Friday, February 17, 2012

Power Transmission Tower for Fukushima I Nuke Plant Fell Because Drain Pipe Wasn't Installed When the Site Was Prepared in 1960s

A mountain stream used to flow near the site for the power transmission tower for Fukushima I Nuclear Power Plant. They dumped a lot of soil and filled the stream to create the embankment, and built the power transmission tower. They thought the water would naturally flow underground at the old surface level. Well it didn't.

From Jiji Tsushin (2/17/2012):


The power transmission tower for Reactors 5 and 6 at Fukushima I Nuclear Power Plant fell because the embankment collapsed from the intense and long shaking from the mega earthquake. In late 1960s the nearby mountain stream was filled but a drain pipe was not installed. TEPCO reported the findings to the Nuclear and Industrial Safety Agency on February 17.


Reactors 5 and 6 lost external power when the tower fell and the electricity supply was cut off when the power lines were severed. But one of the the emergency power generators worked, and the reactors were cooled. For Reactors 1 through 4, the other tower and the power lines remained intact, but the power distribution equipment and the emergency power generators were damaged by the tsunami, resulting in the complete loss of power for the cooling systems.


According to the report. the strongest shaking near the tower from the quake occurred at 2:48PM on March 11, 2011. At 2:49PM, the tower fell and the power lines were severed. According to the blueprint from 1966, there was a mountain stream flowing toward the site for the power transmission tower. After the embankment was built, the stream went underground. The underground stream then flowed at about 2 meters above the old surface, flowing right through the embankment.


TEPCO's Matsumoto explained in the press conference, "When the stream was filled, we assumed that the underground water would flow along the old surface level."

The general contractor who built Fukushima I Nuclear Power Plant is Kajima, who should have known better. The company was, and still is, the first and foremost general contractor in Japan in huge civil engineering projects. I would give them some slack though, as building something that would withstand Magnitude 9 earthquake may be near-impossible.

TEPCO's report to NISA is in Japanese only, and it is not known if NISA will ever provide the English translation. If you read Japanese, the report is here.

The report says the tower fell 30 seconds after the maximum acceleration.

From the report, it looks a large tree jammed into the tower:

The cross section views:


Anonymous said...

2012 - 1960 = 52 years to fail! Do you think its still under warrenty? If this is the level of engineering expertise..and TEPCO is confessing this issue after 52 years..where is the confessing for years 51- today? Forget getting a recommendation for your resumes guys..

Anonymous said...

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.

But seriously, this is just TEPCO shifting blame.

robertb said...

This is like watching a child trying to lie. Denial, placing the blame elsewhere... it's almost like I can see them wiggling in a chair trying to get away. Due to the fact that they know they're caught.

Unfortunately this isn't a child who ripped the head off of his sisters doll...

It's the extinction of our planet.

The nuclear renaissance is over. Time for the nuke guys to develop a new set of skills.

Anonymous said...

it's not that it took 40 years to fail, it's that it took 30 seconds to fail
when the predictable worst case scenario began.

the problem is that you need to assume when a quake occurs bad things will happen. so you need to do lots of planning for that, you can't just react to it.

had they hardened the switchyard and generators at Rac 1-4, they may have done better, but the plants were leaking like sieves.

Bronx Sewer Cleaning said...

Interesting post - thanks for sharing.

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