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Asahi: Fukushima chief Yoshida felt “explosion occurred in the containment vessel” at Reactor No. 2 — Yet none of 4 special investigations have explained why it will only hold 2 feet of water

Published: May 1st, 2012 at 6:12 am ET
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Title: Investigations into Fukushima accident disagree on key points
Source: Asahi AJW
Author: Naoya Kon and Takashi Sugimoto
Date: May 01, 2012
Emphasis Added

Despite investigations by four special committees [Gov't, Diet, Tepco, private sector], key questions remain about the crisis at the Fukushima No. 1 nuclear power plant [...]

WHAT HAPPENED AT THE NO. 2 REACTOR?

One point that none of the investigative committees has uncovered is the extent of damage to the No. 2 reactor.

At a little after 6 a.m. on March 15, a number of workers at the Fukushima No. 1 plant heard the sound of a large impact.

At 6:18 a.m., during a teleconference with TEPCO headquarters, a plant official said that the sound might have been caused by the bottom of the suppression chamber of the No. 2 reactor falling. [See also: NHK: Suppression chamber "may have been destroyed" at Reactor No. 2 (VIDEO)

At 6:50 a.m., a radiation level of 583 microsieverts per hour was recorded at the main gate to the plant about one kilometer from the No. 2 reactor building. That reading was about eight times the level recorded an hour earlier. At 9 a.m., a radiation level of 11,930 microsieverts was recorded, the highest for the entire accident.

The government panel report said, “(Fukushima plant chief) Yoshida felt some sort of explosion occurred in the containment vessel based on information received that a large impact was heard as well as information that the pressure in the suppression chamber of the No. 2 reactor was zero.” [...]

The extent of damage to the containment vessel of the No. 2 reactor is unknown. Once that becomes clear it could be possible to point to the No. 2 reactor as the cause of the high radiation levels. [...]

‘Investigations’ Claim No Explosion

However, the TEPCO panel included an analysis of readings from seismographs at the Fukushima No. 1 plant. There were no observations of shaking caused by an explosion between 6 a.m. and 6:10 a.m. when the sound of an impact was heard at the No. 2 reactor. Shaking was recorded at 6:12 a.m. when an explosion likely occurred at the No. 4 reactor, according to the TEPCO panel.

The government panel also said the impact sound was likely caused by the explosion at the No. 4 reactor. The private-sector panel also rejected the notion that an explosion occurred at the No. 2 reactor.

The panels also could not explain what caused the high radiation levels.

Unexplained Damage

TEPCO used an industrial endoscope on March 26 to check the interior of the reactor. The water level was only about 60 centimeters from the bottom of the containment vessel, much lower than estimated. Water pumped into the reactor more than likely has leaked from damaged parts of the core. However, none of the panels have yet explained how that damage occurred.

Read the report here

More: New Analysis: Large amount of radioactive materials had discharged through breach in primary containment at Reactor No. 2

Published: May 1st, 2012 at 6:12 am ET
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  2. AP: “Hardly any cooling water inside one of the reactors” — Water level only 6% of estimate — Radiation at 10 times fatal dose March 27, 2012
  3. NHK: Water level “far lower than previously thought” at Reactor No. 2 — Just two feet deep — Anticipated it was 5 times higher — Decommissioning reactor could be “much more difficult” (PHOTO) March 26, 2012
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  5. Dr. Koide: Massive amounts of radioactivity may again be released from Fukushima — Mentions “steam explosion” after melted fuel hits water September 9, 2011
May 1st, 2012 | Category: Reactor No. 2
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32 comments to Asahi: Fukushima chief Yoshida felt “explosion occurred in the containment vessel” at Reactor No. 2 — Yet none of 4 special investigations have explained why it will only hold 2 feet of water

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