A previous bid competition to deliver the £120m Box Encapsulation Plant Product Store and Direct Import Facility was abandoned last year after failing to attract sufficient interest.

But since then the nuclear waste processor has been walking interested firms around the half-finished job in the hope of enticing them to bid.

Interested firms must register on the e-tending portal by 7 April.

The “Big Box” project to encapsulate intermediate level waste in cement for above ground storage at the site has suffered a chequered history.

A joint venture between Jacobs, Atkins and Carillion first started work on the project back in 1997.

But the job was halted in 2002, due to technical uncertainties, and the partially completed on-site facilities put in mothballs.

After a project rethink in 2010 Balfour Beatty in joint venture with Babcock secured the early contractor engagement phase of the Box Encapsulation Plant Product Store and Comprehensive Import Export Facility, as the waste store project became known. The project was then valued at around £250m.

Following another strategic review in the face of rising costs, Sellafield bosses decided to cancel this planned expansion and replace it with an alternative simpler facility known as the BEPPS and Direct Import Facility, which formally went to prequalification stage before being cancelled because of insufficient interest.

Sellafield is now confident it has sufficient market interest to run a bid competition for the project.