Demonstration of Regulatory Process Controls on the TSTA Cryogenic Distillation System

Abstract

Due to the nature of its fusion reaction, most of the DT used to fuel the International Thermonuclear Experimental Reactor (ITER) will exit unreacted. This effluent will be purified by the fuel cleanup system so that the isotope separation system (ISS) will be fed only hydrogen isotopes and possibly some helium. The ISS will separate this feed into streams nominally composed of He/H2/HD, D2, DT, and T2. These products will be recycled through appropriate fueling systems back to the fusion reactor or returned to storage. The ISS will have to respond properly to feed conditions which change rapidly. Feed changes will propagate quickly through the entire cascade. It is apparent that an automatic control system will be required to respond to these changes and maintain product quality. It is convenient to divide such a distillation control system into `regulatory` controls and composition controls. The `regulatory` controls include liquid levels, flowrates, reboiler heats, and pressure. A system of regulatory controls has been devised and installed on the four-column cascade of cryogenic columns at the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. This tritium-compatible ISS is designed for approximately 1/10 the ITER flowrate and is dedicated to fusion fuel studies. Details of the TSTA ISS have been published previously.