By Nina Chestney
(Reuters) - British nuclear reprocessing plant Sellafield said it had detected elevated levels of radioactivity at one of its on-site monitors and was operating at reduced staffing levels on Friday.
The plant is located in Cumbria, northwest England.
Since 2005, the plant has been owned by the Nuclear Decommissioning Authority and operated by Sellafield Ltd.
In 2008, the NDA contracted the management of Sellafield Ltd to Nuclear Management Partners, a consortium of U.S. company URS, British company AMEC, and France's Areva. The initial contract was for five years with the option to extend to 17 years.
Facilities at the site include THORP (thermal oxide reprocessing plant) and the Magnox nuclear fuel reprocessing plant.
It is also the site of the remains of Calder Hall, which is being decommissioned, as well as some other older nuclear facilities at Windscale.
The UK's National Nuclear Laboratory also has its central lab on the Sellafield site.
The plant is going through a decommissioning program, which includes dismantling infrastructure and decontaminating nuclear waste.
The cost of decommissioning the plant has been estimated at over 70 billion pounds ($115 billion).
In April 2005, leaked radioactive waste was discovered from THORP through a crack into a sump chamber that might have started as early as August 2004, and was categorized as a level 3 event on the International Nuclear Event Scale, and resulted in fines.
In 2010, the UK government said Sellafield was one of eight possible sites considered suitable for future nuclear power stations.
In 2011, the government confirmed the site was suitable and said it hoped an electricity generating company would choose to build a power station there by 2025.
Objections to the site have been raised by the governments of Ireland, Norway and the Isle of Man, concerned by the risks of contamination.
($1 = 0.6062 British pounds)
(Reporting by Nina Chestney in London; Editing by Will Waterman)