IRID SAW no fuel or water remaining in reactor core of Reactor 1

Following up this article.. Tepco to start “scanning” inside of Reactor 1 in early February by using muon [URL]


IRID (International Research Institute for Nuclear Decommissioning) and High Energy Accelerator Research Organization announced they could not find a potential part of nuclear fuel in Reactor core of Reactor 1.


On 3/19/2015, they released the prompt report of their “scanning” test implemented until 3/10/2015.

The report tells they could not find anything longer than 1m in reactor core, where originally fuel assemblies were set.

The muon equipment was installed in North of Reactor 1 and also in North-West of Reactor 1. However, neither of them detected a potential fuel assembly.

Also, no water is retained in the reactor core of RPV (Reactor Pressure Vessel). These facts found strongly supports the possibility that the molten fuel has already dropped onto the bottom of Primary Containment Vessel. They did not mention the further possibility that the molten fuel has already gone through the outer wall of the vessel.


About the state of Spent Fuel Pool 1, they did not conclude more than “assuming the fuel remains inside the pool, but the size is not identified”.


IRID SAW no fuel or water remaining in reactor core of Reactor 1


2 IRID SAW no fuel or water remaining in reactor core of Reactor 1




Français :

L’IRID n’a trouvé ni combustible, ni eau dans le cœur du réacteur 1


Article lié : Tepco va commencer à “scanner” l’intérieur du réacteur 1 début février en utilisant la recherche des muons

L’IRID (International Research Institute for Nuclear Decommissioning) et la High Energy Accelerator Research Organization ont annoncé qu’ils n’ont pas pu trouver un quelconque morceau de combustible dans le cœur du réacteur 1.

Le 19 mars 2015, ils ont publié un rapport succinct sur leur essai de “balayage” effectué jusqu’au 10 mars 2015.
Ce rapport dit qu’ils n’ont rien pu trouver de plus long que de 1 m à l’intérieur du coeur du réacteur, là où au départ étaient installés les assemblages de combustible.
L’appareillage à muons avait été positionné au Nord et au Nord-Ouest du réacteur 1. Néanmoins, aucun des deux n’a révélé d’éventuel assemblage de combustible.
En outre, il n’y a pas d’eau restante dans le coeur du réacteur de la RPV (= Reactor Pressure Vessel = enceinte pressurisée du réacteur). Ces faits établis appuient fortement la probabilité que le combustible fondu ait déjà atteint le fond de l’enceinte de confinement primaire (= PCV = Primary Containment Vessel). Ils ne parlent pas de l’éventualité que le combustible fondu soit déjà passé à travers les murs extérieurs des enceintes.

Concernant l’état de la SFP1 (Spent Fuel Pool 1 = piscine des combustible usagés du réacteur 1), ile n’en disent rien de plus que “on suppose que le combustible est toujours dans la piscine mais leur volume n’est pas établi”.

IRID SAW no fuel or water remaining in reactor core of Reactor 1
2 IRID SAW no fuel or water remaining in reactor core of Reactor 1

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.


March 2015