Saturday, August 27, 2011

How Reactor 4 at Fukushima I Nuke Plant "Exploded", According to TEPCO

TEPCO is trying to explain what happened to Reactor 4 at Fukushima I Nuclear Power Plant. The explanation is that hydrogen gas along with radioactive materials from Reactor 3 flowed to the main exhaust stack, which then flowed backwards from the exhaust stack through Reactor 4's Emergency Gas Treatment System into the reactor building of Reactor 4.

To support this hypothesis, TEPCO released this diagram on August 27 press conference, which shows the surface radiation levels of the gas filters. Highest radiation is at the filter closest to the exhaust stack, lowest radiation at the filter closest to the reactor building.

The radiation seems low though, considering the amount of hydrogen it must have taken to render the building in a wreck, and therefore the amount of radioactive materials that came with the hydrogen gas must have been high. TEPCO's Matsumoto's explanation was because the gas from Reactor 3 came through the Suppression Chamber - i.e. wet vent. (Matsumoto's answer is via Ryuichi Kino's tweet; Kino is an independent journalist covering TEPCO from the day one of the crisis.)

Reactors 1 and 3 exploded with explosive sounds that were clearly heard and felt in the nearby towns. But there wasn't any such sound when Reactor 4 supposedly exploded. I say supposedly, because no one seem to know for sure exactly what happened, including TEPCO.

Cabinet Secretary Edano at that time said "explosion" of some sort at Reactor 4 on March 15, but the media report was focused on the mysterious "fire" that was spotted by a TEPCO employee who didn't bother to report to the local fire department (as he should have). The fire died down on its own, but then another fire flared up again the next day.

The initial report on the Reactor 4 incident was that one or two wall panels in the northwest corner of the reactor building were blown out, and there was some damage on the roof. It sounded minor.

Then all of a sudden we were shown the wreckage. One or two wall panels blown out? It was more like "one or two wall panels remaining".

Read my earliest post on Reactor 4, on March 15. No photo was released that day.

Here's what TEPCO has put down in the plant status report (page 16). TEPCO does say "explosion" but that's decidedly not what was reported back then:

  • At approx. 6:00am, March 15, an explosive sound was heard and the damage in the 5th floor roof of Unit 4 reactor building was confirmed. At 9:38am, the fire near the northwest part of 4th floor of Unit 4 reactor building was confirmed. At approx. 11:00am, TEPCO employees confirmed that the fire was extinguished.

  • At approx. 5:45am on March 16, a TEPCO employee discovered a fire at the northwest corner of the reactor building. TEPCO immediately reported this incident to the fire department and the local government andn proceeded with the extinction of fire. At approx. 6:15am, TEPCO employee confirmed at the site that there were no sign of fire.

It's about time we get the much better, and precise picture of what happened in the early days of the crisis, now that we've been better educated since March 11.


Anonymous said...

A little late for them to be coming forward to "re-explain" their theory on how Unit 4 ended up looking like a bomb blast? Perhaps we touched a little nerve yesterday, eh? Just show the video Tepco...we know you have it.

steve the jew said...

"now that we've been better educated since March 11."

lol... the original report on this dump back in the 70's is all that anyone has ever needed.

Anonymous said...

At the time of 11 March, is the fuel in the reactor or in then pool ? Why is the level of Bq so low in pool #4 altough the pool has been so hot for a long time ?

Anonymous said...

Quasi-full translation in french :

Anonymous said...

Heres one interesting angle:


arevamirpal::laprimavera said...

@anon at 5:43AM, fuel rods were in the spent fuel pool in Reactor 4, not in the RPV, at the time of the accident. In normal times, the radioactive materials in the SFP water are ND (not detected) or very close to it. SFP4's water has over 100,000 becquerels/liter of radioactive cesium, that's still pretty hot to me. It's less hot than the other pools for sure.

Anonymous said...

Anyone know where the horizontal piping goes to from the suppression torus in the lower right of asahi's diagram?

arevamirpal::laprimavera said...

@anon at 12:51PM, that line probably goes to the exhaust stack. It looks like a wet well (suppression chamber) vent line. See TEPCO's diagram:

Anonymous said...

I'm not a Nuclear physicist,what sort of hydrogen do they propose could have resulted in a spontaneous criticality and associated power excursion?

Anonymous said...


T he
E vil
P ower
C ontrol
O verlord

pat said...

Hydrogen is very bouyant, i'm sure that is in the flow plans.

besides, once Reactor 3 blew up, it would no way be able to flow Hydrogen into unit 4. it would float away from the torn and shredded unit 3.

Anonymous said...

the author of this sight is now supporting some theory from a psychic from the water department rambling on

Anonymous said...

Hydrogen always shows up in a meltdown, criticality and excursion. It is split out of water in a flash. Zirconium ignites and kabloowee, and that all might happen in seconds with a big steam overpressure shooting the lid off number three way up in the air.
It is obvious that Tepco will keep the site wide open with water pouring on to maintain the prompt criticalities and the radiation pouring off in steam. Evil bastards that I hope meet their judgment day soon as the people assert their demands to bury this site deep underground. Prepare the indictment.

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