The question that everyone asking is if the plant is melting down.
It depends on who you ask:
A powerful explosion has hit a nuclear power station in north-eastern Japan which was badly damaged in Friday's devastating earthquake and tsunami.
A building housing a reactor was destroyed, but the authorities said the reactor itself was intact inside its steel container.
The Japanese government has sought to play down fears of a meltdown at the Fukushima plant.
It says radiation levels around the stricken plant have now fallen.
A huge rescue and relief operation is under way in the region after the earthquake and subsequent tsunami, which are thought to have killed more than 1,000 people.
Tokyo Electric Power said four of its workers had been injured in Saturday's blast at Fukushima, 250km (155 miles) north of Tokyo, but that their injuries were not life-threatening.
An evacuation zone around the damaged nuclear plant has been extended to 20km (12.4 miles) from 10km, and a state of emergency declared.
The doomsday take from Stratfor.com
And so now the question is simple: Did the floor of the containment vessel crack? If not, the situation can still be salvaged by somehow re-containing the nuclear core. But if the floor has cracked, it is highly likely that the melting fuel will burn through the floor of the containment system and enter the ground. This has never happened before but has always been the nightmare scenario for a nuclear power event — in this scenario, containment goes from being merely dangerous, time consuming and expensive to nearly impossible.
Read more: Red Alert: Nuclear Meltdown at Quake-Damaged Japanese Plant | STRATFOR
Or an alternate take via HotAir.com.
Rod Adams, an activist who supports nuclear energy and a former operator at a light-water nuclear plant, also argues that the fears here are way overblown:
At [Three Mile Island], the widely predicted and discussed “China Syndrome” did not happen, even though 20-30% of the core melted and slumped to the bottom of the pressure vessel. That melted corium froze again once it contacted the thick metal walls – the maximum measured penetration was just 5/8ths of an inch. Anyone who has ever watched as welder employs a torch to cut through a thick steel wall will understand just how much concentrated power it takes to melt several inches of steel. Avoiding the China Syndrome was not a matter of luck – the scenario is imaginary and only works in fiction. Physics and material science make it impossible….
CNN.comRadiation levels inside the containment will be many times higher than usual, but that is okay because no one needs routine access inside containment buildings and no humans will be over exposed. The containment walls, reactor coolant piping, and other equipment inside the containment building will condense and capture much of the radioactive materials that are entrained in the water. Other than those vented noble gases mentioned above, essentially nothing will be released to the environment.
[3:37 p.m. ET, 5:37 a.m. Tokyo] Japanese authorities have informed the International Atomic Energy Agency that the explosion at Unit 1 reactor at the Fukushima Daiichi plant occurred outside the primary containment vessel, not inside, the agency said Saturday. The plant operator, Tokyo Electric Power Company (TEPCO), has confirmed that the integrity of the primary containment vessel remains intact.
As a countermeasure to limit damage to the reactor core, TEPCO proposed that sea water mixed with boron be injected into the primary containment vessel. This measure was approved by Japan's Nuclear and Industrial Safety Agency and the injection procedure began at 8:20 p.m. local Japan time, the agency said,