HAL / Highly Active Liquor meaning

HAL (Highly Active Liquor) is the heat‑generating, highly radioactive liquid waste produced when spent nuclear fuel is reprocessed, principally at Sellafield. In practice it is the concentrated nitric‑acid liquor of fission products and minor actinides left after uranium and plutonium are separated by the purex process. HAL is an interim material awaiting conversion to glass (vitrification), and its storage is subject to strict regulatory limits on quantity, activity and heat load, with engineered cooling and mixing. The expression is widely used by UK regulators and industry but is not a statutory definition. Legal obligations arise through the nuclear site licensing regime under the Nuclear Installations Act 1965 and through environmental regulation. In England and Wales, limits and monitoring are set via the Environmental Permitting (England and Wales) Regulations 2016 alongside Office for Nuclear Regulation (ONR) licence conditions and safety cases; in Scotland, via the Environmental Authorisations (Scotland) Regulations 2018 and ONR oversight; and in Northern Ireland under the radioactive substances regulatory regime administered by the Northern Ireland Environment Agency. Ireland does not produce HAL but the term appears in cross‑border environmental, radiological‑protection and emergency‑planning contexts. Typical use: nuclear operations, decommissioning, hazard‑ and stock‑reduction programmes, and compliance reporting.