(UPDATE 7/25/2013) Just as back then, TEPCO now says the current steam may be from the Containment Vessel after all, at least in part. See my latest post.
So that steam back then was actually coming from inside the Containment Vessel???
In the regular press conference on July 24, 2013, TEPCO's spokesman said the steam coming out of Reactor 3 in March 2011 after the explosion was from inside the Containment Vessel, and that is known to everybody.
11 minutes 39 seconds into his briefing (video is at TEPCO's site but only for one week), TEPCO's PR manager Ono says,
As you all know, speaking about the area near the shield plug of Reactor 3, it was around this area where the steam was coming from inside the reactor's Containment Vessel right after the accident [explosion of Reactor 3 on March 14, 2011]. We think the current high radiation levels observed around, near the shield plug, are probably due to the effect of that steam.
"As you all know"??? Since when?
As far as I remember, the explosion of the Reactor 3 building is explained by TEPCO as hydrogen explosion (initially some TEPCO workers, including Plant Manager Masao Yoshida, thought it was a steam explosion), but the company never explained where the steam seen rising from the wreckage of the Reactor 3 operating floor after the explosion was coming from.
Now, according to TEPCO, everyone is supposed to know, as a matter of fact after two years and four months later, that the steam in March 2011 was coming from inside the Containment Vessel.
I watched the Q&A section of the press conference, but no one seemed to be bothered by Ono's remark. Was it just me who didn't know about it as the established fact? I had suspected as much from the beginning, but didn't know that's now an accepted fact.
How and what did I miss? I searched my own blog for Reactor 3's posts from the beginning, and the closest reference I found was that the steam looked to be rising from near the Containment Vessel.
Well, on further research on the net, what I seem to have missed was the morning press conference on March 16, 2011 by then-Chief Cabinet Secretary Yukio Edano (link is in Japanese, Asahi Shinbun). He said, about the steam that started to vigorously rise from Reactor 3 around 8:30AM that day and the sharp rise in radiation levels at the plant after 10AM,
We are having experts analyze the situation, but at this point, the highest possibility, not confirmed yet, but the highest possibility seems to be that the steam is being released from some part of the Containment Vessel, just like it happened in Reactor 2. Since it is radioactive steam that was inside the Containment Vessel, high levels of radiation were observed temporarily. Let me repeat that it is not yet confirmed, but that is the most likely scenario at this point.
(Wait a minute. Just like it happened in Reactor 2???)
In the afternoon press conference at 6PM on March 16, 2011 (link is in Japanese, Asahi Shinbun), Edano somewhat backed off and said he had heard the steam might be from the suppression chamber (it is still part of the Containment Vessel, I suppose, but below the 1st floor). NISA thought the rise in radiation levels at the plant in the morning of March 16, 2011 was because of Reactor 2, not Reactor 3.
Mr. Edano talked about it as the hypothesis, that the steam rising from Reactor 3 after the March 14, 2011 explosion was from the Containment Vessel, and that was 2 years and 4 months ago. I do not think (I may be wrong) anyone paid attention to this particular remark or followed up on it.
But now, according to TEPCO, that's what everyone should know, that the steam seen rising from the Reactor 3 wreckage in March 2011 was from the Containment Vessel.