It is indispensable to evaluate precisely and accurately the energy and spatial distribution of the neutron emitted after numerous nuclear reactions including the fission in order to study on the neutronics properties such as the condition to reach the criticality and the power profile of the nuclear reactor. In the early stage of the nuclear development, such simulation was carried out ?gby hand?h for simplified model. However, now, the numerical analysis (computer program) has been adopted for the precise model by use of the high-performance computing infrastructure including the supercomputer.
Japan Atomic Energy Agency tackles vigorously the research and development of such computer simulation technology to support the nuclear energy development. We have been developing the state of the art computer program which simulates the neuron transport in the nuclear reactor and the accelerator facility representing the behavior of the neutron in ultra-fine, i.e., almost continuous neutron energy points and by use of random number.
In recent years besides this program, we have been developing several new computer programs, i) which provides the probability data of the nuclear reaction between neutron and nuclides into the computer program, ii) an integrated nuclear reactor analysis code system based on the modern programing method, and iii) an automated system to carry out the validation process of the simulation program and the adopted data.