tl;dr - it's a lithium, hydrogen, fluoride rocket.
Skip 31:00 (https://youtu.be/KX-0Xw6kkrc?t=1860) for a treatment on the bonkers environmental impact and safety things going on at SSFL. The equivalent wiki article section says uh... "Workers would dispose of barrels filled with radioactive sodium by dumping them in a pond and then shooting the barrels with rifles so that they would explode and release their contents into the air".
tl;dr - it's a lithium, hydrogen, fluoride rocket.
Skip 31:00 (https://youtu.be/KX-0Xw6kkrc?t=1860) for a treatment on the bonkers environmental impact and safety things going on at SSFL. The equivalent wiki article section says uh... "Workers would dispose of barrels filled with radioactive sodium by dumping them in a pond and then shooting the barrels with rifles so that they would explode and release their contents into the air".