Bomb disposal experts have been called to the Sellafield nuclear reprocessing plant to help dispose of chemicals stored at the site that were discovered to have "changed state" during a routine inspection, the British government said on Friday.
The chemical, organic peroxide, is used across many industries and was stored at the Magnox reprocessing site in northwest England, segregated from the nuclear operations of the plant.
"During a routine investigation we noted that the chemical had changed state," Sellafield Ltd. said in a statement.
"The plan, as advised by EOD (Explosive Ordnance Disposal), is to burn the chemicals in a prepared incineration pit on a part of the site away from any buildings or infrastructure."
The incineration was expected to be complete on Friday afternoon.
The reprocessing plant was evacuated as a precautionary measure on Thursday. The plant was not in operation at the time, Sellafield Ltd said.
"Chemical monitoring is undertaken across the site to understand changing chemical states and to inform when and how industrial chemicals should be stored or disposed of," the company said.
"The risk has been identified as a conventional safety issue rather than a nuclear safety risk," it added.
Sellafield is a former nuclear power generating site. The Magnox plant at the site is due to close this year. It processes and separates plutonium and uranium.