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Thu Nov 28, 2013, 03:13 PM

TEPCO plant engineer makes case that earthquake caused reactor cooling problem

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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.

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Reply TEPCO plant engineer makes case that earthquake caused reactor cooling problem (Original post)
kristopher Nov 2013 OP
Bennyboy Nov 2013 #1
FBaggins Nov 2013 #3
kristopher Nov 2013 #4
PamW Nov 2013 #5
FBaggins Nov 2013 #2
PamW Nov 2013 #6
Sirveri Nov 2013 #9
bananas Nov 2013 #7
PamW Nov 2013 #8

Response to kristopher (Original post)

Thu Nov 28, 2013, 04:45 PM

1. This changes the nuclear industry's narrative completely....

 

I knew it too, blaming on everything but the earthquake. because that is the one thing that you cannot prevent against (SPEND HUGE AMOUNTS OF OTHER PEOPLE"S MONEY) and also puts an awful lot of nuke plants in danger including the one on the coast here, Diablo Canyon, which is very similar in design as FUKU and is on at least two and maybe three earthquake faults. And that it doess NOT take a direct hit with the epicenter at the plant to make things go.........

This changes everything about nukes and the argument.

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Response to Bennyboy (Reply #1)

Thu Nov 28, 2013, 05:57 PM

3. Hardly... even if it were true

Which it isn't.

Damage from a roughly design basis earthquake isn't impossible... But it's worlds away from supporting a claim that the damage would have resulted in a meltdown.

Hours of power failure otoh... is a different thing entirely.

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Response to Bennyboy (Reply #1)

Thu Nov 28, 2013, 06:11 PM

4. Yes, it does.

Don't you love how no one who is critical of nuclear power is qualified? At least, that is the position according to the parade of anonymous internet posters trying to sell the technology with an endless series of falsehoods and myths.

The right wing Abe government of Japan is getting set to resume their pronuclear, state sanctioned propaganda campaign.
Gov't eyes reinforcement of publicity activities on nuclear power

(Globalpost/GlobalPost)

The government plans to stipulate in its long-term energy plan that publicity activities on nuclear power should be reinforced, although not in a way that will lead Japan to be stuck in a "safety myth" as seen before the 2011 Fukushima nuclear crisis, a document obtained by Kyodo News showed Tuesday.

...

The government has been restrained in behavior toward publicizing nuclear power after the devastating accident at Tokyo Electric Power Co.'s Fukushima Daiichi power plant raised concerns among the public over the use of nuclear reactors.

But it is apparently seeking to resume publicity activities on nuclear issues after a new medium- to long-term energy plan is compiled next month at the earliest.
...

The discussion taking place among the panel members has so far proceeded with a pro-nuclear tone under Prime Minister Shinzo Abe's government that believes nuclear power should continue to play a role in meeting the country's energy demand...

http://www.globalpost.com/dispatch/news/kyodo-news-international/131126/govt-eyes-reinforcement-publicity-activities-nuclear-p

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Response to Bennyboy (Reply #1)

Thu Nov 28, 2013, 07:42 PM

5. BALONEY!!! Why make up CRAP???

Bennyboy states
including the one on the coast here, Diablo Canyon, which is very similar in design as FUKU

100% WRONG - MADE UP CRAP

The Diablo Canyon plant is NOT "very similar in design to FUKU"; in fact it is NOTHING like it.

Diablo Canyon is a PWR - Pressurized Water Reactor designed by Westinghouse.

http://www.nrc.gov/reading-rm/basic-ref/students/animated-pwr.html

Fukushima reactors are all BWR - Boiling Water Reactor designed by GE, and licensed to Toshiba / Hitachi.

http://www.nrc.gov/reading-rm/basic-ref/students/animated-bwr.html

Diablo Canyon has a PWR type containment building that is a large cylindrical structure designed to handle immense overpressures.

Fukushima has a rather small primary containment, that has to use a pressure-suppression system to keep the pressure within limits.

Fukushima had its backup diesel generators in a non-watertight basement, and the fuel tanks for same were at dockside and out it the open.

Diablo Canyon has backup diesel generators that are in a watertight vault, and the fuel tanks are buried; all as per US NRC regulations.

In addition, go to Google Earth or Bing Aerial and LOOK at the Diablo Canyon site. You can get the coordinates by going to the Wikipedia entry on "Diablo Canyon Nuclear Power Plant" and in the upper right hand corner; there are the coordinates that you can click on thru to either Google Earth or Bing Aerial.

http://en.wikipedia.org/wiki/Diablo_Canyon_Power_Plant

Look at the area just norteast of the plant which is up the hill. There are TWO LARGE pools of backup reactor coolant water. In case of a problem; the water from these pools can be fed by GRAVITY - no need to find a backup for gravity.

So you just made a FALSE statement about Diablo Canyon.

How come anti-nukes always seem to be so DISHONEST. They bleat like mad about the "nuclear industry" telling lies, and how bad that is. However, when push comes to shove; the ones that are really doing the LYING are the anti-nukes.

The good thing about science is that it is true, whether or not you believe in it.
--Neil deGrasse Tyson

PamW

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Response to kristopher (Original post)

Thu Nov 28, 2013, 05:51 PM

2. No. .. He didn't

He made the claim (made it up really)... But the only "case" he made was for questioning how he ever got the label "engineer" since he's clearly never seen this kind of data on a scrammed BWR.

The water should "flow backwards" at that point.

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Response to FBaggins (Reply #2)

Thu Nov 28, 2013, 07:58 PM

6. EXACTLY!!!

FBaggins,

You are correct. The Fukushima reactors are BWRs - Boiling Water Reactors.

That means that water actually boils IN the reactor. So it's like boiling water on your stove.

In either case, a fair amount of the volume of either the BWR reactor ( or your saucepan ) is "steam void".

That is a lot of the volume is "steam bubbles".

When the reactor scrams, and the power drops drastically to 7% ( which is the "decay power", the power due to radioactivity in the reactor. The reactor scram stops the "fission power" ); the steam voids collapse.

Therefore, you do get a flow reversal in all the outlet lines.

The very fact that this "engineer" makes this claim; tells me that he is NO engineer.

A real engineer would not be as STUPID. Real engineers on reactors know what happens in a scram.

PamW

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Response to PamW (Reply #6)

Fri Nov 29, 2013, 07:31 PM

9. It's only 7% while at power.

Scram reduces it to 3% almost instantly, ~1% after about a minute, and it continues to rapidly decrease from there as the short lived radionuclides rapidly decay out. I noticed this when I was researching the data on three mile since I had also always heard the fabled 7% number and wondered why the decay heat post scram didn't line up with 7% since the reactor was functioning at 97% power when they suffered loss of heat sink.

But I otherwise agree with your post.

Still should be at least some sub nucleate boiling but not enough to support steam production, collapse of the steam voids produces a vacuum effect and pulls from the discharge leg. That said he did raise two interesting points if true. Namely:

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....


So it sounds like they had their sump pump cycling on and off repeatedly. This could have been due to a high sump water level that they were planning on pumping down during a later plant evolution. Then the earthquake could have caused water slosh causing the sensor to repeatedly trip and cycle the pump. Or they could have seen their PORV's (Pilot Operated Relief Valve) open up and vent down to the sump, tripping the pump to cycle on. Or there could have been a broken piece of piping, the severity of which is difficult to establish after the loss of instrumentation. Or it could have been an electrical failure due to the earthquake causing a faulty sensor reading, or possibly damaging the sump pump control circuit.

The later claim is difficult to address, since it does not specify where this contamination occurred. According to the article a worker was unable to enter the reactor building due to high radiation. But this high radiation could have occurred from any number of sources, including an open PORV and subsequent degassing of radioactive Argon-41 into the containment vessel and reactor building.

I suppose the real problem with an event like this is that we typically can't stabilize the site for a lengthy period of time, and thus will likely need to wait until 2021 for a more definitive survey of what the actual timeline was.

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Response to kristopher (Original post)

Fri Nov 29, 2013, 11:21 AM

7. That's consistent with previous reports

http://www.thewire.com/global/2011/07/meltdown-what-really-happened-fukushima/39541/

Jul 2, 2011 2:08PM ET / Global
Meltdown: What Really Happened at Fukushima?
Jake Adelstein, David McNeill

<snip>

The authors have spoken to several workers at the plant who recite the same story: Serious damage to piping and at least one of the reactors before the tsunami hit.

<snip>

A second worker, a technician in his late 30s, who was also on site at the time of the earthquake, narrated what happened. “It felt like the earthquake hit in two waves, the first impact was so intense you could see the building shaking, the pipes buckling, and within minutes, I saw pipes bursting. Some fell off the wall. Others snapped. I was pretty sure that some of the oxygen tanks stored on site had exploded but I didn’t see for myself. Someone yelled that we all needed to evacuate and I was good with that. But I was severely alarmed because as I was leaving I was told and I could see that several pipes had cracked open, including what I believe were cold water supply pipes. That would mean that coolant couldn’t get to the reactor core. If you can’t sufficiently get the coolant to the core, it melts down. You don’t have to have to be a nuclear scientist to figure that out.”

<snip>

During his research, Onda spoke with several engineers who worked at the TEPCO plants. One told him that often piping would not match up the way it should according to the blueprints. In that case, the only solution was to use heavy machinery to pull the pipes close enough together to weld them shut. Inspection of piping was often cursory and the backs of the pipes, which were hard to reach, were often ignored. Since the inspections themselves were generally cursory and done by visual checks, it was easy to ignore them. Repair jobs were rushed; no one wanted to be exposed to nuclear radiation longer than necessary.

<snip>

On March 2, nine days before the meltdown, the Nuclear Industrial Safety Agency (NISA) gave TEPCO a warning on its failure to inspect critical pieces of equipment at the plant, which included the recirculation pumps. TEPCO was ordered to make the inspections, perform repairs if needed and give a report to the NISA on June 2. The report is not confirmed to have been filed as of this time.

<snip>

After the Japanese government forced TEPCO to release hundreds of pages of documents relating to the accident in May, Bloomberg reported on May 19 that a radiation alarm went off 1.5 kilometers from the number one reactor on March 11 at 3:29 p.m., minutes before the tsunami reached the plant.

<snip>


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Response to bananas (Reply #7)

Fri Nov 29, 2013, 02:12 PM

8. Except is ISN'T consistent.

IF the earthquake was the modality that cracked the pipes and led to the loss of coolant to the reactor cores, then one would have had a meltdown in the first hour after the earthquake. However, that's NOT what the record shows.

The record shows that the meltdown began over an hour after the quake, a little after the tsunami hit.

PamW

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