Radial hydrides Jean Desquines*, Manfred Puls**, Stphane Charbaut* - - PowerPoint PPT Presentation

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Radial hydrides Jean Desquines*, Manfred Puls**, Stphane Charbaut* - - PowerPoint PPT Presentation

Apr 07, 2023 46 likes •320 views

Influence of Thermo-mechanical Cycling on Pre-hydrogenated Zircaloy-4 Embrittlement by Radial hydrides Jean Desquines*, Manfred Puls**, Stphane Charbaut* and Marc Philippe* *IRSN **MPP Consulting IRSN/FRM-296 ind 5 Context &

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IRSN/FRM-296 ind 5

Influence of Thermo-mechanical Cycling

  • n

Pre-hydrogenated Zircaloy-4 Embrittlement by Radial hydrides

Jean Desquines*, Manfred Puls**, Stéphane Charbaut* and Marc Philippe*

*IRSN **MPP Consulting

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

Context & Objectives

▌ Situations where thermo-mechanical cycling of fuel rods is expected:

  • Dry cask storage,
  • Spent fuel transportation from one spent fuel pool to another one

▌ Expected influence of cycling based on literature data

  • No clear trend (Kearns, Mishima, Chu, Sakamoto, Billone,...)
  • Possibly more radial hydrides and rather stronger embrittlement

▌ Main Goals of the study: clarify the expected influence of cycling on radial

hydride precipitation:

  • Relying on a large data set on single cycle test results using « C »-shaped samples,
  • Then cycle samples and evaluate the radial hydride precipitation and cladding

embrittlement.

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1- Experimental protocol

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“C”-Shaped Compression Tests in the Elastic Range

1 2 3 4 5 6 7 8 0.1 0.2 0.3 0.4 0.5 0.6

fqq= 0.0

X: location within the cladding thickness

(0: Outer Diameter, 1: Inner diameter)

fqq= 0.0

s: curvilinear distance to A (mm)

𝜏𝑢 𝑦, 𝑡 = 𝜏𝑢 𝐵 . 𝑔

𝜄𝜄 𝑦, 𝑡

𝜏𝑢 𝐵 = 𝐺 𝑂 0.013 𝑀 𝑛𝑛

Stress free area Stress free area A q r CCT sample Load Load

x 1 s

A F 𝑀 Equator

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

Radial Hydride Heat Treatments (RHT) considered

100 200 300 350 4 8 12 16 20

Compression load

Temperature (°C) Time (h)

5 N

315°C

FRHT 20°C/h 2h 1h

Temperature (°C) Time (h)

5 N

365°C

FRHT 20°C/h

100 200 300 400 4 8 12 16 20

2h 1h Compression load 350°C Max temperature RHT 400°C Max temperature RHT

  • The load is applied as late as possible to limit the sample creep but

significantly before hydride precipitation

  • The creep is expected to increase linearly with cycle number

F [H] contents – 50 to 236 wppm

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

Equator

Post-test metallography

Using CCT to study radial hydride precipitation

Hydrided sample F RHT, 1 to 30 cycles (Constant Load) F.d at RT Failure test: CCT

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Experimental device

500 N load cell Fan cooling the load cell Furnace Electromechanical tension- compression machine

L1 L2 F.d 2.Re Furnace Simple model of the test

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

𝑋𝑓𝑚𝑚 𝑙𝑜𝑝𝑥𝑜 𝑛𝑏𝑢𝑓𝑠𝑗𝑏𝑚 𝑞𝑠𝑝𝑞𝑓𝑠𝑢𝑧 𝐺𝐹 𝑑𝑏𝑚𝑑𝑣𝑚𝑏𝑢𝑗𝑝𝑜

Interpretation of the RHT load displacement record

F.d Furnace 𝜀 = 𝜀𝑝𝑔𝑔𝑡𝑓𝑢 + 𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑓𝑚

+ 𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑢ℎ𝑓𝑠𝑛𝑏𝑚 + 𝜀𝑡𝑏𝑛𝑞𝑚𝑓 𝑑𝑠𝑓𝑓𝑞 + 𝜀𝑠𝑝𝑒𝑡 𝑢ℎ𝑓𝑠𝑛𝑏𝑚

Reasonably good agreement is obtained between calculations and measurement assuming 0 creep REOR-103 – first cycle

𝑏𝑒𝑘𝑣𝑡𝑢𝑓𝑒

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

Interpretation of the RHT load displacement record

𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑑𝑠𝑓𝑓𝑞

= 𝜀 − 𝜀𝑛𝑝𝑒𝑓𝑚 Creep deformation remains below ~1% diameter change after 30 cycles F.d Furnace time (h)

  • 0.4
  • 0.2

0.0 0.2 0.4 0.6 0.8 100 200 300 400 500

𝜀 − 𝜀𝑛𝑝𝑒𝑓𝑚(𝑛𝑛) REOR-103 –30 RHT cycles

Creep displacement (temperature stabilized)

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RHT & CCT Test matrix

350 & 400°C Max temperature – 1 to 30 cycles – [H] content below 240 wppm Maximum stress at equatorial location: between 190 and 220 MPa

RHT parameters

REOR-XXX ([H](wppm)) – Test ID and associated hydrogen content

Italic: the hydrogen content of tested conditions in past programs.

Cycles Number

1 2 5 10 30

Max RHT temperature(°C)

350

53 ; 63 ; 69 ; 74 ;

REOR-117 (109)

127 ; 141 ; 177 ; 217 ; 309 ; 322 ; 525 ; 540

REOR-114 (176) REOR-118 (95) REOR-115 (101) REOR-110 (139) REOR-106 (203) REOR-119 (86) REOR-116 (94) REOR-111 (138) REOR-112 (209) REOR-113 (210)

400

REOR-131 (61) REOR-133 (141) REOR-134 (187)

217 ; 218 ; 398 ; 478

REOR-126 (62) REOR-120 (78) REOR-125 (147) REOR-123 (236) REOR-121 (75) REOR-124 (148) REOR-135 (177)

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2- Analysis of Metallographic data

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RHT at 350°C max temperature

  • When cycling: higher density but comparable fraction of radial hydrides
  • Saturated influence of cycling over 5 cycles

1 5 10 30 130 200 REOR-17 [11] REOR-14 [11] REOR-110 REOR-106 REOR-111 REOR-112 REOR-113 Cycles [H] (wppm) Metallographs at equatorial location

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RHT at 400°C max temperature

Metallographs at equatorial location 1 5 10 150 200

REOR-134 REOR-125 REOR-123 REOR-124

Cycles [H] (wppm) 75

REOR-120 REOR-133 REOR-135 REOR-131 REOR-121

At H~200 wppm: higher density but comparable fraction of radial hydrides Below H~150 wppm: no influence of cycling

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Influence of cycling and stress on incipient radial hydride precipitation

Slight influence of cycling at 350°C maximum temperature No clear influence at 400°C

Tangential stress (MPa) [H] (wppm)

Mixed radial & circumferential hydrides

Circumferential hydrides

20 40 60 80 100 120 100 200 300 400 500 600 Temp. 1 2 350 5 10 30 RHT cycles

400°C RHT 350°C RHT

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

Influence of cycling and stress on radial hydride precipitation

Limited influence of cycling on radial hydride precipitation stress thresholds

Circumferential hydrides

Tangential stress (MPa) [H] (wppm)

Mixed radial & circumferential hydrides Radial hydrides

(Eq.10) 20 40 60 80 100 120 140 160 180 200 100 200 300 400 500 600

RHT maximum temperature (°C) 1 2 350 400 450 5 10 30 5 10 1 RHT cycles 0% 100% 1

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3- Radial hydride Embrittlement

F, d

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Load displacement records – an illustration

Crack nucleation is associated with the first significant load-drop and deviation to the elastic-plastic trend

2 4 6 8 10 12 14 16 18 20 0.5 1 1.5 2 2.5

Displacement (mm) CCT-112 (209wppm)

Elasticity Plasticity

CCT-115 (101wppm) Crack nucleation Brittle crack propagation Crack nucleation

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Load displacement records

Surprisingly ductile nucleation was associated with brittle crack propagation and brittle crack nucleation with ductile crack propagation

Rather high [H] contents &low fracture toughness Rather low [H] contents &high fracture toughness

Elasticity Plasticity

ductile britlle britle ductile Crack nucleation Crack propagation

F/L(N/mm) Displacement (mm)

2 4 6 8 10 12 14 16 18 20 0.5 1 1.5 2 REOR-110 REOR-106 REOR-111 REOR-112 REOR-113 REOR-114 REOR-115 REOR-116 REOR-117 REOR-118 REOR-119 REOR-120 REOR-121 REOR-123 REOR-124 REOR-125 RCT-126 REOR-131 REOR 133 REOR-134 REOR-135 2.5

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

Crack nucleation displacement – 1 cycle

Maximum sensitivity to crack nucleation at about [H]= 100 wppm, No obvious influence of maximum RHT temperature

Crack nucleation displacement (mm) [H] (wppm)

0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 100 200 300 400 500 600

350°C 400°C 450°C Maximum RHT temperature

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Crack nucleation displacement – several cycles

[H] (wppm)

0.5 1.0 1.5 2.0 100 200 300 400 500 600

Protective influence of RHT cycling Detrimental influence of RHT cycling

2 350 400 5 10 30 5 10 RHT cycles Temp.

Crack nucleation displacement (mm)

350°C RHT cycling trend

  • Regions associated with higher density of radial hydrides have a lower

sensitivity to crack nucleation

  • Protective influence of RHT cycling on crack nucleation
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Conclusion

▌ The thermo-mechanical cycling was studied relying on CCT tests ▌ Analysis of metallographs

  • At 350°C for H contents between 75 and 230 wppm, and at 400°C for H contents

close to 200 wppm: shorter and denser hydrides observed,

  • A 400°C below 200 wppm, no influence of cycling is observed
  • The denser and short hydrides were associated with slightly easier radial hydride

precipitation

▌ A

protective influence

  • f

cycling was

  • bserved
  • n

radial hydride embrittlement.

▌ Extrapolation of these results to irradiated claddings:

If there is any location containing 100 wppm, then no influence of cycling is expected

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Stress at crack nucleation– several cycles

Brittle crack nucleation region remains at [H] contents of about 100 wppm and no influence of cycling is observed in this region

Crack nucleation tangential stress (MPa) [H] (wppm)

Plasticity Elasticity

500 700 900 1 100 1 300 1 500 100 200 300 400 500 600 2 350 400 5 10 30 5 10 RHT cycles Temp.

350°C RHT cycling trend

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19TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY

  • 3.0
  • 2.0
  • 1.0

0.0 0.5 2 4 6 8 10

12

14 16 18

Model Record d(mm) 50 N loading Cooling @ 20°C/h 2h dwell @ 350°C heating Time (h)

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𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑓𝑚

= 𝐺 1 − 𝜉2 2.6410−3𝐹. 𝑀 𝑓 𝑆𝑓 − 𝑓

2.7644

Interpretation of the RHT load displacement record

L1 L2 F.d 2.Re Furnace 𝜀 = 𝜀𝑝𝑔𝑔𝑡𝑓𝑢 + 𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑓𝑚

+ 𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑢ℎ𝑓𝑠𝑛𝑏𝑚 + 𝜀𝑡𝑏𝑛𝑞𝑚𝑓 𝑑𝑠𝑓𝑓𝑞 + 𝜀𝑠𝑝𝑒𝑡 𝑢ℎ𝑓𝑠𝑛𝑏𝑚

𝜀𝑠𝑝𝑒𝑡

𝑢ℎ𝑓𝑠𝑛𝑏𝑚

= −15.510−6 𝑈 − 𝑈0 . 𝑀1 + 𝑀2 𝜀𝑡𝑏𝑛𝑞𝑚𝑓

𝑢ℎ𝑓𝑠𝑛𝑏𝑚

= −5.610−6 𝑈 − 𝑈0 · 2𝑆𝑓

Reasonably good agreement is obtained between calculations and measurement assuming 0 creep REOR-103 – first cycle

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Load displacement records

Surprisingly ductile nucleation was associated with brittle crack propagation and brittle crack nucleation with ductile crack propagation

2 4 6 8 10 12 14 16 18 20 0.5 1 1.5 2 2.5

Displacement (mm) CCT-112 (209wppm) 𝐺 𝑀 𝑂/𝑛𝑛

Elasticity Plasticity

CCT-115 (101wppm) Crack nucleation Brittle crack propagation Crack nucleation

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Elasticity Plasticity

ductile brittle brittle ductile Crack nucleation Crack propagation

F/L(N/mm) Displacement (mm)

2 4 6 8 10 12 14 16 18 20 0.5 1 1.5 2 REOR-110 REOR-106 REOR-111 REOR-112 REOR-113 REOR-114 REOR-115 REOR-116 REOR-117 REOR-118 REOR-119 REOR-120 REOR-121 REOR-123 REOR-124 REOR-125 RCT-126 REOR-131 REOR 133 REOR-134 REOR-135 2.5