Underground structure rapidly heated by up to 40℃ when water reduced

Underground trench water gets rapidly heated when water level decreases, according to Tepco.


On 10/3/2014, Tepco released the report about the failed frozen water wall project. (cf, Tepco to give up the preceding frozen wall and directly fill the trenches with cement instead [URL])

This wall was expected to separate the basement floor of T/B (turbine building) and underground trenches, where extremely highly contaminated water is still retained so they can pump up the retained water from the trenches. If they don’t separate them, coolant water keeps coming from T/B into the trenches even though they pump up the retained water.

In this report, it is stated that water retained in the underground trench got rapidly heated when water level decreased in T/B.


It was the connection part of an underground trench and Reactor 2 T/B. The temperature was measured beside the failed frozen wall.

The rapid increase of temperature was observed a couple of days after the water level decrease. In total, they measured the increase at 5 locations twice.

The largest increase was 40℃ (-30℃→+10℃). The water level of T/B decreased by only 20cm but the water temperature increased by 40℃ from 8/17/2014 to 8/19/2014.

The second largest increase was approx. 35℃.

Tepco assumes it was probably because warm water moved in the underground trench to deny any other hypotheses such as heat is generated by something underground. However, none of the supportive and related data has been published.






Français :

Une structure souterraine qui chauffe rapidement quand l’eau se fait rare …


Selon Tepco, la température des eaux des tranchées souterraines augmente rapidement lorsque le niveau de l’eau diminue.

Le 3 octobre 2014, Tepco avait publié un rapport sur l’échec du mur d’eau congelée. (cf. Tepco abandonne le mur congelé et, à la place, va combler les tranchées avec du ciment)
Ce mur devait séparer le rez-de-chaussée du T/B (bâtiment de la turbine) et les tranchées souterraines qui contiennent toujours des eaux extrêmement radioactives et ceci devait permettre de pomper ces eaus par les tranchées. S’ils n’arrivent pas à les séparer, le liquide de refroidissement continue de s’écouler du T/B vers les tranchées même s’ils pompent.
Dans ce rapport, il est affirmé que les eaux de la tranchée souterraine s’échauffent rapidement lorsque le niveau descend dans le T/B.

C’est dans la partie qui relie une tranchée souterraine et le T/B du réacteur 2. La température a été prise à côté de l’échec de mur congelé.
L’augmentation rapide de la température a été observée deux jours après que le niveau de l’eau ait diminué. Au total, ils ont relevé deux fois l’augmentation en 5 endroits.
La plus grande montée a été de 40 ℃ (-30℃→ +10℃). Le niveau de l’eau du T/B n’avait diminué que de 20 cm et la température de l’eau a augmenté de 40℃ entre le 17 et le 19 août 2014.
Le second record d’écart de température a été d’environ 35 ℃.
Tepco suppose que c’est sans doute parce que des eaux moins froides sont descendues dans la tranchée en niant toute autre possibilité comme une source de chaleur en sous-sol. Néanmoins, aucune donnée n’a été communiquée pour étayer leur hypothèse.


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.


October 2014