Fukushima Daiichi NPS Prompt Report 2013

This is a follow-up report on the statuses of a water droplet found at the batch treatment tank 2A of multi-nuclide removal equipment.

The results of surface contamination measurement utilizing smear filter paper and radiation dose measurement performed on the surface of the tank and on the floor are as follows.

[Surface contamination measurement utilizing smear filter paper]
- Surface of the batch treatment tank (near the welding line discolored): 7,900cpm
- Surface of the batch treatment tank (near the welding line not discolored): 700cpm
- Leaked water receiving pan under the tank (trace of discolored water): 4,300cpm
- Leaked water receiving pan under the tank (a part not discolored): 1,300cpm
(Reference) Background: 180cpm

*cpm: Radiation counts per minute

[Radiation dose measurement]
- Surface of the batch treatment tank (near the welding line discolored): Surface radiation dose
γ ray: 0.09mSv/h
β ray + γ ray: 0.18mSv/h

- Surface of the batch treatment tank (near the welding line not discolored): Surface radiation dose
γ ray: 0.08mSv/h
β ray + γ ray: 0.11mSv/h

- Leaked water receiving pan under the tank (trace of discolored water): Surface radiation dose
γ ray: 0.04mSv/h
β ray + γ ray: 0.04mSv/h

- Leaked water receiving pan under the tank (a part not discolored): Radiation dose in the atmosphere
γ ray: 0.05mSv/h
β ray + γ ray: 0.06mSv/h

According to the above results, there is a possibility of concentrated saltwater leaking from welded part of the tank since the amount detected at discolored part near the welding line of the tank surface and leaked water receiving pan is higher than those detected at the part which is not discolored.
Detailed investigation will be performed from tomorrow.

In addition, stop operation of multi-nuclide removal equipment A system has started at 6:17 PM today (June 16). Suspension of the equipment will take approx. 6 hours to complete.