SAMOSAFER Benchmark for Molten Salt Reactor burnup tools

The benchmark presented is an outcome of EU project SAMOSAFER and its detail are described in the deliverable 3.6 [1] and partly also in journal paper [2], which is cross-referencing this data set.

The background for the benchmark is the MSFR system, and its properties specified in the EVOL benchmark [3]. However, for the needs of the incremental benchmark it is further simplified and utilizes three different geometries. On the other hand, the list of elements treated by reprocessing unit or off-gas system is extended to make the benchmark more challenging. The list of elements treated by reprocessing unit includes all elements with exception of Li, F, and Ac. The list of elements treated by off-gas system is inspired by SAMOSAFER deliverable D3.3 and includes more elements than the EVOL benchmark. However, the respective cycle time of 30 s was kept. This modification creates on purpose a situation where several elements are treated by both removal streams. 

For the initial steps the EVOL benchmark geometry was simplified into an infinite fuel cube with 1 m edge and to semi-infinite fuel cube with reflective boundaries on all fuel walls with exception of the right wall with blanket salt, which uses vacuum boundary condition on the outer surface. All materials are simulated at temperature 900 K.

The benchmark is organized in incremental steps with increasing complexity to separate individual phenomena, which may often compete. These phenomena are:

·         Nuclides decay

·         Nuclides removal from fuel to the reprocessing unit and/or off-gas systems

·         Nuclides irradiation by neutrons

·         Actinides mass control in fuel and/or blanket

·         Reactivity control

·         Nuclides removal from blanket to reprocessing unit and/or off-gas systems

·         Power distribution between fuel and blanket

·         Spectrum change by neutron leakage

 The benchmark is therefore divided into major steps with smaller sub steps. The major steps are:

0.      Decay and removal

1.      Decay, removal and irradiation

2.      Decay, removal, irradiation and control

3.      Decay, removal, irradiation, control and power distribution 

4.      Decay, removal, irradiation, control, power distribution, neutron leakage 

Each of these major steps have sub-steps to separate the effect. Obviously, many such sub-steps can be defined, especially when mass control is applied. The incremental benchmark step sheet indicates if given phenomena take part in the simulation. In case of Nuclides removal, also the number of cycle time is indicated. The respective cycle times and pseudo decay constants λ used for each stream are stored in separated excel worksheets. Since this removal is based on chemistry, it is done elementwise. 

Krepel, J., Giot, L., Lorenzi, S., 2023B, Burnup tools verification by incremental benchmark, Deliverable D3.6, SAMOSAFER project.

Krepel, J., et al., 2026, Source term distribution and mobility – WP3 results of EU project SAMOSAFER, Nuclear Engineering and Design, 114679, 2026.

Brovchenko, M., et al., 2019, Neutronic benchmark of the molten salt fast reactor in the frame of the EVOL and MARS collaborative projects, EPJ Nuclear Sci. Technol. 5, 2 (2019).