The cost of cleaning up the Sellafield nuclear waste site has reached £67.5bn with no sign of when the cost will stop rising, according to a report.
The Public Accounts Committee's report said deadlines to clean the Cumbria site had been missed, leaving crucial decommissioning projects over budget.
It suggested successive governments have failed to "get to grips" with the hoards of waste stored at the site.
The Nuclear Decommissioning Authority said it is facing up to the challenges.
Set up in 2005 as an "arm's length" government body, the authority is responsible for managing the UK's nuclear waste.
Last week Cumbria County Council rejected proposals to build a new underground nuclear waste storage facility in the area, deciding not to press ahead with a study for a possible site.
The Public Accounts Committee report follows criticisms by the National Audit Office (NAO) in November.
The NAO said rundown buildings posed "intolerable risks to people and the environment".
Margaret Hodge MP, chairwoman of the committee, said an "enormous legacy" of nuclear waste had been allowed to build up at the plant.
"Over decades, successive governments have failed to get to grips with this critical problem, to the point where the total lifetime cost of decommissioning the site has now reached £67.5 billion, and there's no indication of when that cost will stop rising," she said.
"Furthermore, now that Cumbria County Council has ruled out West Cumbria as the site of the proposed geological disposal facility, a solution to the problem of long-term storage of the waste is as far away as ever."
The committee's report also calls for a "real sense of urgency" to avoid risk and costs escalating.
John Clarke, chief executive officer of the Nuclear Decommissioning Authority (NDA), said prior to the NDA's formation there was no credible lifetime plan for Sellafield.
He said: "Tough decisions about how we ultimately decommission the site had simply been put off for future generations to deal with.
"We are now facing up to those challenges and for the first time we have a proper plan in place for the decommissioning of Sellafield.
"Since the creation of the NDA in 2005, the financial investment at Sellafield has increased from £900m to over £1.5bn a year.
"Of course, not everything has gone smoothly on such a complex and highly-technical programme, and the report has rightly pointed to areas where we and the site need to do better."
The Public Accounts Committee said 12 of the site's 14 projects were behind schedule and five of them over budget.
'Lack of trust'
"This is an area of considerable deprivation with high unemployment. We are looking for there to be clearer ambition that spending on this huge scale contributes to creating jobs and supports sustainable growth in the region and the UK," said Mrs Hodge, the Labour MP for Barking and former minister.
Gary Smith, national officer of the GMB union, said: "There is an increasing lack of trust in the consortium that runs the site both amongst the workforce and the wider community.
"There needs to be immediate change at the top of the consortium and a radical re-evaluation of the piecemeal hiving-off of the nuclear sector to private companies that are clearly ill-equipped to cope and have little interest in ensuring Britain has world-class nuclear facilities."
Last Wednesday's county council decision saw the authority's cabinet vote against progressing to the next stage of a process that would have seen studies take place in search of a suitable location for an underground nuclear dump.
Cumbria was the only area still considering housing the repository.
About 9,000 people are employed at Sellafield where radioactive waste lies in ponds and silos.