The "reactor-grade" plutonium produced by a regular LWR burnup cycle typically contains less than 60% Pu-239, with up to 30% parasitic Pu-240/Pu-242, and 10 15% fissile Pu-241.
In fact, under those conditions, less than 80% of your plutonium will be the fissile Pu-239, with 19% or more becoming Pu-240.
It's pretty easy, by performing this short-period irradiation, to produce weapons-grade plutonium, where up to 93% of the plutonium created is the fissile Pu-239, with somewhere between 6% and 7% Pu-240.
Loading of TRU from legacy UO2 spent fuel allowed core continuous operation for 180 effective full power days with a net fissile-Pu burning rate of ∼6.4%.
The latter includes denaturing of fissile materials, Pu in particular, as well as the intense radiation field associated with the pyrochemical partitioning method.
The neutron spectra become harder with the lower grade of fissile plutonium vector as well as the increasing of Pu and MA contents in loaded fuel salt.
These would have the nifty trick of generating their own fuel, since fast neutrons can convert non-fissile isotopes of uranium into highly fissile plutonium.
X-ray powder diffraction, X-ray fluorescence, microscopy, X-ray absorption fine structure, and electron probe microanalysis were used to characterize ZrO2 MgO inert matrix fuel containing UO2 (as a fissile element and a Pu homolog) and Er2O3 as a burnable poison.
