What is ALARA principle?

Although regulations specifying maximum occupational dose limits are intended to minimize risk of injury or ill effects, occupational radiation exposure must be kept As Low As Reasonably
Achievable (“ALARA”).

Workers shall ensure ALARA dose by means of TDS (T-Time; D-Distance; S-Shield) technique.

What is Neutron Flux?

Imagine there are Neutrons flying in all directions in selected region. When we consider a unit volume at a particular instance, we can count the number of Neutrons. This number of Neutrons per unit volume is called Neutron Density(D). Now observe that volume for certain time. This will give you total track length covered by the Neutrons inside the volume.This is called Neutron flux(F).

Neutron flux is obtained from the product of Neutron density(D) and Average Neutron Velocity(V)
i.e. F = D x V