Design of a Tritium-In-Air Monitor Using Field-Programmable Gate Arrays

Field-programmable gate arrays (FPGAs) have recently garnered significant interest for certain applications within the nuclear field including instrumentation and control (I&C) systems, pulse measurement systems, particle detectors, and health physics. In CANada Deuterium Uranium (CANDU) nuclear power plants, the use of heavy water (⁠$D2O$⁠) as the moderator leads to increased production of tritium, which poses a health risk and must be monitored by tritium-in-air monitors (TAMs). Traditional TAMs are mostly designed using microprocessors. More recent studies show that FPGAs could be a potential alternative to implement the electronic logic used in radiation detectors, such as the TAM, more effectively. In this paper, an FPGA-based TAM is designed and constructed in a laboratory setting using an FPGA-based cRIO system. New functionalities, such as the detection of carbon-14 and the addition of noble-gas compensation, are incorporated into a new FPGA-based TAM along with the standard functions included in the original microprocessor-based TAM. The effectiveness of the new design is demonstrated through simulations as well as laboratory testing on the prototype system. Potential issues caused by radiation interactions with the FPGA are beyond the scope of this work.