No smoking gun, nor Iranian bomb

According to the ‘Times’ last week, alleged ‘confidential intelligence documents’ show Iran is working on testing a key final component of a nuclear bomb. The notes, the newspaper claims, describe “a four-year plan to test a neutron initiator, the component of a nuclear bomb that triggers an explosion”. President Ahmadinejad denounced the documents as more American forgeries. But even if we take them as genuine, is this a real ‘smoking gun’ — and what do the documents show anyway?
In my opinion they should be read recognising the long Iranian interest in the physics of nuclear fusion. Jim Callaghan, then British foreign secretary, visited Iran in March 1976. The Shah told him that he was particularly interested in the UK’s fusion programme and “if any opportunity arose whereby Iran could come in on the programme, they would be happy to do so”. That interest has continued for more than 30 years. In 1993 Iran agreed with China to co-operate in the study of fusion and there is an continuing programme of work in Tehran.

Fusion
Nuclear fusion is the mechanism whereby the sun shines and sustains life on earth. Nuclear reactors and atomic bombs rely on fission; hydrogen bombs rely on fusion. There are as yet no fusion reactors that produce energy because, even after 50 years of trying, more energy is needed to produce fusion than is obtained from the output. Nevertheless, industrialised countries persist in research in this field. At present the joint EU-US-Japan-China-India-Korea-Russia Iter project is building a fusion reactor prototype at Cadarache in France. Research in this area is allowed by the nuclear non-proliferation treaty.

The ‘intelligence documents’ published by the ‘Times’ describe a four-year project, so if the Iranians were to build a neutron initiator for a nuclear weapon it is not being treated as a matter of urgency. By contrast, the Manhattan Project scientists arrived at Los Alamos in early 1943, and the Trinity test occurred in July 1945.
Then the documents state that “policy is to develop co-operation with research and university centres in order to carry out the projects outside of the centre” and that samples are to be produced “by mutual co-operation … (then presented) to other research centres for marketing purposes”. It is unlikely that nuclear weapon projects would be distributed among several universities, or weapon parts marketed to research centres.

The documents call for two physicists with PhDs and two with masters degrees to carry out the work. That doesn’t sound like a top priority national programme. That sounds more like a university research project.
Then there is uranium deuteride, or UD3. According to the ‘Times’: “Critically, while other neutron sources have possible civilian uses, UD3 has only one application — to be the metaphorical match that lights a nuclear bomb”. That is a surprising statement. In fact the document’s only mention of UD3 states that it would prefer not to use it but to replace uranium with titanium. That gives a clue about what the Iranians are doing.
Titanium deuteride is used to store deuterium gas so that the gas can be generated when it is heated. It seems to me, therefore, that the function of UD3 is to generate deuterium gas so that it can be used in a plasma focus neutron generator. The neutron generator could then produce isotopes for use by other laboratories, hence the reference to market samples. UD3 is not known to be used as a neutron initiator in nuclear weapons: it was not used as an initiator in American, British or Soviet weapons when those weapons were developed.