| BY HIDEYUKI MIURA, THE ASAHI SHIMBUN
KASHIWAZAKI, Niigata Prefecture: Up to 2.000 tons of water from an outdoor pipe broken in the July 16 earthquake inundated the basement of a nuclear reactor building here, Tokyo Electric Power Co. (TEPCO) said. The basement at the TEPCO-run Kashiwazaki-Kariwa Nuclear Power Plant is a "radiation-controlled area" containing radioactive materials. It must be completely shut off from the outside environment. However, the earthquake showed that the area can be linked to the outside environment. According to TEPCO officials, the ground around the building that accommodates the No.1 reactor sank by about 20 to 30 centimeters during the earthquake. Underground electric cables leading from the first basement floor of the building to the outside were pulled down by the ground subsidence, creating a large space on the outer wall. An underground water pipe for fire extinguishing near the cables ruptured in the quake, allowing water to flow into the basement areas through the space. "It was beyond our imagination that a space could be made in the hole on the outer wall for the electric cables," a TEPCO official said. However, he stressed: "As the air pressure in the radiation-controlled area was reduced, no air leaked from the area to the outside environment. No radioactive materials leaked to the outside." (suite)
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TEPCO officials said the building itself did not subside because it had been built on solid ground. But the ground around the building sank because it consists of layers of sand. The water that entered the building flowed down a drainpipe to the fifth basement floor, a radiation-controlled area. The water entered a waste water tank, which soon overflowed, inundating the floor with water to a height of 48 centimeters. An estimated 2.000 tons of water spilled on the floor, equivalent to the volume in five 25-meter-long swimming pools. The flooding also apparently damaged motors that send waste water containing radioactive materials to filtering devices, the officials said. But they added that the radioactive-contamination level of the water that flowed onto the floor was low. "We have already closed the space (of the hole on the outer wall). We never imagined that such a situation could take place," one of the officials said. According to the officials, TEPCO is now considering measures to discharge the water from the building.(IHT/Asahi: July 25,2007) |