Non-empirical study of chemical reactions including fission products in severe light water reactor accidents

Elementary chemical reactions including volatile (gaseous) fission products, such as iodine and cesium, are analyzed from the first principle, so as to enable us to study the kinetic behavior (non-equilibrium state) of fission products in severe light water reactor accidents without experimental rate constants. Activation energies are calculated with a computer program Gaussian94, which is based on the non-empirical (ab initio) molecular orbital theory. Calculated values are expected to agree with those of experiments within an accuracy of a few kcal/mol. Using the values obtained above, rate constants are also calculated in the framework of the transition state theory It is concluded that the derived rate constants can predict the orders of magnitude of experimental values under high temperature conditions (1,000 K or higher) as in severe accidents.