“The first retrievals from the Pile Fuel Cladding Silo are a huge step toward delivering our purpose of creating a clean and safe environment for future generations,” said Euan Hutton, chief executive officer of Sellafield Ltd. “This achievement means that for the first time ever Sellafield is retrieving waste from all four of our legacy ponds and silos.”
The history: Sellafield’s oldest waste storage building, the Pile Fuel Cladding Silo was built in the 1950s to store cladding from used nuclear fuel from the Windscale Piles, the first nuclear reactors to be built at the site. The large concrete silo was designed as a “locked vault,” with no plan for how to retrieve its contents or decommission the building.
After almost 20 years of operations, the silo’s six compartments had reached capacity, and it stopped receiving waste in the early 1970s. In the years that followed, the building underwent several upgrades to ensure it could continue to store its contents safely while a plan for retrievals was developed.
In the last decade, a giant concrete superstructure has been built around the silo, and specially engineered shield doors have been installed on each of its six compartments. In 2017 holes were successfully cut in the top of each compartment, allowing access to the waste for the first time in 65 years.
The process: To empty the silo, Sellafield Ltd. designed, manufactured, tested, and installed nine huge modules containing the machinery necessary to retrieve the waste. This was done in collaboration with Bechtel and Cavendish Nuclear Solutions, working together as Bechtel Cavendish Nuclear Solutions.
In early August, a robotic grab was successfully tested. Operators then remotely used the grab to reach into the silo and pick up the waste, which was then loaded into a specially designed stainless-steel box.
Once filled, the box will be loaded into a shielded flask and transported to a new, fit-for-purpose store called the Box Encapsulation Plant Product Store.
According to Sellafield Ltd., the building currently represents one of the most complex and difficult decommissioning challenges in the world—and one of the highest priorities for the company and the U.K.’s Nuclear Decommissioning Authority.
