'Little sunfish' robot to swim in to Fukushima reactor
Toshiba and a team of researchers have now developed a swimming robot, which is being called "little sunfish", to explore the flooded parts of the nuclear plant. Read more
Title: First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant Author: Dai Tomono, Tetsuya Mizumoto, Atsushi Takada, Shotaro Komura, Yoshihiro Matsuoka, Yo****aka Mizumura, Makoto Oda, Toru Tanimori
We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution. We confirm that the dose distribution is consistent with the one taken by conventional mapping measurements with a dosimeter physically placed at each grid point. Furthermore, its imaging spectroscopy, boosted by Compton-edge-free spectra, reveals complex radioactive features in a quantitative manner around each individual target point in the background-dominated environment. Notably, we successfully identify a "micro hot spot" of residual caesium contamination even in an already decontaminated area. These results show that the ETCC performs exactly as the geometrical optics predicts, demonstrates its versatility in the field radiation measurement, and reveals potentials for application in many fields, including the nuclear industry, medical field, and astronomy.
Japan's Fukushima nuclear plant leaks radioactive water
Around 100 tonnes of highly radioactive water have leaked from a storage tank at Japan's Fukushima nuclear plant, operator Tokyo Electric (Tepco) says. The toxic water may have overflowed after a valve was left open by mistake, Tepco said. Read more
Japan Fukushima tsunami alert after Pacific earthquake
Japan has issued a tsunami advisory for the Fukushima area - where the crippled nuclear plant is located - after a powerful quake in the Pacific Ocean. Read more
Radiation levels hit new high near Fukushima water tanks
Radiation levels around tanks storing contaminated water at Japan's crippled Fukushima nuclear plant have risen by a fifth to a new high, officials say. Ground readings near one set of tanks stood at 2,200 millisieverts (mSv) on Tuesday, the plant operator and Japan's nuclear authority said. Read more
Fukushima leak is 'much worse than we were led to believe'
A nuclear expert has told the BBC that he believes the current water leaks at Fukushima are much worse than the authorities have stated. Mycle Schneider is an independent consultant who has previously advised the French and German governments. Read more
High levels of a toxic radioactive isotope have been found in groundwater at Japan's Fukushima nuclear plant, its operator says. Tokyo Electric Power Company (Tepco) said tests showed strontium-90 was present at 30 times the legal rate. The radioactive isotope tritium has also been detected at elevated levels. Read more
Fukushima fish still contaminated from nuclear accident
Levels of radioactive contamination in fish caught off the east coast of Japan remain raised, official data shows. It is a sign that the Dai-ichi power plant continues to be a source of pollution more than a year after the nuclear accident. About 40% of fish caught close to Fukushima itself are regarded as unfit for humans under Japanese regulations. Read more
Title: Cosmic Ray Radiography of the Damaged Cores of the Fukushima Reactors Authors: Konstantin Borozdin, Steven Greene, Zarija Luki, Edward Cas Milner, Haruo Miyadera, Christopher Morris, John Perry (Los Alamos National Laboratory, Lawrence Berkeley National Laboratory)
The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei. The interaction with the electrons leads to continuous energy loss and stopping of the muons. The interaction with nuclei leads to angle diffusion. Two muon imaging methods that use flux attenuation and multiple Coulomb scattering of cosmic-ray muons are being studied as tools for diagnosing the damaged cores of the Fukushima reactors. Here we compare these two methods. We conclude that the scattering method can provide detailed information about the core. Attenuation has low contrast and little sensitivity to the core.
Tepco releases recordings of Fukushima nuclear crisis
Tokyo Electric Power Company (Tepco), owner of the crippled Fukushima nuclear plant, has released footage of how it managed meltdowns in three reactors. In the footage, workers can be seen dealing with what they thought was an explosion and urgently trying to understand the scale of the problem. Read more