Update on Japan's Nuclear Crisis at Fukushima I

japan nuclear reactor power meltdown earthquake photo
Japanese Prime Minister Naoto Kan attends a meeting on crisis of the Fukushima No. 1 nuclear power plant in Tokyo, Japan, March 15, 2011. Credit: Xinhua/Kyodo/Xinhua Press/Corbis
Latest Update: Japan's Nuclear Crisis: 2 Weeks After the Mega-Quake & Tsunami (March 25, 2011)

2 Reactor Vessels Now Reported Damaged
The crisis at Japan's nuclear reactors is still unfolding, and it can be hard to be sure of exactly what is going on (for example, the media incorrectly reported that the remaining 50 workers had been evacuated from the Fukushima plant -- more on that below). That's why I've tried to put together a timeline of the most important events and announcements from the past day.japan nuclear reactor power meltdown earthquake photo
Credit Image: © Koichi Kamoshida/Jana Press/Zuma Press/Corbis

Yesterday, it was announced that the containment vessel of reactor #2 is cracked.

Today (Wednesday), it was announced that the containment vessel of reactor #3 may have been damaged, but that it was "unlikely to be severe", according to the Japanese authorities.

status-japan-nuclear-reactors image
Status of the Fukushima plant reactors, by Wikipedia contributors (as usual, take Wikipedia material with a grain of salt, but it appears accurate because it is based on this chart by the Japanese Atomic Industrial Forum). Click for large version.

As you can see in the chart above (click on it for a larger version), only the buildings for reactors 5 & 6 are undamaged. That's because these reactors were not operational at the time of the Earthquake and Tsunami. But what matters most is that the containment buildings remain as intact as possible; the outer layers of most buildings seems to have been damaged when the workers vented pressure, but that doesn't necessarily mean that the containment structure itself has been breached.

japan nuclear reactor power meltdown earthquake photo
A woman reads an extra of a newspaper about radiation released by the damaged reactors at Fukushima No. 1 nuclear power plant in Osaka, Japan, March 15, 2011. Credit: Xinhua/Kyodo/Xinhua Press/Corbis

Plans to dump water from helicopters on spent fuel cooling pool at unit 4 were aborted. There was a fire at that unit, but now smoke no longer visible according to reports. The helicopter mission was stopped because of radioactive steam coming out of the reactor #3.

Late yesterday there was a report that the 50 remaining workers had been evacuated, but that was apparently a mis-translation of a speech by Japan's chief cabinet secretary. Most workers have been evacuated, but the 50 remained, and were later joined by 50 others, for a total of 100 workers remaining at the Fukushima nuclear plant.

Reuters is reporting that water is now being poured on unit 5 & 6.

japan nuclear reactor power meltdown earthquake photo
An overview of the Fukushima I nuclear plant in Japan, shortly before an explosion happened at a block of the plant, on 12 March 2011. Credit: EPA/STRINGER/Corbis

On radiation levels, the New York Times writes:

Radiation close to the reactors was reported to reach 400 millisieverts per hour on Tuesday after a blast inside reactor No. 2 and fire at reactor No. 4, but has since dropped back to as low as 0.6 millisieverts at the plant gate. Tokyo Electric and Japanese regulators have not released any statistics on radiation levels inside the containment buildings where engineers are desperately trying to fix electrical systems

But nuclear experts said that indoor radiation levels were likely to be higher because the containment buildings were probably still preventing most radiation from leaving the plant.

radiation chart image

Based on this radiation chart, these levels are still thankfully very low. But the workers on site might be exposed to higher levels if they have to go out of the heavily shielded control room to work closer to the reactors.

Wondering if it can explode like a nuclear bomb? What's a 'meltdown'? Why Chernobyl was different? See:

Mini-FAQ About Japan's Nuclear Power Plant Crisis
6 Important Questions About the Crisis at Japanese Nuclear Power Plants
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