The advanced 3D method for activation analysis of fusion reactor materials

The method allows analyzing the complex objects activated by neutrons (e.g. fusion reactors) combining advantages of the 3D radiation transport by mcnp program with calculations of multiple activation and radioactive decay chains by fispact program. The problem of preparing the gamma-ray sources in cells of 3D geometry was solved by creation of an interface between the mcnp and fispact programs. The interface allows optimizing the process of activation analysis by revealing dominant sources of radiation. The developed interface essentially reduces the time needed for calculations. The main advantage of the method is realization of so-called ‘multibox’ procedure for decay gamma source sampling during decay gamma transport in very large and complex fusion reactor models. Shutdown dose rate calculations are faster (up to 600 times in ITER cryostat) in comparison with applied mcnp standard source definition by using an external user-supplied source subroutine of the ‘multibox’ procedure. The offered method is intended for solution of the activation tasks with deep penetration of radiation. The method was used in the engineering design of ITER-FEAT and RF DEMO-S.