<P> The mean generation time, Λ, is the average time from a neutron emission to a capture that results in fission . The mean generation time is different from the prompt neutron lifetime because the mean generation time only includes neutron absorptions that lead to fission reactions (not other absorption reactions). The two times are related by the following formula: </P> <Dl> <Dd> Λ = l k (\ displaystyle \ Lambda = (\ frac (l) (k))) </Dd> </Dl> <Dd> Λ = l k (\ displaystyle \ Lambda = (\ frac (l) (k))) </Dd> <P> In this formula, k is the effective neutron multiplication factor, described below . </P>

Which reaction takes place in a nuclear fission reactor