Japan's Nuclear Crisis, One Week Later

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Fire trucks are gethered in Iwaki city, Fukushima Prefecture, March 18, 2011. Japanese self-defense force used fire trucks spraying water on the nuclear reactor No.3 at Fukushima No.1 nuclear power plant in a bid to cool down the facility's overheating fuel rods. Credit image: kyodo/XinHua/Xinhua Press/Corbis
Japan Raised the Severity of the Nuclear Accident to Level 5
It's already been a week since a 9.0 earthquake hit Japan, causing a massive tusnami that devastated the North-East of the country, damaging nuclear reactors at the Fukushima I plant. Brave workers are still on site, trying to cool down the still very hot cores and spent fuel rods. The image above shows trucks with fire cannons that have been used to spray reactor #3. Read on for more details on what happened since yesterday.

Fukushima, Japan - Doctor at a hospital conduct test for radiation for those people who are considered to be irradiated in Yamagata prefecture, Japan. Magnitude 9.0 earthquake hit Northern Japan. Several tens of thousands of people are still missing. (Credit Image: © Koichi Kamoshida/Jana Press/Zuma Press/Corbis)
Trucks with fire cannons from the Japan Self-Defense Forces (SDF), rotating with the Tokyo Fire Department (TFD), took turn to spray water on reactor #3. Occasional clouds of steam could be seen emanating from the building
Gregory Jaczko, the chairman of the United States Nuclear Regulatory Commission, said that the problems at Fukushima I could take "weeks" to work through.

Source: Wikipedia
Japan has raised severity of nuclear accident to INES level 5 (out of 7), like 1979's Three Mile Island. By comparison, the Chernobyl accident was a level 7 event. The International Nuclear Event Scale classifies level 5 as "Accident With Wider Consequences" and level 4 as "Accident With Local Consequences". The next level is "Serious Accident".
Japan planned to import about 150 tons of boron from South Korea and France to mix with water to be sprayed onto damaged reactors, French and South Korean officials said Friday. Boron absorbs neutrons during a nuclear reaction and can be used in an effort to stop a meltdown if the zirconium cladding on uranium fuel rods is compromised.
There could be damage to the floor and sides of the spent fuel pool at reactor 4, according to a storey in the LA Times. This could make it more difficult to refill the pool with water to cool down the fuel rods. This damage to the stainless steel lining would probably have been caused by the massive Earthquake that hit Japan last week.

Fukushima II. Photo by DigitalGlobe via Getty Images

American planes collected data by flying over the area and concluded that "the worst contamination had not spread beyond the 19-mile range of highest concern established by Japanese authorities." (source)

TEPCO has reported that the laying of grid cabling to Unit 2 continues. The hope is that cooling pumps are still operational and can be re-started once power is restored.
The IAEA announce the termperature at the spent fuel pond at reactor 5 is 65.5 °C and the temperature of the spent fuel pond at reactor 6 is 62.0 °C, a slight decrease since yesterday at reactor 6 and a slight increase since yesterday at reactor 5.