Salaries and days off are being slashed in a major shake-up of working arrangements at Sellafield.

All new starters with the company will be subject to controversial - and less lucrative - new terms and conditions, that also include fewer paid sick days. However existing employees are not affected.

Sellafield Ltd says the measures, being introduced early next month, are to save around £4 million a year and increase productivity. The unions say however that the move is "detrimental" to the site and "reneges on promises" made to current apprentices who will be subject to the new T&Cs on completion of their courses.

Included in the new terms are:

- starting salaries between 15 and 22 per cent lower. For newly-qualified apprentices for example, the average starting salary will be around £24,000, down from around £28,000.

- removal of 'accrued' days. Currently, staff work 40.75 hours per week (rather than the contracted 38.75) and get 13 extra days off a year. New starters will be contracted to work the 40.75 hours.

- fewer paid sick days. Currently, staff can be paid 261 full sick days in a four-year period. New starters will get full pay for 130 days and half-pay for 60 days in a four-year period.

Holidays, shift and separation area allowances, on-call arrangements and bonus entitlements are unaffected. Those who have been offered jobs at Sellafield Ltd but have not yet started will be subject to the old T&Cs.

Apprentices and trainees are said by Steve Gibbons, of the Unite union, to be hardest hit by the changes. They started a fixed-term contract for their training at the time of the older terms and conditions, but by the time they qualify and become full Sellafield Ltd employees, they will be subject the the new terms.

Mr Gibbons said: "The proposals are a backwards step for the company and renege on promises made to young people at the start of their apprenticeships."

One current technical specialist trainee told The Whitehaven News that she is "outraged" at the move.

She said: "I left a teaching job and took a pay drop to do this course. Now, two years in, the end-game has changed and I've just wasted two years of my life.

"There is also huge injustice that those who chose a two-year course with a lesser qualification will now be better off than those who challenged themselves and did a three-year course for a more in-depth qualification."

Paul Foster, Sellafield Ltd chief executive, said: "These changes are about fairness - to our workforce, our local community and the UK taxpayer.

“We have compared these T&Cs with other employers and what we’re offering is still among the best in the marketplace.

“They save £4m every year from now until our mission ends in over 100 years’ time. That is money we would rather spend creating new jobs and focus on our number one priority – reducing the hazards on the site.

“Changing T&Cs will also help to rebalance the local economy, allowing other companies and the public sector to compete for key skills.

“People are leaving jobs in education and healthcare to join Sellafield Ltd for our T&Cs – that’s not fair or sustainable. We would prefer to see those people stay and serve their local community.

“Sellafield Ltd received record funding from the government of £2bn this year. We have to repay the faith shown in us by proving we can become as cost-effective and productive as possible.”

A number of mass meetings have been organised by unions Prospect, Unite and GMB to gauge workers' views. Their formal response will be made once all the meetings have taken place.