WASHINGTON, Feb. 7 (Xinhuanet) -- US scientists have begun designing a new generation of nuclear arms meant to be sturdier and more reliable and to have longer lives, The New York Times reported Monday.

    The quiet effort so far involves only 9 million US dollars for warhead designers at the country's three nuclear weapon laboratories, Los Alamos, Livermore and Sandia, where federal bombexperts were scrutinizing secret arms data gathered over a half century for clues about how to achieve the new reliability goals.

    The relatively small initial program involves fewer than 100 people, but is expected to grow and produce finished designs in the next 5 to 10 years, the report said, quoting federal officialsand private experts.

    The resulting warheads were lightweight, very powerful and in some cases so small that a dozen could fit atop a slender missile,according to the report.

    Originally, the roughly 10,000 warheads in the American arsenalhad an expected lifetime of about 15 years, officials were quoted as saying. The average age is now about 20 years, and some are much older.

    The US Congress approved a small, largely unnoticed budget itemin late November last year that started the new design effort, known as the Reliable Replacement Warhead program. The designs could eventually help recast the nuclear arsenal with warheads that are more rugged and have much longer lifetimes, experts said.

    Officials said that the program could help shrink the country'snuclear arsenal and the high cost of its maintenance, but arms control advocates said the program was probably unneeded and dangerous, and that it could start a new arms race if it revived underground testing. Enditem