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Evaluation of the consequences of sodium pool fire requires a prediction model that can calculate the fractions of the aerosols of Na20 and Na202 being transported into the atmosphere and onto the sodium pool surface from the reaction zone. In the present model, we applied the laminar diffusion flame theory in a thin layer in the neighborhood of the pool surface. The combustion was modeled assuming the instantaneous chemical equilibrium because the chemistry is fast compared with the mixing. The aerosol transport was assumed to be due to a sum of the drag force, the thermal force and the gravity. The calculated results are in good agreement with experimental data obtained by other investigators for the burning rates and the aerosol release fractions of sodium pool fire. This analysis forms the basis of prediction of aerosol release fraction in the sodium pool fire.

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Flow network models of the upper plenum of reactor vessel and the primary inlet plenum of intermediate heat exchanger (IHX) of MONJU were advanced and each model was validated by the measured data obtained in the previous system start-up tests (SSTs). Then the whole plant dynamics in a plant trip transient of MONJU were simulated by incorporating these flow network models. The natural circulation in the primary and secondary heat transport systems were also validated by these test results. From these validations, we concluded that the plant dynamics model incorporated the advanced models in Super-COPD code could simulate the whole plant dynamics in good accuracy both in the transients and natural circulation conditions and that it was applicable to predict the next SSTs.

This paper describes a thermal fluid-structure interaction analysis code FLUSH that calculates both thermalhydraulics and thermal structure response at the same time. This code has been developed to evaluate the thermal responses of the upper structures of LMFRs, using two different analysis codes of α-FLOW and FINAS. The heat flux on the boundary surface of the fluid region and the temperature on the boundary of the structure region are exchanged in every iterative cycle as the new boundary conditions, and finally the unified thermal fields are calculated. The different mesh method and the detail thermal radiation model were also developed to apply for the large scale models.The 2-D model of the basic experiment for the cover gas thermal-hydraulics was calculated to verify this iterative method. The calculated average temperature on the boundary agreed well with the experimental results. The 3-D large scale models of the out-of-pile experiment for MONJU shield plug were also calculated to verify this method. The calculated temperature both in the annulus and the shield plug agreed well with the experiments. These studies showed that this iterative method of FLUSH was very effective for the predictions in the strong coupled thermal fields.