Sunday, April 10, 2011

#Fukushima I Nuke Plant: TEPCO Says Reactor 1's Pressure Not Rising Enough After Nitrogen Injection

Uh oh.. Nigrogen and radioactive steams escaping from the Containment Vessel (which they call "Primary Containment"; "Secondary Containment" being the building itself, which is already badly damaged in the case of the Reactor 1).

From Yomiuri Shinbun (1:37PM JST 4/11/2011):


TEPCO announced today that the pressure of the Containment Vessel of the Reactor 1 at Fukushima I Nuclear Power Plant has stopped rising above 1.95 atmospheric pressure; TEPCO has been injecting nitrogen in order to prevent a hydrogen explosion. TEPCO thinks that a significant amount of radioactive steam and nitrogen is escaping the Containment Vessel and into the surrounding area.


TEPCO has been injecting 28 cubic meters of nitrogen per hour since early hours of April 7. The pressure inside the Containment Vessel rose gradually from 1.56 atmospheric pressure on April 7 to 1.9 atmospheric pressure on April 9, but the pressure stopped rising at 1.95 atmospheric pressure on April 10.


About 1,000 cubic meters of steam and nitrogen may have been escaped, but there has been no significant change in radiation levels around the Plant.


The plan was to inject 6,000 cubic meters of nitrogen into the Reactor 1's Containment Vessel over 6 days, and raise the pressure from 1.5 atmospheric pressure to 2.5 atmospheric pressure. TEPCO thinks "the containment vessel's seal is compromised, and significant amount [of steam and nitrogen] is escaping." TEPCO will continue to inject nitrogen while trying to figure out what to do in order to avoid a hydrogen explosion.

The US's NRC didn't think the Containment Vessel of the Reactor 1 was broken, but that was March 26.

Earlier today, I was watching the separate press conferences of Nuclear and Industrial Safety Agency and TEPCO (which they did it roughly at the same time). What was interesting was a "doom and gloom" among the Internet audience of these press conferences that were presented live by independent journalists (yes there are such people now in Japan). Many of them were saying (tweeting) that there was something amiss in both press conferences, as if some huge SHTF event was coming soon.


Anonymous said...

Well, seeing as there's a meltdown underway in reactor 1 (as per the extremely high radiation level in drywell) and

it's not hard to guess what's next.

M. Simon said...

The containment vessel could be intact and still leak.

So "containment vessel intact" is commensurate with "containment failure". Very nuanced no doubt. And open to misinterpretation (which could be the intent).

netudiant said...

Steam would efficiently mobilize cesium iodide, the most dangerous contaminant produced by this disaster.
The result would be extensive pollution of the surrounding area.
There are rumors that NISA is considering raising this accident to the INES 7 level, just like Chernobyl.
Has Tokyo written off Fukushima prefecture?

arevamirpal::laprimavera said...

@Anonymous, checking who David Weaver is that Bloomberg has sited often since the accident. He doesn't seem to be the professor - he's listed as "honorary staff" at the school. Just curious.

@M.Simon, "nuanced" is an understatement. TEPCO's official plant status reports that they release once or twice a day says of the hydrogen explosions as "big sound and then white smoke was observed" for all reactors.

M. Simon said...

From anon's link:

There was no damage to the Fukushima Dai-Ichi plant from today’s earthquake and the one on April 7,” Junichi Matsumoto, general manager of the company’s nuclear power and plant fitting division, said in Tokyo today.

Translation: "the rubble bounced".

If this wasn't messing up so many lives it would be hilarious.

arevamirpal::laprimavera said...

@Simon, if the power goes off on the nuke plant on a whimpy earthquake like that, there's something very wrong with the picture.

What did you mean by "The containment vessel could be intact and still leak"?

@netudiant, they are yet to admit Level 6, but just to spite the Americans and French and Russians who are saying Level 6, they may say Level 7. LOL. It's pathetic.

Anonymous said...

God these guys really suck at math or they are just really hopeful, 28 cubic meters per hour x 24 hours = 672 cubic meters per day x 6 days = 4032 cubic meters not 6000. If nitrogen is leaking out then so is any hydrogen that is being generated because it is way lighter. I think they are freaked because the air we breath is 78% nitrogen and it can support explosions. I doubt their leaky attempt at a nitrogen purge has brought the nitrogen volume too much above normal atmospheric levels.

Oh, and I just heard on NHK that Fukushima is now officially an INES 7 accident.

M. Simon said...


A broken seal. Think of an old style mason jar with a thick rubber seal. The rubber could deteriorate. The jar and lid and closure ring (threaded) could be intact and yet the mason jar would leak.

Of course in this case the seal is metal. (usually some soft metal like copper) Such a situation would explain why #1 can hold some pressure. When the pressure gets high enough there is an equilibrium between inflow and outflow.

If it is a seal near the top of the vessel the vessel could hold enough water to keep the rods covered. If it is a bottom seal the rods will be uncovered. I'd bet on the worst given what I have read so far. A bottom seal.

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