President Reagan, at the seven-nation economic summit, will raise the idea of on-site international inspection of nuclear power plants in the Soviet Union and elsewhere following the nuclear disaster at Chernobyl, presidential spokesman Larry Speakes said today.

Speakes reported that airborne radiation from the damaged reactor was spreading over much of Europe and said Reagan believes "on site inspection is a worthwhile goal." He said the president would raise the issue with the leaders of Western Europe, Canada and Japan when the summit officially opens Sunday.

The White House spokesman said that, while it is true that the Soviets have reported the fire at the reactor is smothered, the United States has every reason to believe the fire has been diminished, "but is still smoldering."

Speakes anounced that Vice President George Bush had sent Reagan a written report of a special situation group that met in Washington yesterday and that Bush expressed "serious concern" about the lack of information the Soviets have provided on the reactor accident.

Speakes said the United States, responding to reports from the Polish government, has urged women of childbearing age and children not to travel to Poland "until after the situation is clarified." He also said milk and dairy products from Poland and Eastern Europe should be avoided.

Speakes said discussion of the Soviet nuclear accident has been added to the summit agenda and that Reagan intends to highlight the idea of on-site inspection of nuclear power plants. Speakes said there is currently no treaty governing inspection of nuclear power plants.

Secretary of State Geoge P. Shultz, speaking to reporters after Speakes' briefing, made it clear that the leaders here would focus on what he called the inherent obligation of states to disclose information when something is happening within their borders that affects others.

Shultz, under questioning, suggested that the image of openness Soviet leader Mikhail Gorbachev has been trying to project could be in some doubt. Shultz said the Soviets have not been forthcoming with information and the information Moscow has released is nowhere near the amount of information the United States has obtained from its independent sources. "So it doesn't look like a very open policy," Shultz said.

Shultz, questioned by a reporter, offered to bet $10 that the official Soviet estimate of only two persons dead will turn out to be "very low." He said information the United States has suggests that the impact on individual lives is "much greater than what they've said."

Shultz also noted that Gorbachev, perhaps more than any Soviet leader in the past, has made an important issue of the willingness to allow verification in arms control agreements. Shultz indicated that the United States may now press him on this point because of the breakdown of the Soviet nuclear power plant.