” According to Tepco, highly contaminated water leaked from a water storage tank on 6/26/2016.
All β nuclides density is reportedly 96,000,000 Bq/m3. Cs-134/137 density is also 700,000 Bq/m3.
Tepco states the leaked volume was 72 L. Based on their announcement, at least 6,912,000 Bq of all β nuclides leaked to contain Sr-90.
Tepco says no contaminated water spread to the outside of the tank area.
The type of this tank has unwelded joint parts, which is vulnerable for leakage.
The life of these tanks was reported to be 5 years but in 2013 Tepco admitted it has no basis.
These tanks are not bearable for the contaminated water but these are still in use. ”
by Iori Mochizuki
source with French translation and TEPCO press release links