Monte Carlo Simulation of Prompt Dose in the National Ignition Facility

Lawrence Livermore National Laboratory, Livermore, CA 94550, USA

^* Corresponding author: khater1@llnl.gov

Published online: 15 October 2024

Abstract

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is the world’s largest and most powerful laser system for inertial confinement fusion. The NIF is a 192-laser beam facility that produces more than 2 MJ and 500 TW of ultraviolet light. The facility is expected to generate shots with varying fusion yield (up to 20 MJ or 7.1x1018 neutrons per shot) and a maximum annual yield of 1200 MJ. Monte Carlo simulations have been performed to estimate prompt dose values (neutrons and photons) inside the facility as well as at different locations outside the facility shield walls. The Target Chamber shielding, along with Target Bay and Switchyard walls, roofs, and doors will reduce exposures in occupied areas to acceptable levels. The thicknesses of the different shield doors in the facility were optimized such that prompt dose in occupied areas is limited to < 50 μSv per 20 MJ shot and < 1 mSv for 1200 MJ of annual fusion yield. Most of the normally occupied areas experience limited prompt dose values of < 50 μSv per shot. Low dose values are also expected outside the NIF facility. The maximum annual off-site dose to a maximally exposed individual is small and estimated at 24 μSv for 1200 MJ of fusion yield.