Nearly all fuel melted at Fukushima No. 2 reactor, researchers find

The Fukushima Daiichi disaster is an ugly wart on the Tokyo Electric Power Company’s (TEPCO) record. A recent report reveals that nearly all of the nuclear fuel at Reactor No. 2 has melted. To add fuel to the radioactive fire, TEPCO could have prevented the nuclear meltdown had they appropriately installed the backup generators.

Research scientists from Nagoya University estimated that 70 to 100 percent of the nuclear fuel in Reactor No. 2 melted. The team had been monitoring the Fukushima site since April but was unable to detect the nuclear fuel at the heart of the reactor’s core.(1)

The research scientists used muons — tiny subatomic particles 200 times heavier than electrons — to shed light on the abyss. Muons pass through most forms of matter excluding uranium, which is the element that makes up the nuclear fuel inside the reactors. Scientists were able to gain a better picture of the inside of the building by using a particle detector that tracked the path of the muons as they passed through the reactor.(1)

Comparing nuclear reactors

Reactor No. 5 was one of the only reactors at the Fukushima power plant that was not swallowed by the tsunami in 2011. The researchers compared the muons sprinkled around Reactor No. 2 to Reactor No. 5 and were able to conclude that nearly all of the nuclear fuel had likely melted in the plant’s No. 2 reactor.(1)

TEPCO issued a report last May which stated that a malfunction in Reactor No. 2’s pressure mitigation system was to blame for the accident. That same month, TEPCO announced that nearly all of the fuel in Reactor No. 1 had melted.(1, 2)

Researchers previously used a robot to venture inside the building and measure radiation levels. The robot was among 15 others sent to explore crippled buildings at the Fukushima site. Radiation levels at the power plant were too high for human exploration.(2)

Radiation levels proved too high for robot exploration as well. A robot stopped functioning less than three hours after it had been sent into Reactor No. 1, which was intended to be a 10-hour mission.

TEPCO fails to install backup generators at safe levels

The Fukushima disaster was in part caused by natural disaster. Nevertheless, there were plenty of precautionary measures TEPCO could have taken that could have mitigated the severity of the incident. For example, TEPCO installed backup generators in low-lying areas susceptible to flooding. One backup generation was placed in the basement; the others were placed only 10 to 13 meters above sea level, despite being in an area prone to tsunamis.(2)

Once the tsunami struck, 12 of the 13 backup generators at the Fukushima site were washed away. This prevented the nuclear reactors from being cooled, and this is the reason why 70 to 100 percent of the fuel inside Reactor No. 2 melted, as independent media sources have dutifully reported. Had officials installed backup generators at higher levels, they could have prevented a nuclear meltdown.

Prior to the disaster, TEPCO estimated that the maximum possible rise in sea levels at the Fukushima site was 6.1 meters. This figure was based upon a magnitude 7.5 earthquake, even though much stronger earthquakes had been recorded on the coast. The tsunami drastically exceeded TEPCO’s expectations, with sea level heights spanning 11 meters tall.(2)

Although officials have a better understanding of how much fuel melted, they’re still trying to peer inside Reactor No. 2 to get an estimate of the damage. Conservative estimates suggest that it will take 30 to 40 years to clean up the Fukushima site.

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