Radiological design aspects of the National Ignition Facility.

The National Ignition Facility (NIF) has been designed to accommodate some challenging radiological conditions. The high prompt neutron source (up to 1.6 × 10(19) neutrons per shot) results in the need for significant fixed shielding. Concrete shielding approximately 2 m thick is used for the primary (target bay) shield. Penetrations in this shield, including those required for 192 laser beams, utilities, diagnostics, and 19 shielded personnel access doors, make the design challenging. An additional 28 shield doors are part of the secondary shield. In addition, the prompt neutron pulse results in activated air within the target bay, requiring special ventilation considerations. Finally, targets can use a number of hazardous and radioactive materials including tritium, beryllium, and depleted uranium (the latter of which results in the generation of small quantities of fission products). Frequent access is required to the associated potentially contaminated volumes for experimental setup, facilitating the need for local exhaust ventilation to manage these hazards. This paper reviews some of these challenges, design considerations, and the engineering solutions to these design requirements.

Standing up the National Ignition Facility radiation protection program.

Operation of the NIF requires a large and varied number of routine and infrequent activities involving contaminated and radioactive systems, both in servicing online equipment and offline refurbishment of components. Routine radiological operations include up to several dozen entries into contaminated systems per day, multiple laboratories refurbishing radiologically impacted parts, handling of tens of curies of tritium, and (eventually) tens of workers spending most of their day working in radiation areas and handling moderately activated parts. Prior to the introduction of radioactive materials and neutron producing experiments (capable of causing activation), very few of the operating staff had any radiological qualifications or experience. To support the full NIF operating program, over 600 radiological workers needed to be trained, and a functional and large-scale radiological protection program needed to be put in place. It quickly became evident that there was a need to supplement the LLNL site radiological protection staff with additional radiological controls technicians and a radiological protection staff within NIF operations to manage day-to-day activities. This paper discusses the approach taken to stand up the radiological protection program and some lessons learned.