1. 1 TEPCO’s Challenges for Occupational Exposure Reduction -Installation of Additional CF in Fukushima Daiichi NPP- Shunsuke HORI, Akira SUZUKI Tokyo Electric Power Company Nuclear Power Plant Management Department Radiation Protection Group ISOE International ALARA Symposium September 8-9, 2009, Aomori, JAPAN

2. 2 Profile - Location Electricity sales by the 10 electric utilities

3. 3 TEPCO’s Nuclear Power Plants 17 BWRs including 2 ABWRs (total capacity 17,308MWe) - 27% of generation capacity (FY 2008) Kashiwazaki-Kariwa NPP Fukushima-Daini NPP Fukushima-Daiichi NPP NPP

4. 4 Contents Occupational Exposure in NPP Measures for Reduction of Collective Dose Quality of Feed Water after Installation of Additional CF in Fukushima Daiichi Unit 6 Collective Dose Estimation Secondary Effects by Reduction of CRUD Conclusions

5. 5 Occupational Exposure in NPP (1/2) Collective Dose per Reactor in Nuclear Power Station (BWR) (2006 to 2008 Average)

6. 6 Occupational Exposure in NPP (2/2) Annual Collective Dose Trend per Plant in Japan

7. 7 Measures for Reduction of Collective Dose(1/4) Measures for Reduction of Collective Dose in PCV Improvement of （Ⅰ） Material （Ⅱ） Equipment or System （Ⅲ） Operation Radiation Level Reduction Reduction of Activated Corrosion Products Removal of Activated Corrosion Products Control of Activated Corrosion Products Attachment Optimization of Shield Control / Removal of CRUD Mechanical Decontamination ( Ⅲ ) Chemical Decontamination ( Ⅲ ) Electrochemical Polishing ( Ⅰ ) Pre-filming ( Ⅰ ) Ni/Fe Control ( Ⅲ ) Zinc Injection ( Ⅲ ) Temporary Shield ( Ⅲ ) Permanent Shield ( Ⅱ ) Change in Piping Design(Geometry / Location) ( Ⅱ ) Temperature- Controlled Shutdown( Ⅲ ) CF Volume Increase( Ⅱ ) Use of Low Cobalt Material( Ⅰ ) Use of Corrosion- Resistant Material ( Ⅰ ) Optimized use of CF,C/D and CUW( Ⅲ ) Oxygen Injection( Ⅱ )

8. 8 Measures for Reduction of Collective Dose(2/4) Reactor Primary System （ BWR ） PLR RWCU Main Steam Line Feed Water Moisture Separator Sea Water Condensate Polisher System Heater Feed Water Pump Condenser LP-Turbine HP-Turbine Generator Oxygen Injection

9. 9 Annual Dose per Reactor (person-Sv) Fiscal Year ① Oxygen injection ② Use of low-cobalt material ③ Use of weatherproof steel in component materials for feed water and condensate ④ Control of feed water iron ⑤ CF installation ① ② ③ ④ ⑤ Measures for Reduction of Collective Dose(3/4) Results of Dose Reduction Measures

10. 10 Measures for Reduction of Collective Dose(4/4) CF(Condensate Pre-Filter) in Japan (BWR)

11. 11 Quality of Feed Water Feed Water Iron Concentration Trend after CF Installation (Fukushima Daiichi Unit 6)

12. 12 Collective Dose Estimation Collective Dose Estimation after additional CF Installation (Fukushima Daiichi Unit 6)

13. 13 Secondary Effects by Reduction of CRUD ObjectEffectCost Saving Object Jet Pump Efficiency Improvement Electricity Cost Less Frequency of Cleaning Cleaning Cost C/D Resin Life Extension Replacement Cost Decommissioning Cost Less Frequency of ・ Backwashing ・ Regeneration Water Treatment Cost Chemical Treatment Cost Shutdown Faster Drop in Temperature High Operating Ratio

14. 14 Conclusions We have successfully reduced the concentration of feed water iron in Fukushima Daiichi Unit 6 by the installation of additional CF. We’ll continue to try to reduce occupational exposures by every possible measures after cost performance evaluations.

15. 15 Support Documentation(1/5) LPCP-out Iron Concentration Trend after CF Volume Increase (Fukushima Daiichi Unit 6)

16. 16 Support Documentation(2/5) ppb as Fe Oxygen-injection installation Cycle The concentration of the insoluble iron in the feedwater. Injecting Oxygen Into the Feed Water System (Fukushima Daiichi Unit 1) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

17. 17 Support Documentation(3/5) Cycle Change to low-cobalt material Heating pipes of feedwater heaters Bq/cm 3 as Co-60 The concentration of Co-60 in the reactor water. Use of Low Cobalt Material (Fukushima Daiichi Unit 1)

18. 18 Support Documentation(4/5) Use of weatherproof steel ppb as Fe Cycle The concentration of the insoluble iron in the condensate water Application of weatherproof steel

19. 19 Support Documentation(5/5) Cycle HFF installation ppb as Fe The concentration of the insoluble iron in the condensate water Duplication of condensate purification system (Fukushima Daiichi Unit 1)

20. 20

21. 21 Measures for Reduction of Collective Dose(2/4) H/W LPCP HPCPC/D CF FW Hx FWP Tb Reactor Primary System （ BWR ） CUW RPV