The Nuclear Regulatory Commission (NRC) has launched an investigation into the disappearance of two fuel rods from Millstone 1, which was shut down in 1995.
NRC staff attorney Norman St Amour stated that the investigation could lead to criminal charges.
Engineers carrying out an inventory of the nuclear waste storage pool in November noticed they were missing. The slightly damaged rods were removed in 1972 and placed in the pool. The last reference to the rods was in a 1979 report.
Plant officials are conducting their own investigation, paid for by former owner, Northeast Utilities, and workers are going through paperwork to determine whether the rods were transferred to storage sites or to General Electric laboratories for study. Last year the Millstone plant was sold to Dominion, which has ultimate responsibility for the rods.