Still 960,000Bq Cs-134/137 and 2,336,000,000Bq noble gas discharged from reactors to the air every single hour

On 5/25/2015, Tepco reported still 960,000 Bq / hour of Cesium-134 and 137 is assumed to be discharged from Reactor 1 -4 to the air this April.

This is 2.7 times much as their provisional figure published in the end of April.

Tepco states the difference is caused by the change of calculation method. It strongly suggests the entire historical discharged volume of Cs-134/137 has been underestimated since 311 however they did not disclose the recalculated discharged volume before April of 2014.

Comparing to May of 2014, the discharged volume of Cs-134/137 increased to 180% this April. Tepco however states this is lower than 10% of the set point of “discharge control”, and they haven’t made any explanation on this increase.

Especially in Reactor 3, the discharged volume increased 78 times much as May. 2014. Also, 95,000 Bq / hour of Cs-134/137 is discharged from Reactor 4 building though it does not contain nuclear fuel.


Regarding noble gas (such as Kr-85), PCV (Primary Containment Vessel)  gas control system detected 2,336,000,000 Bq of gas discharged from Reactor 1-3 every hour this April. Tepco states noble gas passes by as radioactive cloud to cause only external exposure so the exposure dose caused by the discharged noble gas should be significantly small.





Français :

Par heure, on a toujours 960 000 Bq de Cs 134/137 et 2,336 millions Bq de gaz rares émis dans l’atmosphère


Le 25 mai 2015, Tepco a rapporté que pour avril dernier ils estiment que 960 000 Bq/heure de césium 134 et 137 s’échappent toujours des réacteurs 1 à 4 dans l’atmosphère.
C’est 2,7 fois plus que leur estimation préliminaire publiée fin avril.

Tepco affirme que la différence s’explique par leur changement de méthode de calcul. Ça laisse fortement penser que la totalité du volume de Cs 134-137 dispersé depuis le début est sous-estimée depuis le 11-3. Ils n’ont pas publié le re-calcul de ce volume pour avant avril 2014.
Comparé à mai 2014, le volume de Cs 134/137 dispersé a augmenté de 180 % en avril dernier. Tepco affirme cependant que ça reste 10 % en dessous du niveau de “contrôle de dispersion” et ils ne donne aucune explication à cette augmentation.
Pour le réacteur 3 en particulier, le volume dispersé est 78 fois celui de mai 2014. En outre, 95 000 Bq / heure de Cs 134/137 se répand depuis le bâtiment du réacteur 4 bien qu’il ne contienne aucun combustible nucléaire.

Concernant les gaz rares (comme le Kr 85), le système de contrôle des gaz de la PCV (Primary Containment Vessel = enceinte de confinement primaire) a relevé 2 336 000 000 Bq de gaz dispersés à l’heure depuis avril à partir des réacteurs 1 à 3. Tepco affirment que les gaz rares s’échappent en nuages radioactifs qui ne provoquent que des expositions externes, donc que la dose d’exposition due à ces gaz rares libérés devrait être vraiment faible.

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.


June 2015