Molten fuel might be out of concrete base to directly damage primary containment vessel of Reactor 1

Photo : Reactor 1 taken on 4/15/2011



Molten fuel might be already outside of the concrete base and damaging the vulnerable part of PCV (Primary Containment Vessel) in Reactor 1.

On 9/10/2014, IRID (International Research Institute for Nuclear Decommissioning) announced it in the meeting of Atomic Energy Society of Japan.


They have admitted the fuel has melted through RPV (Reactor Pressure Vessel) and dropped onto the concrete part inside of PCV, which is called “melt through”. However they haven’t stated the molten fuel has directly touched the wall of PCV to be potentially exposed to the environment.


In this latest report, IRID admitted the possibility that the molten fuel reached where the concrete base is not protecting the vulnerable pipes and directly damaging PCV.


They commented Reactor 2 and 3 are less likely to be in the same situation, but didn’t deny the possibility.



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Français :

Le corium pourrait avoir traversé l’embase en béton et endommagé directement l’enceinte principale de confinement du réacteur 1


Photo : le réacteur 1 au 15 avril 2011

Le combustible fondu pourrait être déjà sorti de l’embase en béton et être en train d’attaquer la partie vulnérable de la PCV (Primary Containment Vessel = Enceinte de Confinement Principale) du réacteur 1.

Le 10 septembre 2014, L’IRID (International Research Institute for Nuclear Decommissioning) a déclaré au cours d’une réunion de la Atomic Energy Society of Japan.

Ils ont reconnu que le combustible avait fondu et traversé la RPV (Reactor Pressure Vessel = Enceinte de confinement primaire pressurisée) et qu’il s’était écoulé sur la base en béton de la PCV, chose qualifiée de “melt through”. Néanmoins, ils n’ont pas affirmé que le combustible fondu était entré directement en contact avec les murs de la PCV et qu’il pourrait les avoir transpercés.

Dans son dernier rapport, l’IRID a reconnu qu’il était possible que le corium ait atteint l’endroit où l’embase en béton ne protège pas la tuyauterie vulnérable et  qu’il ait endommagé la PCV elle-même.

Ils ont déclaré que les réacteurs 2 et 3 risquaient moins d’être dans une situation analogue mais ils n’en nient pas la possibilité.

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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.


September 2014