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TRANSCRIPT
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WPRS - February -13 th 2012 – NEA Headquarter
WPRS
« Sodium Fast Reactor core Feedback and Transient response (SFRFT) Expert Group:
preliminary benchmark results for large cores »
L. Buiron, V. Pascal, F. Varaine, CEA, Cadarache Center
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WPRS - February 13th 2012 – NEA Headquarter
Large core image : oxide and carbide fueled cores
3 600 MWTh Self-breeder cores
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WPRS - February 13th 2012 – NEA Headquarter
Cores description
• For all cores, the benchmark document provide concentration description corresponding to equilibrium beginning of cycle configuration : – Each initial Pu content is described by an averaged representative sub‐assembly with
5 axial concentrations sets corresponding to local depleted zones – Fission products isotopes are replaced by a representative lumped isotope (according
to relevant absorption level) in order to have a generic description in terms of calculation tools.
• Geometric and medium descriptions enable both homogeneous and heterogeneous sub‐assembly modelling suitable for deterministic or Monte‐Carlo codes.
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WPRS - February 13th 2012 – NEA Headquarter
Work to be performed Characterization of end of cycle state : core depletion from a given beginning of cycle description
• K effective • Sodium void effect • Doppler constant • Effective delayed neutron fraction • Control rod worth • Masse balance for Heavy Nuclei • Power distribution
Results to be provided using a formated xls file provided by SFR group For large core cases, preliminary results have been received from :
• France : CEA • United States : ANL • Hungary : Centre for Energy Research, Hungarian Academy of Sciences
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WPRS - February 13th 2012 – NEA Headquarter
Expected results Characterization of end of cycle state : core depletion from a given beginning of cycle description
• K effective • Sodium void effect • Doppler constant • Effective delayed neutron fraction • Control rod worth • Masse balance for Heavy Nuclei • Power distribution
Results to be provided using a formated xls file provided by SFR group For large core cases, preliminary results have been received from :
• France : CEA with ECCO/ERANOS • United States : ANL with REBUS‐3/VARI3D • Hungary : CER with NOTRAKET code system • Germany : KIT with KANEXT
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WPRS - February 13th 2012 – NEA Headquarter
Results (1) Main integral results for carbide core :
10% discrepancies
large discrepancies
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WPRS - February 13th 2012 – NEA Headquarter
Results (2)
Main integral results for oxide core :
Same behavior as seen with carbide core
but CEA and KIT results seem quite
close
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WPRS - February 13th 2012 – NEA Headquarter
Results (3)
Total core heavy nuclei mass at EOC :
ANL, CEA and KIT results are really close but some discrepancies are observed for Am and Curium isotopic concentration CER results seem not relevant (error in geometrical description ?) More in depth analysis need to be performed (in progress but there was only a limited time since data delivery from participants)
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WPRS - February 13th 2012 – NEA Headquarter
Analysis of discrepancies
Some remarks that need data checking
– K effective from ANL and CER at BOC for both cores seem a bit under‐evaluated – Doppler values from ANL do not seem to match the right formula (Celsius vs Kelvin ?) – Control rods worth values can be affected by geometrical description of these subassemblies:
homogeneous description leads to higher control rods than heterogeneous description the reactivity effect overestimation is quantified to be around 15% for large cores description
– Discrepancies on high atomic mass isotopes may comes from différences in the depletion chain used (branching ratio between Am242/Am242m from Am241 for instance)
– BOC mass could also be checked for CER data
Power distribution is under analysis using normalisation, because of the ability of used codes to account or not for energy deposition into no‐fuel volumes
Large core image : oxide and carbide fueled cores Cores description Work to be performedExpected resultsResults (1)Results (2)Results (3)Analysis of discrepancies