Watts per cm2 is the answer.
In other words,
Rate of fission = Macroscopic Cross Section for Fission x Neutron Flux
Units WATTS = cm2 x n- cm/ cm3 sec
-----------------------Divide both sides by Macroscopic Cross Section--------------------------------
Watts per cm 2 = Neutron Flux
LPRMs measure neutron flux.
RBMs a different instrument, average LPRMs nearest the selected rod and normalize it to roughly % local power for block enforcement.