The warhead components are separate chemicals and gases that are dispersed into a cloud and react in midair to form a polymer emulsion--a glue, if you will.

As a result, warhead components are contained within an aluminium honeycomb substructure, sheathed in pyrolytic graphite-epoxy resin composite, with a heat-shield layer on top which is constructed out of 3-Dimensional Quartz Phenolic.

The IAEA is expected on Wednesday to publish new details of evidence of Iran's development of a nuclear military capability, and will identify a site where warhead components are suspected to have been tested.

The warhead component, tritium, has been sold for 25 years in small amounts for research and for making markings that glow in the dark.

The US President authorised the transfer of nuclear warhead components to the UK between 1991 and 1996.

Videotapes from Haidar, the report said, showed "personnel conducting tests of a cluster bomb that appears to utilize submunitions based, in part, on 122-millimeter warhead components."

Production of nuclear warhead components had ceased by the time the grand jury gave the judge its report early this year, but various chemical processing operations were continuing.

The report by the International Atomic Energy Agency (IAEA), which will also identify a suspect site where warhead components have been tested, is the most detailed presentation to date of its evidence for recent nuclear weapons research in Iran.

Britain, meanwhile, is also collaborating with the US on plans to replace nuclear warhead components.

Binary quantum torpedoes shared the same characteristic: They didn't go "live" until their warhead components were mated just two seconds before launch.