The Work crews were at lunch last Oct. 31 when the first smoke and flames appeared. By the time the fire department arrived, the blaze had destroyed components for Brazil's first nuclear reactor, under construction in this quiet resort town 115 miles west of Rio De Janeiro.

Five months later, that fire is still causing embarrassment for the Brazilian government. An official investigation of the fire, which caused an estimated $6 million to $10 million in damage, has concluded that there are significantdeficiencies in the Brazilian nucelear program's safety and security procedures.

This finding, published by the newspaper O Estado de Sao Paulo earlier this month, is unlikely to halt Brazil's nuclear effort, but it has raised a delicate political question at an inopportune moment for the Brazilian government.

Brazil's nuclear program is expected to be a key topic in talks between President Carter and Brazilian officials during Carter's visit here later this week some onservers in Rio and Brasilia are now saying that the disclosures of safety will give short comings Carter more "leverage" in his effort to persuade Brazil to postphone its planned uranium reprocessing and encichment program.

Brazilian officials also seem to think that last October's fire, the most serious, of 71 at the nuclear reactor site over a five month period, will have even wider effects one of the documents published expresses the fear that the security issue will be "exploited" as a lack of Brazilian capacity to construct a thermonuclear reactor and, even more so, to operate it."

There are conflicting reports about what caused the fire. Officially, the cause is said to be a short circuit in the laboratory where instruments were being tested. Some publised documents mention sabotage as a possibility.

According to recent press reports here, West German scientists and engineers working at Angra are also critical of work and safety procedures employed by Brazilian agencies in change of the projects. Under the terms of the $10 billion 1975 Brazilian-West German nuclear agreement, all but the first of Brazil's nine planned nuclear power plants will be bulit with West German technology.

Since these disclousres, Brazilian Mines and Energy Minister Shigeaki Ueki, acting on orders from President Ernesto Geisel, has moved to tighten safety regualtions and procedures. The problems have been resolved and work is progressing normally," Ueki siad two weeks ago, after announcing security had been "redoubled."

"We are following all the norms of secrrity currently in existence in the country of origin of the reactor, which is the U.S.A. ," Ueki said during an interview in Brasilia. "It is normal to have a few fires on a project of this type, but we trust the technology of Westinghouse and American standards of security, which are, after all, among the most rigorous in the world,"

Brazilian scientific leaders, however, still claim that the government's nuclear program is techically and economically unsound.

"We warned them," said Professor Jose Zalts, member of a group of physicists who have been studying safety aspects of the Angra project, "and now we see that we were over estimating the seriousness of those responsible for the program."

"If errors like this persist, we still inveitably have a repetition of a Hiroshima type radiation catastrophe," said Professor Jose Goldemberg of the University of Sao Paulo, president of the Brazilian Society of Physics. We were lucky this time because the accident occurred during a non-nuclear phase of the work."

The only conclusion I can draw from this," Goldemberg added, "is that those responsible for the program have not taken the precautions necessary to guarantee internationally established standards of security.

There has also been some domestic political fallout. Leaders of Brazil's only legal opposition party, who argue that the Brazil-West Germany nuclear accords do not give Brazil enough for its money, have called for congressional investigation of the safety failures at Angra.

All told, three nuclear power plants are scheduled to be built here at Angra. Westinghouse's 600 megawatt Angra I is supposed to go into commercial use sometime next year, and in the early 1980s Angra II and III, built by West Germany's Kraftwerk Union are to be inaugurated.

Ever since constriction of Angra I was begun in 1972, the work site here has been plagued with problems and delays. Angra I was originally scheduled to begin operating in the second half of 1977, and Ueki says that last October's fire means an additional "four or five months delay."

Westinghouse is attempting to obtain replacements for the components destroyed in the fire, but some of the new parts according to the documents published this month, will not be available until next year.

"We don't see any economic damages resulting from all of this," says Ueki, "Our energy system doesn't require the entry of this unit on schedule."