Under the Energy Act 2004, the Nuclear Decommissioning Authority is responsible for the decommissioning and clean-up of the UK's public civil nuclear sites. The cost of disposal is influenced by many different factors, including the inventory of waste, the timing of waste arisings, the geology at the site in question and the design of the geological disposal facility. The NDA's estimate, as given in its 2007-08 annual report, for the undiscounted total lifetime costs of a geological disposal facility for higher activity wastes is £12.2 billion.