57. June 8_Ring Compression Tests_Billone

1. Perspective on Radial-Hydride-Induced
Embrittlement
Mike Billone
Argonne National Laboratory
DOE-UFD Annual Meeting
UNLV
June 7-9, 2016

2. 2
Introduction
Background
Relevant ranges of peak cladding temperature and stress
Previous Results for High-Exposure Cladding
─ As-irradiated cladding
─ Following cooling from 400o
C peak drying-storage temp.
New Data for High-Exposure Cladding
─ As-irradiated condition for Zry-4
─ Following cooling from 350o
C peak drying-storage temp.
FY2016 Tests in Progress
Summary and Perspectives
Outline of Topics

3. 3
Introduction

4. 4
Introduction: Objectives of
Argonne Experimental Program
Argonne Experimental Program
• Generate data for ductility vs. temperature following slow cooling
from T ≤400°C and decreasing hoop stress (σθ)
• Determine ductile-to-brittle transition temperature (DBTT) for each
set of peak drying-storage T and σθ: ductility transition temperature
• Characterize extent of radial hydrides and correlate DBTT with
effective length of radial hydrides (RHCF)
• From data and stress-strain input, determine failure stresses and
strains for PWR cladding alloys (input into codes)
Argonne Collaborations
• EPRI-ESCP Fuels Subcommittee and ORNL: relevant range for σθ
• PNNL and ORNL: relevant range for peak cladding temperatures
• SNL, PNNL, and ORNL: relevant range of NCT loads and fueled-
cladding response to bending-fatigue loads (experimental)

5. 5
Introduction:
Loads on Fuel Rods
 Loads on Fuel-Rod Cladding during Drying & Storage
• Primarily internal gas-pressure loading (hoop & axial stresses)
 Loads on Fuel-Rod Cladding during Transport
• Normal conditions of transport (NCT) include vibration and shock
– Axial bending: axial bending stresses (other stresses at pellet-pellet interfaces)
– “Pinch” loading at grid spacers: hoop bending stresses
• Hypothetical accident conditions include severe impact loads
F
Internal
Pressure pi
Schematic of
Pinch-Loading

6. 6
Introduction: Circumferential and
Radial Hydrides in High-Exposure
PWR Cladding
320 wppm H
As-Irradiated After Cooling from 400o
C/110-MPa
76 wppm H
72 wppm H
350 wppm H
ZIRLO™
M5®

7. 7
Introduction: Relevant Ranges of
Cladding Temperature & Stress
Cladding Temperature
• Peak cladding temperature (PCT)
– Determines maximum hydrogen content in solution and available for precipitation
as radial hydrides: 206 wppm @ 400°C, 126 wppm @ 350°C, 77 wppm @ 300°C
– Likely to occur during vacuum drying
– 400°C NRC-recommended limit; ≤350°C based on UFD S&T calculations
• “Peak” average gas temperature within fuel rods
– Determines peak internal pressure given pressure (RIP) at RT
– May vary from 180°C (vacuum/static-He) to 340°C (vertical cask with 0.5-MPa He)
Cladding Hoop Stress
• Depends on rod internal/external pressure, ID, and wall thickness
• “Reasonable” upper bounds for high-burnup PWR fuel rods
– Standard (UO2/Clad) fuel rods: 60−80 MPa
– Integral Fuel Burnable Absorber (IFBA fuel rods (UO2/10B/ZIRLO™):
• Hollow blanket pellets (HBP): 80−120 MPa; solid blanket pellets (SBP): 115−155 MPa

8. 8
Introduction: Dissolution (Heating)
and Precipitation (Cooling) Curves
0
50
100
150
200
250
300
350
400
450
0 100 200 300 400 500
HydrogenConcentration(wppm)
Temperature (°C)
Kammenzind Cd (Zry-4)
Kammenzind Cp (Zry-4)
Kearns Cd (Zr,Zry-2,Zry-4)
Dissolution
Precipitation
ΔTPD
210 wppm
77 wppm

9. 9
Combined Data and Predictions for
Rod Internal Pressure (RIP) @ 25
o
C
0
1
2
3
4
5
6
7
8
9
10
11
40 45 50 55 60 65 70 75
EOLPWRRIPat25°C(MPa)
Rod Average Burnup (GWd/MTU)
Data: Standard Rods
FRAPCON: Standard Rods
FRAPCON-IFBA-HBP
FRAPCON-IFBA-SBP
Data Average + 3-σ
Data Average

10. 10
Summary of Previous Results:
Cooling from 400o
C

11. 11
Response of M5® Cladding
following Cooling from 400o
C
 Test Matrix for High-Exposure M5® (Zr-1wt.%Nb)
• As-irradiated, 76±5 wppm hydrogen
• After cooling from 400°C/90-MPa, 58±15 wppm
• After cooling from 400°C/111-MPa, 72±10 wppm
• After cooling from 400°C/142-MPa, 94±4 wppm
 Results for High-Exposure M5®
• As-irradiated:
high ductility at T ≥20°C (no cracking up through 1.7 mm disp.)
• 90-MPa, 58±15 wppm: high ductility at T ≥20°C, 37±17% RHCF
• 111-MPa, 72±10 wppm: high ductility at T ≥90°C, 54±20% RHCF
• 142-MPa, 94±6 wppm:
mod.-to-high ductility at T ≥90°C, 61±18% RHCF

12. 12
Ductility vs. Test Temperature
for High-Exposure M5®
0
2
4
6
8
10
12
14
0 25 50 75 100 125 150 175 200 225
OffsetStrain(%)
RCT Temperature (°C)
76±5 wppm H
58±15 wppm H (90 MPa)
72±10 wppm H (111 MPa)
94±6 wppm H (142 MPa)
142 MPa
at 400°C
111 MPa
at 400°C
Ductile
Brittle
High-Burnup M5®
As-Irradiated
90 MPa
at 400°C

13. 13
Radial Hydrides in High-Exposure
M5® following Cooling from 400
o
C
111 MPa
72±10 wppm
82 MPa at 228o
C
54±20% RHCF
90 MPa
58±15 wppm
65 MPa at 210o
C
37±17% RHCF
142 MPa
94±6 wppm
110 MPa at 251o
C
61±18% RHCF

14. 14
Assessment of M5® Database
following Cooling from 400o
C
 Need Data for 90−110 MPa with 75−95 wppm Hydrogen
• Ductility improved with decrease in both hydrogen and hoop stress
• Note: licensing issue; PCT ≤350°C, Peak σθ <80 MPa
• Low H-content and low σθ → no radial hydride issue
 Need End-of-Life (EOL) RIP Data for M5®-clad fuel rods
• No available data
• ≤9 new data points planned for “sister” rod characterization
 Need Tests at <400°C
• Less annealing would occur at lower peak temperatures
• Need to confirm previous results at T ≤350°C

15. 15
Response of Zry-4 Cladding
following Cooling from 400
o
C
 Test Matrix for High-Exposure Zircaloy-4
• As-Irradiated, 300±15, 616±78, 640±140 wppm hydrogen
• After cooling from 400°C/113-MPa, 520±90 wppm hydrogen
• After cooling from 400°C/145-MPa, 615±82 wppm hydrogen
 Results for High-Exposure Zircaloy-4
• As-irradiated
– 300±15 wppm: high ductility at 20°C (no cracking to 1.7 mm displace.)
– 640±140 wppm (>850 wppm local): no-to-low ductility at ≤90°C (brittle?)
– 616±78 wppm: refined test method, ductility = 2.6±0.7% vs. 1% limit
• 113 MPa, 520±90 wppm: low ductility at 20°C, 9±5% RHCF
– Recommended test at 350°C/110-MPa (4 RCT data points at 20°C)
• 145 MPa, 615±82 wppm: low ductility at 90°C, 16±4% RHCF

16. 16
Ductility vs. Test Temperature for
High-Exposure Zircaloy-4
0
2
4
6
8
10
12
14
0 25 50 75 100 125 150 175 200 225
OffsetStrain(%)
RCT Temperature (°C)
300±15 wppm H
640±140 wppm H
520±90 wppm H
615±82 wppm H
Brittle
Ductile
145 MPa
at 400°C
113 MPa
at 400°C
High-Burnup Zircaloy-4
As-Irradiated

17. 17
Ductility vs. Test Temperature for
As-Irradiated, High-Exposure Zry-4
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100 120 140 160
PermanentStrain(%)
RCT Temperature (°C)
300±15 wppm H
640±140 wppm H
616±78 wppm H
Ductile
As-Irradiated
High-Burnup
Zircaloy-4

18. 18
Crack Depth vs. Load Drop for As-
Irradiated Zry-4: Load-Interrupt Tests
44% Wall Crack
27% Load Drop
2.1% “Ductility”
41% Wall Crack
22% Load Drop
2.2% “Ductility”
39% Wall Crack
24% Load Drop
2.7% “Ductility”

19. 19
Response of ZIRLO™ Cladding
following Cooling from 400
o
C
 Test Matrix for High-Exposure ZIRLO™ (Zr-1wt.%Nb-1wt.%Sn)
• As-Irradiated, 530±70 wppm hydrogen
• After cooling from 400°C/80-MPa, 535±50 wppm hydrogen
• After cooling from 400°C/89-MPa, 530±115 wppm hydrogen
• After 3-cycle cooling from 400°C/88-MPa, 480±131 wppm hydrogen
• After cooling from 400°C/111-MPa, 385±80 wppm hydrogen (2 tests)
• After cooling from 400°C/141-MPa, 650±190 wppm hydrogen
 Results for High-Exposure ZIRLO™
• As-irradiated, 530±70 wppm: mod.-to-high ductility at T ≥20°C
• 80 MPa, 535±50 wppm: mod-to-high ductility at T ≥20°C, 9±3% RHCF
• 89 MPa, 530±115 wppm: low ductility at 23°C, 19±9% RHCF
• 88 MPa, 480±131 wppm: low ductility at 23°C, 20±9% RHCF (3-cycle cool.)
• 111 MPa, 350±80 wppm: high ductility at 150°C, 32±13% RHCF
• 141 MPa, 650±190 wppm: brittle at 150°C, mod. ductility at 195°C

20. 20
Ductility vs. Test Temperature for
High-Exposure ZIRLO™
0
2
4
6
8
10
12
14
0 20 40 60 80 100 120 140 160 180
OffsetStrain(%)
RCT Temperature (°C)
530±70 wppm H
535±50 wppm H
530±115 wppm H
480±131 wppm H
385±80 wppm H
Brittle
Ductile
111 MPa
at 400°C
80 MPa
at 400°C
High-Burnup ZIRLO™
As-Irradiated
89 MPa
at 400°C

21. 21
Radial Hydrides in
High-Exposure ZIRLO™
following Cooling from 400
o
C
141 MPa
(128 MPa @ Tp)
650 wppm
111 MPa
(101 MPa @ Tp)
350 wppm
80 MPa
(72 MPa @ Tp)
535 wppm
89 MPa
(80 MPa @ Tp)
530 wppm

22. 22
Response of ZIRLO™ Cladding
following Cooling from 400
o
C
 Assessment of Database for High-Exposure ZIRLO™
• Need data in peak stress range of 90−110 MPa prior to cooling
– DBTT increased by 100°C within this stress range
– Stress range relevant to WEC-IFBA rods
• Need repeat tests to determine DBTT with more precision
– Standard-fuel ZIRLO™ rods: 60−80 MPa relevant peak stress range
• Radial hydride embrittlement not anticipated
– ZIRLO™-clad fuel pellets with ZrB2 (enriched in 10B) coating
Integral Fuel Burnable Absorber (IFBA) rods
Relevant stress ranges: 80−120 MPa and 115-155 MPa for 2 designs
• Need tests at <400°C to determine net effects on DBTT of
reduction in annealing and reduction in dissolved hydrogen
available for precipitation

23. 23
New Data for 350o
C Peak
Drying-Storage Temperature

24. 24
High-Exposure ZIRLO™ and M5®
following Cooling from 350
o
C
 Expectations
• ZIRLO™
– Decrease (80 wppm) in dissolved hydrogen and in precipitation temperature
– Decrease in internal pressure and hoop stress at precipitation initiation
– Possible decrease in annealing of irradiation hardening (lower ductility matrix)
– Anticipated net effect: decrease in DBTT
• M5®
– No change in dissolved hydrogen, precipitation temperature, precipitation stress
– Possible decrease in annealing of irradiation hardening (lower ductility matrix)
– Anticipated net effect: no change in DBTT
 ZIRLO™ Tests at 350°C
• 94 MPa (84 MPa @ Tp), 644±172 wppm, 1-cycle cooling
– Long radial hydrides (37±11%), low ductility @ ≤135°C, mod. ductility @ 150°C
• 93 MPa (83 MPa @ Tp), 564±177 wppm, 3-cycle cooling
– Long radial hydrides (30±11%), low ductility @ ≤120°C, high ductility @ ≥135°C
• No effects of cycling, but DBTT comparable to DBTT for 400°C/111-MPa

25. 25
Ductility Data for High-Exposure
ZIRLO™ following Cooling from 350
o
C
0
2
4
6
8
10
12
14
0 20 40 60 80 100 120 140 160
OffsetStrain(%)
RCT Temperature (°C)
400°C/89-MPa, 530±115 wppm, 1C
400°C/88-MPa, 480±131 wppm, 3C
350°C/93-MPa, 564±177 wppm, 3C
350°C/94-MPa, 644±172 wppm, 1C
400°/111-MPa, 350±80 wppm, 1C
400°/111-MPa, 425±63 wppm, 1C
Brittle
Ductile
High-Burnup ZIRLO™

26. 26
Radial Hydrides in ZIRLO™ for 1- and
3-Cycle Drying Tests following cooling
from 350o
C
1-Cycle-350o
C Test
94 MPa → 84 MPa
37±11% RHCF
≥50% Max. RHCF
3-Cycle-350o
C Test
93 MPa → 83 MPa
30±11% RHCF
≥50% Max. RHCF

27. 27
FY2016 Tests in Progress
 ZIRLO™ following Cooling from 350°C
• 90-MPa (1-cycle) test with lower-H (350 wppm) and 24-h hold time
– High-hydrogen content (644±172 wppm) may have degraded cladding
– 350 wppm is closer to expected hydrogen content at ≤55 GWd/MTU
– Compare results to 400°C/111-MPa test with 350 wppm & 24-h hold
– Use load-interrupt method to improve data analysis and reduce scatter
– If ductility values are still low, investigate effects of annealing
 M5® following Cooling from 350°C
• 90-MPa target hoop stress, 75−95 wppm target H-content
– Radial hydride treatment (RHT) completed
– Metallography: oxide and metal wall thicknesses, 50±14% RHCF
– 89-MPa actual hoop stress
– Hydrogen content: 80±7 wppm; hydrides not continuous in axial
direction; ring compression tests in progress

28. 28
ANL Perspective
 DBTT or Ductility Transition Temperature
• Not a material property like Young’s modulus
• Depends on orientation/length of hydrides and orientation of loads
• Transport at T <DBTT does not imply failure
• ANL data may be used to determine hoop failure stresses/strains
 Relevant Hoop Stresses during Drying and Storage
• Depend on end-of-life internal gas pressures
– Standard rods have lower gas pressures (He-fill + fission gas)
– IFBA rods have higher gas pressures (He-fill + He from B-10 + fission gas)
• Depend on average gas temperature during drying/storage
– Horizontal/He < vertical/vacuum < vertical/He < vertical/convective-He
• “Reasonable” upper-bound hoop stresses
– Standard PWR rods: 60−80 MPa
– ZIRLO™-clad IFBA rods with annular blanket pellets: 80−120 MPa
– ZIRLO™-clad IFBA rods with solid blanket pellets: 115−155 MPa

29. 29
Relevant Publications
 M.C. Billone et al. Phase I Ring Compression Testing of High-Burnup Cladding. FCRD-
USED-2012-000039, Dec. 21, 2011.
 M.C. Billone et al. Baseline Studies for Ring Compression Testing of High-Burnup
Fuel Cladding. FCRD-USED-2013-000040, ANL-12/58, Nov. 23, 2012.
 M.C. Billone et al. “Ductile-to-brittle transition temperature for high-burnup cladding
alloys exposed to simulated drying-storage conditions,” J. Nucl. Mater. 433 (2013)
431-448.
 M.C. Billone et al., “Effects Drying and Storage on High-Burnup Cladding Ductility,”
Proc. IHLRWM Conf., Albuquerque, NM, Apr. 28 – May 2, 2013.
 M.C. Billone et al., “Baseline Properties and DBTT of High-Burnup PWR Fuel Cladding
Alloys,” PATRAM-2013, San Francisco, CA, Aug. 18-23, 2013.
 M.C. Billone et al. Embrittlement and DBTT of High-Burnup PWR Fuel Cladding Alloys.
FCRD-UFD-2013-000401, ANL-13/16, Sept. 30, 2013.
 M.C. Billone et al. Effects of Multiple Drying Cycles on High-Burnup PWR Cladding
Alloys. FCRD-UFD-2014-000052, ANL-14/11, Sept. 26, 2014.
 M.C. Billone et al., “Characterization and Effects of Hydrides in High-Burnup PWR
Cladding Alloys,” Proc. IHLRWM Conf., Charleston, SC, Apr. 12–16, 2015.
 M.C. Billone et al., Effects of Lower Drying-Storage Temperatures on the DBTT of
High-Burnup PWR Cladding. FCRD-UFD-2015-000008, ANL-15/21, Aug. 28, 2015.

30. 30
Acknowledgment
This work is supported by the Used Fuel Disposition
Research and Development, Office of Nuclear Energy
(NE-53) under Contract DE-AC02-06CH11357.
Mike Billone
Manager, Irradiation Performance
Nuclear Engineering Division
Argonne National Laboratory
9700 S. Cass Ave., Bldg. 212
Argonne, IL 60439
630-252-7146
billone@anl.gov

31. 31
Backup Slides

32. 32
“Reasonable” Upper-Bound Hoop
Stresses for Standard PWR Rods
50
60
70
80
90
100
160 180 200 220 240 260 280 300 320 340 360
PWRRodHoopStress(MPa)
Gas Temperature (°C)
10-Micron Oxide
40-Micron Oxide
80-Micron Oxide

33. 33
“Reasonable” Upper-Bound Hoop
Stresses for Standard PWR Rods
80
90
100
110
120
130
140
150
160
160 180 200 220 240 260 280 300 320 340 360
PWRRodHoopStress(MPa)
Gas Temperature (°C)
IFBA-HBP
IFBA-SBP

34. 34
RHT Experimental Method for 1- and
3-Cycle Drying of Pressurized Rodlet
Rodlet Fabrication 175
200
225
250
275
300
325
350
375
400
425
0 10 20 30 40 50 60 70 80 90
Temperature(°C)
Time (hours)
Peak T
≤206 wppm H
in solution
Precipitation T
5°C/h
Δp = Δp(T)
σθ = σθ(T)1-Cycle
Drying

35. 35
Temperature Histories for 1- and 3-Cycle
Tests at 350o
C Peak RHT Temperature
175
200
225
250
275
300
325
350
375
0 10 20 30 40 50 60 70 80
Temperature(°C)
Time (Hours)
4.8°C/h
126-wppm H in solution
Precipitation
Temperature
(285°C)
1 Cycle

36. 36
Ring Compression Test (RCT)
Applied load @ 12 o’clock
Ductility: permanent (dp/Dmo) or offset
strain (δp/Dmo) prior to >50% wall crack
Embrittlement: dp/Dmo <1% or δp/Dmo <2%
Controlled displacement rates
5 mm/s typical
1.7-mm maximum displacement
Controlled temperature
Maximum δp/Dmo ≈10%
for 1.7 mm displacement

37. 37
RCT Benchmark Test with
As-Fabricated M5®
0.0
0.1
0.2
0.3
0.4
0.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Load(PinkN)
Displacement (δ in mm)
KLM = 1.06 kN/mm
Offset Displacement = 0.94 mm
Permanent Displacement = 0.83 mm
KLC = 1.23 kN/mm
0.94 mm
KUM = 0.81 kN/mm
0.83 mm

38. 38
RCT Benchmark Tests with
As-Fabricated and High-Exposure M5®
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Unloading/LoadingStiffnessRatio
Offset Strain (%)
As-Fabricated Cladding
High-Burnup Cladding

39. 39
Load-Displacement Curve and Crack
at ≈6 O’Clock for 3-Cycle Rodlet
Tested at 135o
C RCT
0.0
0.1
0.2
0.3
0.4
0.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Load(kN)
Displacement (mm)
Ring 105E3 at 135°C
564±177 wppm H
30±11% RHCF
11.9% Offset Strain
KLM = 0.90 kN/mm
478 N
423 N
1.12 mm
KU = 0.70 kN/mm

40. 40
Load-Displacement Curves for 1-Cycle
Rodlet Tested at 135o
C RCT
0.0
0.1
0.2
0.3
0.4
0.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Load(kN)
Displacement (mm)
Ring 105F3 at 135°C
644±172 wppm H
37±11% RHCF
1.1% Offset Strain
KLM = 0.90 kN/mm
449 N
43%
0.10 mm
KU = 0.88 kN/mm

41. 41
Load-Displacement Curve and Crack
at 12 O’Clock for 1-Cycle Rodlet
Tested at 150o
C RCT
0.0
0.1
0.2
0.3
0.4
0.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Load(kN)
Displacement (mm)
Ring 105F7 at 150°C
644±172 wppm H
37±11% RHCF
2.9% Offset Strain
KLM = 0.86 kN/mm
322 N
281 N
25%
0.27 mm
KU = 0.79 kN/mm

42. 42
Radial Hydrides in High-Exposure M5®
following Cooling from 350o
C/89-MPa
Maximum – 95% RHCF

43. 43
Radial Hydrides in High-Exposure M5®
following Cooling from 350o
C/89-MPa;
after Grinding off 0.5 mm & Polishing
Maximum – 95% RHCF

44. 44
Radial Hydrides in High-Exposure M5®
following Cooling from 350o
C/89-MPa;
after Grinding off ≈0.1 mm & Polishing
Maximum – 91% RHCF