The family was caught after being placed undercovert surveillance by police following the discovery of the body of worker Christopher Nicholls, 40, in 2008.
The United States and others have expressed concern that Tehran is trying to operate a covert nuclear weapons program under the guise of a nuclear energy program.
This followed the exposure last year of the covert system of referral fees, under which insurers, in effect, stoke up claims against themselves and thus drive up premiums.