Well number 1-12 experienced an over 50 times increase in radiation this week. The well sits between the unit 1 and unit 2 intakes. This reading is the highest to date for this well. It is currently unclear exactly what is causing the increase since no nearby wells increased before or in conjunction with this one.
There are three possible reasons for this well to increase:
1. The groundwater plume of contamination from unit 1 is now reaching this area. TEPCO groundwater plume mapping assumed the contaminated water released from the unit 1 turbine building would eventually reach this area.
2. The concreting of the unit 2 trench that had been full of highly contaminated water since 2011 has caused leaking contaminated water to divert over to this area. TEPCO said within recent weeks that the portions of this trench that were not yet filled in with concrete were seeing contaminated water re-fill …
Source: Fukushima Sub