A former Oak Ridge National Laboratory director, Alvin Weinberg, a prominent figure in American science for decades who coined such familiar phrases as “big science” and “technological fix,” died Wednesday. He was 91.

A member of the National Academy of Sciences, Weinberg helped develop the technology behind the atomic bomb in the 1940s at the University of Chicago and came to Oak Ridge in 1945 as part of the Manhattan Project.

Though he remained a vigorous proponent of nuclear energy, he worried that nuclear weapons would ever be used again in war. He led an effort in 1996 that brought a large “peace bell” cast in Japan to Oak Ridge as a symbol “that bitter enemies can become friends.”

As a scientist, the son of Russian emigrants born in Chicago and educated at the University of Chicago co-authored the standard text on nuclear chain reaction theory with Nobel Laureate Eugene Wigner in the 1940s.

Under his leadership between 1955 and 1973, the Oak Ridge lab broadened its work to include early research into the biological effects of radiation on human genetics, the environmental effects of manmade pollution and the potential impact of energy conservation.

Weinberg was an early proponent of pressurized-water reactors, which became the standard for naval propulsion and most commercial power stations. He also proposed the formation of the American Nuclear Society.

In 1961, Weinberg chaired President Kennedy’s Panel of Science Information, which produced a landmark report on the communication of science to technical and lay audiences that became known simply as the “The Weinberg Report.”

Weinberg was known for vividly articulating issues associated with nuclear energy with such catch phrases as “nuclear priesthood,” “Faustian bargain,” “technological fix,” and “big science” to convey that nuclear physics or space research “require extremely elaborate equipment and staffs of large professionals” to support them.

In 1975, Weinberg founded and became director of the Institute for Energy Analysis at Oak Ridge Associated Universities. He retired in 1985.

“Alvin Weinberg, perhaps more than any single individual, personified Oak Ridge National Laboratory,” the current director Jeff Wadsworth, said in a statement. “[He] was among the first to understand that there are scientific challenges so big and so complex that they can be solved only at places like Oak Ridge National Laboratory.

“His wisdom and ability to articulate complex issues were remarkable, and we still use his concepts,” Mr. Wadsworth said.