IBM's Sequoia has taken the top spot on the list of the world's fastest supercomputers for the U.S. The newly installed system trumped Japan's K Computer made by Fujitsu which fell to second place, BBC News reported.

It is the first time the U.S. can claim pole position since it was beaten by China two years ago.

Sequoia will be used to carry out simulations to help extend the life of aging nuclear weapons, avoiding the need for real-world underground tests. It is installed at the U.S. Department of Energy's Lawrence Livermore National Laboratory in California.

The computer is capable of calculating in one hour what otherwise would take 6.7 billion people using hand calculators 320 years to complete if they worked non-stop.

The IBM supercomputer is also more energy efficient than the Fujitsu model. Sequoia consumes 7.9 megawatts compared to the K computer which uses 12.6 megawatts.

The first computer to take the top position on the list was the CM-5/1024 in 1993, designed by Thinking Machines. According to Prof Dongarra, Sequoia is 273,930 times faster.