1. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 1 Progress of the Zinc Injection in Tsuruga NPP Unit 2 October 12, 2006 THE JAPAN ATOMIC POWER COMPANY Nobuaki NAGATA, Hideaki ICHIGE, Eiichi KADOI HOKKAIDO ELECTRIC POWER CO., INC. Yoshifumi WATANABE THE KANSAI ELECTRIC POWER CO., INC. Hideya IKOMA SHIKOKU ELECTRIC POWER CO., INC. Tsuyoshi SEMBA SHIKOKU RESEARCH INSTITUTE INC. Toshiaki HAMAGUCHI

2. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 2 Objectives Effect of water chemistry during zinc injection Effect of decreasing dose equivalent rate on primary equipment and pipes after zinc injection Evaluation of the fuel performance by observing the external appearance and thickness of oxide film on the fuel installed in core during zinc injection To evaluate followings of the zinc injection for Japanese PWR plants by using Tsuruga-2

3. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 3 Isotope Abundance (%) Radio Isotope Radioactive Half-life Zn-6448.6Zn-65244 D Zn-6627.9 －－ Zn-674.1 －－ Zn-6818.8 Zn-6956 M Zn-69m13.8 H Zn-700.6Zn-70m4 H Natural ZnDepleted Zn Isotope Abundance(%) General idea for dose reduction by application of Zn injection Suppression of the dissolution of corrosion products Suppression of redeposition Outer layer （ Ferrite ） ： NiFe 2 O 4 Inner layer （ Chromite:CoCr 2 O 4 ） : Oxygen :Zinc :Co, （ Ni ） : Cr Pipe Primary Water Fuel Deposition Accumulation Radioactivation Co （ Ni ） 58 Co, 60 Co Zn Redeposition 58 Co, 60 Co Depleted Zn : Suppression of dose increase due to reducing the abundance of Zn-64 below 1% Accumulation and radioactivation of the corrosion products

4. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 4 Zn Injection Equipment designing, manufacturing, setting Fuel Performance FY 2004FY 2005 FY 2006 15/12 ～ 25/2 22/4 ～ 22/5 # 14 Planning and Pre-adjustment Zn Injection Evaluation Water Chemistry Dose equivalent rate # 15 Outage (Tsuruga-2) The Application Study Schedule of Zn Injection Depleted Zn Purchase Start of Zn Injection(10/8) ▼

5. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 5 Zinc Injection System in Tsuruga-2 Tsuruga-2 4 loops PWR Start Operation : Feb. 1987 Electric Power : 1160 MWe

6. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 6 Zn Injection Equipment Equipment Configuration ・ Chemical Tanks : 2 (10 little) ・ Concentration of Zinc Acetate : about 5 ～ 12 （ g/little ） Safety Precaution ・ Chemical tank : low level detection ・ injection pressure : high detection ・ Leakage : detection ・ check valve in sampling sink Automatic stop Connection Point Sampling Sink Zn Injection Equipment Zn injection equipment was downsized with making consideration to safety precaution, and was connected to the sampling return line. Chemical Tanks Drain Line Zn Injection Equipment

7. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 7 Zn Injection Plan Zn injection had been performed in Tsuruga-2 for eight months within a range of 5-7 ppb based on the European experience. (Upper limit : 10 ppb) Zi Concentration in Primary Water (ppb) Incubation Period ※ ※ Because most of the Zinc is incorporated in the oxide layers on primary equipment and piping, zinc concentration of primary water is not detected in a early stage of Zn injection.

8. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 8 Primary Water Chemistry during the Zn Injection Although concentration of the radioactive Co was increased by a factor of ten with Zn injection than before, the increase was expected based on the European experience. RCS purity, pH and conductivity, was not affected. Start of Zn Injection #14 Operation cycle#15 Operation cycle pH Conductivity Co-58 Ion Zinc Ion Co-60 Ion Electric Power (Mwe) Concentration (ppb) pH (-) Cond. (μS/cm 2 ) Concentration (Bq/ml)

9. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 9 Measurement of the Radioactive Zinc (Verification of the depleted Zinc) The increase in Zn-65 was not found due to using depleted zinc. 14/1/0413/4/0412/7/0410/10/048/1/058/4/057/7/055/10/053/1/06 3/4/06 0.001 0.01 0.1 1 10 100 Activity Concentration (Bq/ml) Zn-65CrudZn-69mCrud Zn-65IonZn-69mIon #14 Operation Cycle#15 Operation Cycle Start of Zn Injection

10. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 10 Relative dose equivalent rate on the primary equipment and pipes The zinc injection reduced the dose rate of primary equipment and pipes to 70-80 % than that of previous outage. This effect of dose reduction is higher than expectation based on the foregoing plants. However, low temperature nonregenerater had no effect due to zinc injection.

11. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 11 Behavior of dose equivalent rate in SG Channel head Dose equivalent rate in SG channel head had increased with age, but was reduced to its about 20-30% thanks to the application of zinc injection. 0 10 20 30 40 50 60 70 80 90 100 123456789101112131415 Outage # Dose equivalent rate (mSv/h) SG channel head (Hot) SG channel head (Cold) Zn Injection ※ ※： Radiation source decay due to unscheduled plant shutdown when dose rate was measured

12. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 12 #13 Operation Cycle Fuel Burn-up : 13202MWd/t Specific Power ratio : 0.84 #14 Operation Cycle Fuel Burn-up : 31265MWd/t Specific Power ratio : 1.15 #13 Operation Cycle (Zn Injection) Fuel Burn-up : 46365MWd/t Specific Power ratio : 1.00 # R 08 (46365MWd/t) # P 02 (46560MWd/t) Evaluation of the Fuel Cladding - Visual Inspection of the fuel external appearance - Fuel surface showed no significant differences with or without zinc injection. (The region looked white on the figure due to difference of growth of the oxide film (thickness, crystal structure) does not show an abnormality for the fuel performance.) Fuel experienced Zn injectionFuel experienced no Zn injection

13. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 13 Evaluation of the Fuel Cladding - Measured thickness of oxide film - In the result of the evaluation, it was not considered that zinc injection would affect corrosion on fuel cladding because the measured thickness of oxide film was included in past database.

14. ISOE/ATC ALARA Symposium 2006 The Japan Atomic Power Company 14 Summary Water Chemistry ・ Concentration of zinc in primary water was controlled well within the target value (5-7 ppb). ・ Although concentration of the radioactive Co was increased by a factor of 10 with Zn injection than before, the increase was included within the expectation based on the European experience. ・ The increase in Zn-65 was not found due to using depleted zinc. Dose equivalent rate ・ The zinc injection reduced the dose equivalent rate of primary equipment and pipes to 70-80 % than that of previous outage. Fuel Performance ・ It was not considered that zinc injection (eight months) would affect corrosion on fuel cladding by observing the fuel external appearance and thickness of oxide film on the fuel cladding. Zinc injection in Tsuruga-2 will continue to be performed. Influence of long-term zinc injection on the plant and fuel performances will be estimated.