| 内容記述 | The SIMMER-III code has been developed to evaluate the sequences of core disruptive accidents (CDAs) in fast reactors (FRs). In order to reasonably evaluate the mass of molten fuel remained in the core region and the consequence of re-criticality, it is important especially for the code to evaluate phenomena adequately such as ejection, freezing and blockage formation inside the escape path. The freezing model for the molten fuel has been developed and improved through the SIMMER-III phase 1 and 2 assessment programs. Especially, in the phase 2 assessments, knowledge of the metallurgy area was introduced, and it was found that a molten material formed the supercooling layer in the vicinity of structure wall and that the temperature of this layer dominated the energy loss of molten material and eventually the mass ejected into flow channel. This supercooling temperature was determined for each material based on the experimental result respectively as a constant input variable. 0n the other hand, experimental data used for the assessments of freezing model did not cover the temperature condition of CDA completely. In this study, a semi-empirical correlation which is comprised of thermophysical properties is proposed to predict supercooling temperatures, in order to increase reliability and accuracy of SIMMER-III freezing model. To attain the generality of this semi-empirical correlation, not only the experimental data with molten uranium dioxide but also the data with tin and wood's metal were used in the derivation of this correlation, which have different thermophysical properties and temperature conditions. In addition, it was confirmed through the evaluation of experimental data that this correlation could be applied to the molten stainless steel freezing phenomena.
著者所属: 日本原子力研究開発機構(JAEA) |
