The Washington summit hosted by Barack Obama comes amid fears Islamic State could try and create a dirty bomb.
World leaders are set to gather in Washington to discuss how to prevent terrorists getting hold of radioactive material, with the UK poised to play a leading role in protecting nuclear facilities from cyber-attack.
The UK and the United States will hold a joint exercise next year to prepare for any online attack against nuclear power plants and waste storage facilities.
Prime Minister David Cameron is to offer British expertise to other countries to protect their own civil nuclear installations, amid fears Islamic State could attempt to create a dirty bomb.
The Nuclear Security Summit (NSS), hosted by President Barack Obama, will see heads of government consider what their response to such a scenario would be.
The recent terror attacks in Brussels have renewed concerns about the threat of nuclear terrorism.
According to Belgian media, two of the suicide bombers in the attacks, Ibrahim and Khalid El Bakraoui, had video footage of a senior official at a Flanders nuclear waste facility.
A UK Government source said there was no “credible evidence” terrorists were targeting British facilities.
But the joint exercise with the US would make sure both governments and their civil nuclear industries were prepared and could rectify any potential weaknesses.
The source said: “You saw just last week in Belgium concerns that were raised around the security of civil nuclear sites and therefore, in the world in which we currently live, we think it’s the right thing to do.”
Mr Cameron will also use the summit to offer British expertise on cyber security.
The Government source said countries including Japan, Turkey, South Korea and Argentina have all expressed an interest in learning from British “experience and expertise”, with other nations expected to follow.
The UK will also commit £10m this year to improve security around nuclear plants and waste facilities.
“We do think there is a role we can play along with the US in terms of improving these standards,” the source said.
The summit will be the fourth and final NSS, following on from the last meeting at The Hague in the Netherlands in 2014.
The gatherings were a personal initiative pushed by President Obama, and the final meeting will see world leaders take part in a “scenario-based session” focusing on the “threat from nuclear terrorism”.
The UK wants to support the US to make sure there was a “lasting legacy” from the summits, the British source added, with the International Atomic Energy Agency taking forward the work on nuclear security.