“This is a titanium barrel filled with low and medium-level radioactive waste.”

Use this on a segment of armor to make your ship radioactive. This is commonly done on accident, while the barrel is unidentified.

An actinide waste cannon can be created from 8 barrels of radioactive waste at Tinker Gatherings.

Sapiens will frequently have radioactive waste in their ships.

A unidentified barrel of waste will appear in your inventory soon after refueling your ship with a uranium fuel rod.

Be careful not to apply that barrel onto your armor, otherwise, you will be irradiated, which is not a good thing.