The impact of dose rates due to decay photons on the design of the IGNITEX device

In the experimental areas of a fusion ignition experiment, it is desirable to gain access inside the primary shielding so that hands-on adjustments can be made in a timely manner. For the IGNITEX (Fusion Ignition Experiment) device, these considerations are complicated by the use of D-D and D-T fuel and the resulting radioactivity induced in the structures surrounding the plasma. Photons from the decay of the induced radioactivity will determine what access times will be allowable. An analysis of the anticipated radiation dose due to decay photons at various positions surrounding the IGNITEX device has been performed. Because of the low power of the D-D runs, this fuel will have a minimum impact on access time. However, for D-T fuel operations, the materials that are used in the structure of the device play an important role in determining dose rates. For the lowest dose rates, the amount of stainless steel used in the support structure must be minimized, especially toward the outer edge of cryostat