Japan Nuclear Emergency : Facts and Details

              The nuclear crisis in Japan has developed rapidly on many fronts, making it difficult to track the threads...The crisis began Friday when a magnitude-8.9 earthquake and tsunami cut off regular electricity to the oldest unit at the Fukushima Dai-ichi nuclear complex, 170 miles (270 kilometers) northeast of Tokyo.

                    A partial meltdown of nuclear fuel rods has occurred in two, or perhaps three, nuclear reactors at the Fukushima Daiichi power plant in Japan (A meltdown is when the uranium dioxide fuel melts. The melting temperature of uranium dioxide is 5,189 degrees Fahrenheit (2,865 degrees Celsius)

Here will see some question  about Japan Nuclear crisis ...

• Exactly what is a meltdown, and why is it potentially dangerous?

-- A meltdown occurs when a reactor's radioactive core, which holds its uranium fuel, gets so hot that it begins to melt. A complete meltdown can breach a reactor's steel pressure vessel and other protective barriers — and spread radioactive byproducts like iodine and cesium into the surroundings. That endangers the environment and nearby residents. However, a reactor will not explode like an atomic bomb.

• What are the worries?

-- At Unit 1, which began operating in 1971, workers are trying to prevent a meltdown, complicated by the fact that a need to release a pressure buildup in the reactor vessel led to a hydrogen explosion that blew off the roof and walls of the containment building. Officials say the reactor vessel is intact, but worry about the overheated uranium fuel. In a desperate move, officials have piped large amounts of seawater into the reactor vessel to try cooling the severely overheated uranium core.

As with the other troubled reactors, the key is to cool the nuclear fuel by circulating new cool water around the fuel rods. If the rods are fully exposed, that increases the temperature of the rods and could hasten the path to complete meltdown.

• What is the significance of using seawater?

-- With so many equipment failures, plant operators face challenges using mobile generators powered by batteries. They also need a dependable high-volume water source. The Pacific Ocean solves the supply problem. But using it assures that these very expensive reactors will never be used again to generate power. The salty sea water, accompanied by a boron mix, is very corrosive.

• Any indications of radiation exposure to humans yet?

-- Of the more than 180,000 people evacuated from around the two Fukushima complexes, up to 160 may have been exposed. And at one point, officials said the radiation detected outside the Dai-ichi Unit 1 in a one-hour period represented the allowed rate for an entire year.

• How long will the crisis last?

-- One expert said cooling down all the reactors will "take days, not hours." But even if circumstances improve, conditions can still turn negative again.

• How about personal health danger?

-- Exposure to radioactive iodine released in a nuclear power accident can cause thyroid cancer.

• Is there a way to protect against the effects of radiation exposure?

-- Potassium iodide pills can help prevent thyroid cancer.

• what will be  the worst-case scenario?

-- The attempts to cool the reactors fail, resulting in meltdowns and widespread radioactive contamination. If that occurs, everyone will be hoping the wind blows east, into the Pacific, as it usually does.

• Immediate action in nuclear emergency :

1. In any nuclear emergency the immediate action is to minimise exposure. People living within 12 miles of the plant have been evacuated; those living up to 18 miles away have been told to stay indoors.
2. Potassium iodide tablets have also been distributed. If taken at least two hours before exposure to a radiation cloud, these protect the thyroid gland from radioactive iodine.

• Effects on body :

This causes symptoms of radiation sickness.With a mild dose, nausea and vomiting can start within a day or two, followed by fatigue and headaches.

   If there is high exposure to radioactivity, vomiting can start within an hour.Victims suffer a high fever, disorientation and problems with their immune system. The fatality rate at this level is around 50%. Survivors are also at increased risk of cancer in the future.

• Japan nuclear crisis Won’t Affect Other Countries  : 

The health risks from contamination by nuclear reactors affected by the earthquake in Japan seem low and the winds should take all the radiation to the Pacific, without threatening other nations,experts say .