Development of combined system of monte carlo calculation and activation calculation for evaluation of decay gamma ray dose rate in nuclear fusion reactor

In order to evaluate the decay gamma ray dose rate in the DT nuclear fusion reactor, we developed the Monte Carlo decay gamma ray transport calculation system. By connecting the Monte Carlo calculation code with the activation one, we successfully developed the calculation system. The decay gamma ray dose rates after shutdown calculated by the developed system agree well with the experimental results performed by FNS at JAERI within the experimental error of 10%. We also successfully developed the variance reduction method for the decay gamma generating source. It is confirmed that the calculation time can be drastically reduced by applying the developed method. The present calculation system with be useful for the evaluation of the decay gamma ray dose dose rate in the DT nuclear fusion reactor. (author)