2. Common constraints

2.1 Safety and safety demonstration

The primary vocation of the nuclear technologies discussed here is the production of electrical energy, and it is imperative that this be done safely. In the past, this condition has led to the a priori rejection of certain neutronically interesting but intrinsically dangerous options, particularly when they risk bringing materials liable to cause an explosion into contact with each other inside the reactor (e.g. heavy water, the best moderator, and sodium, the best coolant): heavy water, the best moderator, and sodium, the best coolant), or when the reactor was unstable: this condition led in the 1970s to the abandonment of the heavy water moderated, boiling light water cooled reactor concept, and should, for the same reasons, have ruled out the...