Neutronics and Shielding Analysis of the National Ignition Facility

The Department of Energy (DOE) is proposing to construct the National Ignition Facility (NIF) by the year 2001 to embark on a program to achieve ignition and modest gain in the laboratory. The NIF will use 1.8 MJ of 0.35 µm laser light, nearly a fifty-fold increase in energy over the Nova laser at Lawrence Livermore National Laboratory (LLNL). A 5-m radius spherical aluminum chamber will contain the target experiments and allow access to diagnostics for data collection. Based on a projected maximum annual yield of 385 MJ (1.4 × 10²⁰ 14 MeV neutrons), prompt annual doses will be < 1.2 µSv at the nearest site boundary, < 0.43 mSv immediately outside the Target Area, and < 30 µSv in the warroom and control room. The target chamber material has been selected in a trade-off between its mechanical properties and its neutron activation qualities. External target chamber shielding has been selected such that the total annual occupational dose to Target Area workers will be ≤ 5 mSv. Finally, some Target Area systems have been redesigned based on their neutron activation and residual dose rates. The operation of the NIF will have an insignificant impact to workers and the general population.