PNNL

Abstract

Nuclear proliferation signature radionuclides can be delivered to the aquatic environs via direct liquid discharges or atmospheric routes. The candidates for detection are 3H, 90Sr, 95Nb, 95Zr, 99Tc, 106Ru, 125Sb, 129I, 134Cs, 137Cs, 144Ce, 147Pm, NatU, 238U, 235U, 237Np, 239Pu, 240Pu, and 241Pu. The criteria for detection are the limits of radionuclide analysis, the nature of background concentrations, and the transport characteristics between the source and sample site. Potential radionuclide releases can be transported beyond 100 km at concentrations that are sufficient to be detected with current measurement technologies. Although releases into an aquatic system are improbable, they could be transported longer distances than releases into the atmosphere. The costs of collection and analysis are less expensive for aquatic detection than for atmospheric sampling and analysis. Typical sample types are water, sediment, and aquatic biota. The type of sample to be taken is determined by the signature radionuclides sorption on/in the media sampled. Non-sorbing radionuclides such as 3H, 99Tc, and 129I are in the water whereas the Pu radionuclides are in the transported sediments. Results are discussed for weekly releases of radionuclides such as 90Sr, 137Cs, 239Pu, and 235U for variable flow-rate conditions as well as for typical backgrounds and typical detection limits.