Before revision: Including the effect of an external neutron source ("external" to the fission process, not physically external to the core), one can write a modified evolution equation: where is the rate at which the external source injects neutrons into the core .
After revision: in neutrons/ΔtIncluding the effect of an external neutron source ("external" to the fission process, not physically external to the core), one can write a modified evolution equation: where is the rate at which the external source injects neutrons into the core .