The NAC-LWT (Legal Weight Truck) cask system is the industry workhorse of U.S. commercial spent nuclear fuel transportation casks, and has been used for many types of solid and liquid wastes. The NAC-LWT is versatile – it can be loaded wet in a storage pool, or dry in hot-cell facilities or at facilities with small pools and limited crane capacities. The system is used for packaging research reactor spent fuel, nuclear power plant spent fuel assemblies and fuel rods, and other irradiated materials.

The U.S. Nuclear Regulatory Commission (NRC) Certificate of Compliance for the NAC-LWT was last revised in 2015 and has been extended to 2020. The NAC-LWT certification is fully compliant with the latest regulations, including TSR-1 regulations (IAEA 96) implemented by NRC in 2004.