[Reactor4] Tepco “There was no hydrogen gas from SFP4”

Still nobody knows what actually happened in reactor4, what caused the explosion.

Nuclear accident investigation committee of the government commented that the hydrogen explosion of reactor4 was caused by both of hydrogen gas from heated SFP4 and reactor3. (cf. Investigation committee “there is a possibility that the earthquake damaged equipment”)

However, Tepco published the report to deny the possibility that hydrogen gas was emitted from SFP4 on 7/24/2012.

Japanese version of the report was not published and they only emphasize that there was enough amount of water in SFP4.

Nothing can be more irrelevant for the criticism of the investigation committee. They pointed out the temperature of the water, not the water level of SFP4.

However, according to the study of JAEA or Tokyo university, when water is so hot that steam air bubble comes up, the amount of hydrogen significantly increased.
Considering the volume of reactor4 building, 13.7m3 of hydrogen gas is enough to make detonating gas.
18.1m3 of hydrogen gas was probably produced within a day from the amount of water in SFP4, which is enough to make detonating gas.
It is therefore rational to think the hydrogen gas from both of reactor3 and SFP4 caused explosion, but quantitative assessment is still impossible.


The report of Tepco’s own shows the water temperature was between 80 ~ 90℃ before the explosion of reactor4.


↓ Tepco’s report published on 7/24/2012.

[Reactor4] Tepco "There was no hydrogen gas from SFP4"


[Reactor4] Tepco "There was no hydrogen gas from SFP4" 2


Source 1 2



About this site

This website updates the latest news about the Fukushima nuclear plant and also archives the past news from 2011. Because it's always updated and added live, articles, categories and the tags are not necessarily fitted in the latest format.
I am the writer of this website. About page remains in 2014. This is because my memory about 311 was clearer than now, 2023, and I think it can have a historical value. Now I'm living in Romania with 3 cats as an independent data scientist.
Actually, nothing has progressed in the plant since 2011. We still don't even know what is going on inside. They must keep cooling the crippled reactors by water, but additionally groundwater keeps flowing into the reactor buildings from the broken parts. This is why highly contaminated water is always produced more than it can circulate. Tepco is planning to officially discharge this water to the Pacific but Tritium is still remaining in it. They dilute this with seawater so that it is legally safe, but scientifically the same amount of radioactive tritium is contained. They say it is safe to discharge, but none of them have drunk it.


July 2012