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http://www.guardian.co.uk/g2/story/0,3604,983646,00.html
It's one of the burning questions of the moment: how easy would it be for a country with no nuclear expertise to build an A-bomb? Forty years ago in a top-secret project, the US military set about finding out. Oliver Burkeman talks to the men who solved the nuclear puzzle in just 30 months...
The quest to discover whether an amateur was up to the task presented the US Army with the profoundly bizarre challenge of trying to find people with exactly the right lack of qualifications, recalls Bob Selden, who eventually became the other half of the two-man project.. Both men had physics PhDs - the hypothetical Nth country would have access to those, it was assumed - but they had no nuclear expertise, let alone access to secret research..
.. the participants have been asked to design a nuclear explosive which, if built in small numbers, would give a small nation a significant effect on their foreign relations."
Dobson's knowledge of nuclear bombs was rudimentary, to say the least. "I just had the idea that ..you had to quickly put a bunch of fissile material together somehow," he recalls.. Bob Selden found a book on the Manhattan Project that culminated in America's development of the bomb. "It gave us a road map," Dobson says. "But we knew there would be important ideas they'd deliberately left out because they were secret..
They faced one key decision, Dobson says: whether to design a gun-style bomb, like the one dropped on Hiroshima, that used a sawn-off howitzer to crash two pieces of fissile material together, or a more complex implosion bomb, like that dropped on Nagasaki. By now they were beginning to enjoy the challenge, so they went for the harder, more impressive option. "The gun device needed a large amount of material, and didn't make a very big bang," Dobson says. "The other one was more bang, less material."
Dobson and Selden had decided to assume that their fictional Nth Country had already obtained the requisite plutonium.. the two amateurs were ironically aided by information published as part of President Dwight Eisenhower's "Atoms for Peace" program, which spread word of the benefits of non-military nuclear power around the world. And Atoms for Peace was only the most prominent example of a fad for everything nuclear that propelled a huge amount of technical detail into the public domain.
Eventually, towards the end of 1966, two and a half years after they began, they were finished. "We produced a short document that described precisely, in engineering terms, what we proposed to build and what materials were involved," says Selden. "The whole works, in great detail, so that this thing could have been made by Joe's Machine Shop downtown."
Agonisingly, though, at the moment they believed they had triumphed, Dobson and Selden were kept in the dark about whether they had succeeded. Instead, for two weeks, the army put them on the lecture circuit, touring them around the upper echelons of Washington, presenting them for cross-questioning at defence and scientific agencies. Their questioners, people with the highest levels of security clearance, were instructed not to ask questions that would reveal secret information. They fell into two camps, Selden says: "One had been holding on to the hope that designing a bomb would be very difficult. The other argued that it was essentially trivial - that a high-school science student could do it in their garage." If the two physics postdocs had pulled it off, their result, it seemed, would fall somewhere between the two - "a straightforward technical problem, but one that involves some rather sophisticated physics".
Finally, after a valedictory presentation at Livermore attended by a grumpy Edward Teller, they were pulled aside by a senior researcher, Jim Frank. "Jim said, 'I bet you guys want to know how it turned out,'" Dobson recalls. "We said yes. And he told us that if it had been constructed, it would have made a pretty impressive bang." How impressive, they wanted to know. "On the same order of magnitude as Hiroshima," Frank replied.
"It's kind of a depressing thing to know, that it could be that easy," Dobson says. "On the other hand, it's far better to know the truth." And the truth today, he is certain, is that terrorists - with a bit of luck and, crucially, access to the right materials - could easily build a nuclear bomb. "Back in the 50s, there were two schools of thought - that the ideas could be kept secret, and that the material could be locked up. Now? Well, hopefully the materials can still be locked up, but we all have our doubts about that." Obtaining sufficiently enriched fissile material could be difficult but, when it comes to creating the bomb, "It turns out it's not overwhelmingly difficult
It's one of the burning questions of the moment: how easy would it be for a country with no nuclear expertise to build an A-bomb? Forty years ago in a top-secret project, the US military set about finding out. Oliver Burkeman talks to the men who solved the nuclear puzzle in just 30 months...
The quest to discover whether an amateur was up to the task presented the US Army with the profoundly bizarre challenge of trying to find people with exactly the right lack of qualifications, recalls Bob Selden, who eventually became the other half of the two-man project.. Both men had physics PhDs - the hypothetical Nth country would have access to those, it was assumed - but they had no nuclear expertise, let alone access to secret research..
.. the participants have been asked to design a nuclear explosive which, if built in small numbers, would give a small nation a significant effect on their foreign relations."
Dobson's knowledge of nuclear bombs was rudimentary, to say the least. "I just had the idea that ..you had to quickly put a bunch of fissile material together somehow," he recalls.. Bob Selden found a book on the Manhattan Project that culminated in America's development of the bomb. "It gave us a road map," Dobson says. "But we knew there would be important ideas they'd deliberately left out because they were secret..
They faced one key decision, Dobson says: whether to design a gun-style bomb, like the one dropped on Hiroshima, that used a sawn-off howitzer to crash two pieces of fissile material together, or a more complex implosion bomb, like that dropped on Nagasaki. By now they were beginning to enjoy the challenge, so they went for the harder, more impressive option. "The gun device needed a large amount of material, and didn't make a very big bang," Dobson says. "The other one was more bang, less material."
Dobson and Selden had decided to assume that their fictional Nth Country had already obtained the requisite plutonium.. the two amateurs were ironically aided by information published as part of President Dwight Eisenhower's "Atoms for Peace" program, which spread word of the benefits of non-military nuclear power around the world. And Atoms for Peace was only the most prominent example of a fad for everything nuclear that propelled a huge amount of technical detail into the public domain.
Eventually, towards the end of 1966, two and a half years after they began, they were finished. "We produced a short document that described precisely, in engineering terms, what we proposed to build and what materials were involved," says Selden. "The whole works, in great detail, so that this thing could have been made by Joe's Machine Shop downtown."
Agonisingly, though, at the moment they believed they had triumphed, Dobson and Selden were kept in the dark about whether they had succeeded. Instead, for two weeks, the army put them on the lecture circuit, touring them around the upper echelons of Washington, presenting them for cross-questioning at defence and scientific agencies. Their questioners, people with the highest levels of security clearance, were instructed not to ask questions that would reveal secret information. They fell into two camps, Selden says: "One had been holding on to the hope that designing a bomb would be very difficult. The other argued that it was essentially trivial - that a high-school science student could do it in their garage." If the two physics postdocs had pulled it off, their result, it seemed, would fall somewhere between the two - "a straightforward technical problem, but one that involves some rather sophisticated physics".
Finally, after a valedictory presentation at Livermore attended by a grumpy Edward Teller, they were pulled aside by a senior researcher, Jim Frank. "Jim said, 'I bet you guys want to know how it turned out,'" Dobson recalls. "We said yes. And he told us that if it had been constructed, it would have made a pretty impressive bang." How impressive, they wanted to know. "On the same order of magnitude as Hiroshima," Frank replied.
"It's kind of a depressing thing to know, that it could be that easy," Dobson says. "On the other hand, it's far better to know the truth." And the truth today, he is certain, is that terrorists - with a bit of luck and, crucially, access to the right materials - could easily build a nuclear bomb. "Back in the 50s, there were two schools of thought - that the ideas could be kept secret, and that the material could be locked up. Now? Well, hopefully the materials can still be locked up, but we all have our doubts about that." Obtaining sufficiently enriched fissile material could be difficult but, when it comes to creating the bomb, "It turns out it's not overwhelmingly difficult