In the future, control systems will be needed to reduce tritium levels in the primary coolant and reactor building of water cooled fusion devices. This paper presents a method to determine the size and configuration of the control system required to meet federal regulations including the as low as reasonably achievable (ALARA) guideline. A cost expression is developed that includes a cost for population exposure based on an ALARA guide (cost/man-rem). The optimum configuration and resulting tritium levels are determined by optimizing the cost expression. Application is made to an ETR/INTOR class of fusion reactor.