Boron is used in the primary coolant of pressurized water reactors in nuclear power generation for shim control. If boron concentration is decreased, fewer neutrons are adsorbed and more fission occurs. When boron concentration increases, less fission occurs. The boron concentration can be controlled by the use of ion-exchange resins operating in the Boron Thermal Regeneration System (BTRS). A better understanding of BTRS kinetics can enhance its potential use for chemical shim control. The concentration and temperature effects on boron sorption and desorption with Amberlite IRN-78LC resins are investigated both experimentally and theoretically for BTRS operating conditions from 0.1-0.2 mol/dm(3) boron and 10-60 degreesC. A model, based on a postulated boron-sorption mechanism, assuming linear driving force through the film with fast, reversible, local reaction equilibrium, is presented. Comparison with experimental data validates that the model predictions are reasonable. The results are also applicable to other boron ion-exchange systems, such as initial breakthrough predictions from water polishers used in manufacturing microchips.