Because primaries tend to be bulky, especially in diameter, plutonium is the fissile material of choice for pits, with beryllium reflectors.

It's made not of a bulky tube, but of a thin layer of a semiconductor material that serves as the gamma detector.

The Indian stove is clearly a work in progress it is too bulky and not durable enough to survive the rigors of an African village.

The calves were bulky blocks of metal with pipes bolted together for the ankles and a yellow rubber foot with the raised rubber line from the toe to the ankle to look like a vein.

But the problem was that the gamma detectors were these huge, bulky tubes, and they were filled with these scintillating crystals, and you just couldn't get them close enough around the breast to find small tumors.

In the personal computing business which moved from the bulky Apple II to the sleek and intelligent iPhone 4s (announced the day before Steve s death) Steve was the only true showman of what is now one of the world s biggest industries.