Tokyo Electric Power Co. said April 2 water contaminated with radiation exceeding 1,000 millisieverts per hour was detected in a shaft near an outlet of No. 2 reactor of its crippled Fukushima No. 1 nuclear power plant.
Tokyo Electric Power Co. said April 2 water contaminated with radiation exceeding 1,000 millisieverts per hour was detected in a shaft near an outlet of No. 2 reactor of its crippled Fukushima No. 1 nuclear power plant.
TEPCO said the shaft, which stores supply cables, had a crack 20 centimeters long in the concrete.
The utility also confirmed contaminated water from the shaft had leaked into the sea. Workers have begun pouring concrete into the shaft to seal the crack, TEPCO said.
Officials said March 31 that water collected March 30 afternoon about 330 meters south of outlets from the Fukushima No. 1 plant had levels of iodine-131 that were 4,385 times the acceptable limit. Water collected the same day about 30 meters north of the outlets from the No. 5 and No. 6 reactors had iodine-131 levels 1,425 times the acceptable level.
Earlier April 2, the Nuclear and Industrial Safety Agency of the Ministry of Economy, Trade and Industry announced that it detected radioactive iodine about double the normal limit in seawater 40 kilometers south of the Fukushima No. 1 nuclear power plant March 30.
The spread of radioactive iodine in the sea presents no immediate danger to human health. However, the detection shows that contamination by radioactive substances has spread widely in the ocean off the Japan coast.
The high concentration of radioactive iodine was detected in an area where 79.4 becquerels per liter of radioactive iodine were found on surface water. The normal concentration limit is 40 becquerels. The detection was made in a part of the ocean being monitored by the science ministry.
NISA officials say that contamination by the radioactive iodine, which had been confirmed around the Fukushima No. 1 nuclear power plant, has spread to southern sea areas due to north-south ocean currents.
The officials also said the government is preparing to inject nitrogen into reactor buildings to prevent explosions caused by hydrogen leaking from the reactors.
The Tokyo Electric Power Co. resumed spraying of liquid synthetic resins in the Fukushima No. 1 nuclear power plant compound on April 2 to prevent radioactive dust and particles from becoming airborne.
TEPCO had done similar work Friday on an experimental basis and confirmed that the resins were effective. TEPCO plans to spray the material in the 30,000 square-meter area of the compound for the next two weeks.
The synthetic resins were initially developed to prevent sand and other materials from becoming airborne at construction sites. According to Kurita Water Industries Ltd., which manufactures the resins, they become solid in half a day when the weather is good and are effective for six to 12 months.
Previously, radioactive dust and particles had been scattered by wind, rain and explosions that rocked the facilities housing the nuclear reactors.
Meanwhile, the Wall Street Journal reported that the U.S. Department of Energy said Friday that up to 70 percent of the nuclear fuel at the No. 1 reactor of the Fukushima No. 1 nuclear power plant and up to one-third of the No. 2 reactor of the plant is damaged.
In a nuclear accident at Three Mile Island in 1979, at least 45 percent of entire reactor cores were melted by the time the cooling functions were revived more than 10 hours later.