An internal investigation at the Fukushima Daiichi Nuclear Power Plant showed that one of the nuclear reactors damage may be worse than originally thought, according to the New York Times.
The findings raised concerns over the stability of the plant and make clean up efforts complicated, according to the Associated Press.
The plant's three reactors were damaged when a powerful earthquake and tsunami ravaged the Tokyo Electric Power Company's power plant in March 2011, according to the AP.
The company announced that the water level in the No. 2 reactor was far below than what it was estimated to be. This raised concerns that the damaged uranium might not be completely submerged and could heat up again, the New York Times reported.
The investigation also found that radiation levels were at 72.1 Sieverts inside the containment vessel, which is enough to kill someone in a matter of minutes, according to the AP.
The high levels of radiation could complicate work to find and remove the damaged uranium, according to the New York Times.
The reactors 1 and 3 could be even worse condition than reactor 2, because hydrogen explosions blew out the outer walls of those reactors, according to the AP.
The plant could run the risk of another large radiation leak should arise with cooling the fuel, reported the AP.