Security systems for future nuclear plants should be planned to prevent terrorists from stealing their nuclear fuel and building nuclear bombs, a Harvard professor said yesterday.

Richard Wilson, professor of Physics and an expert on nuclear safety, said that although the security in present plants is adequate, future innovations in nuclear power plant design will cause a need for better systems.

"A group of a dozen skilled people could make a nuclear bomb when pure materials are available," Wilson said in a New York Times opinion-page article on January 3. But he said few United States reactors use fuel pure enough to make a nuclear bomb.

In addition, Wilson said in the article that now better methods are available to terrorists than nuclear bombs to "create havoc," such as nerve gas and biological weapons.

However, the breeder reactor--which is now experimental--will use purified fuel. Although none of the experimental breeders that produce their own fuel are operating in the United States, Wilson said yesterday that "it's reasonable to say the breeder will be in commercial operation by 1990 or 1995."

Breeder reactors are now operating in France, Great Britain, and the Soviet Union.

Wilson said $100 million would be sufficient for a nationwide system that would be effective. "That's less than $1.0 million per plant and less than one per cent of the total electric cost," he said.

Wilson said that the nuclear power industry could easily handle the cost because "it's not in that bad financial shape."

The need for breeder reactors won't become severe for about 30 years, he said. But when that time comes, "There may be a war in the Middle East," Wilson said.

"Certainly the reactors should not be developed without the safety systems," Wilson said. "The French have a breeder, but they don't give a damn about safety."