Nuclear Reactor Method (7.32)
The nuclear reactor method obtains a more consistent color throughout the diamond. The major advantage of this method is its capacity. Instead of irradiating a few stones at a time, it accepts several hundred carats of rough or polished stones at a time. It is thus much less expensive to operate (per stone). After the irradiation process is complete, the required degree of annealing depends on the desired final color.
The above illustration is courtesy of: https://www.navneetgems.com/types-of-irradiation-methods-in-blue-topaz/