Although to most the term ‘fission reactor’ brings to mind something close to the commonly operated light-water reactors (LWRs) which operate using plain water (H2O) as coolant and with sluggish, thermal neutrons, there are a dizzying number of other designs possible. Some of these have been in use for decades, like Canada’s heavy water (D2O) reactors (CANDU), while others are only now beginning to take their first step towards commercialization.
