Inside Britain's top secret nuclear bunker

Times

20-06-2025

Secure vaults containing decades-old enriched uranium and plutonium are dotted across Britain's sprawling atomic weapons establishment site in the Berkshire countryside.
Some are underground, inside 1960s-era buildings, guarded by police on the roof tops armed with C8 Carbine assault rifles used by the Special Air Service (SAS). Cameras keep watch and security guards patrol the perimeter — lined by a fence and razor wire, like a prison — and 56 dogs are on hand to sniff out any sign of toxic chemicals.
'The guards and guns are not here to protect us, they are here to protect the material,' said one of the scientists giving a tour of the grounds. 'You can't get anywhere near them [the vaults] even if you tried,' added another.
There are measures in place to ensure that if an air­liner hit the site inadvertently, the risk of a radioactive fallout would be ­minimised. The threat of terrorists trying to steal the uranium is greater than that of a jet deliberately bombing the site.
It is the first time in more than a decade that journalists have been allowed access here. On one side of the 700-acre site are crumbling chimneys towering above an 'out of service' factory where uranium was once enriched. Due to its international treaty obligations, Britain no longer ­enriches material. Once its stockpile runs out, it will be recycled.
It is at this site in the quaint village of Aldermaston that scientists examined the teapot containing the lethal pol­onium-210 used to kill Alexander ­Litvinenko, the Russian defector, in London in November 2006. Some £15 billion is now being poured into modernising the facility, once a Second World War air force base and now home to 9,500 ­employees — 1,000 more than there were two years ago.
The Ministry of Defence is drawing up designs for the next generation of sovereign nuclear warheads, known as Astraea, and the focus on Britain's ­nuclear programme is intensifying.
The Astraea, also known as the A21/Mk7, will replace the Holbrook warheads on the Trident missiles deployed on Britain's four nuclear deterrent submarine boats. It has been two decades since the AWE (Atomic Weapons ­Establishment) worked on warheads, which is why the site needs a huge ­investment programme to prepare the facilities. Astraea is being developed in parallel with the US W93/Mk7 warhead but not together with the US because the nuclear material cannot be transported overseas.The plan is for the warhead to be ready for use in the 2030s, ­although it is still in ­design phase.
Amid warnings of a 'third nuclear age' in which Britain is threatened by multiple enemies ­including Russia, speed will be critical.
'This is a new era of threat and there's a sense of urgency. We need to step up,' said ­Marina Dawes, director of science at the site.
The nuclear bombs are made up of fissile materials including uranium, plutonium and other components such as high explosives.
For the first time, the bombs that are produced will never have been tested in real life. The UK, along with others, has agreed not to test its nuclear bombs in the way Robert Oppenheimer oversaw the testing of the world's first nuclear weapon, nicknamed Trinity, in the ­Jornada del Muerto desert within the Alamogordo Bombing Range in New Mexico, in July 1945.
Instead, scientists and engineers in the UK today rely on the Orion laser, which enables them to simulate the hot and dense conditions at the moment of detonation but without the need for ­nuclear materials.
'We create the condition at the ­moment of detonation,' said another scientist, showcasing the equipment. This isn't a giant death ray, but a ­bespoke scientific tool,' added another.
Twelve lasers beam down on to one tiny target — no more than 5mm long and painstakingly created by hand over many months.
There is an entire building for a super-computer, which is able to make four trillion calculations in a second. It has stored data from previous experiments and is used to validate tests to ­ensure what the scientists are creating will work in a realistic scenario.
Bunkers store massive quantities of high explosives across the base. At ­Aldermaston, the components are manufactured before they are shipped off to another site, at AWE Burghfield, less than ten miles away. There they are put together and later weaponised ready for use.
Transporting the materials is a huge endeavour involving highly secure trucks, escorted by more than 50 vehicles, including a tow truck, police cars and motorbikes.
Down the road is the Blacknest site, where scientists monitor for seismic signals that may suggest another country has tested a nuclear weapon.
Those who work at Aldermaston are proud of the work they do. 'Being a ­nuclear weapons state is an awesome responsibility. It is the most serious of serious things,' said another senior ­employee at the site.
At Aldermaston and other defence nuclear industry sites, salaries average £45,500 — 20 per cent higher than the UK average — yet they are still desperate to recruit. Women from diverse backgrounds and the neuro-diverse are among those being targeted. At present, only 20 per cent of the workforce is female, according to Mandy Savage, the engineering director.
YouGov polling commissioned by the MoD found that in March this year, 65 per cent of those polled supported maintaining the UK's independent ­nuclear deterrent. This was the highest level of support since the MoD began polling in June 2018.
Amid fears the US could bomb Iran's nuclear facilities, triggering a wider conflict in the Middle East, John Healey, the defence secretary, was given his first tour of the site on Thursday. He said the technology being developed was 'keeping us all safe every minute of the day'. He added: 'The skilled men and women working here play a fundamental role in deterring global conflict and that cannot be underestimated.'