On the Nature of the Breakaway Corrosion Phenomenon during Zr and Zr - - PowerPoint PPT Presentation

On the Nature of the Breakaway Corrosion Phenomenon during Zr and Zr Alloy Oxide Growth

Brendan Ensora, Arthur Mottab, J. Partezanac, Ashley Lucentea, John Seidenstickera, and Zhonghou Caid

The Naval Nuclear Laboratory is operated for the U.S. Department of Energy by Fluor Marine Propulsion, LLC, a wholly owned subsidiary of Fluor Corporation aNaval Nuclear Laboratory, bThe Pennsylvania State University, cWestinghouse Electric Co., dArgonne National

Laboratory

19th International Symposium on Zirconium in the Nuclear Industry

• Development of Zircaloys in the

1950s addressed the unstable

• xide growth that was observed

in pure Zr

• Small amount of alloying

elements solve the problem

• Why?
• Unstable Oxide Growth
• Accident scenarios (LOCA)
• Neutron Irradiation Induced
• Poor alloy performance

2

Zirconium Alloy Corrosion

Crystal Bar Zr 10 days, 360°C Zircaloy-4 70 days, 360°C

What is Unstable Oxide Growth?

Unstable oxide growth is defined as having any or more of the following characteristics:

A) White, spalling oxide B) Acceleration of corrosion rate away from linear post-transition rates C) Uneven oxide growth at the metal-oxide interface that significantly deviates from a generally planar appearance with only minor short-order differences D) Formation of nodules or other local regions

• f advanced oxide growth

Oxide

A B C D

Nodule

B) T. Kido, K. Kanasugi, M. Sugano and K. Komatsu, "PWR Zircaloy cladding corrosion behavior: quantitative analyses," Journal of Nuclear Materials, vol. 248, pp. 281-287, 1997; C) A. T. Motta, M. J. G. da Silva, A. Yilmazbayhan, R. J. Comstock, Z. Cai and B. Lai, "Microstructural characterization of oxides formed on model Zr alloys using synchrotron radiation," Journal of ASTM International, vol. 5, no. 3, pp. 1-20, 2008.; D) T. R. Allen, R. J. M. Konings and A. T. Motta, "Corrosion of Zirconium Alloys," in Comprehensive Nuclear Materials, vol. 5, R. J. M. Konings, Ed., Oxford, UK, Elsevier, 2012, pp. 49-68.

No Oxide Stable Oxide Unstable Oxide 3

What is Breakaway Corrosion?

4

• Sudden change in the oxidation kinetics leading to rapid

corrosion of the metal

• Loss of oxide protectiveness without the ability to recover
• Recognized by white color of the oxide (as opposed to a black

protective oxide)

• Corrosion of Crystal

Bar Zr of various temperatures

Hillner, Edward, "Corrosion of Zirconium- Base Alloys—An Overview,“ Zirconium in the Nuclear Industry, ASTM STP 633, A. L. Lowe,

• Jr. and G. W. Parry, Eds., American Society for

Testing and Materials, 1977, pp. 211-235.

4

What is Breakaway Corrosion?

5

• Not predictable/repeatable
• As opposed to commercial zirconium alloys which corrode in a regular

fashion

Alloy 43 - Zircaloy-4 20 40 60 80 100 120 140 100 200 300 400 500 Exposure time (days) Weight gain (mg/dm2)

43-9 43-10 43-11 43-12 43-13 43-14 43-15 43-16 Archive

43-10 43-15

c)

Alloy 42 - Crystal Bar Zr 20 40 60 80 100 120 20 40 60 80 100 Exposure time (d) Weight gain (mg/dm2)

42-9 42-10 42-11 42-12 42-13 42-14 42-15 42-16 Archive

42-10

b)

Alloy 41 - Sponge Zr 20 40 60 80 100 120 20 40 60 80 100 Exposure time (d) Weight gain (mg/dm2)

41-9 41-10 41-11 41-12 41-13 41-14 41-15 41-16 Archive

41-9 41-10

a)

Plots from INERI (International Nuclear Energy Research Initiative ) final report

5

Causes of Unstable Oxide Growth

• First let’s examine “breakaway corrosion”
• Zr metal undergoes breakaway, most zirconium alloys do not
• What about the alloying elements corrects uneven oxide growth?
• Difference is only a few tenths of a percent in alloying element
• How do alloying elements stabilize oxide growth?
• Is there some baseline alloying element content that allows for even oxide

growth (a minimum amount that promotes stable oxide growth)

Unstable Oxide Growth: Breakaway Corrosion Accumulation

• f stresses at

the oxide- metal interface Uneven oxide growth Hypotheses put forth here Alloying Elements

Heterogeneous distribution of alloying elements causes differential oxide growth, leading to accumulation of stresses and eventually breakaway corrosion (unstable growth)

6

Elemental Effects on the Stability of Zirconium Oxide Growth - Alloy Fabrication

Name Nominal Composition ZC1

Zr (crystal bar)*

ZS1

Zr (sponge)*

FC1

Zr-0.1Fe-0.05Cr

FC2

Zr-0.05Fe-0.025Cr

FC3

Zr-0.05Fe-0.05Cr

FE1

Zr-0.2Fe

CR1

Zr-0.1Cr

SN1

Zr-0.2Sn

SN2

Zr-0.4Sn

SN3

Zr-0.1Sn

Luvak Inc. Chemical Analysis (wt %) Sample H O Fe Cr Crystal Bar 0.0014 0.011 0.0061 <.0005 Sponge 0.0050 0.058 0.0200 0.013 Alloy Fabrication

• Alloys were prepared by arc-melting

300 g buttons

• β-solution treated at 1050°C for 30 min

in a vacuum furnace

• Hot-rolled after pre-heating for between

580 - 720°C for 10 min

• Cold-rolled three times to a final

thickness

• Between each rolling step, sheets were

intermediate-annealed at a temperature between 580-720°C

• Final anneal to recrystallize the

samples (800°C for 30min)

• Surface treatment (pickling) was done

in 45H2O:45HNO3:10HF

• Sheets were cut into ~1” x 1” coupons,

with a thickness of ~30 mils.

• Piece was sent for elemental analysis

7

• Corrosion Testing
• 600°C in air for 40 hours
• 360°C water in autoclave for 70 days
• SEM
• FIB/SEM
• EBSD
• Raman Spectroscopy
• Synchrotron X-ray fluorescence

8

Characterization

• First tests were done in a furnace with 600°C oxygen, 40 hrs

Alloy Composition KR12 Zr-0.4Sn KR14 Zr-1.2Sn KR21 Zr-0.2Nb KR22 Zr-0.4Nb KR41 Zr-1.0Nb KR42 Zr-1.5Nb KR43 Zr-2.5Nb

ZC1-7 KR12 KR14 KR21 KR22 KR41 KR42 KR43

Xbar 2.5Nb 0.4Sn 1.2Sn 0.2Nb 0.4Nb 1.0Nb 1.5Nb

↑Sn ↑Nb

20 40 60 ZC1-3 N101 N102 N201 N202 N203 N302 Oxide Thickness (µm)

Xbar 1.0Fe 1.0Fe 0.5Cr 0.6Fe 0.6Fe 0.3Cr 0.6Fe 0.3Mo 0.5Mo 1.0Cr

Fe/Cr/Mo Stabilized Oxide Growth

Additional Model Zr alloys and alloys provided by Westinghouse were tested

Alloy Composition N101 Zr-1.0Fe N102 Zr-1.0Fe-0.5Cr N201 Zr-0.6Fe N202 Zr-0.6Fe-0.3Cr N203 Zr-0.6Fe-0.3Mo N302 Zr-0.5Mo-1.0Cr

↑Sn

Fe/Cr Stabilized Oxide Growth

9

Elemental Effects on the Stability of Zirconium Oxide Growth

↑Sn

Fe/Cr Stabilized Oxide Growth

10

Elemental Effects on the Stability of Zirconium Oxide Growth

10 20 30 40 50 0.5 1 1.5 2 2.5 Oxide Thickness (µm) Sn or Nb Content (Weight %)

Oxide Thickness as a function of Sn or Nb Content

Sn (Model Zr) Sn (Westinghouse) Nb

• First tests were done in a furnace with 600°C oxygen, 40 hrs

Alloy Composition KR12 Zr-0.4Sn KR14 Zr-1.2Sn KR21 Zr-0.2Nb KR22 Zr-0.4Nb KR41 Zr-1.0Nb KR42 Zr-1.5Nb KR43 Zr-2.5Nb

Additional Model Zr alloys and alloys provided by Westinghouse were tested

Alloy Composition N101 Zr-1.0Fe N102 Zr-1.0Fe-0.5Cr N201 Zr-0.6Fe N202 Zr-0.6Fe-0.3Cr N203 Zr-0.6Fe-0.3Mo N302 Zr-0.5Mo-1.0Cr

50 µm

Elemental Effects on the Stability of Zirconium Oxide Growth- Furnace T ested Samples (SEM)

SN1 (Zr-0.2Sn) SN3 (Zr-0.1Sn) SN2 (Zr-0.4Sn) SN2 (Zr-0.4Sn)

11

Elemental Effects on the Stability of Zirconium Oxide Growth- Furnace T ested Samples (SEM)

SN1 (Zr-0.2Sn) SN3 (Zr-0.1Sn)

Increasing the Sn content increases the amount of oxide grown on the alloys in 40 hours. Areas of advanced

• xide growth begin to appear, consistent with different

metal grains. Suspected to be the different levels of Sn in each metal grain

12

Elemental Effects on the Stability of Zirconium Oxide Growth-Autoclave Tested Samples

5 10 15 20 25 30 35 10 20 30 40 50 60 70 Weight Gain (mg/dm2) Time (days) Zr-Sn Alloys, Zircaloy-4, Zr-Fe-Cr Alloys, Zr-Fe Alloy, Zr-Cr Alloy, Sponge Zr, Crystal Bar Zr (Multiple samples of each)

(b)&(c) (a)

(b)&(c)

• To better replicate corrosion conditions, model Zr alloys were corroded in autoclave

with 360°C water for up to 70 days, with periodic removals for weight gain

(a)

13

3 samples experienced breakaway, 2 more showed signs of unstable oxide growth

Elemental Effects on the Stability of Zirconium Oxide Growth-Autoclave Tested Samples

10 20 30 40 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Weight Gain (mg/dm2) Alloying Element Content (Weight %) ■ 1 day ♦ 3 days

• 10 days

▲ 20 days

⃰ 40 days

▬ 70 days

14

• Interesting note: Less alloying elements generally led to less

weight gain…

• …although also tended to have breakaway corrosion

Minimum amount of alloying elements needed for stable growth?

Elemental Effects on the Stability of Zirconium Oxide Growth

• Autoclave Tested Samples (SEM)

FC2 (Zr-0.05Fe-0.025Cr) 20 days, 360°C, 1.3 µm FC3 (Zr-0.05Fe-0.05Cr) 20 days, 360°C, 1.3 µm SN3 (Zr-0.1Sn) 20 days, 360°C, 1.0 µm ZS1 (Sponge Zr) 70 days, 360°C, 1.4 µm ZS1 (Sponge Zr) 10 days, 360°C, 0.8 µm SN1 (Zr-0.2Sn) 3 days, 360°C SN1 (Zr-0.2Sn) 3 days, 360°C ZC1 (Crystal Bar Zr) 10 days, 360°C

Grain-to-grain Differential Growth

EBSD 15 CR1 (Zr-0.1Cr) 20 days, 360°C, 0.9 µm FC1 (Zr-0.1Fe-0.05Cr) 20 days, 360°C, 1.2 µm

Elemental Effects on the Stability of Zirconium Oxide Growth: Autoclave Samples - Synchrotron µXRF

20 µm

Oxide ‘fingers’ Oxide O-rich Zr Zr Metal

ZC1-12 (crystal bar Zr) Synchrotron XRF (normalized to Zr L) Site Sn L Cr Kα Fe Kα Location A 16 12 63 Metal, nonpenetrating D 45 27 278 Metal, nonpenetrating E 21 17 126 Metal, nonpenetrating B 13 7 50 Metal, penetrating C 11 8 43 Metal, penetrating

A E C D B

Advanced Oxide Growth Precipitate

ZS1-6 (sponge Zr) Synchrotron XRF (normalized to Zr L) Site Sn L Cr Kα Fe Kα Location A 113 23 83 Metal, nonpenetrating C 27 26 74 Metal, nonpenetrating B 36 25 63 Metal, nonpenetrating E 7 13 40 Metal, nonpenetrating D 7 7 42 Metal, penetrating

Heterogeneous distribution of alloying elements leads to regions of advanced oxide growth in areas with less alloying elements.

ZC1 (Crystal Bar Zr)

10 days, 360°C, spalled

ZS1 (Sponge Zr) 70 days, 360°C, 1.4 µm 16

Elemental Effects on the Stability of Zirconium Oxide Growth

• Autoclave Tested Samples (SEM)

ZC1 (Crystal Bar Zr) 10 days, 360°C

T908-4 - Zircaloy-4 70 days, 360°C, 1.8 µm

FC2 (Zr-0.05Fe-0.025Cr) 20 days, 360°C, 1.3 µm ZS1 (Sponge Zr) 10 days, 360°C, 0.8 µm

Nodule-like oxide formations in all model Zr alloys apparent

• n surface. Cross-sections reveal advanced oxide growth.

17

Elemental Effects on the Stability of Zirconium Oxide Growth: Oxide Morphologies-Precursors

FC2 (Zr-0.05Fe-0.025Cr) 20 days, 360°C, 1.3 µm ZC1 (Crystal Bar Zr)

10 days, 360°C, spalled

18

Grain Boundary

FC3 (Zr-0.05Fe-0.05Cr) 20 days, 360°C, 1.3 µm ~1.24 µm ~0.98 µm

Key effects of Alloying Elements on Unstable Oxide Growth in Zirconium Alloys

• In 600°C oxygen, Sn and Nb lead to accelerated oxide

growth; Sn distribution leads to grain to grain differential growth; Zr-Nb alloys near monotectoid at 620°C

• In 360°C water, breakaway corrosion can occur, with three

precursor oxide morphologies (grain boundary penetration, grain-to-grain differential growth, and nodule-like formation)

• Dominant precursor morphology is nodule-like formation
• Heterogeneous distribution of alloying elements

causes unstable oxide growth The distribution of alloying elements can lead to unstable

• xide growth in zirconium alloys

19

Thank you for your attention Questions?

This research has been authored by the Naval Nuclear Laboratory under Contract No. DOE- 89233018CNR000004 with the U.S. Department of Energy. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research was performed (B. Ensor) under appointment to the Rickover Fellowship Program in Nuclear Engineering sponsored by Naval Reactors Division of the U.S. Department of Energy.

20

Extra Slides

21

Causes of Breakaway Corrosion

22

• Compared to stable oxide growth in zirconium alloys, zirconium metal exhibits

uneven oxide growth

H1313J- Zircaloy-4 259 days, 400°C, 9.1 µm T908-4 - Zircaloy-4 70 days, 360°C, 1.8 µm ZC1-12 – Crystal Bar Zr 10 days, 360°C SN1-2 – Zr-0.2Sn 3 days, 360°C

22

Causes of Breakaway Corrosion

23

• Compared to stable oxide growth in zirconium alloys, zirconium metal exhibits

uneven oxide growth

H1313J- Zircaloy-4 259 days, 400°C, 9.1 µm T908-4 - Zircaloy-4 70 days, 360°C, 1.8 µm ZC1-12 – Crystal Bar Zr 10 days, 360°C SN1-2 – Zr-0.2Sn 3 days, 360°C FC1-7 – Zr-0.1Fe-0.05Cr 20 days, 360°C, 1.2 µm ZS1-5 –Sponge Zr 70 days, 360°C, 1.4 µm SN3-5 – Zr-0.1Sn 20 days, 360°C, 1.0 µm

23

Raman – Tetragonal Fraction from Model Zr Alloys

fT= IT 264+IT 148 IT 148+IT 264 +IM 181+IM 192

200 400 600 800 1000 1200 50 150 250 350 450 550 650 Intensity Wavenumber (cm-1) Tet 445 cm-1 Tet 148 cm-1 Tet 264 cm-1

? ? ?

Tet 375 cm-1 Mono 100 cm-1 Mono 181 cm-1 Mono 192 cm-1 Mono 222 cm-1 Mono 303 cm-1 Mono 335 cm-1 Mono 345 cm-1 Mono 383 cm-1 Mono 475 cm-1 Mono 503 cm-1 Mono 535 cm-1 Mono 560 cm-1 Mono 615 cm-1 Mono 637 cm-1 Tet 650 cm-1 0% 5% 10% 15% 20% 25% 30% 35% 0.008 0.031 0.082 0.105 0.094 0.113 0.158 0.183 0.377 1.75 ZC1 ZS1 FC2 FC3 CR1 SN3 FC1 FE1 SN2 Zry4

Raman Spectroscopy Average Tetragonal Percentage for Model Alloys

3 day 10 day 20 day 70 day 0% 5% 10% 15% 20% 25% 30% 35% 4 8 12 16 20 24 28 32 Percentage Tetragonal Phase Weight Gain (mg/dm2)

Model alloys with < 0.15 wt%

• f alloying elements

Zr-0.4Sn Zircaloy-4 Zr-0.2Fe

• Raman spectroscopy was

used to measure fT in model Zr alloys (surface ~0.7 µm)

• fT decreases with

increasing weight gain

• fT increases with more

alloying elements

24

Elemental Effects on the Stability of Zirconium Oxide Growth - Alloy Fabrication

Name Nominal Composition Actual Composition Heat Treatment

ZC1 Zr (crystal bar) Zr (crystal bar) Standard; 580°C ZS1 Zr (sponge) Zr (sponge) Standard; 580°C FC1 Zr-0.1Fe-0.05Cr Zr-0.1Fe-0.058Cr Standard; 720°C FC2 Zr-0.05Fe-0.025Cr Zr-0.056Fe-0.024Cr Standard; 720°C FC3 Zr-0.05Fe-0.05Cr Zr-0.05Fe-0.055Cr Standard; 720°C FE1 Zr-0.2Fe Zr-0.18Fe Standard; 720°C CR1 Zr-0.1Cr Zr-0.088Cr Standard; 650°C SN1 Zr-0.2Sn Zr-0.18Sn Standard; 580°C SN2 Zr-0.4Sn Z-0.37Sn Standard; 580°C SN3 Zr-0.1Sn Zr-0.11Sn Standard; 580°C

Luvak Inc. Chemical Analysis (all numbers in weight %) Sample H C N O Fe Cr Hf Crystal Bar 0.0014 0.007 <.005 0.011 0.0061 <.0005 0.035 Sponge 0.0050 0.004 <.005 0.058 0.0200 0.013 0.028 RJ Lee Group Chemical Analysis Sample H (ppm) C N O Fe Cr Sn ZC1 17 0.011 0.002 0.019 0.006 <0.002 0.002 ZS1 19 0.012 0.003 0.100 0.026 0.005 <0.002 FC1 12 0.007 0.002 0.015 0.100 0.058 <0.002 FC2 12 0.008 0.001 0.015 0.056 0.024 0.002 FC3 13 0.005 0.001 0.007 0.050 0.055 <0.002 CR1 17 0.006 0.002 0.018 0.006 0.088 <0.002 FE1 15 0.010 0.003 0.010 0.180 0.003 <0.002 SN1 16 0.006 0.001 0.010 0.004 <0.002 0.180 SN2 14 0.008 0.001 0.010 0.007 <0.002 0.370 SN3 12 0.005 0.001 0.020 0.003 <0.002 0.110

Alloy Fabrication

• Alloys were prepared by arc-melting

300 g buttons

• β-solution treated at 1050°C for 30 min

in a vacuum furnace

• Hot-rolled after pre-heating for between

580 - 720°C for 10 min

• Cold-rolled three times to a final

thickness

• Between each rolling step, sheets were

intermediate-annealed at a temperature between 580-720°C

• Final anneal to recrystallize the

samples (800°C for 30min)

• Surface treatment (pickling) was done

in 45H2O:45HNO3:10HF

• Sheets were cut into ~1” x 1” coupons,

with a thickness of ~30 mils.

• Piece was sent for elemental analysis

25

Elemental Effects on the Stability of Zirconium Oxide Growth - Furnace Tests (600°C, O2)

Alloy Composition Alloy Composition KR12 Zr-0.4Sn N101 Zr-1.0Fe KR14 Zr-1.2Sn N102 Zr-1.0Fe-0.5Cr KR21 Zr-0.2Nb N201 Zr-0.6Fe KR22 Zr-0.4Nb N202 Zr-0.6Fe-0.3Cr KR41 Zr-1.0Nb N203 Zr-0.6Fe-0.3Mo KR42 Zr-1.5Nb N302 Zr-0.5Mo-1.0Cr KR43 Zr-2.5Nb

Name ZC1 ZS1 FC1 FC2 FC3 FE1 CR1 SN1 SN2 SN3 Nominal Composition Zr (crystal bar) Zr (sponge) Zr- 0.1Fe- 0.05Cr Zr- 0.05Fe- 0.025Cr Zr- 0.05Fe- 0.05Cr Zr- 0.2Fe Zr- 0.1Cr Zr- 0.2Sn Zr- 0.4Sn Zr- 0.1Sn

Furnace Testing Visual Results

26

Elemental Effects on the Stability of Zirconium Oxide Growth - Furnace Tests (600°C, O2)

Alloy Composition Alloy Composition KR12 Zr-0.4Sn N101 Zr-1.0Fe KR14 Zr-1.2Sn N102 Zr-1.0Fe-0.5Cr KR21 Zr-0.2Nb N201 Zr-0.6Fe KR22 Zr-0.4Nb N202 Zr-0.6Fe-0.3Cr KR41 Zr-1.0Nb N203 Zr-0.6Fe-0.3Mo KR42 Zr-1.5Nb N302 Zr-0.5Mo-1.0Cr KR43 Zr-2.5Nb

Name ZC1 ZS1 FC1 FC2 FC3 FE1 CR1 SN1 SN2 SN3 Nominal Composition Zr (crystal bar) Zr (sponge) Zr- 0.1Fe- 0.05Cr Zr- 0.05Fe- 0.025Cr Zr- 0.05Fe- 0.05Cr Zr- 0.2Fe Zr- 0.1Cr Zr- 0.2Sn Zr- 0.4Sn Zr- 0.1Sn

Furnace Testing Visual Results

10 20 30 40 50 0.5 1 1.5 2 2.5 3 Oxide Thickness (µm) Sn or Nb Content (Weight %)

Oxide Thickness as a function of Sn or Nb Content Sn (Model Zr) Sn (Westinghouse) Nb

27

Elemental Effects on the Stability of Zirconium Oxide Growth- Furnace Tested Samples (SEM)

ZC1 (Crystal bar Zr)

SN1-1 (Zr-0.2Sn) Cracks from polishing due to brittle material

Suboxide Oxide Metal

Mo Stable oxide growth

ZC1 (Crystal bar Zr)

Zr Oxide

ZS1 (Sponge Zr)

Region of increased

• xide growth

25 µm EBSD

Furnace oxide characteristics: (1) Suboxide (2) Transitions (3) Grain to grain differential growth (associated with regions of advanced oxide growth)

28

Elemental Effects on the Stability of Zirconium Oxide Growth- Furnace Tested Samples (SEM)

ZC1 (Crystal bar Zr)

SN1-1 (Zr-0.2Sn) Cracks from polishing due to brittle material

FC1 (Zr-0.1Fe-0.05Cr)

Suboxide Oxide Metal

Mo Stable oxide growth

ZC1 (Crystal bar Zr)

O-rich Zr Thin suboxide Zr Oxide

ZS1 (Sponge Zr)

Mo Region of increased

• xide growth

Grain boundary Horizontal cracking 25 µm EBSD

Furnace oxide characteristics: (1) Suboxide (2) Transitions (3) Grain to grain differential growth (associated with regions of advanced oxide growth)

29

Elemental Effects on the Stability of Zirconium Oxide Growth-Autoclave Test (360°C, Water)

0.1 0.2 0.3 0.4 0.5 Exponent 'n'

Exponent 'n' in 360°C water for 70 days

Cubic

2 4 6 8 10 12 14 16 18 20 Pre-exponential 'A'

Pre-exponential 'A' in 360°C water for 70 days

𝑋 = 𝐵𝑢𝑜

This study

Literature

This study has corrosion kinetics consistent with previous studies on Zr alloys with Fe, Cr, and Sn

30

Elemental Effects on the Stability of Zirconium Oxide Growth-Autoclave Test (360°C, Water)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

10 20 30 40 50 60 70

Corrosion Rate (mg/dm2/day)

Days Corrosion Rate over Time for Model Zr Alloys

CR1-2 CR1-8 FC1-6 FC1-7 FC2-2 FC2-8 FC3-2 FC3-8 FE1-2 FE1-7 SN1-2 SN1-6 SN2-10 SN2-6 SN3-2 SN3-5 ZC1-11 ZC1-12 ZS1-5 ZS1-6 T908-1 T908-2 T908-3 T908-4

0.1 0.2 0.3 0.4 20 30 40 50 60 70

5 10 15 20 25 30 35 0.1 0.2 0.3 0.4 Weight Gain (mg/dm2) Alloying Element Content (Weight %) Oxide Growth as a function of Alloying Element Content for Zr-Fe-Cr alloys 1 day Fe-Cr 3 days Fe-Cr 10 days Fe-Cr 20 day Fe-Cr 40 day Fe-Cr 70 day Fe-Cr

• Corrosion rate supports that Sn alloys have

more oxide, same behavior, increased rate of

• xide growth
• Increasing Fe+Cr leads to decreased weight

gain, different from Sn and overall alloying element effect

31

Elemental Effects on the Stability of Zirconium Oxide Growth-Autoclave Test (360°C, Water) Raman

100 200 300 400 500 600 50 100 150 200 250 300 350 400 450 500 50 100 150 200 250 300 350 400 450 500 550 600 650 700 FC3 Intensity SN2 Intensity Wavenumber (cm-1) SN2 FC3

32