drink that day. the water feeds everything. the showers, the water faucets, the soda machines. reporter: how serious is it when water has to be secured because they ve picked up contaminants? had that ever happened to you before? this was the first. i think that was first for everybody on board. reporter: the reagan also saild through the post meltdown nuclear plume for hours, leading to this thorough decontamination. the ship locked down the ventilation systems, simmons said. that fits with the prior reporting by cnn s bill weir, who tried to get on the ship for a story and was waved off by commanders citing radiation concerns. the navy declined our interview request because of the pending litigation, but in a statement a spokesman said, there is no indication that any u.s. personnel supporting operation tomodachi experienced radiation exposure at levels associated with the occurrence of long-term health effects. the navy acknowledged the ship saild through the nuclear plume