The irradiated fuel is placed in a heavily shielded flask (called a “cask” in US terminology). Different flask designs are used for different fuel types.
| Parameter | Typical UK Magnox Flask |
|---|---|
| Overall shape | Cube-shaped, water-filled |
| Total weight | ~50 tonnes |
| Length | 2.56 metres |
| Wall thickness | 360 mm of steel |
| Fuel capacity | ~850 kg of irradiated fuel |
| Shielding | Provided by the thick steel walls (also gives structural integrity) |
US transport casks and UK PWR fuel flasks are generally cylindrical in design.