A model to explain tritium release behavior from irradiated Li4SiO4, in the model reported so far by the present authors, it is required to use so small reaction rates for the surface reactions as one several thousandth of the observed values reported in the previous papers to get the good fitting.

In this study the mass transfer resistance between grain surface and surface water is newly introduced because it is preferable to use the same reaction rate as that reported previously. The estimated values using the new model give good agreement with the observed tritium release curves and also with the release curves estimated using the model so far.