Neutron activation of the NIF final optics assemblies and their effect upon occupational doses

During routine operations, the National Ignition Facility (NIF) will attain fusion yields as high as 1200 MJ/yr with individual experiments reaching 20 MJ. Neutron activation of components within the NIF Target Bay will result in occupational doses that must be understood and limited to {le} 10 person-rem/yr. Previous work has shown that the final optics assemblies (FOAs) are the key to worker doses. The present work gives results for three-dimensional analyses including dose rates and worker doses. Results for modified FOA designs are also presented. Finally, a concept for a polyethylene shielding plug is discussed and shown to substantially reduce occupational doses