Summary:
Regular patrol found that the pump transferring water from the "K" Drainage to the "C" Drainage had stopped. The earth leakage circuit breaker of the generator was in operation and the electrical source was down. As a result, water from the
"K" Drainage was not being diverted to the port and was flowing out to the ocean.
Time and Date of the Incident:
Tuesday, 21 April 2015, problem identified at approximately 8:45 Measures taken since the start of the operation:
Start of operation: Friday, 17 April from 13:33 Three operations a day since the start, at 8:00. 12:00 and 14:30 daily.
20 April 14:30, patrol finds no abnormalities found neither in the transfer pump or the generator.
21 April 8:45, patrol finds that transfer pump has stopped.
Today's survey result:
Attempts were made at the site to restore the earth leakage circuit breaker via the generator and insulation resistance measurement was
taken on the control panel and the pump. Neither showed any irregularities so it was decided that the generator was causing the stoppage.
The generator engine interior as well as the control panel was checked for rainwater and other substance, but none was found. The generator will be brought off site and checked internally.
*As of 8:09 PM on 21 April, the generator was replaced with an emergency generator and pumping and water transfer were re‐started.
Regarding the stoppage of the water pump transfer from the "K"
Drainage to the "C" Drainage at Fukushima Daiichi
Generator Control
panel
Transferring pumps
<Reference>
April 21 2015 Tokyo Electric Power Company
1
Overview of “K” Drainage water discharging pump installation plan (Ahead of rerouting “K” Drainage to discharge inside the port, “K”
Drainage rainwater has been transferred to “C” Drainage (which leads to the port) using the pumps installed as below. (operation started April 17 13:33.)
Drainage K
“C” Drainage
Transfer line Distance: 80m A
(Seaside)
(Plan) A
“C” Drainage
(Seaside)
8 temporary pumps
(Mountain Side)
Bottom plate Transferring line
Groundwater bypass line
Detail
Groundwater bypass line “C” Drainage (Catch basin) Photo①
Horizontal pipe (Photo①)
Pumps (Photo②) Photo②
（A‐A Section） A
Generator
“C” Drainage
[Pump specification]
‐2 6‐inch pumps
Capacity/pump: 0.055m3/sec
‐6 8‐inch pumps
Capacity/pump: 0.075m3/sec
‐Total capacity
6‐inch pumps: 0.055m3/sec×2＝0.11m3/sec 8‐inch pumps: 0.075m3/sec×6＝0.45m3/sec
Total capacity: 0.56m3/sec (Approx. 2000m3/h)
2 North
Regarding the stoppage of the water pump transfer from the "K"
Drainage to the "C" Drainage at Fukushima Daiichi
South embankment
Temporary dyke
Groundwater bypass line Temporary dyke
8 temporary pumps
Transferring line
3
<Reference> Drainage control inside the port (Plan for rerouting “K” Drainage)
Note: the above figure is extracted from the materials for the April 13, 2015 “On‐site adjustment meeting for decommissioning/decontamination water countermeasures
Drainage control is to be performed inside the port by rerouting “K” Drainage into the port within FY2015. (piping route is under examination)
Exit of “K” Drainage is to be joined with the exits of existing “B”
and “C” Drainage
New route for “K” Drainage
New route for “B” & “C”
Drainages (completed) Existing “K” Drainage route
4
<Reference> Drainage layout
Area
“A” Drainage
“A” Drainage
“C” Drainage
“K” Drainage
“K” Drainage
“B” Drainage
“C” Drainage Unit 1 Unit 2 Unit 3 Unit 4
The same point with C‐2‐1
Side gutter drainage radiation monitor Loading dock
drainage
Unit 6 Unit 5
: Major drainage, river : Side ditch, branch pipes
: Manual sampling by TEPCO employee (Before Jan 14, 2015)
: Automatic water sampling (after Jan 19, 2015)
Jinbasawa River
