Explosion Devastates Reactor Building at Japan Nuclear Plant - 50,000 Evacuated

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After being unable to control rising temperatures inside Unit 1 at the Fukushima Daiichi Nuclear Power Plant located 160 miles northeast Tokyo, near the town of Okuma in the Futaba District of Fukushima Prefecture, the reactor building exploded, sending white smoke into the air, following large tremors at the reactor.

Updated 4:33 PM ET - According to AFP The US Nuclear Regulatory Commission says it has sent two experts to Japan to help assist local authorities.

The Japanese government has declared an “Atomic Power Emergency” following the earthquake near Sendai.

Four workers have suffered fractures during the blast. Prior to the blast, radiation levels had already reached 20 times what is considered normal levels.

The Unit 1 reactor’s cooling system was severely damaged by the massive 8.9 magnitude earthquake that ravaged Japan on Friday, causing a tsunami that caused massive destruction around Japan.

Japan’s NISA (Nuclear and Industrial Safety Agency) had already issued a warning that the reactor could be nearing a meltdown, as evidenced by the presence of cesium and radioactive iodine having already been detected in the area.

Cesium is one of several elements that are released as a result of overheating of a nuclear reactor that has experienced core damage. Normally submerged under a water solution, fuel rods comprising the reactor will overheat when exposed to air.

The Japanese Army has been mobilized and has launched a large-scale military rescue operation to evacuate thousands of people within a danger zone radius of the nuclear power plant. An evacuation order was issued to people living within 3 kilometers (1.9 miles) of the plant. Initially, approximately 5,800 residents are involved in the evacuation effort. As the situation became more dire, the evacuation range was first expanded to 10 kilometers (6.2 miles) and then to 20 kilometers (12.4 miles).

In total, 50,000 people have been evacuated surrounding the Fukushima Daiichi Unit 1 Nuclear Power Plant.

At 2:00am JST, the pressure inside the Unit 1 reactor was measured at 87 psi (pounds per square inch), which is 29 psi higher than normal. At 5:30am JST, the pressure had increased to 120 psi, which is 2.1 times the design capacity of the nuclear reactor.

To alleviate the mounting pressure within the reactor, potentially radioactive steam has been released into the surrounding containment structure.

The primary cause of a nuclear reactor meltdown is a failure of the cooling system for each nuclear reactor unit. Cooling is needed to remove the residual heat not used to power the turbine generators that is generated by the nuclear reactor as it operates.

The Fukushima Daiichi (Unit 1) Nuclear Power Plant is operated by the Tokyo Electric Power Company (TEPCO) and the reactor was built by GE (General Electric) in the late 1960’s, having gone into commercial operation in March 1971.

Ironically, Unit 1 was scheduled to be shutdown and decommissioned in March, 2011.

Image credit: Wikipedia

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