I've a setting where some abandoned facility that was run by a joint venture of the military and a high-tech company, has its direct surrounding, outside the facility, littered with barrels full of a toxic, radioactive liquid waste product.
The radioactivity is of the stuff is of a level that you should not mess around with it, but you wouldn't be fried on the spot.
I'm looking for a plausible 'something' that they made or researched at this facility, that would be the source of barrels full of toxic waste. This 'something' could be of any nature, from microscopic size up to around the size of about half a standard shipping container.
The High-tech contractor had access to enough funds to toy around with whatever they though may lead to something useful for the military. They also had well paid PR people to explain away just about anything, if the general public somehow got the idea that their ethics where dubious.
The military is happy to put anything to good use, that is supplied to them. From drugged up soldiers to viral agents that (supposedly) selectively affect a certain group of people to neutron mortar shells, they would quickly find an operational use for it.