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Visualizing nuclear radiation: Team images gamma rays to help decontaminate Fukushima

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A Kyoto University team has developed a new camera to visualize radioactive hotspots

Extraordinary decontamination efforts are underway in areas affected by the 2011 nuclear accidents in Japan. The creation of total radioactivity maps is essential for thorough cleanup, but the most common methods, according to Kyoto University’s Toru Tanimori, do not ‘see’ enough ground-level radiation.

“The best methods we have currently are labor intensive, and to measure surface radiation accurately,” he says, “complex analysis is needed.”

In their latest work published in Scientific Reports, Tanimori and his group explain how gamma-ray imaging spectroscopy is more versatile and robust, resulting in a clearer image.

“We constructed an Electron Tracking Compton Camera (ETCC) to detect nuclear gamma rays quantitatively. Typically this is used to study radiation from space, but we have shown that it can also measure contamination, such as at Fukushima.”

The imaging revealed what Tanimori calls “micro hot spots” around the Fukushima Daiichi Nuclear Power Plant, even in regions that had already been considered decontaminated. In fact, the cleaning in some regions appeared to be far less than what could be measured by other means.

Current methods for measuring gamma rays do not reliably pinpoint the source of the radiation. According to Tanimori, “radiation sources including distant galaxies can disrupt the measurements.”

The key to creating a clear image is taking a color image including the direction and energy of all gamma rays emitted in the vicinity.

“Quantitative imaging produces a surface radioactivity distribution that can be converted to show dosage on the ground,” says Tanimori. “The ETCC makes true images of the gamma rays based on proper geometrical optics.”

This distribution can then be used to relatively easily measure ground dosage levels, showing that most gamma rays scatter and spread in the air, putting decontamination efforts at risk.

“Our ETCC will make it easier to respond to nuclear emergencies,” continues Tanimori. “Using it, we can detect where and how radiation is being released. This will not only help decontamination, but also the eventual dismantling of nuclear reactors.”

https://phys.org/news/2017-03-visualizing-nuclear-team-images-gamma.html#jCp

March 23, 2017 Posted by | Fukushima 2017, Fukushima continuing | , , , , | Leave a comment

TEPCO reinserts camera in Fukushima reactor 2

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What appears to be rust is seen on a foothold inside the containment vessel of the No. 2 reactor at the Fukushima No. 1 nuclear plant in this image provided by Tokyo Electric Power Co.

 

TEPCO reinserts camera in Fukushima reactor

TEPCO, the operator of the damaged Fukushima Daiichi nuclear plant, has again begun using a camera probe inside the containment vessel of the No. 2 reactor.
Taking pictures of the molten fuel inside is regarded as an important step towards decommissioning the reactors that melted down.
On Tuesday, workers at the plant tried to insert a camera into a pipe leading into the containment vessel.
But the camera got stuck in the pipe’s opening. The rubber, which had shrunk due to cold, blocked it.
In a second attempt on Thursday, workers tried to push the camera into the pipe while warming the rubber with thermal material. They were successful.
Footage from the camera shows a black substance adhering to the surface of metal rails in the vessel. The rails will be used as tracks for a robot to do a survey in February.
TEPCO expects the camera may capture footage of molten fuel for the first time since the 2011 meltdown

https://www3.nhk.or.jp/nhkworld/en/news/20170126_31/

TEPCO begins taking video inside Fukushima No. 1 nuke plant reactor

Tokyo Electric Power Co. (TEPCO) began work on Jan. 26 to take video inside the No. 2 reactor at its tsunami-hit Fukushima No. 1 nuclear plant, company officials said.

A camera attached to the tip of a pipe was inserted into the reactor containment vessel to shoot video inside of the vessel to check the condition of the melted fuel within. It was also done in preparation for sending in a camera-equipped robot to get a closer look at conditions. The robot will follow 7.2-meter-long rails leading to an area just below the reactor’s pressure vessel.

Video released by TEPCO on Jan. 26 shows dripping liquid and what appears to be steam drifting inside the containment vessel. What looks like rust is seen on a foothold and the rails, but nothing that could block the robot has been found.

TEPCO is poised to use a longer pipe to check if there is any obstacle inside the reactor next week and beyond. Company officials said the firm may be able to photograph the melted fuel.

http://mainichi.jp/english/articles/20170127/p2a/00m/0na/002000c

January 27, 2017 Posted by | Fukushima 2017 | , , | Leave a comment