Latest reports find damage at Fukushima Daiichi worse than originally believed

Latest reports find damage at Fukushima Daiichi worse than originally believed

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News & Events - Engineering News

December 1, 2011

The results of a comprehensive investigation into the meltdown at Japan's Fukushima Daiichi nuclear power plant revealed damage was far more significant than scientists initially believed.

In March, a 9.0-magnitude earthquake triggered a tsunami that battered the Japanese coast. The northeast region of Japan was especially hard hit by the natural disasters. The Fukushima Daiichi nuclear power plant was battered by strong waves, and officials have struggled in the wake of the incident to control searing temperatures and prevent radiation from affecting local residents.

Tokyo Electric Power Company (TEPCO), which operates the plant and has come under intense scrutiny for its response, released this week a series of reports detailing ongoing efforts to salvage the nuclear power facility. The company's continued investigation revealed damage could have been far more substantial than engineers originally believed.

In one report, TEPCO concluded that molten nuclear fuel could have seeped into the floor of at least one of the plant's nuclear reactors. Engineers had previously contended that such a scenario had not occurred, but as they gain new insight into the details surrounding the event, they affirmed they are adjusting their initial assessments.

TEPCO engineers asserted their initial reports on the meltdown were not entirely accurate. In fact, officials from the company, which has shed billions of dollars over the past year as it endeavored to contain the meltdown, said that their newest simulation suggested the meltdown was more severe.

The company released a flurry of updates on the nuclear plant, and company engineers affirmed they had begun to restructure some of their original judgments on how significantly the tsunami and earthquake had damaged the facility's nuclear reactors.

TEPCO said that one of its most recent simulations concluded that overheated fuel could have eaten through the thick concrete floor in the plant's Number 1 reactor. Such findings stand in contrast to what company executives originally told Japanese lawmakers during the height of the crisis.

Engineers asserted that the overheated fuel came within 12 inches of reaching a steel barrier protecting a concrete basement, the last hurdle it would have had to cross to reach the earth. Had the fuel melted the steel and escaped into the underground space, it could have bled into the soil, risking a significant public health threat.

Many nuclear engineers have criticized TEPCO's response at the nuclear power plant. The New York Times reports a number of scientists have questioned whether the company's makeshift cooling system is capable of cooling nuclear fuel that could have trickled into the concrete. While they paint a far bleaker picture than earlier reports, TEPCO's latest assessments are still optimistic in many regards, according to Kyoto University Research Institute assistant physics professor Hiroaki Koide.

"This is still an overly optimistic simulation," Koide said. He noted that although TEPCO is hoping the nuclear fuel did not penetrate the outermost protective barriers, "even by their own simulation, it's very borderline."

The London Guardian reports the latest news on Fukushima Daiichi has emboldened many of TEPCO's critics. A series of scathing new reports concluded that TEPCO ignored warnings that the nuclear power facility was at risk of damage from the tsunami. Further, they accused TEPCO of balking at recommendations that it should implement improved seawater flooding controls, according to The Guardian.

Ultimately, seawater flooded power supply lines at Fukushima, disabling cooling systems that prompted the failure of three of the facility's' six nuclear reactors. Japan is a global leader in its use of nuclear power, with such facilities accounting for more than two-thirds of the nation's electricity supply.


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