The balance for delayed neutron precursors

Let the production of the nuclei of delayed neutron precursor i due to absorption in a fission event be 

Following the procedure of Section 21.6, we may substitute rtc = (n/l)St and let 5f 0 to give the rate of production of delayed neutron precursor nuclei per 

The rate of increase of concentration of delayed neutron precursors is the rate of production minus the rate of dscay  

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