The damaged Japanese nuclear plants at Fukushima are not yet under control. Recent reports from Japanese agencies and news sources suggest that the situation may be far more serious than previously thought.
On March 11, 2011, an earthquake that registered 9.0 on the Richter Scale struck just off the eastern shore of the island of Honshu, Japan. Within minutes, a series of tsunami waves came ashore, adding to the devastation. The earthquake was among the most severe ever recorded. The tsunami reached a height, at one point, of 124 feet or over 37 meters.
The Fukushima Daiichi Nuclear Power Station and Fukushima Daini Nuclear Power Station were affected by the earthquake and the tsunami. Fukushima Daini's reactors suffered little damage. The Fukushima Daiichi Nuclear Power Station sustained severe damage from both and a nuclear disaster developed. The tsunami at the Daiichi site was measured at 15.5 meters or 51 feet. That height is three times higher than site planners had allowed for in their designs.
The Eurosafe Forum 2011, held November 7-8 in Paris, provides the following basic information. There are six nuclear reactors at the Fukushima Daiichi site. Units one through three were in operation at the time of the earthquake while unit four was shut down for maintenance. Units five and six were shutdown for refueling. Units one through four were affected by the natural disasters.
The loss of electrical power at the site and a series of accidents caused reactors one through three to meltdown in the period March 11-14. The reactor buildings for units one through four suffered explosions due to hydrogen buildup during emergency cooling operations from March 12-15.
Radioactive material was released into the air, into ground water and the sea. Exposure to cesium 137, the most common radioactive isotope produced by the Fukushima disaster, increases a person's cancer risk. Asahi Shimbun reports in its English edition of November 21, that 8 percent of Japan has been contaminated by radioactive cesium - over 11,000 square miles.
The AP reports that the latest data from Fukushima suggest that the meltdown of reactor one may have eroded the concrete floor of the containment vessel and threatened the structure's foundation. Some of the measuring devices within the three reactors that melted down have ceased operation. Data on the condition of the pile of semi-liquid uranium in each of the containment vessels is limited. In addition, the site is littered with explosive debris and pools of water that can be highly radioactive.
On November 27, the site managers reported an increase in temperatures at two points in reactor two. Other readings from a greater distance remained normal. This may be a glitch but it may also suggest that a fission reaction is continuing in the melted fuel in that reactor. The current plan is to have reactors one through three in cold shutdown by year end.
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