WASHINGTON — Scientists unveiled the world’s fastest supercomputer yesterday, a $100 million machine that for the first time has performed 1,000 trillion calculations a second in a sustained exercise.

The technology breakthrough was accomplished by engineers from the Los Alamos National Laboratory and IBM Corp. on a computer to be used primarily on nuclear weapons work, including simulating nuclear explosions.

The computer, named Roadrunner, is twice as fast as IBM’s Blue Gene system at Lawrence Livermore National Laboratory, which itself is three times faster than any of the world’s other supercomputers, according to IBM.

“The computer is a speed demon. It will allow us to solve tremendous problems,” said Thomas D’Agostino, the head of the National Nuclear Security Administration, which oversees nuclear weapons research and maintains the warhead stockpile.

But officials said the computer also could have a wide range of other applications in civilian engineering, medicine, and science, from developing biofuels and designing more fuel-efficient cars to finding drug therapies and providing services to the financial industry.

To put the computer’s speed in perspective, it has roughly the computing power of 100,000 of today’s most powerful laptops stacked 1.5 miles high, according to IBM. Or, if each of the world’s 6 billion people worked on hand-held computers for 24 hours a day, it would take them 46 years to do what the Roadrunner computer can do in a single day.

The IBM and Los Alamos engineers worked six years on the computer technology.