Engineers have successfully replaced vital elements of a nuclear reprocessing plant in Cumbria.
Technical problems put the operation back 24 hours
A section of the roof of the Thorp facility at Sellafield was removed to allow four huge vessels to be lowered into position by a giant crane.
Technical difficulties meant the operation, involving 20-tonne vessels used to process liquid waste, was put back 24 hours.
Experts said the operation had proved to be "very challenging".
The vessels, which are 11m (36ft) long and cost £5m each, process liquid waste at the site, which is concentrated before it is sent to be turned into glass.