838. 動力炉反応度事故条件下における浸水燃料の破損しきい値の解析的評価

抄録

Failure behavior of a waterlogged fuel rod is analyzed with WTRLGD, a computer code for the analyses of pressure behavior of the waterlogged fuel rod, in order to evaluate its failure threshold energy under a RIA condition of a power reactor. Parameters considered here are pulse width of a transient power, fuel stack length, volumetric fraction of water, total energy deposition and an axial power profile.
The numerical results show that water in the gap region changes nearly iso-volumetrically When the fuel stack length is as long as that of a power reactor, that is, they show that the process of change is like that of a fully waterlogged fuel rod and that of a partially waterlogged one with the end peaks in the NSRR experiments. Additionally, the calculated failure threshold energies agree with those obtained in these experiments. It is also revealed that the calculated failure threshold energy of the waterlogged fuel rod with a long fuel stack is hardly influenced by the analytical parameters.
Consequently, the failure threshold energy of the waterlogged fuel rod under a RIA condition of a power reactor is evaluated by the results of the NSRR experiments described above.