Tokyo Electric Power Company says it has detected radioactive materials 10-million-times normal levels in water at the No.2 reactor complex of the Fukushima Daiichi nuclear plant.
The plant operator, known as TEPCO, says it measured 2.9-billion becquerels of radiation per one cubic centimeter of water from the basement of the turbine building attached to the Number 2 reactor.
The level of contamination is about 1,000 times that of the leaked water already found in the basements of the Number 1 and 3 reactor turbine buildings.
The company says the latest reading is 10-million times the usual radioactivity of water circulating within a normally operating reactor. TEPCO says the radioactive materials include 2.9-billion becquerels of iodine-134, 13-million becquerels of iodine-131, and 2.3-million becquerels each for cesium 134 and 137.
These substances are emitted during nuclear fission inside a reactor core.
The company says the extremely contaminated water may stem from damaged fuel in the reactor, and are trying to determine how the leakage occurred.
University of Tokyo graduate school professor Naoto Sekimura says the leak may come from the suppression chamber of the Number 2 reactor, which is known to be damaged. The chamber is designed to contain overflows of radioactive substances from the reactor.
前回の記事でリンク貼りましたが、IRSN; Institut de Radioprotection et de Sûreté Nucléaire の日本原発情報関連ページです。この団体は日本での原子力安全・保安院にあたるのかと思いますが、日本の保安院が経済産業省枠内にあるのに対し、仏IRSN は防衛省、産業省、環境省、研究と健康と発展省(なんてのがあるのね)などに関連し、EDF(仏電気会社)とデータを共有、ASN/Autorité de sûreté nucléaire ともコラボしているそうです。なおIRSNで働く人の数は1750人だそうで、そのうち研究者・技術者・医師・獣医など専門家も多い。これはCNRSやINSERMなどの研究団体と同じ、Établissement public à caractère scientifique et technologique というカテゴリーに入る。
« To Japanese people and our Japanese colleagues : IRSN collaborators are very concerned with the seriousness of these events and work to help you understand the phenomena. We do hope you and your family are well and that people of Japan keep strength to overcome these difficult times. »
More high levels of radioactive material have been found in seawater near the troubled Fukushima Daiichi nuclear power plant.
Tokyo Electric Power Company says samples collected 30 meters from one of the plant's water outlets on Sunday contained 46 becquerels per cubic centimeter of iodine-131. That's 1,150 times higher than the regulated standard level.
On Friday and Saturday, water samples collected 330 meters south of another outlet showed levels of iodine-131 that were higher than 1,000 times the standard level. However, on Sunday the levels had dropped to 250 times the standard level.
The government's nuclear safety agency says radioactive materials may have leaked from the plant and drifted with the current from south to north.
TEPCO is struggling to remove highly radioactive water from the turbine buildings of 3 reactors before work to restore their cooling systems can begin.
On Tuesday, the company intends to pump fresh water, instead of sea water, into spent fuel storage pools of 2 reactors.
Fresh water was pumped into the reactors by Saturday, to prevent the salt water from corroding the cooling system.
Radioactive levels in the air are decreasing at most observation points in the surrounding areas on Monday.
The reading in Fukushima City, 65 kilometers northwest of the nuclear power plant, was 3.84 microsieverts per hour at 1 AM.
The annual total limit of radiation exposure considered safe for humans is 1,000 microsieverts based on standards set by the International Commission on Radiological Protection.