The Nuclear Decommissioning Authority has published its latest financial accounts and has revealed that the cost of cleaning up Sellafield nuclear plant in West Cumbria was nearly six billion pounds over its estimate for last year.
The authority described the decommissioning of Sellafield as "one of its most challenging environmental restoration projects."
Last year, nuclear management partners - who were awarded the contract, were heavily criticised for initial overspend on the clean up project.
The latest cost of decommissioning at Sellafield is due to be released today.
The Nuclear Decommissioning Authority will present the figures to Parliament.
There has already been severe criticism of previous over-spends, which have put up the costs to 70 billion pounds.
Since decommissioning work began in 2007, 100 buildings have now been demolished at the Cumbrian nuclear plant.Read the full story ›
Campaigners have held another protest outside Sellafield nuclear site about plans to cull dear which are trapped between two security fences.
Sellafield says it has received independent advice from leading experts stating the most humane option is to kill the animals.
But protesters say wildlife charities have offered to try and get the deer out alive.
"Sellafield should back down, do the popular thing, the correct thing, the humane thing."
The Nuclear Decommissioning Authority which own the Sellafield site have said today that they will aim to achieve the recommendations laid out by the Public Account Committee but say they are already making progress.
“The NDA welcomes the scrutiny of the Public Accounts Committee (PAC) into our vitally important mission to decommission Sellafield.
"We have made good progress towards implementing the recommendations laid down by the PAC following its original report into Sellafield last year and will now focus on achieving the aims of the six recommendations set out in this latest report.
"Both NMP and the NDA now have a much better understanding of the issues and complexities that exist at the site and the challenges that lie ahead.
"Whilst progress has been made on a number of fronts we will require significant improvements during the next contract period. We have had extensive discussions with NMP and made clear where these improvements must be made.
"We will continue to monitor performance closely and remain focused on achieving our goal of safe, effective, value for money decommissioning at Sellafield – as we are seeing elsewhere across our portfolio of sites.”
Challenges of cleaning up waste at a Cumbria nuclear site are "unprecedented" and more complex than "any other operational or decommissioning nuclear site in the world", the head of the team overseeing Sellafield nuclear site.
NMP chairman Tom Zarges dodged claims costs were spiralling out of control and said the consortium was focused on building on "our experience of the last five years".
The challenges at Sellafield are unprecedented, with complexities exceeding any other operational or decommissioning nuclear site in the world, therefore demanding extraordinary technology and skills.
The first term of our contract has been characterised by many successes but also a number of disappointments and areas for improvement.
Our job now is to build on our experience of the last five years to safely and reliably deliver our customer's mission, while further accelerating the pace of change and providing value for money to the NDA, Government and the UK taxpayer.
The consortium overseeing the clean up of waste at Sellafield nuclear site has failed to meet taxpayer demand and the National Audit Office should review the management of the site, MPs have said.
The American-led management were accused of failing to train and keep staff to the detriment of the project, as well as planning a future for the site which "doesn't make sense".
We are not confident taxpayers' interests are being protected in the contractual relationships between the private companies involved in managing and operating the Sellafield site.
The Authority has not properly explained how it is going to deal with the large stock of plutonium stored at a cost of around £40 million a year.
It wants to build a 'MOX' plant for converting plutonium into fuel for nuclear power stations - but no UK power stations can use this fuel.
The cost of building and operating a MOX plant would be more than the value of the fuel produced. It just doesn't make sense.
The cost of cleaning up nuclear waste at Sellafield has soared to "astonishing" levels, with latest figures estimating the bill has already hit £70bn, according to a group of influential MPs.
The Public Accounts Committee (PAC) said the cost would continue to rise and blasted "poor" progress at the Cumbria site.
They also accused Nuclear Management Partners (NMP), who were brought in to manage the clean up, of letting timescales slip and running a project with "escalating" costs.
Among a series of recommendations MPs called on the Nuclear Decommissioning Authority (NDA) to terminate the contract with NMP if their performance did not improve.
The report said the consortium had been brought in six years ago to help Sellafield improve its performance and had its contract extended last October despite "spiralling costs and poor performance".
A committee of MPs has severely criticised the private consortium that manages the Sellafield nuclear plant in Cumbria.
In its latest report, the Commons' Public Accounts Committee says it is extremely concerned about spiralling costs and delays to projects.
Chair of the Committee, Margaret Hodge MP, says the contract for Nuclear Management Partners (NMP) should have been reconsidered, before an extension was awarded.
An anti-nuclear group from Cumbria is protesting in London today.
Radiation Free Lakeland is opposed to the idea of an underground nuclear waste store being built in the county.
They are planning to demonstrate outside the Department of Energy and Climate Change.