A consortium consisting of Amec, Arriva and Balfour Beatty has been tipped to win a £600m job to build a repository for high-level radioactive waste in Sellafield

The job, which was put out to tender by Sellafield last year, is thought to be one of the few major decommissioning jobs likely to be let over the next few years given the current squeeze on the Nuclear Decommissioning Authority’s £2.7bn annual budget.

The consortium is understood to have beaten other teams, including: Sir Robert McAlpine, Hochtief and Costain; Jacobs, Laing O’Rourke, Nuvia and Doosan Babcock; Australia-based Worley Parsons and D&Z Constructions; and Singapore-based Simon Carves.

The job, known as the Highly Active Storage Tank, is to build a repository for waste that is so radioactive that it generates heat, and is seen as one of the few “must haves” on the decommissioning programme. Sources said the job would be worth a few million pounds to the winner this year, but could be worth up to £600m in total.

Last year the Treasury started to review the decommissioning budget to see if spending from 2011 onwards could be reprioritised, delayed or made more efficient.

The contractor will have to design the storage tank, ventilation and abatement systems, and connect the tank to existing plants.