7. Reactivity control

7.1 Core life

Core life is conventionally defined as the energy, expressed in nominal power equivalent days (NPED), that the core can supply, from its first divergence, to a state of exhaustion such that it can no longer diverge at peak xenon following a shutdown after power operation, despite a low primary temperature, but sufficient for steam production that can still be used for propulsion. Service life is determined by the vessel's operating rhythm and the frequency of general maintenance campaigns. In particular, this takes into account the forecast annual energy consumption (of the order of 40 to 80 JEPN for a warship in peacetime), the duration of fuel unloading and loading operations (minimum 1.5 months), and the frequency of major maintenance operations (major refits every...