Contact Author:
Mr John Killeen
j.killeen@iaea.org
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Fuel Modelling at Extended Burnup: IAEA Coordinated Research Project FUMEX-II
J C Killeen (IAEA), J A Turnbull (Consultant)
The International Atomic Energy Agency has concluded a Coordinated Research Project on Fuel Modelling at Extended Burnup (FUMEX-II). Nineteen fuel modelling groups participated with the intention of improving their capabilities to understand and predict the behaviour of water reactor fuel at high burnups. The exercise was carried in coordination with the OECD/NEA.
The participants used a mixture of data derived from actual irradiation histories of high burnup experimental fuel and commercial irradiations where post-irradiation examination measurements are available, combined with idealised power histories intended to represent possible future extended dwell commercial irradiations and test code capabilities at high burnup. All participants have modelled various cases made available to them for the exercise from the IAEA/OECD Irradiated Fuel Performance Experimental Database.
Calculations carried out by the participants, particularly for the idealised cases, have shown how varying modelling assumptions affect the high burnup predictions, and have led to an understanding of the requirements of future high burnup experimental data to help discriminate between modelling assumptions. This understanding is important in trying to model transient and fault behaviour at high burnup.
This paper summarises some of the code predictions and demonstrates that the modelling of fuel behaviour is well understood at current commercial burnup levels, and highlights where uncertainties still exist at extended burnup.
The codes in the Coordinated Research Project have been designed for different applications and have differing assumptions and validation ranges. They are used for conditions as diverse as CANDU fuel operation with thin wall collapsible cladding and PWR, BWR and WWER with freestanding cladding.