Low-activation materials safety studies. Annual report for fiscal year 1981, October 1, 1980-September 30, 1981

The nucleonics calculations considered low activation material substitution in the STARFIRE design of SiC for the first wall, SiC for the coolant tubes and shell structure for the blanket, graphite as a reflector, Al, SiC and B4C for a water cooled shield, and aluminum as structure and stabilizing conductor for the superconducting magnet. All materials included 1 appM iron as an impurity. Neutron multipliers were not needed. Nucleonics calculations gave neutron flux levels, radioactive material inventories, nuclear heating rates, decay heat rates and post-shutdown gamma dose levels. A breeding ratio of 1.09 tritons per neutron and a nuclear heating of 16.6 MeV per D-T reaction were obtained with the low activation blanket. Afterheat was reduced to a level where it is no longer a concern. The radioactivity and biological hazard potential (BHP) are reduced by a factor of one million at one day after shutdown. Dose rates of 20 mRem/h behind the reflector permit limited personnel access. Practically all the radioactivity problems are due to the 1 appM iron impurity. Thus further improvements are still possible