Xpost Good Reads: New "bulge" in wall of Fukushima reactor building 4 worries public [View all]

[kristopher]

http://www.democraticunderground.com/101629729

Lapses at Japan's Fukushima Daiichi nuclear power plant worry public
By Hiroko Tabuchi and Matthew Wald
The New York Times

TOKYO — What passes for normal at the Fukushima Daiichi nuclear plant today would have caused shudders among even the most sanguine of experts before an earthquake and tsunami set off the world's second most serious nuclear crisis after Chernobyl.

Fourteen months after the accident, a pool brimming with used fuel rods and filled with vast quantities of radioactive cesium still sits on the top floor of a heavily damaged building, covered only with plastic.

The public's fears about the pool have grown in recent months as some scientists have warned that it has the most potential for setting off a new catastrophe. The three nuclear reactors that suffered meltdowns are in a more stable state, but frequent quakes continue to rattle the region.

The worries gained traction in recent days after the operator of the plant, Tokyo Electric Power Co., or TEPCO, said it had found a slight bulge in one of the walls of the reactor building, stoking fears over the building's safety.

To try to quell such worries ...

Read more: Lapses at Japan's Fukushima Daiichi nuclear power plant worry public - The Denver Post http://www.denverpost.com/nationworld/ci_20719791/lapses-at-japans-fukushima-daiichi-nuclear-power-plant#ixzz1w4tW0g7k


The 311 Tohoku earthquake that damaged Fukushima NPP was centered almost 100 miles from Fukushima. Researchers are now concerned that an earthquake prone fault in the Fukushima area might soon result in another quake that would be strong enough to cause Building 4 spent fuel pool (discussed above) to collapse.
This study is what has brought attention to the issue. It looked at a magnitude 7 earthquake in Iwaki (about 40miles from Fukushima) that occurred in April 2011, and concluded that there exists a heightened possibility of a severe earthquake centered under Fukushima presenting forther concerns about the plant's safety. You can download the full paper. It even has some nuce graphics if you like that sort of thing.

Tomography of the 2011 Iwaki earthquake (M 7.0) and Fukushima nuclear power plant area
[font size="1.5"]P. Tong1,2, D. Zhao1, and D. Yang2 1Department of Geophysics, Tohoku University, Sendai 980-8578, Japan
2Department of Mathematical Sciences, Tsinghua University, Beijing, China
Correspondence to: P. Tong, D. Zhao Published: 14 February 2012
Solid Earth, 3, 43–51, 2012 [/font]

Abstract.
High-resolution tomographic images of the crust and upper mantle in and around the area of the 2011 Iwaki earthquake (M 7.0) and the Fukushima nuclear power plant are determined by inverting a large number of high-quality arrival times with both the finite-frequency and ray tomography methods. The Iwaki earthquake and its aftershocks mainly occurred in a boundary zone with strong variations in seismic velocity and Poisson’s ratio. Prominent low-velocity and high Poisson’s ratio zones are revealed under the Iwaki source area and the Fukushima nuclear power plant, which may reflect fluids released from the dehydration of the subducting Pacific slab under Northeast Japan. The 2011 Tohoku-oki earthquake (Mw 9.0) caused static stress transfer in the overriding Okhotsk plate, resulting in the seismicity in the Iwaki source area that significantly increased immediately following the Tohoku-oki mainshock. Our results suggest that the Iwaki earthquake was triggered by the ascending fluids from the Pacific slab dehydration and the stress variation induced by the Tohoku-oki mainshock. The similar structures under the Iwaki source area and the Fukushima nuclear power plant suggest that the security of the nuclear power plant site should be strengthened to withstand potential large earthquakes in the future.

Download study here: http://www.solid-earth.net/3/43/2012/se-3-43-2012.pdf