Gamma monitor for assay of radioactive solid-waste shipments

A gamma waste monitor has been developed and evaluated at the Savannah River Plant (SRP). The purpose of the monitor is to improve estimates of the radionuclides in solid wastes arriving at the plant's burial ground. This monitor, a computer-based spectrometer, quantitatively measures many radionuclides in SRP waste, including waste in heavily shielded shipping casks. Radionuclides emitting gamma rays of sufficient energy to penetrate the shipping container walls can be measured directly. Other radionuclides that are beta emitters or which emit gamma photons too weak to penetrate the walls of the waste containers can often be estimated by their association with measurable gamma photons. Development of the monitor was initiated to find a more accurate method of estimating the quantities of radioactive materials accumulated in the burial ground and to ensure compliance with burial limits imposed by SRP technical standards. Another benefit from the monitor is that it provides specific radionuclide data which are essential to environmental impact evaluations and decommissioning planning. The gamma waste monitor is described. (WHK