When nuclear fuel is transported from power stations for reprocessing, they need to be kept under certain conditions.
The fuel rods are cooled for 90 days in dry storage or by immersing them in cooling ponds. This significantly reduces their power output to about 25 watts, similar to that of an electric light bulb.
Batches of 200 rods are loaded under water in an open top steel skip which is then placed into a 50 ton transport container called a flask. The flask is sealed to the outside elements with walls up to 35 cm thick.
How these flasks are forged and then tested is truly incredible.