The Mainichi reports that based on new underwater surveys, TEPCO says that the spent fuel in Fukushima Daiichi Reactor 4 may have undergone further damage since it was last inspected in April 2011. Tokyo Electric Power Co. said that visibility in the pool is only about 1 meter, far less than the approximately 5 meters the utility was able to see through last spring. TEPCO plans to use a camera that can move underwater to conduct a more detail survey and consider ways to improve the situation, company officials said, adding they were not sure whether the water was clouded by algae or other substances floating inside or there was a problem with the camera.
TEPCO also said it has put a camera inside the No. 4 reactor’s pressure vessel for the first time since the accident and found some rubble inside it, apparently as a result of a hydrogen explosion which blew off the roof of the building housing the reactor.