SOURCE: Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant, Stohl, A., Seibert, P., Wotawa, G., Arnold, D., Burkhart, J. F., Eckhardt, S., Tapia, C., Vargas, A., and Yasunari, T. J., October 20, 2011
“Fortunately, due to the maintenance outage and the survival of one diesel generator, it seems that unit 5 reactor cores as well as spent fuel ponds have not suffered major fuel damage,” says the study.
Though, Reactor No. 5 is mentioned again several pages later:
“Total a posteriori [experienced levels] 133Xe emissions are 16.7 EBq, one third more than the a priori value [predicted levels] of 12.6 EBq (which is equal to the estimated inventory) and 2.5 times the estimated Chernobyl source term of 6.5 EBq.”
If there was only 12.6 EBq of xenon-133 inventory that could be emitted from reactors 1-3 and spent fuel pool No. 4 — yet 16.7 EBq was experienced — where did the extra xenon come from, according to the study?
- “There is the possibility of additional releases from unit 5.”
- Another possibility is that recriticality has occurred in one of the reactor units.
The study says the a priori emissions could have been overestimated, but discounts the notion that the initial 12.6 EBq figure so poorly underestimated the amount of xenon in Reactors 1-3 and SFP 4, “It is unlikely that the 133Xe inventories of the reactor units 1–3 were one third higher than estimated.”
Published: October 28th, 2011 at 11:25 am ET