MIPT scientists, together with foreign colleagues, have identified the optimal approach for calculating thermal regimes in two-fluid liquid fuel reactors – some of the most promising installations for closing the nuclear fuel cycle. The research will help engineers more accurately design emergency cooling systems for such reactors.
In new type reactors, instead of traditional fuel rods, a liquid alloy of uranium and chromium is planned to be used, which circulates in a special circuit and is cooled by molten lead. This approach increases efficiency by approximately one third and allows for continuous fuel reprocessing. However, liquid metal transfers heat differently than water or air, and existing turbulence models do not account for this feature, which creates uncertainty in temperature regime calculations.
As noted by MIPT, if a model makes errors in temperature calculations, it can lead either to underestimation of thermal loads or to overly conservative design. It is especially important to accurately know the temperature distribution for reliable operation of safety systems.
Scientists created a computer model of the experimental DFR reactor and, using a supercomputer, calculated the movement of nuclear fuel and its temperature when flowing around heat exchange rods. Then, reference calculations were compared with predictions from two turbulence models – the complex RSM GBSL and the simplified k-omega-SST. It turned out that the simpler model performs even better.
In the future, reactor developers will be able to use simplified models in validated regimes and obtain accurate temperature predictions without costly supercomputer modeling. The obtained data will form the basis for emergency cooling system designs for Generation IV reactors.