Site owner the Nuclear Decommissioning Authority (NDA) will give the plant a record £1.2bn to spend in the next financial year, but insiders say the sum is not enough.
In order to plug the gap, some projects will be put off to a later date, while contractors have been warned they will be expected to cut costs and boost efficiency.
Steve Morgan, director of commercial and contract management for Sellafield said: “National funding priorities have placed constraints on the NDA and that means they have placed constraints on us, but we cannot sit around and wish we had more money.
“We must use what we have to the best of our ability. Our budget is larger than it has ever been before and a third of the money will be spent on clean-up.
“Having said that, it is inevitable that some of our projects will be delayed.
“None will be cancelled but the need versus the cost will be constantly assessed. We have to be flexible and we have to strive to deliver quality as efficiently as we can.
“We need the supply chain to work closely with us to make more efficiency savings and to improve safety.”
Pete Lutwyche, Sellafield director of nuclear decommissioning and major projects, said: “These are difficult issues for us all to deal with and this has inevitably led to the reprioritisation of a number of our work activities. Despite the reprioritisation programme, Sellafield Ltd’s spend on Nuclear Decommissioning and Major Project Group activities in the new financial year will still be higher than in 2007/08.”