TEPCO plant engineer makes case that earthquake caused reactor cooling problem

[kristopher]

Kimura authored paper titled “Leakage from the piping in the Fukushima No. 1 nuclear power plant caused by vibrations from the earthquake.” in September of this year.

Cracks in Tepco’s 3/11 narrative
SENTAKU MAGAZINE
NOV 17, 2013


<snip>

The transient phenomena recorder records various measurements in a nuclear power plant at every one-hundredth of one second. It accumulates such data as a reactor’s output, pressure and temperature and coolant’s flowing volume. Analysis of these data makes it possible to accurately identify “process behaviors” or what is happening in an nuclear reactor.

<snip>

...In analyzing the data, Kimura took special note of the fact that natural circulation of coolant stopped. Along with an isolation condenser, natural circulation of coolant constitutes the “lifeline” in case loss of all the power sources occurs. Even if a primary loop recirculation pump, which pumps coolant water into the reactor core, stops functioning due to loss of all the power sources, natural circulation of coolant is supposed to maintain 10 percent of normal core flow of coolant.

Analysis of the data showed, however, that immediately after the earthquake hit, about 30 percent of coolant inside the core started flowing backwards and that after the coolant flow returned to the normal flow direction, the core flow fluctuated and eventually became less than zero. All these occurred before the nuclear power plant was struck by the tsunami.

Why is it that cooling by natural circulation of coolant became dysfunctional along with the isolation condenser right after the earthquake? Kimura believes that piping rupture was the very cause of the loss of these two “lifelines”

There are a couple of phenomena that seem to correspond to what Kimura believes happened. One is that a pump designed to draw up water from the bottom of the containment vessel seems to have been activated frequently, indicating that damage to piping caused coolant to leak and accumulate at the bottom of the vessel.

The other is that radioactive contamination was taking place at a much faster rate than was estimated by Tepco....

http://www.japantimes.co.jp/opinion/2013/11/17/commentary/cracks-in-tepcos-311-narrative/#.UomNzXCf_wxvia


The article goes on to discuss the consequences to Japan's nuclear program should they acknowledge that the rather distant earthquake caused the cooling failure. It is important to know that the earthquake at its epicenter was vastly stronger than the forces that hit the nuclear plant and that instruments at the plant show that the quake forces there exceeded design parameters of the plant by just a small amount.

[Control-Z]

1. There are members here

who argue that nuclear power plants are safe during earthquakes - that Japan sustained damage only after the tsunami hit. I expect this information will be denied by a few.

[kristopher]

2. Yep.

Denial of risk runs very deep with nuclear advocates.

[davidpdx]

3. Very interesting, I hadn't heard this.