* Low-level radioactive material ended up in dump
* Costs of nuclear waste could reach 67 billion pounds
By John McGarrity
LONDON, Nov 15 (Reuters) - British regulators filed charges against the owners of the Sellafield nuclear waste site on Thursday on allegations of illegal dumping of radioactive waste, adding to the plant's history of controversy and complaints.
The nine charges relate to the dumping of low-level waste in a landfill in 2010, the latest in a string of issues involving Sellafield, which for the last 60 years has handled Britain's spent nuclear fuel.
"The regulators' joint action follows an extensive investigation," Britain's Environment Agency and the Office for Nuclear Safety said in a statement.
The regulators alleged that Sellafield Ltd, which runs the plant, had breached permits by dumping four bags of nuclear waste material at the nearby Lillyhall landfill without authorisation.
The penalties for such a breach are expected to be relatively small, but the prosecution comes at an inopportune time for Sellafield following a highly critical report earlier this month, said Paul Dorfman, a nuclear waste expert at Warwick University.
"It's another suggestion of laissez faire management," he said.
Earlier this month, Sellafield's operators promised to make improvements after the National Audit Office said hazardous waste stored in antiquated buildings at the reprocessing plant posed "intolerable risks".
Nuclear Management Partners, which has operated the Sellafield Nuclear reprocessing plant since 2008, is a consortium of French nuclear technology company Areva , UK engineering firm AMEC and U.S. construction firm URS.
The Lillyhall dump was given an official permit to handle low-level atomic material only in 2011, although before last year the landfill was authorised to accept waste from Sellafield under specific licenses or 'exemptions'.
Sellafield breached those exemptions, the government agencies said, claims that will be heard by an English court next month.
The issue of how Britain will fund the enormous cost of storing nuclear waste is expected to come into sharp focus in the coming months. Upgrading and adding storage at Sellafield alone could cost 67 billion pounds ($106.2 billion) by 2120, authorities estimate.
The nuclear industry is hoping the government's forthcoming energy reform bill will outline how to finance the costs of new plants and the reprocessing of their radioactive refuse.