Brazil has ended a row with the International Atomic Energy Agency by allowing it to inspect a new uranium enrichment plant.
Brazil said it feared industrial espionage
The UN body wanted to check that Brazil was not breaking international accords on the spread of a chemical, which can be used to make nuclear bombs.
Brazil had argued it needed to protect its nuclear technology.
The two sides agreed the IAEA would inspect pipes at the plant, without looking at the machines themselves.
US diplomats had said Brazil's refusal to allow inspections would send a bad signal at a time of concern about the nuclear programmes of Iran and North Korea.
The IAEA inspection of the Brazilian plant in the town of Resende will take place in October.
Brazil's constitution prevents the nation from owning nuclear
weapons. It decided to abandon its nuclear weapons ambitions in 1990.