Nuclear fuel cycle studies aim to provide an overview of the impacts of possible strategies (plants deployment, fuel recycling...) on an electronuclear fleet. They might be useful devices to advise political decisions. To investigate innovative scenarios and alternative
technologies, a nuclear fuel cycle simulation tool, CLASS (Core Library for Advanced Scenario Simulation)[1], is under development at Subatech Laboratory in the framework of a collaboration between CNRS/IN2P3 and IRSN.
This tool models material flows evolution in an entire fuel cycle. Thus, all the units of the fuel cycle shall be included (fuel fabrication and separation plants, reactors, cooling, storage...) and all the processes occurring during fuel evolution (nuclear reactions, decays) have to be described. The code implementation relies on physical models which build the fresh fuel and calculate its isotopic composition during evolution. These models are based on neural networks built using databanks inventorying fuel characteristics (isotopic composition, k∞ , averaged cross sections) evolution from previous reactors simulations performed with the software MURE (MCNP Utility for Reactor Evolution)[2] based on the transport code MCNP (Monte-Carlo N Particle)[3].
In this study, the code CLASS is used to investigate plutonium multi-recycling and incineration in Pressurized Water Reactors (PWR). In the current french fleet, the plutonium produced during UOx irradiation is mono-recycled in MOx fuel. Spent MOx fuel is then stored, waiting for SFR deployment. In the meantime, several fuels dedicated to plutonium multi-recycling are investigated to stabilize plutonium inventory, since it is the main contributor of spent fuel radiotoxicity[4]. The implementation in CLASS of a MOx enriched uranium support fuel (MOx-EUS), allowing plutonium multi-recycling in PWR will be presented.
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References
[1] Mouginot, B., Leniau, B., et al., 2014. Core library for advanced scenario simulation, C.L.A.S.S.:
Principle & Applications. In: PHYSOR 2014 – The Role of Reactor Physics toward a Sustainable Future,
The Westin Miyako, Kyoto, Japan, September 28 – October 3, 2014.
[2] Méplan, O., Nuttin, A., Laulan, O., David, S., et al., 2005. MURE: MCNP utility for reactor evolution.
In: ENC 2005 - European Nuclear Conference, France.
[3] Pelowitz, D., 2013. MCNP6 User’s Manual, Ver. 1, Tech. Rep., LA-CP-13-00634. Los Alamos National
Laboratory.
[4] Ernoult. M, 2014. Gestion avancée du plutonium en REP – Complémentarité des cycles thorium et
uranium (Ph.D. thesis). Université Paris-Sud.
[5] Youiniou, G., Vasile, A., et al., 2005. Plutonium Multirecycling in Standard PWRs Loaded with
Evolutionary Fuels, Nuclear Science and Engineering vol(151), 25–45