Japan's government acknowledged Wednesday it might need the help of U.S. military forces to halt continuing radioactive emissions from a nuclear power plant severely damaged by last Friday's tsunami, triggered by the magnitude nine earthquake.
Chief Cabinet Secretary Yukio Edano told reporters the assistance of the United State military is now being considered, but that it might be too risky to use helicopters to drop water on the damaged reactors to try to keep cool the radioactive fuel rods.
The top government spokesman says the containment vessel of Reactor Three at the Fukushima nuclear power plant may have cracked. He says it is highly probably that this may be the source of a cloud of white smoke being seen in video images relayed from a helicopter 30 kilometers away from the crippled nuclear facility.
Reactor 3 earlier suffered an explosion after difficulty in cooling the fuel rods.
Japanese officials acknowledge they are being reduced to desperate measures in an attempt to stop what may become a significant and continuing spread of radiation into the atmosphere from the crippled nuclear power generating facility.
Earlier in the day, Tokyo Electric Power Company spokesman Hajimi Motojuku acknowledged the possibility that spent fuel rods at the number four reactor at the same plant could again enter a state of a nuclear chain reaction.
The spokesman says a fire was again spotted for about 30 minutes Wednesday morning coming from the reactor's spent fuel cooling pond. He says the cooling pond water may be boiling off, exposing the rods again to the atmosphere.
That would allow them again emit radioactive substances. The utility is now considering using helicopters to spray boric acid on the rods.
The fire was originally spotted Tuesday, apparently triggered by a hydrogen explosion. But Tokyo Electric said they halted fire-fighting operations late in the day because workers believed the flames had been extinguished.
Radiation levels are so dangerous on the ground at the Fukushima plant that workers have had to give up trying to pour water into the cooling pool and all of the facilities' 800 workers have now evacuated the site.
Two reactors at the plant have apparently suffered partial melting of their cores when the normal cooling functions ceased, following last Friday's tsunami triggered by a magnitude nine quake. That is believed to be at least partly responsible, for soaring background radiation levels at the facility, deemed dangerous to people who stay there for an extended time.
There have been a series of accidents and failures at the six-reactor facility, deemed critical, along with a nearby newer plant, for adequately supplying Tokyo with electricity. Officials also say there are less severe, but potentially dangerous cooling issues at the nearby site.
The nuclear crisis is distracting Japan's top officials from devoting their time to the unprecedented natural disaster. The confirmed number of dead and missing is above 10,000, in this part of the country. But local and regional officials say there may be many thousands more people buried in debris following Friday's huge earthquake, which triggered tsunami that washed out an uncertain number of coastal communities.