Hydrogen concentration of reactor 1 has been fluctuating violently since 6/3/2012.
On the daily press conference of 6/4/2012, Tepco explained hydrogen gas is heterogeneous inside of PCV, the indicator captured the mass of high concentration by chance.
(14:40~)
However, it dropped once on 6/9 and it picked up on 6/10 again.
There are 2 indicators for hydrogen concentration, system A and B. Both are in the same trend.
If hydrogen concentration goes over 4% (Oxygen 5%), there is the possibility of hydrogen explosion. Tepco is injecting nitrogen to control the hydrogen concentration.
Iori Mochizuki