Containment of gaseous fission products in caverns

Experimental study and computer code development have been made for the evaluation of the transport of gaseous fission products contained in a cavern into the environment. In the first part, the adsorption and desorption characteristics of iodine and methyl iodide in various samples of soil and sand were reported for various conditions. Descriptions of the test facilities and the variables chosen for the tests are presented together with the experimental results. In the second part, the computational model and the outline of the code for evaluating the transport of gas mixture in soil and sand are described. In the third part, computational evaluation is made for the F.P. containability of a cavern, assuming a loss of coolant accident in an underground LWR. One of the notable features found from this simulation study was that the energy of the high temperature steam from a reactor is quickly absorbed by the large capacity of the ground. Concentration profile of Kr gas, pressure profile in porous media and other typical variables are presented as functions of elapsed time and distance. (Aoki, K