DCHAIN-SP 2001, Code System for Analyzing Decay and Build-up Characteristics of Spallation Products

1 - Description of program or function: DCHAIN-SP 2001 estimates the nuclide inventories and radiation environment of high energy accelerator related facilities and was designed to resolve issues regarding spallation neutron utilization facilities. DCHAIN-SP2001 is an update of DCHAIN-SP. For analyzing the decay and build-up characteristics of spallation products, DCHAIN-SP was developed on the basis of CCC-370/DCHAIN2 by revising the decay data and implementing the neutron cross section data. The decay data are newly processed from the data libraries of EAF 3.1, FENDL/D-1 and ENSDF. The neutron cross section data taken from FENDL/A-2 are also prepared to take account of the transmutation of Nuclides by the neutron field at the produced position. The new version includes corrections to known errors. 2 - Methods: DCHAIN -SP solves the time evolution of decay and build-up of Nuclides in every decay chain by the Bateman method. It can calculate the nuclide inventory, radioactivity, decay heat and gamma-ray energy spectra on the basis of the nuclide production rate calculated by the nucleon-meson transport code NMTC/JAERI97. 3 - Restrictions on the complexity of the problem: Nuclear reactions induced by neutrons with energies below 20 MeV in the radiation field produced in the spallation target are taken into account in the code. However, due to the lack of available cross section data, nuclear reactions above 20 MeV are not treated in the present release. The code cannot estimate the build-up of fission products by the fission reaction because fission yield data are not implemented in the present library, so that the applicable atomic number range is effectively limited to less than 83 although decay data and neutron reaction cross section data are prepared for Nuclides with atomic number 1 through 100