Preliminary radiological assessment of the Fusion Ignition Research Experiment (FIRE)

Detailed activation analysis has been performed for FIRE. The machine is assumed to have an operation schedule of 3000 D-T pulses with a pulse burn of 10 seconds and 2 hours between pulses. At shutdown, the decay heat induced in the first wall is less than 0.1% of the nuclear heating generated in the first wall during operation. The ratio between the shutdown decay heat and nuclear heating generated in the vacuum vessel during operation is on the order of 0.01%. At the end of the machine life, all components would qualify for disposal as Class C low level waste. The biological dose rates behind the vacuum vessel and the divertor remain high during the first year following shutdown. The biological dose rates behind the outboard magnet are acceptable only at locations where the vacuum vessel is more than 40 cm thick. Using a 30 cm thick POLY/CAST shield drops the dose rates on the top of the shield to acceptable levels within a week from shutdown