The Imperial College Reactor Centre (ICRC), part of Imperial College London, has become the first reactor site to be fully decommissioned in UK nuclear history under modern regulatory controls. The site was delicensed by the Office for Nuclear Regulation (ONR) following years of work to defuel and then decommission the site in Ascot after the shutdown of the consort research reactor in 2012.

ICRC has now been assessed by ONR as posing no danger to the public, and no longer requires ONR regulatory controls. The Imperial centre is only the third UK reactor site in history to be fully decommissioned, and its land has now been returned for re-use. Currently, ONR regulates 35 licensed nuclear sites in the UK.

ONR says its inspectors have studied the Silwood Park site’s final Environmental Management Plan in recent months and are content that the concluding decommissioning work, including asbestos surveillance and landscaping, has been completed. As a result, ICRC is no longer subject to regulations under the Environmental Impact Assessment for Decommissioning Regulations (EIADR) 1999.

“This is a highly significant achievement and milestone in UK nuclear decommissioning history and testament to all the hard work that has been put in at the Imperial College Reactor Centre to reach this final end state,” said Ian Phillips, ONR’s Head of Safety Regulation for Decommissioning, Fuel & Waste sites. “It represents the conclusion of a 65-year journey for the ICRC which can now be recognised as the country’s first ever fully decommissioned reactor site under modern regulatory controls – a fantastic accomplishment.

He added: “Our regulatory oversight ensured that all necessary conditions involved in the defuelling, decommissioning, demolition, and delicensing process were realised to meet the high standards we demand in order to maintain the ongoing safety of workers and the public.”

The ICRC was constructed in the early 1960s and the consort reactor achieved criticality in 1965. The small 100 kW research reactor was moderated, cooled, reflected, and partially shielded by light water. Following a significant decline in the volume of research conducted in the facility, shutdown of the reactor began 13 years ago. Defuelling was completed in 2014 and 31 fuel elements were removed and transported to Sellafield in Cumbria for interim storage pending reprocessing.

Decommissioning of the reactor and surrounding bioshield was completed in February 2020, and the demolition of all building structures, removal of the base slab and below ground services finished in April 2021.

“Imperial College London is indebted to the Reactor Centre team who provided deep technical and operational oversight throughout the project, as well as support contractors and the site Nuclear Safety Committee for their dedication,” said Trevor Chambers, former Head of ICRC. “Releasing the site from regulatory control has created a recreational space at the heart of Imperial’s Silwood Park eco-campus, which may now be used without restriction by staff and students at the forefront of biodiversity science and policy.”

Image (top left): Original consort reactor site in the 1960s (courtesy of Imperial College Reactor Centre)

Image (bottom right): The consort reactor site after full decommissioning (courtesy of Imperial College Reactor Centre)