Where Was the Only Nuclear Reactor to Be Constructed Inside a Listed Building?

King William's Quarter
Old Royal Naval College, Greenwich, London

Listed: 1973
Grade: I
NHLE entry: Listing details for King William's Quarter

The Old Royal Naval College in Greenwich is now a popular tourist attraction, part of the Maritime Greenwich world heritage site. Constructed between 1696 and 1712, the college was originally built as the Royal Hospital for Seamen and then became the principal training centre for Royal Navy officers until 1998. For centuries, the college was seen as an institution that helped to guarantee the survival of the British Empire. But it wasn't until relatively recently that the story of its role in Cold War nuclear deterrence was uncovered. Between 1962 and 1996, the King William's Quarter building (now part of the University of Greenwich) housed 'JASON', a nuclear reactor residing secretly in the heart of London.

By wisdom as much as war

The college's motto, 'Tam minerva quam marte - By Wisdom as Much as War'- aptly symbolises how it readily adapted to new scientific and social advances. Designed by Sir Christopher Wren, the magnificent hall, dome and colonnade of King William's Quarter were finished in 1703, and the west front completed to the designs of John Vanbrugh in 1728. For the majority of its life, the building served as a part of the seamen's hospital, and was then transformed into the naval college in 1841. Because of the transition from sail to steam, the Navy needed more sophisticated technical equipment and training, and so, from the late 19th century, officers were taught new aspects of naval science. In 1939, the first women were admitted to the Navy as 8,000 WRNS (Women's Royal Naval Service) personnel underwent training at the college.

Nuclear secrets inside a baroque masterpiece

The college's ability to adapt to technological change was again underlined in 1962, when an Argonaut series 10-kilowatt nuclear reactor was installed in the basement. Nicknamed JASON, the reactor was operational at the site from 1962 to 1996. It was small compared to those in contemporary nuclear power stations, measuring only about 12 feet high, and was surrounded by more than 300 tons of steel and concrete cladding. JASON was used by the Royal Navy for experimental and training purposes - in particular, for the training of future engineering officers on nuclear-powered submarines.


JASON was decommissioned and dismantled between 1996 and 1999. Despite its size, the cladding had gradually become irradiated and needed controlled removal and disposal. At that time, no similar reactor had ever been dismantled. Indeed, the European Commission took the United Kingdom to the European Court of Justice for failing to fulfil its safety obligations under the 1957 Euratom Treaty, which governs the use and management of nuclear reactors. The case was finally dismissed in 2005. No trace of the reactor now remains inside the Old Royal Naval College. Undoubtedly this was the only reactor ever installed inside a Grade I-listed 17th-century building! Yet, when the building was listed in 1973, this facility was top secret, and therefore no mention of it appears on the official list entry.