Donald Richards, 58, a personnel adviser; Robert Wilcox, 51, a general manager; and Colin Read, 46, a purchasing manager, received pounds 230,000 in bribes in return for leaking confidential contract information, Southwark Crown Court in south London was told.
During a five-year conspiracy, they peddled top-secret material allowing certain companies to undercut rivals and win lucrative government- funded orders for the nuclear power industry.
Stephen Batten, for the prosecution, said Richards, who admitted two charges of conspiracy to corrupt, and Read and Wilcox, who each pleaded guilty to one similar count, all worked for NEI Thompson Kennicott, a Wolverhampton installation services company.
Richards, of Great Missenden, Buckinghamshire, was jailed for two years, fined pounds 30,000, made subject to a pounds 120,000 confiscation order and ordered to pay nearly pounds 8,000 towards prosecution costs. Wilcox, of Danbury, Essex, was jailed for a year and Read, of Telford, Shropshire, was sentenced to six months and ordered to pay pounds 8,000 prosecution costs.