A REVIEW OF HYDROGEN-PRODUCTION DURING MELT WATER INTERACTION IN LWRS/

This article reviews the available modeling and experimental data on h ydrogen production during melt-water interactions once melt contacts r esidual coolant in the lower head of a light-water reactor (LWR). The two principal limiting mechanisms, oxygen diffusion through an oxide l ayer and hydrogen diffusion through the steam film at the metal surfac e, are described. An appendix contains a description and discussion of the available experimental data in this area. A detailed discussion o f the extant modeling is given. The models vary greatly in their sophi stication, with the most developed being applicable to the case of mel t droplets in film boiling, where the models have provided useful insi ghts into the factors governing hydrogen production. Scoping calculati ons are reported for the configurations of coarse mixing, a stratified melt pool under water, and a steam explosion. These suggest that addi tional oxidation of core material in the lower head will add a few per cent to the total hydrogen production. However, no firm upper limit on hydrogen production can be supported on the basis of the available da ta and models.