Saturday, October 8, 2011

#Fukushima I Nuke Plant Reactor 1 Hydrogen Gas Conundrum

So TEPCO tried to expel hydrogen gas inside the pipe that leads to the Containment Vessel of Reactor 1 yesterday. But the word is that the work is stopped, because the hydrogen gas in the pipe, which initially had dropped to 0.1% concentration with nitrogen gas injection, went back up again after 2 hours, indicating continuous supply from somewhere (like the CV, maybe).

As the pipe is originally for the water spray system not for hydrogen gas or any type of gas, the hydrogen gas seems to permeate, even if the valves are closed off.


From Yomiuri Shinbun (10/8/2011):


TEPCO announced on October 8 that the concentration of the hydrogen gas in the pipe that leads to the Containment Vessel of Reactor 1 at Fukushima I Nuclear Power Plant didn't go down to the intended level of "less than 1%".


Injection of nitrogen gas in the pipe to expel hydrogen gas lowered the concentration of hydrogen gas in the pipe from 63% to less than 0.1%. However, it wet back up to 3.9% in 1 to 2 hours. Hydrogen gas is considered to still remain in the pipe. TEPCO said it will do the nitrogen injection again on October 9.


The company plans to install the "gas management system" that will filter the radioactive materials in the gas inside the Containment Vessel. If the concentration of hydrogen gas is high, it may explode during the installation of the system.

Independent journalist Ryuichi Kino tweeted yesterday that TEPCO either doesn't know (or is not telling) the hydrogen gas concentration, if any, inside the Containment Vessel. The company remain curiously incurious.

The Fuku-1 worker tweeted that he suspects hydrogen gas may be coming from the "torus" (= suppression chamber). He says, as does Kino, that the valves for a water system would not stop hydrogen gas even if they are closed.

TEPCO will repeat the same procedure on October 9, hoping to lower the concentration below 1% so that the pipe can be cut safely to install the gas filtering system. And if hydrogen gas keeps coming through the pipe? TEPCO apparently don't care to know.

To recap, their optimistic diagram of the attempt:


Anonymous said...

Good Lord. Is that their diagram? That it says 'To Outside Vent' instead of, say, contaminant filtration would indicate dumping of radioactive gas out of the CV, up the stack and on to Tokyo or a city hopefully not near you...


Anonymous said...

Correction: outside Exhaust, not vent. They talked about a gas management system, which tend to use compressors. Perhaps translation vagueness, but the symbol used is for a blower.
Still: it does not inspire confidence that they don't include any detail of that in this plan.


arevamirpal::laprimavera said...

The blower is just to blow the gas out. TEPCO hasn't released info on what kind of "gas management system" it is planning.

TEPCO is not very interested in telling anything or knowing anything. Never heard back from them about those ultra-hot spots that measure "over 10 sieverts/hr" - how much over, no one knows.

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