1. Hokuriku Electric Power Company Dose Reduction Measures at Shika Nuclear Power Station Unit-1 Takahashi Toshihiko Hokuriku Electric Power Company

2. Location of Shika NPP Toky o Hamao ka

3. Hokuriku Electric Power Company Major Specification of Shika Unit-1&2 Shika Unit-1Shika Unit-2 Commercial operation July 1993March 2006(Plan) Reactor type BWR5ABWR Electric power 540MW1358MW Condensate polishing system hollow fiber filter ＋ demineralizer hollow fiber filter ＋ demineralizer RWCU flow rate 64t/h154t/h (2% of feed-water flow rate)

4. Hokuriku Electric Power Company Dose reduction measures on design and construction stage Improvement of the procedures of work Automatic or remote system Automatic equipment for In Service Inspection Automatic machine for CRD replacement Automatic decontamination machine for reactor well Improvement of the environment of the work field Reduction of corrosion product Use of materials with low-cobalt content Dual Condensate polishing system Oxygen injection into the feed-water system Reinforcement of shielding Shielding of PLR piping Shielding of high radiation rate piping

5. Hokuriku Electric Power Company Corrosion Resistant Steel Dual Condensate Polishing System Oxygen Injection Alternative Material for Stellite Low Cobalt Containing Materials Co ≦ 0.05% Reactor Pressure VesselHigh Pressure Turbine Low Pressure Turbine Condenser Generator Hollow Fiber Prefilter Demine- ralizer High Pressure Heater Reactor Waler Cleanup System Corrosion Resistant Steel Iron Crud Reduction Procedures Cobalt Reduction Procedures Low Cobalt Containing Materials Co ≦ 0.05% Fe/Ni Ratio Control with Iron Injection Low Pressure Heater Measures for reducing corrosion product in Shika unit 1

6. Hokuriku Electric Power Company The Systematic approach to dose reduction of each work （ PDCA cycle ） Mentioning the measures in manuals Radiation control during the work Confirming the effect of measures Planning the dose reduction measures for each work

7. Hokuriku Electric Power Company temporary shielding minimizing the drainage range Dose rediction measures on operation stage securing the distance between source and working area preventing the thoughtless access to source shortening the work time by mock-up control the work time Shield Time Source removal Chemical decontamination RHR low temperature shutdown cooling operation Distance

8. Hokuriku Electric Power Company Sv Weld line crack check of PLR piping Partial replacement of PLR piping Collective Dose of Plant Outage at Shika Unit-1 Collective dose(man/Sv) regular work Special work The inspection of PLR pump&valves Plant outage 1 st 2 nd 3 rd 4 th 5 th 6 th 7 th 8 th 9 th Chemical decontamination

9. Hokuriku Electric Power Company :extent of decontamination RHR F017A PLR F002A PLR F001A PLR(A) ● ● ● ●● ● Ａ Ｂ Ｃ Ｄ Ｅ Ｆ ●● ＧＨ :extent of decontamination RHR F017B PLR(B) PLR F002B CUW F001 RHR F010B RHR F010A PLR F001B ● ● ● ●● ● Ａ Ｂ Ｃ Ｄ Ｅ Ｆ ●● ＧＨ The result of 8th outage Chemical decontamination Chemical decontamination

10. Hokuriku Electric Power Company Results of Chemical Decontamination (example of EL.6260) EL.6260 PLR(A) PLR(B) PLR(A) PLR(B) PLR(A) PLR(B) PLR(A) PLR(B) Before Decon. After Decon. 4th outage PLR(A) 5th outage PLR(B) Chemical decontamination

11. Hokuriku Electric Power Company The results of chemical decontamination of PLR piping outage Dose reduction (calculated) work 4th 0.8man/Sv ・ The inspection of PLR pump(B)&valves 5th 0.95man/S v ・ The inspection of PLR pump(B)&valves 8th 3.99man/S v ・ Weld line crack check of PLR piping ･ Partial replacement ofPLR pipes Chemical decontamination

12. Hokuriku Electric Power Company Co-60 deposition on PLR piping with decontamination Chemical decontamination

13. Hokuriku Electric Power Company RHR low temperature shut down cooling operation 50 100 150 200 250 300 350 -50510152025303540 Passed time after reducing reactor pressure （ h ） Reactor Water temp. （℃） Past shutdown cooling Start of reducing pressure op. RHR preparation start Operation start of RHR SHC(150 ℃ ) Past SHC LT-SHC :Period of reactor cooling by condenser ： Period of reactor cooling by RHR RHR preparation Low temperature shutdown cooling RHR LT-SHC ( ≦ 110 ℃ ) start

14. Hokuriku Electric Power Company Radioactivity deposition on RHR piping during shutdown cooling shutdown cooling start temperature