The world's first commercial nuclear power plant, which operated for almost half a century, has been defueled. Opened by Queen Elizabeth II on October 17, 1956, Calder Hall was the first nuclear reactor site built for industrial-scale civilian power generation and connected to a national electrical grid.

Originally designed to run for only 20 years, Calder Hall remained in service until March 31, 2003. According to its present operator, Sellafield Ltd, during its 47 years in service, it generated enough energy to meet the average electricity demand of England and Wales for three months.

Calder Hall's four Magnox reactors are different from those being built today in that they are gas-cooled reactors that are fueled with rods made out of enriched natural uranium, and use blocks of graphite as a moderator and carbon dioxide gas as a coolant. A simple design, it served as the template for 22 Magnox reactors built in Britain at 10 sites, as well as two more sites in Italy and Japan.

After it was closed in 2003, decommissioning began in 2007 by the Nuclear Decommissioning Authority’s Magnox Operating Programme with the demolition of the cooling towers, and in 2011 the first of 38,953 spent fuel rods were removed from the reactors by the same handling gear previously used to fuel them.

The fuel rods were sealed inside special shielded and armored flasks and transported to Sellafield’s Fuel Handling Plant, where they will be allowed to cool in water-filled storage ponds before being stripped of their zirconium alloy cladding and reprocessed to extract uranium-235 and plutonium for reuse.

According to Sellafield, Calder Hall’s reactor buildings have been granted "care and maintenance" status, which means they will be protected against deterioration until the site, which has been extensively dismantled and recycled, is reduced to only the concrete bio-shield containing the reactor core after 2027.

"This is a truly iconic moment," says Stuart Latham, head of remediation for Sellafield Ltd. "Calder Hall was the birthplace of the civil nuclear industry. It inspired the world and put our site at the forefront of the atomic age. Completing the defueling program is an important moment for Sellafield. The defueling team have completed the task safely and professionally and have made a huge contribution to our mission."

Source: Sellafield Ltd