Nuclear reactor which produce delayed neutrons have half lives for their decay by neutron emission that range from milliseconds to as long as several minutes, and so considerable time is required to determine exactly when a reactor reaches the critical point. Keeping the reactor in the zone of chain-reactivity where delayed neutrons are "necessary" to achieve a critical mass state allows mechanical devices or human operators to control a chain reaction in "real time"; otherwise the time between achievement of criticality and nuclear meltdown as a result of an exponential power surge from the normal nuclear chain reaction, would be too short
Integral Molten Salt Reactor batches are periodically added to the reactor system. As the reactor uses circulating liquid fuel this process does not require complex mechanical refueling machinery. The reactor vessel is never opened, thereby ensuring a clean operating environment. During the 7 years, no fuel is removed from the reactor; this differs from solid fuel reactors which must remove fuel to make room for any new fuel assemblies, limiting fuel utilization. Nuclear power reactors have three fundamental safety requirements: control, cooling, and containment. Nuclear reactors require control over the critical nuclear chain reaction. As such, the design must provide for exact control over