UWFDM-1057 Neutronics Parameters in the Divertor Diagnostic Cassette of ITER

The 3-D neutronics analysis for the standard ITER divertor cassettes was extended to determine the nuclear parameters at specified locations and address streaming and neutronics issues for the diagnostic cassettes. The nuclear parameters in the attachment keys and coolant pipes for the dome and plasma facing liners of the central diagnostic cassette indicated that the top attachment keys for the outer plasma facing liners have the highest nuclear heating and damage. Rewelding of the coolant pipe connections for the dome block is of particular concern and these connections should be placed farther away from the dome surface. The nuclear parameters in the waveguides and their coolant pipe connections confirmed that rewelding is feasible for these connections. The damage in the VV due to streaming through the viewing slots is much lower than that resulting from streaming through the pumping ducts in the standard cassette and rewelding remains feasible. The increased toroidal gaps between the central diagnostic cassettes and the adjacent cassettes due to cut-outs for X-point viewing increase the total magnet heating by less than 0.1 kW in the 20 TF coils. The increased streaming will be compensated by the added attenuation in the diagnostic equipment and coolant pipes in the ports at the diagnostic cassettes. The nuclear parameters were determined in the candidate materials for the mirror assemblies in the diagnostic cassettes. These are molybdenum, tungsten and copper. Tungsten experiences the lowest damage and is the preferred candidate from the neutronics point of view.