Neutrons emanating from a tokamak nuclear fusion reactor can be absorbed into a suitably covering blanket around the reactor, spallating further neutrons which similarly can be absorbed by a suitable blanket of waste, effecting a transmutation of the waste. This form of tATW requires the infrastructure of a practically operating tokamak nuclear fusion reactor. ITER is currently under construction in France with an expected completion in 2035 or 2050.
Prof WM Stacey of Georgia Institute of Technology leads a group which has completed significant tATW studies
A far smaller dedicated apparatus which could be built today with existing technology already proven in pieces in separate applications, but never yet all together, is from an alternative source of neutrons from muon catalyzed fusion reactors in mATW. My postdoctoral research into the method which results in neutron collimation was discovered in the context of muon catalyzed fusion but only later gave rise to the notion of its advantages for ATW. This gives rise to mATW but the method would also be applicable to the proton accelerator version of sATW but probably not tATW.