Japan Nuclear Crisis : Of half truths and half disclosures

Radiation Exposures : Experts Opinion Conflicts

The authorities are still battling to contain the nuclear events in Fukushima Prefecture that came in the wake of the country's largest recorded earthquake.

There are conflicting accounts of the radiation levels being measured in the vicinity of the Fukushima Daiichi plant - where sea water is being injected into at least two of the reactors in an attempt to prevent the nuclear fuel from melting as the temperature continues to rise.

There was an explosion at the plant's number one reactor on Saturday - but the government says the massive concrete containment structure surrounding the nuclear core remains intact.

But it has also been confirmed that the temperature is continuing to rise in at least one of the other reactors due to a failure of the back-up cooling systems.

And a state of emergency had been declared at the Onagawa plant - although officials say radioactivity levels have now returned to normal standards.

How bad is 'bad'?
The International Atomic Energy Agency (IAEA) developed the International Nuclear and Radiological Event Scale to identify the severity of incidents involving nuclear energy.

Chernobyl was a level 7 accident, the highest level, denoting a "major accident."

Three Mile Island was classified a category 5, which is an "accident with wider consequences."

The IAEA is rating the incident in Japan at category 6 on the INES scale.
What does this mean? As some 200,000 people are evacuated from the area, is Japan facing a nuclear disaster?

Is the nightmare scenario of nuclear meltdown becoming real? And what can be done to contain the nuclear threat while at the same time dealing with the widespread destruction caused by the country's largest recorded earthquake?

As the prospect of a nuclear disaster looms, Japan's government says it's doing all it can to mitigate the crisis.