From memory, not active research:


Ukraine has nuclear reactors that create weapons-grade Plutonium as a "by product" of the reaction. True.
The amount produced by these reactions is miniscule.

The UAEA has been all over that. They know exactly how much Plutonium is created per Mega Watt created. They actively regulate the production and disposal of that material.

If the conspiracy is that all of the Plutonium is diverted to a secret weapons program, then that's probably not possible. The number of people involved would be in the thousands. Too many to keep quiet, IMO. *shrug*

If the conspiracy is that only an unmeasurably small amount is being hidden from inspectors, such that trained physicists are being fooled into accepting less than they were told... then... OK. Not an easy ask, but far, far fewer conspirators needed.

But then the rate at which you're acquiring material is so absurdly miniscule that you're talking a decades long program to obtain enough material to produce a weapon.


So it's not beyond imagination that some attempt at collecting that Plutonium could happen.
It's just that any non-insane number of conspirators means the utility of the program is moot.