation ratio and enriched uranium support and burner SFR

Scatterometric Porosimetry for porous low-k patterns characterization

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COSI6: A Tool for Nuclear Transition Scenario Studies and Application to SFR Deployment Scenarios with Minor Actinide Transmutation

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Characterizing plasma-damaged porous low-k

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Feasibility of future prospects and transition scenarios for the French fuel cycle

International audienceThis paper presents the industrial feasibility analysis of scenarios involving the progressive deployment of multiple recycling of plutonium in French sodium fast reactors (SFR), in line with the French Act dated 28 June 2006 on the sustainable management of radioactive materials and waste. Four successive phases have been defined with different degrees of SFR deployment in order to understand how best to accomplish this fuel cycle transition