The nuclear crisis in earthquake-ravaged Japan has hit a new peak of worry – engineers are concerned that two more reactors at the Fukushima Dai-ichi complex may have become unstable.

Plant operators were considering the removal of panels from units 5 and 6 reactor buildings to prevent a possible buildup of hydrogen, the International Atomic Energy Agency (IAEA) said in a statement.

It was a buildup of hydrogen at units 1, 2, and 3 that led to explosions at the Dai-ichi facilities in recent days.”

Units 5 and 6 at the plant were reportedly filled will nuclear fuel but not in production when the huge quake and tsunami struck. Initially, they were regarded as stable, but last night nuclear officials in Japan warned temperatures were rising.

The power for cooling is not working well and the temperature is gradually rising, so it is necessary to control it, said Chief Cabinet Secretary Yukio Edano.

Autorité de Sûreté Nucléaire (ASN), France's nuclear safety authority said the Japanese disaster ranks at a level 6 on the international scale of 1 to 7. (The Chernobyl calamity in Ukraine in 1986 rated a 7; while The 1979 accident at the Three Mile Island in Pennsylvania was rated a level 5.)

It is very clear that we are at a level 6, ASN President Andre-Claude Lacoste told a news conference in Paris. We are clearly in a catastrophe.

The Fukushima plant’s unit 4 suffered an explosion yesterday, which created two big holes in the container that holds the nuclear fuel rods. The fuel storage area then ignited into flames, resulting the direct release of radioactive materials into the atmosphere.

Reportedly, much of the leaked radiation came in the form of steam from boiling water, which is not as dangerous as if it were emitted by the fuel rods directly.

The Prime Minister of Japan Naoto Kan has confirmed that low levels of radiation have spread from the power plant complex in northeast Japan to other regions of the country.

The possibility of further radioactive leakage is heightening, Kan said.

Officials at Tokyo Electric Power Co. (TEPCO), the operator of the nuclear power plants, said they may use helicopters to drop cold water on a boiling rooftop storage pool for spent uranium fuel rods. The rods are reportedly still radioactive and potentially as hot and dangerous as the fuel rods inside the reactors.

“The only ideas we have right now are using a helicopter to spray water from above, or inject water from below,” a power company official said, according to The New York Times.

“We believe action must be taken by tomorrow or the day after.”

“It’s way past Three Mile Island already,” said Frank von Hippel, a physicist and professor at Princeton, the Times reported.

“The biggest risk now is that the core really melts down and you have a steam explosion.”