evaluation of creep during dry storage in low and high burnup fuels
DESCRIPTION
Evaluation of creep during dry storage in low and high burnup fuels. F. Feria, L.E. Herranz. CONTENTS. Motivation and objective Extension of FRAPCON-3.3 creep law Creep assessment Final remarks. 1. MOTIVATION AND OBJECTIVE. Safety objectives:. Radiation dose Subcriticality - PowerPoint PPT PresentationTRANSCRIPT
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
Evaluation of creep during dry storage Evaluation of creep during dry storage
in low and high burnup fuelsin low and high burnup fuels
F. Feria, L.E. Herranz
CONTENTS
1.1. Motivation and objectiveMotivation and objective
2.2. Extension of FRAPCON-3.3 creep lawExtension of FRAPCON-3.3 creep law
3.3. Creep assessmentCreep assessment
4.4. Final remarksFinal remarks
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
1. 1. MOTIVATION AND OBJECTIVEMOTIVATION AND OBJECTIVE
Safety objectives: - Radiation dose
- Subcriticality
- Confinement
- Retrievability
Degrading mechanisms
SCC Creep DHC
Cladding integrity
Evaluation in low and high burnup
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
dtd cp
In-FRAPCON modelling
r,z,id Ti
pi
pi
eii
2. 2. EXTENSION OF FRAPCON-3.3 CREEP LAWEXTENSION OF FRAPCON-3.3 CREEP LAW
2321
cc ))(f)·T(f)·(f(
4
)4.967·10exp(725.2)(f -81
)RT/10000exp()T(f 2
-293 5.129·10)(f
Creep law:
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
2. 2. EXTENSION OF FRAPCON-3.3 CREEP LAWEXTENSION OF FRAPCON-3.3 CREEP LAW
Creep law validity range
Restricted to in-reactor conditions
Extension of the creep law is needed to apply the code to dry storage conditions
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
Zircaloy-4 database (EDF)
cs
cp
c
s,pi)t(f)·t(f)·T(f)·(f i4i3i2i1ci
2. 2. EXTENSION OF FRAPCON-3.3 CREEP LAWEXTENSION OF FRAPCON-3.3 CREEP LAW
Generic correlation
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
CIEMAT creep law
5.0321 t)·t(f)·T(f)·(f
b1 2
a)(f
273T
cexp)T(f 2
)t·dexp()t(f3
2. 2. EXTENSION OF FRAPCON-3.3 CREEP LAWEXTENSION OF FRAPCON-3.3 CREEP LAW
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
CIEMAT creep law
0.0
0.1
0.2
0.3
0 100 200 300 400 500 600
t(h)
(%
)
CIEMAT
EDF
0
0.1
0.2
0 200 400 600 800 1000
t(h)
(%
)
CIEMAT
EDF
2. 2. EXTENSION OF FRAPCON-3.3 CREEP LAWEXTENSION OF FRAPCON-3.3 CREEP LAW
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
Implementation
≥ 121 MPa → Creep law parameters derived from irradiated claddings data
≤ 121 MPa → Creep law parameters derived from non-irradiated claddings data
2. 2. EXTENSION OF FRAPCON-3.3 CREEP LAWEXTENSION OF FRAPCON-3.3 CREEP LAW
Together with a suitable logic that allows choosing between the “in-reactor” equation and the dry storage equation, according to the prevailing conditions at the calculation time
The extension splits in two hoop stress ranges:
No experimental data is available with irradiated material under low hoop stress
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
0
5
10
15
20
25
30
35
0 500 1000 1500 2000 2500
t(days)
Ave
rag
e lin
ear
po
wer
(kW
/m)
0
5
10
15
20
25
30
35
40
0 500 1000 1500 2000 2500
t(days)
Av
era
ge
lin
ea
r p
ow
er
(KW
/m)
0.0
0.2
0.4
0.6
0.8
1.0
0 200 400 600 800
t(days)
T
3. 3. CREEP ASSESMENTCREEP ASSESMENT
a) Zircaloy-445 GWd/tU
1º) In-reactor irradiation
2º) Pool storage (1 year)
3º) Dry out (1 day)
4º) Dry storage (2 years)
Phasesb)
Zircaloy-463 GWd/tU
Postulated scenarios
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
3. 3. CREEP ASSESMENTCREEP ASSESMENT
Resultsa)
Zircaloy-4 45 GWd/tU
b) Zircaloy-463 GWd/tU
-0.8-0.7
-0.6-0.5
-0.4-0.3
-0.2-0.1
00.1
0.2
0 400 800 1200 1600 2000 2400
t(days)
(%
)
Trillo
Dry storageIn-pool cooling
-1
-0.5
0
0.5
1
1.5
0 400 800 1200 1600 2000 2400
t(days)
(%
)
Trillo2
Dry storageIn-pool cooling
Once dry storage starts hoop stress causes a creep-out situation
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
The creep main impact would take place during the first months
3. 3. CREEP ASSESMENTCREEP ASSESMENT
Results
In no case creep reaches 1 % strain limit
Nearly 4 times higher hoop strain as burn-up is increased by 40 % 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 100 200 300 400 500 600 700 800
t(days)
D
(%)
45 GWd/tU
63 GWd/tU
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
4. 4. FINAL REMARKSFINAL REMARKS
High burn-up effect seems substantial and causes major differences in the nuclear fuel response in terms of creep
Further work:
• Extend CIEMAT creep law to irradiated fuel rods submitted to low stresses
• Extend the study up to 100 years to estimate the final creep asymptotic value
The results would have a conservative nature because the irradiation hardening effect is not considered at low stresses
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
ACKNOWLEDGMENTSACKNOWLEDGMENTS
The authors are indebted to ENRESA for their financial support and the technical discussions held and to the FRAPCON-3 developers for their technical support during this work
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Nuclear Safety Research Unit Vienna (Austria), 31.05-4.06.2010
IAEA meeting
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