Assertion: decay's neutron | /r/HasProperty | necessary
Facets:
value: to achieve a critical mass state
type: PURPOSE
Source sentences:
text: 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 to allow for intervention.
text: More neutrons are released than are needed to maintain the chain reaction; when uranium-238 absorbs just the excess, plutonium is created, which helps to make up for the depletion of uranium-235.
text: For this reason, one or more neutrons are necessary for two or more protons to be bound into a nucleus.