Measurement of the NIF Gunite Shielding Composition and Implications for Neutron Activation and Worker Doses

In December 1999 and January 2000, a 40-cm-thick spherical shell of sprayable concrete (“gunite”) was applied to the exterior surface of the National Ignition Facility (NIF) target chamber. Glow-discharge mass spectroscopy has been used to determine the elemental composition of multiple gunite samples, which were collected at the time of application. These measured compositions are compared to the anticipated composition and both are used for neutron activation calculations. Contact dose rates are reported and implications for doses rates during operation and for the eventual facility decommissioning are discussed.