What's wrong with the reactors at Fukushima

Report made at 7:00 am in Lisbon
Data updated at 7:00 am in Lisbon, when it was already 15:00 in Japan, indicated that the status of four of six reactors at a nuclear power plant in Fukushima was still too complicated, according to information published on the website of the Japan Times.
Publication says that the third reactor may have damage to the containment vessel, according to information given by the spokesman of the Government, which may be causing the leakage of radiation to the exterior and the increased levels of radiation near the central .
According to the Nuclear Security Agency of Japan, the radiation levels to which the population was exposed reached, briefly, 10 millisieverts per hour, which must have contributed also leakage of radiation from the reactor 2.
 

It is estimated that the radiation necessary to increase the risk of cancer is 100 millisieverts, a level which would strike within 12 hours of exposure to these levels indicated. But the plant itself, the levels that were 400 millisieverts arrived yesterday to reach the 600 to 800, according to BBC online, which meant that all staff had temporarily abandoned the plant. The company TEPCO, Tokyo Electric Power, which manages the center, put an army helicopter to free boric acid to prevent fires in reactors, such as what occurred in the reactor 4, though controlled.

Reactor 1
 Opened: 1970 Power: 460 MW 
 Failure in the cooling system; partial melting of the core, with 70 percent of the fuel rods affected; explosion on Saturday, due to accumulation of hydrogen, destroying the building's external reactor. Cooling is being made with sea water.

Reactor 2 
Opened: 1973 
Power: 784 MW
 Failure in the cooling system, fuel rods were partially exposed, about 33 percent damaged; explosion on Tuesday by the accumulation of hydrogen may have affected the reactor core, steam release. Cooling is being made with sea water.

Reactor 3 
Opened: 1974 
Power: 784 MW 
Cooling system failure, possible partial melting of the core; escape of steam, use of seawater for cooling the reactor building damaged by explosions, high levels of radiation detected on Tuesday, possible damage to the reactor containment vessel .



Reactor 4 
Opened: 1978 
Power: 784 MW 
Maintenance was in place when the earthquake of 11 days ago. This reactor has been the scene of two fires, possibly due to hydrogen explosions inside the building. Water levels in the reactor are not known. Pumping water is not always possible.

Reactors 5 and 6
 Opened: 1977 and 1979
 Power: 784 MW and 1100 
In maintenance when the earthquake occurred. The reactor temperature increased but little.