The Nuclear Claims Tribunal in the Marshall Islands has been told that people exposed to the US weapons tests in the 1950s continue to suffer psychological stress.
Dr Robert J. Lifton, a world recognised authority on the psychological impact of radiation exposure, contributed testimony by satellite in Utrik Atoll's claim for compensation.
Utrik Islanders were doused with radioactive fallout from the 1954 Bravo hydrogen test at Bikini atoll.
They have experienced a high incidence of thyroid tumours and cancers and other health disorders as a result of their exposure to the fallout.
The islanders are asking for compensation to clean up the atoll and for hardships suffered as a result of the testing programme.
Dr Lifton told the Tribunal that those exposed to radiation or other invisible contamination retain a life long fear that does not go away.
He says the fear of radiation exposure is very real and documented in numerous studies.
Dr Lifton says any group exposed to significant radiation will experience some fear.
He says a well designed education prgramme can help alleviate some of the psychological distress of the Utrik people, but the fear of radiation will not go away.