Nuclear fuel cycle

Contenu(s)

F4. Nuclear fuel cycle

(Lecture: 13h, Tutorials: 4h, Practicals: 3h), Ch. Poinssotand JP. Grouiller (CEA)

Lectures (13h) : Definition of the fuel cycle. Situation in France.

 Front-end fuel cycle:

•  Uranium ressources (ores, earth crust, types of rocks...), uranium ore deposit typology, ore mining techniques and mine types
• On-site ore purification to yellow cake, additional purification techniques and conversion to UF4 and UF6
• Fuel enrichment: definitions of SWU, different available enrichment techniques

 Fuel reprocessing and actinide recycling

• Composition and relevant properties of spent fuel for subsequent processing
• Front-end processes: from fuel assembly to nitric solution, the dissolution steps
• Core processes: extraction of major actinides U,Pu from the dissolution solution, processes and chemical engineering
• Production of recycling fluxes: uranium and plutonium conversion
• Specificity of Pu recycling: from PuO2 to MOX fuels

 Nuclear wastes conditioning and long term management

• Designing of specific matrices for waste confinement (glasses, concrete, compacted waste) and conditioning steps; focus on the vitrification technology.
• Classification of nuclear wastes: origin, volumes, flux, specific long term management options for shorter lived waste (TFA, FMA)
• Radioactive waste repository: from the 1991 Law towards the selection of the Meuse/Haute-Marne repository to be decided in 2015 through the help of the Underground Research labs.

From the current towards the future fuel cycles

•  Background: meeting the future energy needs by increasing the sustainability of nuclear energy in the societal, economic and environmental fields.
• Significant input of Pu mono-recycling for the sustainability of nuclear energy: resources economy, waste toxicity decrease. Necessity to prevent any divertion of fissile material: development of COEX process (separation, conversion)...
• From the Pu mono-recycling towards the Pu multi-recycling and U-recycling: limitations of mono-recycling, requirement for fast neutrons reactors, towards a fuel cycle without any front-end anymore.
• From the Pu/U-recycling towards the MA recycling: limiting the waste toxicity and inventory for the long term, increasing the public acceptance, optimising the repository resources, specific processes under development, various options considered (GANEX, SANEX-TODGA, EXAm).

Fuel cycle scenarios and perspectives

Tutorials and practicals:

• Simplified design of a fuel processing unit by liquid/liquid extraction (determination of mass flows, evaluation of performances). Use of SIMULEX simulation code.
• Scenarios studies (calculation of mass fluxes).
• Simplified modelling of representative radionuclides migration within the environment considering the relevant processes (speciation, retention, diffusion).