Annex I.C. United States experience of stack dismantling: Stack dismantling at the Idaho National Engineering and Environmental Laboratory

Since its establishment in the late 1940s, the Idaho National Engineering and Environmental Laboratory (INEEL) has built and operated 52 nuclear reactors. Since most of these were built to support reactor safety research for various types of electrical power generating nuclear systems, most were operated for only relatively short periods of time before being shut down and decommissioned. Many of these reactor facilities contained their own exhaust systems including a dedicated exhaust stack. The size and complexity of these stacks ranged from relatively short and simple to tall and complex. In general, heights ranged from slightly less than 30 m to greater than 60 m. Construction ranged from simple, small diameter metal piping supported on a concrete base with anchoring cables, to massive brick lined concrete structures of more than 10 m diameter. Contamination within these stacks consisted primarily of mixed fission products (137Cs, 60Co and 90Sr). Very low levels of 235U existed in some of the stacks. The following sections describe the decontamination and decommissioning (D and D) efforts associated with two types of stack located at the INEEL