The Working Party on Multi-scale Modelling of Fuels and Structural Material for Nuclear Systems (WPMM) was established in 2007 to deal with the scientific and engineering aspects of fuels and structural materials, aiming at establishing multi-scale models and simulations as validated predictive tools for the design of nuclear systems, fuel fabrication and performance. The WPMM’s objective was to promote the exchange of information on models and simulations of nuclear materials, theoretical and computational methods, experimental validation, and related topics. It also provided member countries with up-to-date information, shared data, models and expertise. The Working Party assessed nuclear modelling improvement needs and addressed these needs by initiating joint efforts. The WPMM reviewed and evaluated the multi-scale modelling and simulation techniques currently employed in the selection of materials used in nuclear systems. It also provided advice to the nuclear community on the developments needed to meet the requirements of modelling for the design of different nuclear systems.
The WPMM liaised closely with other NEA working groups, especially those operating under the guidance of the Nuclear Science Committee (NSC) in order to ensure the complementarity of the respective work programmes. Particularly close working relationships were maintained with the Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC), the WPFC Expert Group on Innovative Fuel Elements (EGIFE), the WPFC Expert Group on Innovative Structural Materials (EGISM), the Expert Group on Accident-tolerant Fuels for Light Water Reactors (EGATFL), the Expert Group on Multi-physics Experimental Data, Benchmarks and Validation (EGMPEBV), the Expert Group on Reactor Fuel Performance (EGRFP) and the NEA Project on Thermodynamics of Advanced Fuels International Database (TAF-ID).
The WPMM mandate ended in 2020, and the materials science activities are now carried out under the auspices of the Working Party on the Materials Science Issues in Nuclear Fuels and Structural Materials (WPFM).
The WPMM was structured into three areas of focus: general multiscale modelling methods, multiscale modelling of nuclear fuels and structural materials modelling.
Tonks, M. et al., "Unit mechanisms of fission gas release: Current understanding and future needs", Journal of Nuclear Materials, vol. 504, June 2018, Elsevier, pp. 300-317, doi: doi.org/10.1016/j.jnucmat.2018.03.016.
The expert group dealt with the activities associated with the certification of experimental data and benchmark models along with establishing the processes and procedures for using the data and benchmark models for validation of modelling and simulation tools and data. The group's work was completed in 2020 and its scope of work is currently addressed in the Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS).
The Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS) studies the reactor physics, fuel performance, and radiation transport and shielding in present and future nuclear power systems.
The Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC) studies advanced nuclear fuel cycles, including fuel cycle scenarios, innovative fuels and materials, separation chemistry, waste disposal and coolant technologies.
Under the guidance of the Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC), the Expert Group on Innovative Fuel Elements (EGIFE) conducts joint and comparative studies to identify technical issues and support the development of innovative fuels that can be implemented in advanced nuclear fuel cycles.
The expert group conducts joint and comparative studies to support the development, selection and characterisation of innovative structural materials that can be implemented in advanced nuclear fuel cycles, under extreme conditions such as high temperature, high dose rate, and corrosive chemical environment and long service lifetime.
Under the guidance of the Nuclear Science Committee (NSC) and under the mandate of the Working Party on Multi-scale Modelling of Materials (WPMM), the scope of the Expert Group on Multi-scale Modelling Methods (EGM3) is to provide an overview of the various methods and levels of models used for modelling materials for the nuclear industry (fuels and structural materials).
Under the guidance of the Nuclear Science Committee (NSC) and under the mandate of the Working Party on Multi-scale Modelling of Fuels and Structural Materials for Nuclear Systems (WPMM), the objective of the Expert Group on Multiscale Modelling of Fuel (EGM2F) is to share and support the development of a multi-scale modelling approach of fuels in support of current fuel optimisation programmes and innovative fuel design.
The main objectives of this expert group are to assess the limitations of the NRT-dpa standard, in the light of both atomistic simulations and known experimental discrepancies; and to revisit the NRT-dpa standard and examine the possibility of proposing a new improved standard of primary damage characteristics.
The objectives of the expert group are to assess the accuracy and calculation time of the various first principle tools applied in the assessment of the properties of the nuclear materials; assess the accuracy and calculation time of the various classical molecular dynamic tools applied in the assessment of the properties of the nuclear materials; and define the needs for the development of the tools applied in the benchmarks.