During the endoscope operation of 3/26/2012, Tepco measured the radiation level of inside of container vessel. Tepco published the data the next day, 3/27/2012.
It was measured at 8 points, 50~100cm away from the wall.
The highest reading was 73Sv/h.(100,000 times higher than the radiation level of the container vessel in periodic checkup) Other readings were 31.1~57.4 Sv/h.
In this level of radiation, human starts vomiting within a minute and dies within 8 minutes. It is impossible to have human work inside of container vessel.
Actually, Tepco did not intend to watch the fuel debris in this endoscope operation. Tepco is assuming that the fuel is in pedestal, which is separated from where they checked with endoscope this time with concrete wall. (Like this picture below.)
To see where Tepco assumes the fuel debris is, they have to put the camera under the pressure vessel, surrounded by the concrete of pedestal. About this potential attempt, actual Fukushima worker Happy11311 tweeted like this below.
ただいまっ(^O^)2号機格納容器内の線量はMax73Sv/hってオイラが思ってたより低かったでし。とは言え、人間が近付ける線量ではないけど…。多分ﾍﾟﾃﾞｽﾀﾙの中や入口は1000Sv/h以上あるはずだから今回使った線量計じゃスケールオーバーで測定できないでし。
— ハッピー (@Happy11311) March 27, 2012
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The highest reading of 73 Sv/h was lower than I thought, but no one can get close to there. Probably it is higher than 1000Sv/h inside or in front of the entrance of the pedestal. The endoscope used this time can’t resist the radiation of higher than 1000Sv/h so it would be over scale.
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続き1:まだ燃料ﾃﾞﾌﾞﾘは確認出来てないけど今回の調査ではっきりしたの事は東電が計画している格納容器内を水で満たすには相当な時間を要するか、無理だろうって事。あと中長期工程で10年後に燃料取出着手って言ってるけど、それも無理で何年後になるかわからなくなった事でし。
— ハッピー (@Happy11311) March 27, 2012
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The fuel debris has not been checked yet, but this operation made it clear that it would take considerable amount of time to fill container vessel with water as Tepco is planning, or it would be simply impossible. and they are planning to take out the fuel in 10 years but it would take way more than 10 years. I don’t know how long it takes.
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Iori Mochizuki