Britain and Japan have signed a framework civil nuclear co-operation pact, the UK energy ministry has said.
The announcement has come this week as UK Prime Minister David Cameron kicked off his tour of Asia in Japan, aiming to boost trade and investment ties.
The nuclear pact follows the devastating Fukushima nuclear plant meltdown in March last year and opens up Japan's multi-billion pound decommissioning sector to UK companies.
"British companies have significant expertise in nuclear decommissioning and clean-up, with 19 nuclear sites in the UK currently being managed through the process," Cameron said.
The two-way exchange will involve Japanese companies offering technical expertise in new plant design and construction in return for the UK's decommissioning and waste-management experience.
"The countries will share expertise, experience and technology in the remediation, decontamination and decommissioning of the Fukushima nuclear site," the UK energy ministry said.