Fatal radiation levels were detected outside reactor buildings at Japan’s Fukushima Daiichi plant for the first time, complicating efforts to contain the worst nuclear disaster since Chernobyl in 1986.
Water in an underground trench outside the No. 2 reactor had levels exceeding 1 sievert an hour, a spokesman for plant operator Tokyo Electric Power Co (Tepco) told reporters in the capital on Monday, reported Bloomberg. Thirty minutes of exposure to that dose would trigger nausea and four hours might lead to death within two months, according to the US Environmental Protection Agency.
For comprehensive coverage of the Japanese nuclear power disaster and efforts under way to resolve it, visit PennEnergy’s Japan Earthquake and Nuclear Emergency 2011 special section.
Preventing the most contaminated water from leaking into the ground or air is key to containing the spread of radiation beyond the plant. A partial meltdown of fuel rods in the No. 2 reactor probably caused a jump in the readings, Japan’s chief government spokesman said.
A magnitude-9 earthquake and ensuing tsunami on March 11 knocked out power at the plant, disabling its cooling systems and forcing Tepco to dump thousands of tons of sea water on the complex as a stopgap measure. Damage to reactor buildings, including a possible breach in the No. 2 unit’s containment vessel has made it harder for workers to get close enough to fix the equipment without risking their health.
Chief Cabinet Secretary Yukio Edano said: "The high radiation levels seem to have come from fuel rods that partially melted down and came into contact with water used to cool the reactor. It’s very regrettable, but we’re trying to contain the whole situation while preventing the health impact from spreading."
Soil near the Fukushima plant will be tested for plutonium contamination, the government said. The radioactive metal was part of the fuel mix in reactor No. 3 and its presence outside the plant would suggest those fuel rods were also exposed.
Tepco said it needs to drain water lying in four reactor turbine buildings to determine where it came from and assess damage to the fuel rods. Water in the No. 2 turbine building is as high as 1 meter (3.2 feet) deep, a company official said.