Tepco started stating molten fuel might be out of pedestal of Reactor 1

Tepco has been stating the molten fuel dropped into pedestal under RPV (Reactor Pressure Vessel), but started changing their tone since the end of 2014 for some reason.

Pedestal is a part of PCV (Primary Containment Vessel) under RPV surrounded by concrete. Tepco and the government of Japan have been saying though molten fuel had a core-concrete reaction in pedestal, but it stopped sinking in the concrete.


In their report published on 3/26/2015, Tepco admits the possibility that molten fuel has reached outside of pedestal at least in Reactor 1.

In this report, they did not mention the possibility that molten fuel went outside of PCV, however if the fuel is already outside of pedestal as suggested, they cannot remove the fuel from the top of RPV.

In order to inspect the potential fuel outside of pedestal, Tepco needs to investigate the subbasement floor of Reactor 1. It is reported that the feasibility of inspection would be confirmed in the end of 2015.








Français :

Tepco commence à dire que du combustible fondu pourrait avoir traversé le piédestal du réacteur 1


Tepco affirmait que le combustible fondu (corium) était tombé et resté sur le piédestal situé sous la RPV (Reactor Pressure Vessel = enceinte pressurisée) mais fin 2014 ils ont commencé à changer leur chanson.

Le piédestal fait partie de la PCV (Primary Containment Vessel = enceinte de confinement primaire), sous la RPV entourée de béton. Tepco et le gouvernement japonais affirmaient que bien que le combustible fondu ait réagi avec le béton du piédestal, il avait arrêté de s’y enfoncer.

Dans leur rapport publié le 26 mars 2015, Tepco reconnaît qu’au moins pour le réacteur 1, il est possible que le corium ait traversé le piédestal.
Ils n’évoquent pas de possibilité que le corium soit sorti de la PCV dans ce rapport, néanmoins si, comme ils le supposent, il a déjà dépassé le piédestal, ils ne pourront jamais retirer de combustible par le haut de la RPV.
Tepco doit inspecter les fondations du réacteur 1 pour pouvoir établir si le corium a traversé le piédestal. Ils disent que la faisabilité d’une telle inspection pourra être établie pour fin 2015.


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.


April 2015