More blasts at Japan nuclear plant, radiation reaches dangerous levels

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Tokyo, March 15, 2011 — Radiation released from the earthquake-damaged Fukushima Daiichi nuclear power plant has reached levels that are dangerous to humans, the Japanese government reports.

Japanese Prime Minister Naoto Kan spoke in a nationally televised statement to warn the public of the threat and update the world on the government’s response to the nuclear emergency that stemmed from Japan’s 9.0 magnitude earthquake and accompanying tsunami. The disasters may have killed up to 10,000 people, according to estimates.

The latest explosion (the fourth to impact Fukushima Daiichi) affected Unit 2 of the plant. Plant workers are pumping seawater into this reactor to restore its temperature to manageable levels.

The BBC has reported that this latest explosion may have damaged the Unit 2 reactor containment vessel. This is the first reported damage to a containment vessel since the start of this emergency.

Those reports have not yet been confirmed by plant operator Tokyo Electric Power Co., which has only said that it is investigating the damage the explosion caused.

An explosion and fire also broke out at Unit 4, which had been shut down prior to the earthquake for regularly scheduled maintenance.

There was a hydrogen blast in Unit 3 March 14, following another in Unit 1 March 12. Units 1 and 3 had been flushed out with seawater to return them to temperatures below 100 degrees — an effort that was reportedly successful.

The blast was heard about 6 a.m. local time and originated from within the power station, according to TEPCO’s latest updates. The explosion damaged the fourth-floor rooftop of the Unit 4 reactor building.

Also, the fuel rods in reactor No. 2 were not fully submerged in water for at more than 5 hours during March 14, causing the utility to reduce the number of workers at the plant due to increased radiation risks, TEPCO said.

The 4.7 GW-rated Fukushima Daiichi plant is located about 135 miles north of Tokyo, and about 7 miles north of the 4,400 MW Fukushima Daini power plant, which was also affected by the earthquake and tsunami. TEPCO operates both facilities.

The Japanese government has ordered evacuations of the area surrounding the plant, and encouraged people to stay indoors, make their homes airtight and even to avoid drying wet laundry outdoors.

The levels of detected radiation, according to the International Atomic Energy Agency, have ranged from 11.9 millisieverts per hour to as high as 400 millisieverts per hour.

Previously the government had said that the amount of radiation around the plant was within relatively safe amounts, further stating that a Chernobyl-style nuclear disaster was unlikely.

“Plant conditions as well as potential outside radiation effects are currently under investigation,” according to a TEPCO release. “TEPCO, along with other involved organizations, is doing its best to contain the situation. Simultaneously, the surrounding environment is being kept under constant surveillance.”

TEPCO has also instituted rolling blackouts of about 3 hours each as of March 14. The utility has asked its customers to avoid using electricity unless it is absolutely necessary to help ensure reliability.

At TEPCO’s Fukushima Daini, the plant’s four reactors are in cold shutdown status with stable water levels and offsite backup power available.

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The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at

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