Robots are going to be employed to crawl over nuclear missile silos in the US, automating maintenance that has previously been done manually.
Some 400 steel and concrete silos housing Minuteman III intercontinental missiles are spread across Wyoming, Montana and North Dakota. Constructed in the early 1960s for an earlier generation of missiles, the silos were designed to withstand megaton-level nuclear strikes. Each is 30 metres deep and 5 metres across, with a missile inside.
Longevity wasn鈥檛 a major consideration when the silos were constructed, and the missiles and silos are both years beyond their planned service lives. The US Air Force鈥檚 Minuteman III missiles were introduced in the 1970s, acting as a US nuclear deterrent, and they will continue in this role until they are replaced by Sentinel missiles in new silos, which is planned in the next decade.
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To check whether the existing facilities are still fit for purpose, silos have previously been inspected by subjective, manual methods, says a spokesperson for Gecko Robotics, which has won a $1.5 million contract to make assessments of the silos with robots. Yet it can be hard for a person to check the sheer, curved internal wall of a silo when much of the space is occupied by a missile, and dropping a tool in that environment could conceivably lead to damage or explosions.
, based in Pittsburgh, Pennsylvania, has pioneered crawling robots to inspect metal boilers, storage tanks and ship鈥檚 hulls. Its TOKA series robots can climb walls, crawl at up to 20 metres a minute and are loaded with ultrasonic and magnetic sensors and HD cameras. Typically, a robot takes a reading every 25 millimetres, enabling the creation of a high-resolution 3D model of the area being surveyed.
鈥淲ith the crawling robots, we鈥檙e able to provide the Air Force with a digital twin of the facilities to help them identify problem areas that would be missed under current assessment processes,鈥� says the spokesperson.
Under the 18-month contract, Gecko Robotics will also equip these robots with echo-based tools to assess reinforced concrete.
at the University of Leeds, UK, says that the echo impact sounders that Gecko Robotics is employing will be useful for assessing the quality of concrete, being essentially an automated version of a skilled surveyor tapping with a hammer and listening for a change in note.
Purnell says most problems with reinforced concrete relate to the steel reinforcing bars corroding due to water intrusion. Improved understanding of the chemistry involved makes modern concrete far more durable.
鈥淚f you wanted something to have a 200-year life, that could now be built,鈥� says Purnell. 鈥淏ut many of the concrete structures built in the 60s will not last another hundred years.鈥�
The robotic survey should reveal whether the silos are fit for purpose, need repairs or should be taken out of service.
