New bombs?Where does the nuke deal leave us with any optios as far as this is concerned?
How to build a greener H-bomb
Last Updated: 12:01am BST 26/06/2007
Super-lasers could help to develop Britain's next generation of nuclear weapons, reports Roger Highfield
The steel skeleton of a building the shape of a teardrop rears high above the barbed wire that surrounds the sprawling site where Britain maintains its home-grown nuclear weapons.
Cloud of destruction: the first H-bomb is tested in the Pacific in 1952
I last stepped inside the security gates, past the guard dogs and armed police, almost a decade ago.
Then, grizzled boffins from the glory days of nuclear weapons testing were fretting about how to attract young blood to work on H-bombs.
It looked like an industry in decline. Last week, I was invited back to see how the Atomic Weapons Establishment (AWE) in Aldermaston, Berkshire, could - if the Government chooses - design and build the next generation of British nukes.
The 750-acre site still felt like the set from Dr Strangelove; most buildings date from the 1950s and 1960s.
But that steel skeleton on the western perimeter, soon to become a Â£180 million laser facility called Orion, tells a different story. It is part of a Â£1 billion, three-year refurbishment programme that will run until 2008, with the same again to be spent on running costs.
The workforce is being expanded from 4,300 to almost 5,000 - and it is getting younger, too; from an average age of 43 four years ago, to 39 today.
The Comprehensive Test Ban Treaty in 1996, which ruled that Britain could no longer carry out nuclear testing in the Nevada desert, seemed to signal the end of the development of nuclear weapons technology.
Not so, according to Dr Brian Bowsher, Aldermaston's director of research and applied science. Using supercomputers, bomb makers are able to detonate virtual 3D nuclear explosions using complex mathematical modelling, data from non-nuclear laboratory tests, information gathered from the 45 British nuclear tests between 1952 and 1992, and the ultra-high temperatures and pressures which will be generated by Orion's lasers.
He was less forthcoming about what goes on inside a nuke, but the old guard I met years ago had provided me with the basics. If you open a Trident warhead you see a sphere of high explosive; when this is detonated, focused shock waves compress an inner shell of plutonium for a millionth of a second or so. When critical mass is achieved, the nuclear chain reaction is kick-started, aided by a squirt of neutrons.
Experiments into exactly what happens in this primary part of Trident are being carried out at Aldermaston. High explosive implodes hollow shells of heavy metals - not the plutonium found in the real thing - in bomb chambers.
All that can be heard from the nearby road is the warning siren: air gaps in the chambers' double walls muffle the explosions, as powerful flashes of X-rays reveal how the materials flow, mix and deform in these "hydrodynamic" tests.
But for Trident to be a true H-bomb, its primary weapon stage must be used as a fuse for a secondary stage utilising lithium deuteride fusion fuel. The result is Armageddon. This part of the weapon is currently being studied using AWE's Helen laser.
Its two green beams focus one million million watts of power on tiny targets to study the squirt of plasma, radiation and shock waves, and how they interact. I witnessed Helen firing last week. The laser blast proved an anticlimax, without so much as a pop. The science is anticlimatic too: Helen can achieve the pressures within a nuclear blast, but not the temperatures.
By 2011 Helen will be replaced by Orion, which is 1,000 times more powerful. When it is fired, a millimetre-sized target will be bombarded with laser light from 10 angles. Almost simultaneously, two other laser beams will fire shorter pulses, heating the sample to up to 10 million degrees, and compressing it to 100 times the density of water.
The action will take place behind five-foot thick concrete walls to shield staff from the pulses of gamma radiation.
Next door, a Â£70 million building called Gemini is under construction. By 2009, it will house 1,400 scientists and engineers who will use the latest computer visualisation methods to work on nuclear warheads.
Jonathan Brown, Aldermaston's director of infrastructure, said that a new hydrodynamic test facility was also planned, along with refurbished plutonium and uranium handling facilities. And, on a separate 225-acre site, at Burghfield, seven miles east, AWE is to build more plants, including one to assemble and disassemble warheads.
AWE has also invested in a Â£20 million Cray XT3 "Redwood" supercomputer, which provides the power of six billion people doing 7,000 calculations a second. With it, virtual nuclear weapons can be endlessly detonated to test and hone designs.
But all this investment to what end? The official line is that studies at Orion will keep the current stockpile of 200 ageing Trident warheads in service.
These have already been carried by submarines for 15 years and, although 40 are to be decommissioned this year alone, Trident is expected to remain our nuclear deterrent into the 2020s.
However, Dr Bowsher said that Orion could stay in operation until 2036, suggesting that it will also be used to develop a new warhead - perhaps one that is safer, easier to construct, or more able to cope with being knocked about. Or, perhaps, a more flexible warhead where the size of the bang can be varied at the turn of a dial.
The Aldermaston folk are happy to discuss anything but this. Instead, we were shown an interminable safety video that tells you what to do in the event of a "criticality alert". A leaflet sent to locals last week declares that in more than 50 years, "AWE has never had a radiation or other emergency that has affected the public".
(A half-truth that ignores the unease triggered by years of incidents and leaks).
They bang on about the environment too. Along with recycling plutonium and highly enriched uranium from old warheads, carcinogenic materials in Trident now have to be replaced to meet new safety standards, said David Glue, an AWE director. The use of bicycles, buses and car sharing among staff is encouraged, along with rainwater harvesting and recycling building materials.
After bidding the Dr Strangeloves goodbye, I was struck by the surreal picture emerging in Aldermaston; one of enthusiastic young boffins who want to build a weapon of mass destruction that is kinder to our planet: a green nuke.