THORP

THORP
Raymond Knapman · CC BY-SA 2.0 · source
Name	THORP
Location	Sellafield, Cumbria, England
Coordinates	54.420°N 3.554°W
Operator	British Nuclear Fuels Limited
Type	Reprocessing Plant
Construction	1970s
Commissioning	1994
Closure	2018 (operations ceased)

THORP

The Thermal Oxide Reprocessing Plant was a civil nuclear fuel reprocessing facility at Sellafield in Cumbria, England, built and operated to chemically separate plutonium and uranium from irradiated nuclear fuel. It connected with international nuclear fuel cycles involving reactors such as Advanced Gas-cooled Reactor, Pressurised Water Reactor, Boiling Water Reactor, and engaged customers from countries including France, Japan, Germany, Spain, and Italy. The facility was subject to regulatory oversight by bodies such as the Health and Safety Executive and the Environment Agency (England and Wales).

Overview

THORP processed spent oxide fuel from reactors including Dungeness B, Hartlepool Nuclear Power Station, Sizewell B, Hinkley Point B, and foreign reactor fleets like Fessenheim Nuclear Power Plant, Koeberg Nuclear Power Station, and Kashiwazaki-Kariwa Nuclear Power Plant. The plant's operations linked to international agreements and trade governed by entities such as the International Atomic Energy Agency, the European Atomic Energy Community, and bilateral contracts with utilities like Électricité de France, Tokyo Electric Power Company, RWE, and Endesa. Key corporate actors included British Nuclear Fuels Limited, UKAEA, Nuclear Decommissioning Authority, and later Sellafield Ltd. THORP's economic role intersected with policies from the Department of Energy and Climate Change and the Treasury (United Kingdom).

History

Plans for a large oxide reprocessing facility at Sellafield emerged amid Cold War and civil nuclear industry developments alongside institutions like Atomic Energy Research Establishment and projects such as Windscale Piles and the Magnox Reprocessing Plant. Construction began after approvals involving ministers from HM Government, with engineering contractors including BNFL partners and firms like British Steel and Bechtel. THORP was formally commissioned in the early 1990s, following technical exchanges with teams from CEA (France), ORNL, and Oak Ridge National Laboratory personnel, and came into full operation in 1994. Throughout the 1990s and 2000s THORP featured in debates alongside events such as the Chernobyl disaster and the Fukushima Daiichi nuclear disaster that shaped public policy and regulatory change. Investigations and inquiries involved institutions like the National Audit Office, the Royal Commission on Environmental Pollution, and parliamentary committees of the House of Commons.

Design and Operation

Designed to implement the PUREX (Plutonium Uranium Redox EXtraction) chemistry used in facilities such as La Hague, Sellafield Magnox Reprocessing Plant, and Mayak, THORP's process included dissolution, solvent extraction, and conversion stages handled in shielded hot cells and gloveboxes supplied by engineering firms comparable to Siemens and Westinghouse. Feedstock included oxide fuel assemblies from AGR and PWR types. Key operational systems interfaced with plant-wide controls inspired by industrial automation suppliers like ABB and Siemens PLM Software, and quality assurance followed standards from International Organization for Standardization frameworks used by nuclear firms including AREVA and Rosatom. The plant's product streams—recovered uranium for potential reuse in reactors such as EPR and separated plutonium for fabrication facilities—connected to fuel cycle activities at facilities like Sellafield MOX Plant and research centres including Imperial College London and University of Manchester nuclear engineering groups.

Safety and Environmental Impact

THORP's safety case was maintained under regimes involving the Nuclear Installations Inspectorate and environmental monitoring by agencies such as the Environment Agency (England and Wales), with oversight shaped by laws like the Nuclear Installations Act 1965 and international safeguards of the IAEA. Releases and effluents were compared with other sites like La Hague and Dounreay, provoking scrutiny from non-governmental organisations such as Greenpeace, Friends of the Earth, and campaign groups active in Cumbria. Radiological monitoring linked to research by Public Health England and academic studies at institutions including University of Oxford and University of Cambridge. Incidents and operational challenges prompted reviews by bodies such as the Health and Safety Executive and led to improvements in containment, instrumentation, and emergency preparedness coordinated with local authorities including Cumbria County Council and agencies like the Met Office for weather-dependent dispersion modelling.

Decommissioning and Legacy

THORP ceased active reprocessing operations and entered a staged shutdown and decommissioning regime managed by the Nuclear Decommissioning Authority and executed by Sellafield Ltd, drawing on expertise from contractors including Serco, Babcock International, and international partners from Areva and Westinghouse Electric Company. Decommissioning activities align with programmes at legacy sites like Windscale, Chapelcross, and Berkeley Nuclear Power Station and inform policy at bodies such as the Committee on Radioactive Waste Management. Legacy issues include long-term radioactive waste management to facilities similar in remit to Onkalo (repository) and policy debates in parliaments including the United Kingdom Parliament and assemblies in Scotland and Wales. THORP's scientific and technical record contributes to literature preserved in repositories such as the National Archives (United Kingdom), and its impact continues to be assessed by research centres including Sellafield Ltd Research Centre, university nuclear engineering departments, and international forums like the Generation IV International Forum and the Nuclear Energy Agency.

Category:Nuclear reprocessing