Controlled Demolition Group has won a new contract for decommissioning work at BNFL's Trawsfynydd station.
The group has been working at the Welsh plant since 1997, demolishing the boiler head, incinerator building, boron dust building and turbines. The 2-unit Magnox plant ceased operation in July 1993.
In the new contract - the company's eighth at the site, worth £1.6 million - the main turbine hall will be demolished. The hall is 77m wide, 110m long and up to 43m high.
Four weeks of a total planned contract time of 46 weeks have already been carried out. The project will now take a break while BNFL reroutes services.
Some 18,500t of rubble from the site will be crushed as backfill and 5000t of steel will be recycled.