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Industry Position on the RIA Failure Limit Robert Montgomery ANATECH Corp. NRC – Industry Workshop RIA Criteria October 16, 2007 Washington, DC
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Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

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Page 1: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

Industry Position on the RIA Failure Limit

Robert MontgomeryANATECH Corp.

NRC – Industry Workshop RIA Criteria

October 16, 2007

Washington, DC

Page 2: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

2© 2006 Electric Power Research Institute, Inc. All rights reserved.

Discussion Topics

•Summary of Interim Failure Criteria• Industry methodology to adjust experimental data

•Data adjustment approaches– Pulse width effects for BWRs– Temperature Scaling of NSRR tests– MOX effects

•Summary

Page 3: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

3© 2006 Electric Power Research Institute, Inc. All rights reserved.

NRR Interim RIA Failure Criteria:

• Fuel Cladding Failure Criteria– Enthalpy thresholds defined for both PCMI and post-DNB failure

modes

• Pellet-Cladding Mechanical Interaction (PCMI) Failure– Threshold on prompt fuel enthalpy rise (ΔH) – Function of corrosion layer thickness (PWRs) or hydrogen content

(BWRs)

• High temperature failure– Threshold on peak enthalpy as a function of rod pressure in

HZP/HCP cases (170 cal/gm→150 cal/gm)– DNBR/CPRR for at-power conditions

Page 4: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

4© 2006 Electric Power Research Institute, Inc. All rights reserved.

PCMI Fuel Cladding Failure Criterion - PWR

Page 5: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

5© 2006 Electric Power Research Institute, Inc. All rights reserved.

PCMI Fuel Cladding Failure Criterion - BWR

Page 6: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

6© 2006 Electric Power Research Institute, Inc. All rights reserved.

Conservatisms in PCMI Failure Criteria

• NSRR CZP tests may over emphasize role of corrosion/hydrogen– Anticipate that tests in the HTHP capsule in NSRR will allow

better scaling of NSRR CZP tests

• Interpretation of MOX tests conservative– Continued use of data from MOX tests to set UO2 limits

• BWR threshold is conservative for temperatures > 20ºC and broader power pulses– Hydrogen solubility and temperature effects on cladding ductility– Effects of pulse width on temperature and ductility

Page 7: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

7© 2006 Electric Power Research Institute, Inc. All rights reserved.

Re-assessment of RIA-Simulation Test Database

• Use mechanistic approach to adjust experimental data for non-representative conditions– Low initial coolant temperature– Narrow pulse width– MOX pellet behavior– Spalled oxide layers

• Identify most appropriate independent variable to express failure threshold– Oxide thickness or hydrogen content

Page 8: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

8© 2006 Electric Power Research Institute, Inc. All rights reserved.

Methodology to Adjust RIA Experimental Data

• Validated analytical model that represents fundamental thermal and mechanical behavior of fuel rod under rapid heating– Transient heat generation, storage, and conduction in pellet, gap,

and cladding– Thermal expansion of pellet and cladding– Pellet-cladding mechanical interaction– Pellet and cladding elastic and plastic deformation

• Parameter/method to assess cladding failure– Function of cladding condition (fluence, temperature, hydrogen

content and morphology, etc.)– Compatible with failure mechanism observed

Page 9: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

9© 2006 Electric Power Research Institute, Inc. All rights reserved.

FALCON-SCANAIR (and FRAPTRAN) Comparison

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70SED - SCANAIR (MJ/m3)

SE

D -

FALC

ON

(MJ/

m3)

Unfailed UO2 Rods

Failed UO2 Rods

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00Measured Hoop Strain (%)

Pre

dict

ed H

oop

Stra

in (%

)

CABRI UO2 - Falcon

CABRI UO2 - Scanair

CABRI UO2 - FRAPTRAN

Permanent Hoop Strain

Strain Energy Density

Reasonable agreement between the codesSome differences noted at higher strains

Page 10: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

10© 2006 Electric Power Research Institute, Inc. All rights reserved.

Cladding Failure Model

• Cladding performance indicators from mechanical testing– Yield stress or ultimate tensile stress– Uniform or total strain– Critical strain energy density (CSED) or fracture toughness

• Choose CSED to develop failure model– Energy approach can accommodate the multi-axial stress state

failure mode observed in RIA experiments– Put different mechanical test methods on similar basis to

maximize use of irradiated cladding database

Page 11: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

11© 2006 Electric Power Research Institute, Inc. All rights reserved.

Stress-Strain Curve Nomenclature

CSED – Area Under the Stress-Strain Curve

σy

σu

σt

εe εe + εue εe + εte

εue εte

True Strain

True Stress

Page 12: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

12© 2006 Electric Power Research Institute, Inc. All rights reserved.

CSED Model Develop/Application

• Derived from mechanical property tests on irradiated cladding material– Ring tension, axial tension, and burst tests– Correlated with corrosion thickness or hydrogen content, alloy type and

temperature– Model validated using results from non-failed and failed CABRI and NSRR tests

• Recent focus on burst test results correlated as function of local hydrogen content in fracture region

– Reduces data scatter and separate treatment of spalled/non-spalled oxide thickness samples

– Working to improve temperature dependency

• Mechanical property data overpredicts failure potential for PCMI loading– Difficult to reproduce PCMI conditions in mechanical property tests– Inconsistencies in loading conditions, frictional effects, and active gauge section

Page 13: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

13© 2006 Electric Power Research Institute, Inc. All rights reserved.

Original CSED Database and Model

Oxide/Cladding Thickness Ratio

0.00 0.05 0.10 0.15 0.20 0.25

Crit

ical

Stra

in E

nerg

y D

ensi

ty, M

Pa

0

10

20

30

40

50

60 Ring Tension 280 - 400 C Burst 300 - 350 C Best Fit to Non-SpalledBest Fit to Spalled

Note: Solid symbols are spalled data

Data scatter caused variations in test and material conditions

Oxide/Cladding Thickness Ratio

0.00 0.05 0.10 0.15 0.20 0.25

Crit

ical

Stra

in E

nerg

y D

ensi

ty (M

J/m

3 )0

2

4

6

8

10

12

14

16

18Temperature < 150ºC

Page 14: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

14© 2006 Electric Power Research Institute, Inc. All rights reserved.

Validation of Best-Fit CSED/SED Approach

CSED/SED Methodology Able to Separate Failed and Non-Failed Tests

O xide /C ladd ing T h ick ness R a tio (-)

0 .00 0 .05 0 .10 0 .15 0 .20 0 .25 0 .30

Stra

in E

nerg

y D

ensi

ty (M

J/m

3 )

0

5

10

15

20

25

30

35

40

45

N on-S pa lled C S E D M ode lS pa lled C ladd ing C S E D M ode l

R E P N a-2

R E P N a-3R E P N a -5

C IP 0 -2R E P N a -4R E P N a -10 R E P N a-8

C IP 0 -1

Spalled Rods

CABRI Test Rods (T > 280°C)

Solid symbol - test rods with cladding failure

HBO 2

HBO 1

HBO 4

HBO 5

HBO 3 HBO 7HBO 6

TK 2

TK 7

TK 5TK 4

TK 3

TK 6TK 1

0

5

10

15

20

25

30

35

0.00 0.02 0.04 0.06 0.08 0.10Oxide/Cladding Thickness Ratio

SE

D a

t Fai

lure

of A

fter P

ulse

(MJ/

m3)

Best Fit Non-Spalled CSED Model (T < 150°C)

NSRR-PWR Test Rods (T < 150°C)

Page 15: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

15© 2006 Electric Power Research Institute, Inc. All rights reserved.

Cladding Failure Model – PWR

0 200 400 600 800 1000 1200 1400 1600 1800 20000

5

10

15

20

25

30

35

40

Burst Tests

Best-Fit to Burst DataSpalled

Local Hydrogen Content (ppm)

CSE

D (M

J/m

3 )Burst Tests from Zr-4 Cladding

TE < 3%300-350ºC

Page 16: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

16© 2006 Electric Power Research Institute, Inc. All rights reserved.

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

0 200 400 600 800 1000 1200 1400

Hydrogen Content (ppm)

CSE

D (M

J/m

3)

New CSED Model - Burst Tests

CABRI Rods Non-Failed

CABRI Rods - Failed

Fuel Rod Failure Prediction for CABRI Tests

REP Na-2

REP Na-3

REP Na-5

CIP0-2REP Na-4

CIP0-1

REP Na-8

REP Na-10

CSED Model from Burst Tests (T > 280ºC)

FALCON Results

Page 17: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

17© 2006 Electric Power Research Institute, Inc. All rights reserved.

Cladding Failure Model - BWR

Rapid Burst Tests - 25°C (NFIR-IV and TEPCO)

0 100 200 300 400 500 6000

10

20

30

40

Burst Test DataBest-Fit to Rapid Burst Data

Hydrogen Content (ppm)

CSE

D (M

J/m

3 )

Page 18: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

18© 2006 Electric Power Research Institute, Inc. All rights reserved.

0.00

200.00

400.00

600.00

800.00

1000.00

1200.00

1400.00

0 20 40 60 80 100 120 140Oxide Thickness (microns)

Hyd

roge

n C

onte

nt (p

pm)

Cladding Hydrogen Content Estimates -CABRI

Na-2Na-5CIP0-2

Na-4

~15% H-Pickup for 17x17 Cladding

Na-3

Na-8

Na-10

CIP0-1

Na-7 Na-12

Na-1

Na-1

Rod Q02

Page 19: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

19© 2006 Electric Power Research Institute, Inc. All rights reserved.

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

0 20 40 60 80 100 120 140Oxide Thickness (microns)

Est.

Hyd

roge

n C

onte

nt (p

pm)

Cladding Hydrogen Content Estimates - NSRR

~15% H-Pickup for 17x17 Cladding

Page 20: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

20© 2006 Electric Power Research Institute, Inc. All rights reserved.

0

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800 1000 1200 1400Estimated Test Rod Hydrogen Content (ppm)

Fuel

Ent

halp

y R

ise

(cal

/gm

)

CABRI UO2 Non-FailedCABRI UO2 - FailedCABRI MOX Non-FailedCABRI MOX FailedNSRR - Non-FailedNSRR FailedNSRR MOX Failed

PWR RIA Database as Function of Hydrogen

Page 21: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

21© 2006 Electric Power Research Institute, Inc. All rights reserved.

Improvement for the Final PCMI Failure Criteria

• Account for the effect of pulse width on BWR failure threshold at CZP conditions

• Improve temperature scaling of the CZP NSRR experiments based on upcoming HTHP capsule results

• Improve MOX scaling using new NSRR tests and CABRI results

• Reformulate PWR PCMI criteria into hydrogen space to address oxide spallation/high hydrogen conditions

• Perform assessment and comparison of analytical methodologies to determine best approach for improved temperature scaling

Page 22: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

22© 2006 Electric Power Research Institute, Inc. All rights reserved.

Pulse Width Effects for BWRs

Page 23: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

23© 2006 Electric Power Research Institute, Inc. All rights reserved.

BWR-Specific Issues in Control Rod Drop Accident

• Accident can initiate at temperatures well below 280ºC• Power pulse shapes significantly non-gaussian,

especially at low temperature with large fraction of non-prompt energy deposition

• Assessment is required to justify interim BWR threshold or develop new failure threshold for BWR CRDA

Page 24: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

24© 2006 Electric Power Research Institute, Inc. All rights reserved.

Ways to Improve the BWR PCMI Failure Criterion

• Interim failure criterion uses lower bound of NSRR tests on BWR rods– Include consideration of pulse width differences (4 ms versus 30

ms) between experiments and postulated rod drop accident

• Overly conservative when combined with most limiting accident analysis– Include heat conduction impact on cladding properties

• Awaiting HZP test in NSRR (LS-2) and CABRI (?)

Page 25: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

25© 2006 Electric Power Research Institute, Inc. All rights reserved.

Schematic of BWR CRDA Power PulseLo

g Fu

el R

od P

ower

Time

Prompt Pulse Delayed Pulse

Pulse Width

DepositionEnergyTotalDepositionEnergyomptPrFP =

( )K,T,DH,BuFPW coolmax1=

( )K,T,DH,BuFF coolmax2p =

( )213 F,F,tF)t(P =

Page 26: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

26© 2006 Electric Power Research Institute, Inc. All rights reserved.

Pulse Width versus Dynamic Control Blade Worth

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00

Dynamic Control Blade Worth ($)

Puls

e W

idth

(sec

)

20C-BOC 20C-EOC 20C-BOC 20C 20C BOCFRG Rpts Literature 20C BOC APEX 20C20C 20C 100C 100C 160C 160C286C 286C 286C

Dynamic blade worth is defined as the peak reactivity during the transient.

Most blades have a dynamic worth less than $1.60.

BWR Pulse Widths versus Control Blade Worth

Page 27: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

27© 2006 Electric Power Research Institute, Inc. All rights reserved.

Action Plan to Develop BWR Specific Failure Threshold

• Develop BWR-specific Power Pulse Shapes

• Develop CSED model for BWR Cladding

• Validate BWR-specific CSED model and FALCON

• Construct BWR-Specific Failure Threshold

Page 28: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

28© 2006 Electric Power Research Institute, Inc. All rights reserved.

General Assumptions used in FALCON Analyses

• Model based on the FK-6 test geometry• Gaussian pulse used for the peak pulse energy• The delayed tail based on IBERINCO calculations for

20°C • Modified with various peak pulse energies and pulse

widths– 70-131 cal/g peak energy– 10 to 30 ms pulse widths

Page 29: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

29© 2006 Electric Power Research Institute, Inc. All rights reserved.

0

20000

40000

60000

80000

100000

120000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Time (secs)

Line

ar P

ower

(KW

/M) FK-6 (4.3 ms)

131 cal/g @ 30 ms

Example of the Power Pulse Shape used in FALCON Analyses

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0.3 0.8 1.3 1.8 2.3 2.8Time (secs)

Line

ar P

ower

(KW

/M) FK-6 (4.3 ms)

131 cal/g @ 30 ms

Page 30: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

30© 2006 Electric Power Research Institute, Inc. All rights reserved.

Fuel Enthalpy as a Function of Time Calculated by FALCON

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7 8 9 10

Time (secs)

Enth

alpy

(cal

/g)

FK-6 (4.3 ms)131 cal/g @ 30 ms + tail131 cal/g @ 20 ms + tail131 cal/g @ 10 ms + tail

Page 31: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

31© 2006 Electric Power Research Institute, Inc. All rights reserved.

FALCON Calculated Strain Energy Density as a Function of Cladding Mid-Wall Temperature

0

5

10

15

20

25

30

20 40 60 80 100 120 140 160 180 200

Cladding Mid-Wall Temperature (C)

Cla

ddin

g St

rain

Ene

rgy

Den

sity

(MJ/

M3)

30 ms pulse + tail

FK-6 (4.3 ms pulse)

20 ms pulse + tail

10 ms pulse + tail

Failure Point

For FK-6

Page 32: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

32© 2006 Electric Power Research Institute, Inc. All rights reserved.

Temperature Effect on BWR Mechanical Behavior

0.00

5.00

10.00

15.00

20.00

25.00

0 50 100 150 200 250 300 350 400

Temperature (C)

Max

imum

Hoo

p St

rain

(%)

BWR Failed 60-130 ppmH BWR Non-Failed 60-130 ppmH BWR Failed 250-350 ppmHBWR Non-Failed 250-350 ppmH PWR Failed 320-570 ppmH PWR Non-Failed 470 ppmH

Irr. Zr-2 60-130 ppmH

Irr. Zr-2 250-350 ppmH

Irr. Zr-4 320-570 ppmH

Studsvik EDC Test ResultsRange of NSRR Initial Coolant Temperature in Tests with Cladding Failure

H content 200 to 450 ppm

Page 33: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

33© 2006 Electric Power Research Institute, Inc. All rights reserved.

Temperature Dependent CSED Model for BWRs

Rapid Burst Tests - (NFIR-IV and TEPCO)

0 100 200 300 400 500 6000

10

20

30

40

50

Burst Test Data 25°CBurst Test Data 150°CBurst Test Data 250°CBurst Test Data 300°C

300°C

200°C150°C25°C

Hydrogen Content (ppm)

CSE

D (M

J/m

3 )

[ ]04.4e5.26)T,H(FCSED )(H0113.0(T +⋅∗= ⋅−

FT > 1.0 for H>Hcrit

FT = 1.0 for H<Hcrit

FT = 1.0 for T<25ºC

Page 34: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

34© 2006 Electric Power Research Institute, Inc. All rights reserved.

Observations

• FALCON calculations demonstrate improvement in cladding ductility with increased temperature for characteristic BWR power pulse shape

• Potential increase in fuel enthalpy at failure – BWR PCMI hydrogen contents between 75 and 250 ppm

• An Action Plan has been developed for generating a BWR specific failure threshold that includes the characteristic BWR pulse shape

Page 35: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

35© 2006 Electric Power Research Institute, Inc. All rights reserved.

Alternative BWR PCMI Failure Criteria –Improved Consideration for NSRR Tests

NSRR Database of BWR rods

0 50 100 150 200 250 300

Fuel

Ent

halp

y R

ise

(cal

/gm

)

200

0

175

150

125

100

75

50

25

Nonfailed NSRR BWR Fuel

Failed NSRR BWR Fuel

BWR Failure Criteria

Hydrogen Content (ppm)

- Pulse Width Adjustment

Page 36: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

36© 2006 Electric Power Research Institute, Inc. All rights reserved.

Improved Temperature Scaling

Page 37: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

37© 2006 Electric Power Research Institute, Inc. All rights reserved.

Improvement for Final Failure Criteria–Temperature Scaling

• Interim failure criteria use a lower bound of adjusted RIA-simulation test results – Adjustments developed using FRAPTRAN– Adjustments were made assuming no difference exists between:

• Room temperature and hot-zero power cladding ductility

• Newer experimental data and fully qualified analytical methods can improve data adjustments to account for;– Improved cladding ductility with increase in temperature and

hydrogen solubility effects

• Results dependent on the analytical methods used

Page 38: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

38© 2006 Electric Power Research Institute, Inc. All rights reserved.

Need for Temperature Scaling

• Most PWR and BWR NSRR experiments with high burnup fuel have been performed at room temperature– Rod failure controlled by low ductility of highly irradiated cladding

at room temperature

• Fuel enthalpy at PCMI failure can be higher at high temperature due to the recovery of cladding ductility– Improved Zircaloy matrix strain accommodation– More zirconium hydride deformation capability

Page 39: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

39© 2006 Electric Power Research Institute, Inc. All rights reserved.

Active Fuel Rod Deformation and Failure Mechanisms

Test Rod

Failure Enthalpy (cal/g)

Rim Temp at Failure

(°C)

Total Hoop Strainat Failure*

( % )

Estimated Cladding Hydrogen Content

(ppm) HBO-1 60 1500 0.70 300

TK-2 60 1369 0.60 200

FK-7 62 1887 0.62 220

FK-6 70 2288 0.71 220

HBO-5 77 1702 0.74 300

REP Na 10† 79 1415 0.67 >600

REP Na 8† 82 1365 0.69 >600

TK-7 86 1918 0.94 200

FK-9 86 1978 0.94 150

*- Elastic+plastic cladding hoop strain as calculated by FALCON

† - Spalled oxide layer and localize hydride formations

Low cladding strain at failure PCMI-Induced Failure Mechanism

Pellet-clad gap

Clad ductility

Burnup

ΔH

Burnup

Failure by post-DNB operation

Failure by PCMI

30-40 GWd/T

Pellet-clad gap

Clad ductility

Burnup

ΔH

Burnup

Failure by post-DNB operation

Failure by PCMI

Pellet-clad gap

Clad ductility

Burnup

ΔH

Burnup

Failure by post-DNB operation

Failure by PCMI

Pellet-clad gap

Clad ductility

Burnup

ΔH

Burnup

Failure by post-DNB operation

Failure by PCMI

30-40 GWd/T

Fuel Rod Failure in High Burnup UO2 Fuel is controlled by PCMI and cladding ductility

Page 40: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

40© 2006 Electric Power Research Institute, Inc. All rights reserved.

Temperature Effect on Ductility of Hydrided Cladding

NFIR Burst Tests

0 50 100 150 200 250 300 350 400 4500.0

0.5

1.0

1.5

2.0

2.5

3.0

H = 450 - 930 ppm

H = 430 - 640 ppm

Temperature (C)

Tota

l Pla

stic

Elo

ngat

ion

(%)

Irradiated Zr-4 tubes

Page 41: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

41© 2006 Electric Power Research Institute, Inc. All rights reserved.

Temperature Increases Strain to Fracture

Higher temperature has twice the fracture strain

Recrystallized Cladding - 25°C - 300 °CCold-Work Stress-Relieved Cladding - 25°C - 300 °C

300°C Trend Line

25°C Trend Line

Plane-Strain Ring Tests on Unirradiated, Pre-hydrided Cladding

Page 42: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

42© 2006 Electric Power Research Institute, Inc. All rights reserved.

Action Plan to Adjust CZP NSRR Tests

• Confirm HZP CSED model using HTHP tests at NSRR– Identify adjustments for 4 ms pulse width– May require detailed modeling to account for small rodlet

geometry– Results expected in 2008

• Use CSED model for HZP conditions to calculate enthalpy at failure for CZP NSRR PWR tests– Develop ΔH adjustment as function of hydrogen content to be

added to CZP NSRR test results

Page 43: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

43© 2006 Electric Power Research Institute, Inc. All rights reserved.

HTHP Capsule Tests

• A new type of NSRR test capsule was developed to confirm the high temperature effect on PCMI failure limit– High Temperature/High Pressure enables tests at LWR

operation / hot startup conditions

• Total of 5 tests are planned in the HTHP capsule– Only one test reported at this time (RH-2)

Page 44: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

44© 2006 Electric Power Research Institute, Inc. All rights reserved.

High Temperature / High Pressure Test Capsule

Page 45: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

45© 2006 Electric Power Research Institute, Inc. All rights reserved.

Comparison Between RT and HTHP Capsules

Page 46: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

46© 2006 Electric Power Research Institute, Inc. All rights reserved.

Planned High Temperature Tests in 2007-2008

Fuel Type, Cladding, BurnupRoom

Temperature Tests*

High Temperature

tests **Corrosion/Hydrogen

PWR-UO2, MDA, 78 GWd/t VA-1 VA-3 ~70 μm / 760 ppm

PWR-UO2, ZIRLO, 79 GWd/t VA-2 VA-4 ~70 μm / 660 ppm

BWR-UO2, Zry-2, 69 GWd/t LS-1 LS-2 ~25 μm / 300 ppm

PWR-MOX, Zry-4, 59 GWd/t BZ-2 BZ-3 ~20 μm / 150 ppm

* The 4 RT tests resulted in PCMI Failure

** Corresponding RT and HTHP Test fuel rods were sampled from an identical fuel segment

4Q 2007

2Q 2008

3Q 2008

1Q 2008

Page 47: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

47© 2006 Electric Power Research Institute, Inc. All rights reserved.

Test RH-2 Description

Page 48: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

48© 2006 Electric Power Research Institute, Inc. All rights reserved.

Preliminary Test Results for RH-1 and RH-2

* Based on Numerical Analyses

RH-2 RH-1Fuel Enthalpy Increase 104 cal/g* 127 cal/g*

Failure state No Failure No Failure

DNP Occurance occurred No DNB

Cladding Residual Hoop Strain (Max) 1.06% 0.96%

(Avg) 0.80%

Fission Gas Release during Test TBD 21.40%

RH-2 (HTHP) RH-1 (RT)

Page 49: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

49© 2006 Electric Power Research Institute, Inc. All rights reserved.

FALCON Comparisons for RH-2

9.4

9.42

9.44

9.46

9.48

9.5

9.52

9.54

9.56

9.58

9.6

0 20 40 60 80 100 120 140Axial Position (mm)

Cla

d O

uter

Dia

met

er (m

m)

Measured BeforeMeasured AfterFALCON

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100 120 140Axial Position (mm)

Res

idua

l Hoo

p St

rain

(%)

Measured

FALCON

Page 50: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

50© 2006 Electric Power Research Institute, Inc. All rights reserved.

FALCON Comparisons for RH-1

9.4

9.42

9.44

9.46

9.48

9.5

9.52

9.54

9.56

9.58

9.6

0 50 100 150 200Axial Position (mm)

Cla

d O

uter

Dia

met

er (m

m)

Measured Before

Measured After

FALCON

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200

Axial Position (mm)

Res

idua

l Hoo

p St

rain

(%)

Measured

FALCON

Page 51: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

51© 2006 Electric Power Research Institute, Inc. All rights reserved.

Effect of Temperature on FALCON Calculated Strain Energy Density

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

0 20 40 60 80 100 120 140Enthalpy (cal/g)

SED

(MJ/

m3)

RH-1RH-2

Page 52: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

52© 2006 Electric Power Research Institute, Inc. All rights reserved.

Conclusions Based on RH-2 HTHP Capsule Test

• Test RH-2 showed an as-predicted level of cladding residual hoop strain in comparison with the room temperature test RH-1.

• Calculations show improved cladding ductility at higher initial temperatures compared to room temperature tests.– Potential increase in fuel enthalpy at failure – PWR PCMI oxide thickness levels between 25 and 60 μm

• Temperature effect on PCMI failure limit will be confirmed in coming tests.

Page 53: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

53© 2006 Electric Power Research Institute, Inc. All rights reserved.

Alternative PWR PCMI Failure Criteria –Improved Consideration for MOX and NSRR Tests

-Temperature adjustment

Temperature Considerations

0.00 0.04 0.08 0.12 0.16 0.20

50

100

150

200

250

300

350

Oxide/Wall Thickness

Adj

uste

d Fu

el E

ntha

lpy

Ris

e (c

al/g

)

BIGRCABRI UO2

IGRNSRRPBFSPERT

CABRI MOX

Filled Symbols – Cladding Failure

Page 54: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

54© 2006 Electric Power Research Institute, Inc. All rights reserved.

Discussion of MOX Effects

Page 55: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

55© 2006 Electric Power Research Institute, Inc. All rights reserved.

Improvement for Final Failure Criteria – MOX Effect

• Interim failure criteria based on lower bound of adjusted RIA-simulation test results that included MOX fuel – Adjustments were made assuming no difference exists between

UO2 and MOX fuel pellet response– More severe loading response in irradiated MOX fuel pellet due

to widely distributed high burnup structure throughout pellet

• Recent results from MOX tests on BWR and PWR rods from NSRR – Burnups range from 45 to 59 GWd/tU– Tested in room temperature capsule– Lower burnup BWR rod survived, two high burnup PWR rods

failed – MOX effect or Temp. effect ?

Page 56: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

56© 2006 Electric Power Research Institute, Inc. All rights reserved.

MOX Pellet Behavior More Severe than UO2

REP Na-8Bu = 63 GWd/MTUHfail = ~80 cal/gHmax = ~100 cal/g

REP Na-7Bu = 55 GWd/MTHMHfail = ~113 cal/gHmax = 150 cal/g

Countries that use MOX fuel have proposed (or implemented) separate criteria for MOX fuel

Page 57: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

57© 2006 Electric Power Research Institute, Inc. All rights reserved.

MOX Effect on Fuel Rod Expansion

y = 0.026x - 0.5265R2 = 0.9999

y = 0.0118x - 0.2674R2 = 0.9871

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

20 25 30 35 40 45 50 55 60 65 70

Test Rod Burnup (GWd/tU)

Dis

plac

ed S

odiu

m V

olum

e (c

m3 )

UO2 Fuel

MOX Fuel

Trend Line - MOX

Trend Line - UO2

Fuel rod volume expansion in MOX fuel 2-3 times larger than UO2 fuel

@ fuel enthalpy = 70 cal/gm

Page 58: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

58© 2006 Electric Power Research Institute, Inc. All rights reserved.

MOX Tests DW-1, BZ-1 and BZ-2

First NSRR experiments with MOX fuel irradiated in commercial plants

Page 59: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

59© 2006 Electric Power Research Institute, Inc. All rights reserved.

BWR Cladding Deformation UO2 – MOX Comp.

Different ?

Below Burnup for Strong PCMI Effect in FALCON MOX model

45 GWd/tU

Page 60: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

60© 2006 Electric Power Research Institute, Inc. All rights reserved.

Fuel Enthalpy at Failure

Page 61: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

61© 2006 Electric Power Research Institute, Inc. All rights reserved.

PWR Fuel Enthalpy at Failure

+

Temperature Effect or MOX Effect ?

Page 62: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

62© 2006 Electric Power Research Institute, Inc. All rights reserved.

Comparison of UO2 and MOX Fuel - NSRR

UO2 Test OI-11 – Brittle Behavior

MOX Test BZ-2 – Ductile Behavior

Temperature Effect on Ductility Makes Observation of MOX Effect Difficult in CZP NSRR

Page 63: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

63© 2006 Electric Power Research Institute, Inc. All rights reserved.

Action Plan to Adjust REP Na-7 MOX Test

• Validate MOX model using both NSRR CZP/HTHP and CABRI MOX tests– Confirm MOX vs. Temperature effect in NSRR using BZ-3 test– May require detailed modeling to account for small rodlet

geometry used in HTHP capsule– Results expected in 2008

• Use FALCON to calculate enthalpy at failure for CABRI REP Na-7 as UO2 rod– Develop ΔH adjustment to be added to MOX test results– Preliminary assessments find ΔH adjustment ~80 cal/gm

Page 64: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

64© 2006 Electric Power Research Institute, Inc. All rights reserved.

Summary

Page 65: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

65© 2006 Electric Power Research Institute, Inc. All rights reserved.

Areas of Improvement for Final Failure Criteria

• Newer experimental data and fully qualified analytical methods can improve data adjustments to account for;– BWR pulse width effects– Improved cladding ductility with increase in temperature and hydrogen

solubility effects– More severe loading response in irradiated MOX fuel pellet– Improved cladding mechanical response at higher oxide thickness levels

• Perform assessment and comparison of analytical methodologies todetermine best approach for improved temperature scaling

• Reformulate PWR PCMI criteria into hydrogen space to address oxide spallation/high hydrogen conditions

• Potential increase in fuel enthalpy at failure – PWR PCMI oxide thickness levels between 25 and 60 μm– BWR PCMI hydrogen contents between 75 and 250 ppm

Page 66: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

66© 2006 Electric Power Research Institute, Inc. All rights reserved.

Alternative BWR PCMI Failure Criteria –Improved Consideration for NSRR Tests

NSRR Database of BWR rods

0 50 100 150 200 250 300

Fuel

Ent

halp

y R

ise

(cal

/gm

)

200

0

175

150

125

100

75

50

25

Nonfailed NSRR BWR Fuel

Failed NSRR BWR Fuel

BWR Failure Criteria

Hydrogen Content (ppm)

- Pulse Width Adjustment

Page 67: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

67© 2006 Electric Power Research Institute, Inc. All rights reserved.

Alternative PWR PCMI Failure Criteria –Improved Consideration for MOX and NSRR Tests

-Temperature adjustment - MOX Adjustment

MOX and Temperature Considerations

Spallation Considerations

0.00 0.04 0.08 0.12 0.16 0.20

50

100

150

200

250

300

350

Oxide/Wall Thickness

Adj

uste

d Fu

el E

ntha

lpy

Ris

e (c

al/g

)

BIGRCABRI UO2

IGRNSRRPBFSPERT

CABRI MOX

Filled Symbols – Cladding Failure

Page 68: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

68© 2006 Electric Power Research Institute, Inc. All rights reserved.

Backup Slides

Page 69: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

69© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:FRAPCON 3.3/FRAPTRAN 1.3 Capabilities

• FRAPCON/FRAPTRAN are NRC licensed fuel codes• Based on finite difference methods• 1-D thermal solution• Rigid pellet and thin-shell clad• Uses modified MATPRO to reflect the burnup

dependency of thermal and mechanical properties• Includes behavior models for fission gas, clad corrosion,

etc.

Page 70: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

70© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:Input Deck Construction

• Comparisons made for steady-state, power ramp, and RIA cases

• Input decks were prepared by converting FRAPCON/FRAPTRAN input decks for use in FALCON

• Comparisons of temperature and mechanical performance for RIA cases presented to demonstrate differences between the codes– FK-2 and FK-4 modeled

Page 71: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

71© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:FK2 Test Case

0.00 0.50 1.00 1.50 2.00 2.50 3.00 0

500

1000

1500

2000

TIME (S)

TEM

PER

ATU

RE

(K)

FUEl SURFACE TEMP

FALCON_1029 FRAPTRAN_1.3

0.00 0.50 1.00 1.50 2.00 2.50 3.00 250

300

350

400

450

TIME (S)

TEM

PER

ATU

RE

(K)

CLAD TEMP

FALCON_1029FRAPTRAN_1.3

Page 72: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

72© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:FK2 Test Case

0.00 0.50 1.00 1.50 2.00 2.50 3.00 0.00

0.50

1.00

1.50

2.00

TIME (S)

HO

OP

STR

AIN

(M/M

)

x10 -3

HOOP STRAIN

FALCON_1029FRAPTRAN_1.3

Page 73: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

73© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:FK4 Test Case

0.00 0.50 1.00 1.50 2.00 2.50 3.00 0

5

10

15

20

TIME (S)

FIS

SIO

N G

AS R

ELE

ASE

(%)

FISSION GAS RELEASE

FALCON_1029 FRAPCON_3.3

0.00 0.50 1.00 1.50 2.00 2.50 3.00 0

500

1000

1500

2000

2500

TIME (S)

MA

X FU

EL T

EMPE

RAT

UR

E (K

)

FALCON_1029 FRAPCON_3.3

MAXIMUM FUEL ROD CENTERLINE TEMPERATURE

Page 74: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

74© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:FK4 Test Case

0.00 0.50 1.00 1.50 2.00 2.50 3.00 0

500

1000

1500

2000

2500

TIME (S)

TEM

PER

ATU

RE

(K)

FUEl SURFACE TEMP

FALCON_1029 FRAPCON_3.3

0.00 0.50 1.00 1.50 2.00 2.50 3.00-0.20

0.00

0.20

0.40

0.60

0.80

1.00

TIME (S)

GAP

TH

ICK

NES

S (M

M)

x10 -1

GAP THICKNESS

FALCON_1029 FRAPCON_3.3

Page 75: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

75© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:FK4 Test Case

0.00 0.50 1.00 1.50 2.00 2.50 3.00 0.00

0.50

1.00

1.50

2.00

2.50

TIME (S)

HO

OP

STR

AIN

(M/M

)

x10 -2

HOOP STRAIN

FALCON_1029 FRAPCON_3.3

Page 76: Industry Position on the RIA Failure LimitTK 2 TK 7 TK 4 TK 5 TK 3 TK 1 TK 6 0 5 10 15 20 25 30 35 0.00 0.02 0.04 0.06 0.08 0.10 Oxide/Cladding Thickness Ratio SED at Failure of After

76© 2006 Electric Power Research Institute, Inc. All rights reserved.

FRAPTRAN-FALCON Comparison:Summary

• Comparisons for steady-state and slow power ramp cases so good agreement between codes

• For the RIA cases (FK-2 and FK-4) peak fuel temperature predictions were similar

• Mechanical deformations were similar for the low energy disposition case (FK-2)

• Large variance in mechanical performance for the high energy disposition case (FK-4)– Sensitive to how the fuel-cladding gap is modeled

• Results highly sensitive to input modeling parameters