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. 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

3. General idea for dose reduction by application of Zn injection
Primary Water
58Co, 60Co
Redeposition Zn
Pipe
58Co, 60Co
Deposition
Accumulation
Pipe Zn Co
Fuel
Radioactivation （ Ni ） Zn Zn
Suppression of the dissolution of corrosion products
Accumulation and radioactivation of the corrosion products
Suppression of redeposition
Outer layer （Ferrite）
： NiFe2O4
Inner layer （Chromite:CoCr2O4 ）
: Oxygen
:Zinc
:Co,（Ni）
: Cr
Isotope
Abundance
(%)
Radio
Isotope
Radioactive
Half-life
Zn-64
48.6
Zn-65
244 D
Isotope Abundance(%)
Zn-66
27.9 － －
Zn-67
4.1 － －
Zn-68
18.8
Zn-69
56 M
Zn-69m
13.8 H
Natural Zn
Depleted Zn
Zn-70
0.6
Zn-70m
4 H
Depleted Zn : Suppression of dose increase due to reducing the abundance of Zn-64 below 1%

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

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

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
Chemical Tanks
Drain Line
Zn Injection Equipment
Sampling Sink
Zn Injection Equipment
Zn injection equipment was downsized with making consideration to safety precaution, and was connected to the sampling return line.

7. Zi Concentration in Primary Water
Zn Injection Plan
Nov., 2005
Jan., 2006
Mar., 2006
May, 2006
Jul., 2005
Aug., 2005 2 1
May, 2005 6 5 4 3 10 9 8 7
About 5 ppb
About 7 ppb
Detection Limit : １ｐｐｂ
Start of Zn Injection
Outage #15
Zi Concentration in Primary Water
(ppb)
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.

8. Primary Water Chemistry during the Zn Injection
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)
Cond. (μS/cm2)
pH (-)
(Bq/ml)
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.

9. The increase in Zn-65 was not found due to using depleted zinc.
Measurement of the Radioactive Zinc (Verification of the depleted Zinc)
100
#14 Operation Cycle
#15 Operation Cycle 10
Start of Zn Injection 1
Activity Concentration (Bq/ml)
0.1
0.01
Zn- 65
Crud
Zn-
69m
Crud
Zn- 65
Ion
Zn-
69m
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.

10. Relative dose equivalent rate on the primary equipment and pipes
Charging pump
Reactor Vessel
Steam generator (SG)
Nonregenerative heat exchanger (1.1)
Zn injection equipment
Demineralizer
Volume control Tank
(VCT)
Sampling Rack
Sample water return ＊
Injection Pump
Zinc Acetate Tank
Crossover leg
(0.69)
SG channel head
( )
Cold leg
(0.81)
Hot leg
(0.73)
Regenerative heat exchanger (0.3)
RCS pump
(0.86)
: Dose rate measuring points
(Ratio from the previous outage）
The zinc injection reduced the dose rate of primary equipment and pipes to % 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. Behavior of dose equivalent rate in SG Channel head
Zn Injection
100
SG channel head (Hot) 90
SG channel head (Cold) 80 70 ※ 60
Dose equivalent rate (mSv/h) 50 40 30 20 10
※：Radiation source decay due to unscheduled plant shutdown when dose rate was measured 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Outage #
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.

12. Evaluation of the Fuel Cladding - Visual Inspection of the fuel external appearance -K J H G F E N M D C P B A R 1 2 3 4 5 6 7 8 9 10 11 15 14 13 12
Fuel experienced Zn injection
Fuel experienced no Zn injection
#13 Operation Cycle
Fuel Burn-up : 13202MWd/t
Specific Power ratio : 0.84
#13 Operation Cycle (Zn Injection)
Fuel Burn-up : 46365MWd/t
Specific Power ratio : 1.00
#14 Operation Cycle
Fuel Burn-up : 31265MWd/t
Specific Power ratio : 1.15
# R 08 (46365MWd/t)
# P 02
　(46560MWd/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.)

13. Evaluation of the Fuel Cladding - Measured thickness of oxide film -
※　Sendo et al. AESJ, 2003，Mitsubishi Heavy Industrial,LTD, NHI-NES-1012
Thickness of oxide film (μm)
Past database ※ 20 40 60 80
100
120
140
160
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)
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)
低ｽｽﾞｼﾞﾙｶﾛｲ-4 (高浜３号機) **
低ｽｽﾞｼﾞﾙｶﾛｲ-4 (敦賀２号機；亜鉛経験なし)
低ｽｽﾞｼﾞﾙｶﾛｲ-4 (敦賀２号機；亜鉛経験あり) 10 30 50 70 * ( 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
（高燃焼度等燃料に関するもの）に関する報告書、平成 12 年 3 月
** (
：Slightly rough surface
Average of fuel burn-up(GWd/t)
Past Data ※
: Zircaloy-4 (No Zn injection)
: Zircaloy-4 (Zn injection)
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. Summary Water Chemistry Dose equivalent rate Fuel Performance
・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 % 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.