The U.S. Nuclear Regulatory Commission (NRC) says the radiation level is extremely high at the Unit Four nuclear reactor in Fukushima, Japan.

Chairman of the commission, Gregory Jaczko, told a Senate committee hearing Thursday that all the water that is used to cool the fuel rods at the reactor has dried up following an explosion at the Unit Four reactor a few days ago.

He said that the fuel rods could heat up to a point where they begin to melt down and that radiation levels are extremely high near the reactor site, which could possibly impact the ability to take corrective measures.

He added that if the U.S. was faced with a situation like Japan's, Washington would have issued an evacuation order for a wider area.

He said Washington has advised Americans within 80 kilometers of the Fukushima power plant to leave the area immediately.