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Helion Energy has asked the NRC not to delay in moving to a licensing framework for a commercial fusion industry
regulation, and oversight requirements across the NRC and Agreement State jurisdictions; add decision criteria to determine whether a specific fusion energy system is a utilisation facility; and reduce the potential need for the use of exemptions, licence conditions, or orders to apply appropriate regulatory criteria.
Rulemaking for fusion In its ‘options’ paper the staff set out some fundamental differences between fission and fusion for its purposes. Fusion involves no plutonium or uranium-235, so the self-sustained neutron chain reaction that defines nuclear fission reactors in NRC documents is not possible and there is no associated fission product hazard. The tritium and other radioactive materials used in fusion are normally categorized by the NRC as byproduct material. There are three common plasma confinement
approaches in fusion: magnetic, inertial, and magneto- inertial. Fusion devices will generally work with charged particles (eg free electrons and atomic nuclei) in the plasma in a vacuum. They will accelerate particles and impart kinetic energy (ie raise plasma temperature and discharge the resultant particulate into a medium (into the plasma,
walls, or breeding blankets, creating radioactive material, such as tritium and other activation products). A survey by the Fusion Industry Association revealed that fusion power plants are expected to vary from kilowatts to gigawatts of thermal power. Nevertheless, the expected tritium inventory at commercial fusion power plants is expected to be less than 100g, with 0.1g or less actually in the plasma during operations.
In the event of a vessel breach and loss of vacuum, the
plasma that sustains fusion reactions will collapse, ending the reaction and minimising both the energy to drive a radioactive release and the material available for release. In addition, unintended large power excursions are limited because new fuel must continue to be introduced, and burnt fuel removed, to sustain the fusion reaction. So the key areas for protecting public health and safety
are: ● Confinement of radioactive materials; gamma and
neutron radiation shielding; the presence or absence of supporting systems for breeding tritium; and the inventories of tritium or other radionuclides at the site, which may be in significant quantities and permeated into structural materials.
Above: A steerable neutral beam injector at the DIII-D National Fusion Program facility
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