THe Cause of Fukushima Daiichi
The Fukushima Daiichi nuclear disaster occurred after a 9.0 magnitude earthquake on Friday March 11, 2011. The magnitude is based off of the Richter magnitude scale. An earthquake is assigned a magnitude number based off of the quantified energy released by the earthquake.
After the earthquake three Fukushima Daiichi reactors were disabled and their cores experienced a meltdown. Between the earthquake and following tsunami, the plant's generators that pumped cooling water for the reactors were destroyed. Without cooling, the cores went into meltdown and lead to the subsequent nuclear disaster. High temperature zirconium cladding in the presence of steam yielded exothermically an excess of hydrogen, which then caused multiple explosions in the upper service floors in Unit 1 and 3. Unit 4 had not been operating but was affected by the hydrogen explosions in Unit 3. |
The RadioactivityA majority of the radioactivity was released by the explosions that happened in these units. The accident was rated a 7 on the International Nuclear and Radiological Event Scale (INES). The INES scale is a tool used to communicate promptly to the public about the safety of events associated with the sources of radiation. The scale has seven levels. Levels 1-3 are stated to be “incidents” and levels of 4-7 are stated as “accidents”. The levels consider people and the environment, radiological barriers and control, and the defense in depth. The rating Fukushima Daiichi was given is due to the high amounts of radioactive releases over the 4-6 days. The emissions caused significant radiation and isotope concentrations measured in the environment by involved institutions. Measurements were performed on different media like soil, water, and food products. Because of such high levels of radioactivity thousands of people were taken out of their homes to protect them from further future damage. Within one day, 134,000 people were evacuated to avoid the released radiation plume. Four days later an additional 354,000 people were evacuated. The radiation levels are still high, and the government is hesitant to allow residents to return to their homes. |
Fukushima Daini
Fukushima Daini was another plant that was shut down by the earthquake. Units 1-4 were shut down automatically because of the earthquake. The tsunami affected the generators causing cooling problems and damage to heat exchangers in Units 1, 2, and 4. Despite this, the radiation monitoring figure remained at low levels at Daini. It is believed that the Daini plant will be able to restarted at some point. However, Tepco said they planned to transfer the fuel from the four reactors to used fuel ponds.
For follow up on the information go to:
"World Nuclear Association." Fukushima Accident. World Nuclear Association, n.d. Web. May 2015.
"World Nuclear Association." Fukushima Accident. World Nuclear Association, n.d. Web. May 2015.