Documents from Tokyo Electric, the operator of the Japanese nuclear plants in crisis after Friday's devastating quake and tsunami, reveal that the company tested the Fukushima plant to withstand a quake up to magnitude 7.9. That threshold is well below the force of Friday's quake, recently upgraded to 9.0.
Snip from Wall Street Journal:
Tepco's last safety test of nuclear power plant Number 1--one that is currently in danger of meltdown--was done at a seismic magnitude the company considered the highest possible, but in fact turned out to be lower than Friday's quake. The information comes from the company's "Fukushima No. 1 and No. 2 Updated Safety Measures" documents written in Japanese in 2010 and 2009. The documents were reviewed by Dow Jones. The company said in the documents that 7.9 was the highest magnitude for which they tested the safety for their No. 1 and No. 2 nuclear power plants in Fukushima.Japan Tries Using Seawater to Cool Damaged Reactor (WSJ)
Thousands of evacuees from areas around Japan's Fukushima nuclear power plant were scanned for radiation exposure, though the Japanese government insists radiation levels are low. Video courtesy of Reuters
Simultaneous seismic activity along the three tectonic plates in the sea east of the plants--the epicenter of Friday's quake--wouldn't surpass 7.9, according to the company's presentation.
Photo (Reuters): The damaged roof of reactor number No. 1 at the Fukushima Daiichi nuclear plant after an explosion that blew off the upper part of the structure is seen in this handout photo released by Tokyo Electric Power Company (TEPCO) in Fukushima Prefecture, northeastern Japan, March 12, 2011. Japanese authorities battling to contain rising pressure in nuclear reactors damaged by a massive earthquake were forced to release radioactive steam two plants, after evacuating tens of thousands of residents from the area. Tokyo Electric Power Co also said fuel may have been damaged by falling water levels at the Daiichi facility, one of its two nuclear power plants in Fukushima, some 240 km (150 miles) north of Tokyo. Picture taken March 12, 2011.