- An automated radiochemical flow analysis (ARFA) system was developed which integrates chemical and radiochemical techniques into one system through the use of a microcomputer. The operator, through the microcomputer, controls valves and pumps to transfer sample and reagent solutions to counting loops, ion exchange columns and holdup reservoirs. A Ge(Li) detector monitors the radioactivity of samples delivered to counting loops or of species retained on ion exchange resins. The microcomputer controls the acquisition of gross count and pH information and signals a minicomputer-multichannel analyzer to acquire a gamma ray spectrum. Computer control of solution handling allows count rates to be reduced through alternate counting geometries, dilution, sample holdup, preconcentration and separation of interferences with ion exchange resins. Extensive software was developed to allow the user to operate the ARFA system in three basic modes: 1) dedicated for on line monitoring of reactor coolant water, 2) interactive with step by step control of operations by the operator and 3) automatic sequence execution based on job stream programming, The versatility of the ARFA system is demonstrated with four applications: 1) automated on line monitoring of simulated reactor coolant water, 2) analysis of non-radioactive chemical samples, 3) analysis of low level radioactive samples and 4) studies of trace metal humic acid interactions. In the first application five count rate reduction methods were used to extend the dynamic range of counting up to six orders of magnitude. For the second application trace metals present in tap and river water samples were concentrated on Chelex-100 ion exchange resin, stripped with acid, activated and counted. Zn, Cu, Mn, Br and K were determined at nn/mL concentrations and 0y, Eu, and U were detemined at sub no/m1 concentrations. In the third application of the ARFA system, species in reactor coolant water at the OSU TRIGA reactor were concentrated and counted directly on an ion exchange column, decreasing analysis time by a factor of 2-5 while increasing the peak to Compton ratio by approximately a factor of twenty compared to initial counting loop measurements. In the final application, test solutions of Mn²⁺, Eu³⁺, In³⁺, Dy³⁺ tracers and humic acid were passed through a Chelex-100 resin. The retention behavior of the metal tracers was used to follow the kinetics of the metal complexation.