ISOEATC ALARA Symposium 2006 1 Progress of the

ISOE/ATC ALARA Symposium 2006 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 The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 2 Objectives To evaluate followings of the zinc injection for Japanese PWR plants by using Tsuruga-2 • 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 The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 General idea for dose reduction by application of Zn injection 58 Co, 60 Co Primary Water Redeposition 58 Co, 60 Co Fuel Radioactivation Accumulation and radioactivation of the corrosion products Outer layer （Ferrite） Suppression of redeposition Inner layer （Chromite: Co. Cr 2 O 4 ） Isotope Abundance(%) ： Ni. Fe 2 O 4 Natural Zn Depleted Zn Pipe Zn Zn Co Deposition Accumulation Ni （ ） Zn Zn Suppression of the dissolution of corrosion products 3 : Oxygen : Cr : Zinc : Co, （Ni） Isotope Abundance (%) Radio Isotope Radioactive Half-life Zn-64 48. 6 Zn-65 244 D Zn-66 27. 9 － － Zn-67 4. 1 － － Zn-68 18. 8 Zn-69 56 M Zn-69 m 13. 8 H Zn-70 0. 6 Zn-70 m 4 H Depleted Zn : Suppression of dose increase due to reducing the abundance of Zn-64 below 1% The Japan Atomic Power Company

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

ISOE/ATC ALARA Symposium 2006 5 Zinc Injection System in Tsuruga-2 　　4 loops PWR 　　Start Operation : Feb. 1987 　　Electric Power : 1160 MWe 　　　　　 Steam generator (SG) Pressurizer Sampling rack Demineralizer Zinc acetate tank ※ Sample Water Return Injection Pump ※ Reactor vessel Primary Loop Volume control tank (VCT) Zn injection equipment Charging pump Chemical Volume Control System Sampling Room for Primary Water The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 6 Zn Injection 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 Automatic stop ・Leakage : detection ・check valve in sampling sink Connection Point Chemical Tanks Drain Line Sampling Sink Zn Injection Equipment Zn injection equipment was downsized with making consideration to safety precaution, and was connected to the sampling return line. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 7 Zi Concentration in Primary Water (ppb) Zn Injection Plan 10 9 8 7 6 5 4 3 2 1 0 Outage #15 About 7 ppb Start of Zn Injection About 5 ppb Detection Limit : １ｐｐｂ May, 2005 Jul. , 2005 Aug. , 2005 Nov. , 2005 Jan. , 2006 Mar. , 2006 May, 2006 Incubation Period ※ 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) ※　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. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 Concentration (Bq/ml) p. H (-) Cond. (μS/cm 2) Concentration Electric Power (ppb) (Mwe) Primary Water Chemistry during the Zn Injection 8 Start of Zn Injection #14 Operation cycle #15 Operation cycle Zinc Ion p. H Conductivity Co-58 Ion Co-60 Ion 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, p. H and conductivity, was not affected. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 9 Measurement of the Radioactive Zinc (Verification of the depleted Zinc) Activity Concentration (Bq/ml) 100 #14 Operation Cycle #15 Operation Cycle 10 Start of Zn Injection 1 0. 01 Zn-65 Crud Zn-69 m Crud Zn-65 Ion Zn-69 m Ion 0. 001 14/1/04 13/4/04 12/7/04 10/10/04 8/1/05 8/4/05 7/7/05 5/10/05 3/1/06 3/4/06 The increase in Zn-65 was not found due to using depleted zinc. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 Relative dose equivalent rate on the primary equipment and pipes Steam generator (SG) Hot leg (0. 73) Regenerative heat exchanger (0. 3) Nonregenerative heat exchanger (1. 1) Sampling Rack Demineralizer SG channel head (0. 64 - 0. 78) ＊ Reactor Vessel 10 Volume control Tank (VCT) Crossover leg RCS pump (0. 69) Cold leg (0. 86) (0. 81) Zinc Acetate Tank ＊ Sample water return Injection Pump Zn injection equipment Charging pump : Dose rate measuring points (Ratio from the previous outage） 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. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 Behavior of dose equivalent rate in SG Channel head 100 Dose equivalent rate (m. Sv/h) Zn Injection SG channel head (Hot) SG channel head (Cold) 90 11 80 70 ※ 60 50 40 30 20 10 ※：Radiation source decay due to unscheduled plant shutdown when dose rate was measured 0 1 2 3 4 5 6 7 8 Outage # 9 10 11 12 13 14 15 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. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 Evaluation of the Fuel Cladding 12 - Visual Inspection of the fuel external appearance R 1 2 3 4 5 6 7 P N M L K J H G F E D C B A #13 Operation Cycle Fuel Burn-up : 13202 MWd/t Specific Power ratio : 0. 84 Fuel experienced Zn injection Fuel experienced no Zn injection #13 Operation Cycle (Zn Injection) Fuel Burn-up : 46365 MWd/t Specific Power ratio : 1. 00 8 9 10 11 12 13 14 15 #14 Operation Cycle Fuel Burn-up : 31265 MWd/t Specific Power ratio : 1. 15 # R 08 (46365 MWd/t) # P 02 　(46560 MWd/t) 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. ) The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 13 Evaluation of the Fuel Cladding - Measured thickness of oxide film - 160 *　(財)原子力発電技術機構、平成 11年度 軽水炉改良技術確証試験 12年 3 月 　 （高燃焼度等燃料に関するもの）に関する報告書、平成 ** (財)原子力発電技術機構、平成 10年度 軽水炉改良技術確証試験 11年 3 月 　 （高燃焼度等燃料に関するもの）に関する報告書、平成 従来ｽｽﾞｼﾞﾙｶﾛｲｰ 4 低ｽｽﾞｼﾞﾙｶﾛｲ-4 (先行照射) Thickness of oxide film (μm) 140 Past database Data ※ ※ 低ｽｽﾞｼﾞﾙｶﾛｲ-4 (Vandellos 2) * 低ｽｽﾞｼﾞﾙｶﾛｲ-4 (North Anna 1) 120 低ｽｽﾞｼﾞﾙｶﾛｲ-4 (高浜３号機) ** : Zircaloy-4 (No Zn injection) : Zircaloy-4 (Zn injection) 低ｽｽﾞｼﾞﾙｶﾛｲ-4 (敦賀２号機；亜鉛経験なし) 100 低ｽｽﾞｼﾞﾙｶﾛｲ-4 (敦賀２号機；亜鉛経験あり) 80 60 40 20 0 ：Slightly rough surface 00 10 20 30 40 50 60 70 Average of fuel burn-up(GWd/t) ※　Sendo et al. AESJ, 2003，Mitsubishi Heavy Industrial, LTD, NHI-NES-1012 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. The Japan Atomic Power Company

ISOE/ATC ALARA Symposium 2006 Summary 14 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. The Japan Atomic Power Company