Measures for rainwater around the tanks/ contaminated water at Fukushima Daiichi Nuclear Power Station July 24, 2014 Fukushima Daiichi D&D Engineering Company Tokyo Electric Power Company
Outline of measures for rainwater around the tanks / contaminated water Tank leakage early detection [1] Tank patrol (Flanged tank: 4 times/ day Welded tank: twice/ day) [2] Monitoring with tank water level gauge (constant monitoring) Expansion prevention of leakage area of rainwater and contaminated water [3] Rising up the height of dikes [4] Installation of outer dike. (discharge valves are automated controlled.) [5] Prevention of water penetration inside the outer dike. (facing) Suppression of contaminated water flowing out to the ocean [6] Covering up drainage. [7] Installation of radiation monitor to the discharging route. [8] Directing discharging water to inside the port. [9] Installation of a gate at the drainage. Water level gauge Tank Inner dike Outer dike Drainage General discharged water/ rainwater Covering-up Drainage gate Rising 堰のかさ上げ up dike height Facing 電動弁 Motor valve X-ray monitors to drainage Water level gauge To the port South 放水口側へ To South water outlet 1
1. Rising up the height of dike and double diking The rising up the dike height for existing tank areas has been done in order to reduce leakage risk of contaminated water flowing outside the dike. Dikes for the areas of D, G7, J1, J2, J3, J4, and J5, which are currently under construction, are to be built in order in accordance with the installation of tanks. As further measures, coating inside the dike and building outer dike are to be addressed. Also, a pit is added to the dike to make it easier the rainwater remained inside the dike to be discharged, thus, for the outer dike, a drainage pit with motor valve is installed just within. Drainage pit Pump pit Coating works Rising up the dike height Penetration prevention 浸透防止工 works Water stop valve Outer dike Discharge tank Tank Discharge valve for emergency For closed position To outer dike P Outer dike Steel dike Concrete coating Resin coating Concrete dike Concrete dike Penetration prevention (concrete) Pump pit Coating works inside the dike Dike with height rising done Double diking 2
1. Rising up dike height and double diking Works done Double diking works progress control table existing areas (as of July 22) Measures for rainwater(dike ht. 60 cm) Justification of height Outer dike/ penetration prevention Area Dike (inst.) Coating (inst.) Rain gutter (inst.) Inner dike name Installation Coating Outer dike name Installation Coating B North C East B South C West B( Concrete dike) C( Concrete dike) B C E E( Steel dike) E H1 East H1( Steel dike) H1 H2 North H2 South H2( Steel dike) H2 H3 H3( Steel dike) H3 H4 North H4A( Steel dike) H4 East H4 H4 H4B( Steel dike) H5 H5( Steel dike) H5 H6 H6( Steel dike) H6 H8 North H9 H8 South H9 West H8( Steel dike) H9( Steel dike) H8 H9 G3 East G3A( Concrete dike) G3 West G3B( Concrete dike) G3 North G4 North - G4( Concrete dike) G3-G5 G4 South - G5 - G5( Concrete dike) G6 North G6 South G6( Concrete dike) G6 Total 23/23 26/26 26/26 Total 17/17 17/17 Total 13/13 13/13 Countermeasures works have been completed for all tank areas 3
1. Rising up dike height and double diking <Progress Status Map> (as of July 22) 共用プール HTI SPT G4 G3A 開閉所 G5 B Drainage B G6 G7 G3B H3 H4A H2 H4B H6 C ( Ea st) J1 ( 中 ) Legends H1 East J2 ( We st) Inner dike Steel methods H9 D E H5 J4 J3 Concrete methods Outer dike Earth dike/ natural slope Retaining wall H8 J5 Works done (Area where the coating works have been completed for each inner and outer dike) 4
2. Covering up drainage Covering up works of the drainage has been done to prevent contaminated water from flowing into the drainage and letting it out to the ocean directly. (Feb 2, 2014, completed) Double pressed pipe FPR Pipe FRP Cover Drainage C Concrete Cover L=70m Drainage B Water stop gate Manhole Double pressed pipe Water stop gate Image by JAPAN SPACE IMAGING CORPORATION DigitalGlobe Dated Mar 12, 2013, Fukushima Daiichi Nuclear Power station 5
3. Installation of diversion drains and radiation monitors to drainage A diversion drain has been installed to prevent contaminated water, just in case, leaked out of tank flowing into the ocean directly from the drainage. (Of two drains, one was opened on July 14 letting water pass through, and the other is planned to be done in the end of July.) Radiation monitors are installed in order to detect any inflow of radioactive materials into the drainage when abnormal activities are identified with tanks inside the outer dike. (Operation has started from July 14) Water outlets of Units 1 to 4 Diversion 付替排水路 drain X ray monitors Diversion drain Water outlet(temporary drainage) Drainage C Drainage B Drainage C X-ray monitors to drainage Image by JAPAN SPACE IMAGING CORPORATION DigitalGlobe Dated Mar 12, 2013, Fukushima Daiichi Nuclear Power station 6