Britain will ship 700 kilograms of nuclear waste to the United States under a deal to be announced by Prime Minister David Cameron at a nuclear security summit in Washington on Thursday, a British government source said.
In return for the shipment, the largest ever movement of highly enriched uranium, the United States will send Europe a different type of nuclear waste that can be used to produce medical isotopes for the treatment of some cancers.
"The prime minister will be announcing a landmark deal that we have agreed with the US and with (European Atomic Energy Community) Euratom," the British government source said, on condition of anonymity.
"It is a win-win. We get rid of waste and we get back something that will help us to fight cancer."
At the two-day summit, being attended by more than 50 world leaders, Britain and the US will also announce plans to host a joint exercise later this year to test the ability of their governments and nuclear industries to deal with a cyber attack in the civil nuclear sector.
The source said this was not in response to intelligence about a specific threat, but "prudent planning".
Last week, Belgian newspaper DH reported suicide bombers who blew themselves up in Brussels were originally considering an attack on a nuclear site in Belgium.
Britain will also invest more than 10 million pounds ($14 million) in improving nuclear security standards worldwide and, separately, launch a scheme to help other countries strengthen their ability to withstand cyber attacks on their nuclear sectors.
Japan, South Korea, Turkey and Argentina are among those expected to be involved in that scheme, the source said.
"They have come to us and said they would like to benefit from expertise we have in this area and work with us on it," the source said.