DORT analyses of decay heat experiment on tungsten for ITER

Abstract

The decay heat experiment on tungsten for ITER performed with an ITER-simulated neutron field at JAERI/FNS was analyzed by the DORT code in order to assess the accuracy of DORT calculations with and without self-shielding corrected multigroup libraries on the production of 186W, which is the main source of decay heat of tungsten in the ITER neutron environment. Neutron multigroup libraries (175 groups and 46 groups) with and without self-shielding correction were generated from FENDL/E-1.1 by the NJOY and TRANSX codes. The followings were found through the comparison among the present calculations, an MCNP calculation with FENDL/MC-1.1 and the measured data for 186W production: 1. The DORT calculations with the self-shielding corrected libraries are almost the same as the MCNP one and underestimate the measured data by 20%. 2. The difference of 187W production between the DORT calculations with and without the self-shielding corrected libraries is seemingly small for neutron 175 group structure, while 187W production in the DORT calculation without the self-shielding corrected library of neutron 46 group structure is 40% smaller than that with the self-shielding corrected one. It was concluded that DORT calculations have almost the same accuracy as MCNP ones for 187W production in the divertor and baffle regions in ITER if a self-shielding corrected multigroup library is used.