Lessons Learned From GEN I Carbon Dioxide Cooled Reactors

This paper provides a review of early gas cooled reactors including the Magnox reactors originating in the United Kingdom and the subsequent development of the Advanced Gas-cooled Reactors (AGR). These early gas cooled reactors shared a common coolant medium, namely carbon dioxide (CO₂). A framework of information is provided about these early reactors and identifies unique problems/opportunities associated with use of CO₂ as a coolant. Reactor designers successfully rose to these challenges. After years of successful use of the CO₂ gas cooled reactors in Europe, the succeeding generation of reactors, called the High Temperature Gas Reactors (HTGR), were designed with Helium gas as the coolant. Again, in the 21st century, with the latest reactor designs under investigation in Generation IV, there is a revived interest in developing Gas Cooled Fast Reactors that use CO₂ as the reactor coolant. This paper provides a historical perspective on the 52 CO₂ reactors and the reactor programs that developed them. The Magnox and AGR design features and safety characteristics were reviewed, as well as the technologies associated with fuel storage, reprocessing, and disposal. Lessons-learned from these programs are noted to benefit the designs of future generations of gas cooled nuclear reactors.