At the Washington office of the International Physicians for Prevention of Nuclear War, the phone rang about every 30 seconds yesterday.

"It's revived my French," said national Executive Director Jane Wales as she wound up an interview with a Czech reporter. "I haven't spoken French since I was 18."

She had been going mainly on coffee since hearing the news Thursday night that the group has won the Nobel Peace Prize. Hours earlier, she had let three of her staff of six take off for a long weekend in the Berkshires.

"I thought, what could happen on a Friday anyway?"

Wales, who has been director for two years, actually supervises 30 people, but most are still in Cambridge, Mass., where the organization was founded in 1961 as Physicians for Social Responsibility. Since last spring the office has been gradually moving to Washington, where a small branch was established in 1982. IPPNW is the umbrella group, headquartered in Moscow, London and Washington, representing 135,000 physicians in 41 countries.

The office at 200 Third St. SE is very Washington: narrow corridors, tiny offices crammed with papers and books, maps on the walls, a sense of intimacy and purpose.

"Originally we were strictly American," Wales said. "But in 1979 our founder, Dr. Bernard Lown who shares the IPPNW presidency with Soviet cardiologist Yevgeny Chazov, personal physician to the last three Soviet presidents helped found the IPPNW. In this country there are 50,000 members, of whom 29,000 are doctors, dentists and medical students. The rest are mostly in the health-care field."

At first the focus was short-term: to publicize the medical effects of nuclear war. With symposia, lectures and media campaigns, the group dramatized what a single small bomb could do to a community. The director and producer of the TV film "The Day After" were, "we like to think," galvanized by a physicians' symposium, said Wales. Dr. Helen Caldicott, a leader in the antinuclear movement, became active in the effort. Dr. Robert Jay Lifton, a board member of the group and a specialist in the effects of the bomb, advised the BBC producers of the film "Threads."

The point of all these programs was to show the bomb as a public health threat, as something, like polio and smallpox, that cannot be cured but can be prevented.

"We feel we have demonstrated now that the bomb cannot be survived," Wales said. "The next question is how to stop it."

Dr. Justin Frank, a Washington psychoanalyst who heads the Washington area local -- one of 154 chapters in the United States -- said the group's focus is widening to include educating the public about the psychological causes and effects of nuclear warfare, such predicted ecological effects as nuclear winter and what the organization considers the principle of "informed consent."

"When you're being given some strong medication or treatment, you need to be informed of the side effects before you can consent to it," he said. "The same is true of nuclear war. People need to be informed of the effects of the arms race itself, the cost, the money that is siphoned off from other concerns, and so on. An educated society is the best society."

The membership covers a broad political spectrum, he added, "most unusual for doctors."

Why doctors anyway?

"Maybe people in general find it hard to relate to the Soviets, but physicians have a model for working together with them. It took international cooperation to eradicate smallpox, for instance," Frank said. The International Geophysical Year, polar exploration and other projects have involved joint work by American and Soviet scientists.

Why the award this year?

"It could be linked to the summit talks in Geneva," Wales said. "Maybe the Nobel people are telling the leaders to get to it."

Is the Soviet branch of IPPNW a "propaganda outfit," as some Western diplomats suggest?

"Not at all," replied Frank. "When we held an international symposium in Russia it was carried for hours on nationwide TV, seen by 100 million people. We weren't able to get anything like that kind of coverage in this country. The Russian people are much more aware than we are of the dangers. They know what it's like to lose 50 million people in a war, after all."

For years, the local chapter has held monthly meetings, open to the public, featuring talks by scientists, government officials, military people and others. Attendance has been lackadaisical.

But yesterday, business was picking up.