Over 1% of hydrogen was found in 2 parts of the pipe in reactor 1.
In order to take off the radioactive gas from container vessel,Tepco was planning to cut off the pipes connected to the container vessel.
In the process,near the pipes which they were planning to cut off on the first floor of the plant 1,they detected over 10,000ppm of hydrogen at 2 places.
Tepco announce that hydrogen explosion can happen only when 4% of hydrogen and 5% of oxygen are mixed together,so there is least explosion risk now.
(WHO DOES TRUST THEM ANY LONGER ?)
However,they are injecting nitrogen to reduce hydrogen for now.
They have not checked if there is hydrogen left in reacor 2 and 3 yet.
“Expert”,Okamoto from Tokyo university suggests 3 possibilities.
1.The gas that caused the hydrogen explosion in March still remained there.
2.Water in the reactor produced hydrogen because of radiation.
3.Both.
They are still injecting nitrogen,but there may be hydrogen left in other places still.
http://www3.nhk.or.jp/news/html/20110923/t10015807331000.html
http://news.goo.ne.jp/article/yomiuri/nation/20110923-567-OYT1T00340.html