The vitrified HLW containers are stored in a specially designed on-site waste store building. The containers are stacked 10 high in sealed cylindrical pits that are air-cooled by natural convection. The current policy is to store the waste for a minimum of 50 years before final disposal.
After several decades of cooled storage, the heat output will have reduced sufficiently that the waste may be reclassified as intermediate level waste (ILW) and placed in a repository for permanent disposal.