Cuba Nuclear Plant Could Pose Hazards : Safety: A U.S. official says construction flaws cited by former workers are cause for concern.

Recent reports by defecting workers at a nuclear power plant under construction in Cuba were the “first real indication” of potential safety problems at the facility, a Bush Administration official told members of Congress on Wednesday.

Michael G. Kozak, a deputy assistant secretary of state, told members of the House Foreign Affairs subcommittee on inter-American affairs that the examples cited by the defectors of serious flaws at the nuclear plant are cause for concern, but not for panic.

Kozak said that the Administration intends to contact President Fidel Castro’s government about the safety of the Soviet-designed reactor. He said that the matter also could be raised at an expected summer summit meeting between President Bush and Soviet President Mikhail S. Gorbachev.

Until now, Kozak said, the United States has relied primarily on Cuba’s acceptance of International Atomic Energy Agency monitoring of the project near Cuba’s south coast port of Cienfuegos, 150 miles south of Florida. The plant site also was visited in 1989 by a representative of the U.S. Nuclear Regulatory Commission.

“Our experts will be talking to them. Another visit will be helpful,” Kozak said. “No single visit by anybody is going to guarantee safety.”

Kozak was questioned by lawmakers about testimony by Vladimir Cervera Cruz, 27, a Soviet-educated former quality control engineer at the plant. Cervera defected last month at a Canadian airport as he was en route to the Soviet Union.

Cervera, who appeared before the subcommittee Wednesday, estimated that 10% to 15% of the welded joints in the plant are faulty. “I hope if the plant is completed, the IAEA will know enough about its conditions to say that it should not operate,” he said.

Cervera and another recent defector, Soviet-trained geophysicist Jose Oro, have asserted in previous news conferences and interviews that Cuba lacks the scientific infrastructure and trained personnel to build the nuclear complex, scheduled for completion in 1993.

Oro said at a news conference Tuesday that the project is in an earthquake-prone area near a nuclear fuel reprocessing and storage area, a potential source of ground and water pollution. But when Kozak was asked about the fuel reprocessing center, which could permit Cuba to produce weapons-quality uranium, the State Department official responded that “we don’t have evidence of Cuban preparations for reprocessing.”

Nils Diaz, a University of Florida nuclear scientist who interpreted for Cervera at Wednesday’s hearing, told reporters that a serious malfunction at the Cuban plant could send a radioactive cloud over much of the Caribbean and Florida.