There is no water left in the spent fuel pool of reactor 4 at Japan's Fukushima nuclear plant, resulting in "extremely high" radiation levels, the chair of the US Nuclear Regulatory Commission warned on Wednesday.
"In addition to the three reactors that were operating at the time of the incident, a fourth reactor is also right now under concern. This reactor was shut down at the time of the earthquake," said NRC chairman Gregory Jaczko.
"What we believe at this time is there has been a hydrogen explosion in this unit due to an uncovering of the fuel in the spent fuel pool," he said, noting the explosion happened several days ago but its effects were cause for concern.
"We believe that secondary containment has been destroyed and there is no water in the spent fuel pool and we believe that radiation levels are extremely high which could possibly impact the ability to take corrective measures."