Bernard S, .

Ledieu M, .

Moysan, I.

Pontillon, Y.

English

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HAL Id: cea-02338477
https://hal-cea.archives-ouvertes.fr/cea-02338477
Submitted on 24 Feb 2020
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New Insight on Volatile Fission Products (I and Cs)
release from high burnup UO_2 fuel under LOCA type
conditions
Y. Pontillon, I. Moysan, S. Bernard, M. Ledieu
To cite this version:
Y. Pontillon, I. Moysan, S. Bernard, M. Ledieu. New Insight on Volatile Fission Products (I and Cs)
release from high burnup UO_2 fuel under LOCA type conditions. TOPFUEL 2018 - Light Water
Reactor (LWR) Fuel Performance Meeting, Sep 2018, Prague, Czech Republic. ￿cea-02338477￿
Page 1Y. Pontillon, G. Ducros (DEC)Restricted use to the DEN Scientific Committee (20/10/2014)
NEW INSIGHT ON VOLATILE FISSION PRODUCTS
(I AND CS) RELEASE FROM HIGH BURNUP UO2
FUEL UNDER LOCA TYPE CONDITIONS
Y. Pontillon, I. Moysan, S. Bernard, M. Ledieu
CEA, DEN, CAD, DEC, F-13108 Saint-Paul-lez-Durance, 
France.
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING
September 30th – October 4th, 2018
Page 2
Outline
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018 Y. Pontillon et al.(DEC)
 Context 
 MERARG vs VERCORS(VERDON)
 Results:
 FGR comparison
 Some new insights from the 
VERCORS tests regarding FP
 Conclusion and perspectives VERDON MERARG
Page 3
Context: Generalities (1/2)
A hypothetical LOCA type transient in a light water reactor
The knowledge of the amount of radioactivity released from the core to the environment, the 
determination of the “source term”, is of prime and crucial importance
Y. Pontillon et al.(DEC)
Large break
R&D analytical programs ?
1200°C
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
NEA, OECD, Nuclear Fuel Behaviour in Loss-of-coolant Accident 
(LOCA) Conditions, State-of-the-art Report n°6846, 2009
Page 4
Context: Generalities (2/2)
Y. Pontillon et al.(DEC)
One of the most useful way: Separate effect Tests 
Model validation / Code qualification
PTE
TEM
Experimental Loop 
MERARG, MEXIICO, VERDON
SEM
µ-XRD +
MARS beam line
Annealing test coupled to (on 
line) measurements:
ST quantification (FP kinetics)
Temperature
Pressure, …
µ-structural examinations 
before and after test:
Evolution during the test 
EPMA
SIMS
What is needed ?
FP release (gases, volatiles, …)
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
Page 5
MERARG vs VERCORS (1/3)
Y. Pontillon et al.(DEC)
Most of the analytical programs focusses: 
On gas behavior (LOCA type 
sequences): GASPARD program
CEA - MERARG loop:
Accurate ST quantification (FGR
kinetics by gamma 
spectrometry)
Accurate Temperature 
measurements (typically up to 
1200°C)
Main part of the experiments: no 
access to FP behavior
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
MERARG
Y. Pontillon, et al., J. Nucl. Mater. vol 385, issue 1, 2009, 137
Noirot, J., Pontillon Y., J. Nucl. Mater., 446(1–3), 163-171, 2014
Page 6
MERARG vs VERCORS (1/3)
Y. Pontillon et al.(DEC)
Most of the analytical programs focusses: 
On gas behavior (LOCA type 
sequences): GASPARD program
CEA - MERARG loop:
Accurate ST quantification (FGR
kinetics by gamma 
spectrometry)
Accurate Temperature 
measurements (typically up to 
1200°C)
Main part of the experiments: no 
access to FP behavior
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
Typical GASPARD thermal sequence
Temperature
time history (°C)
Time
300
T Max. Holding time
TMAX between 1000°C and 
1200°C,
Holding time between 0 and 15 
minutes.
Y. Pontillon et al., 2004 Water Reactor Fuel Performance 
Meeting, ORLANDO, FLORIDE, September 2004
Page 7
MERARG vs VERCORS (2/3)
Y. Pontillon et al.(DEC)
Most of the analytical programs focusses: 
On all FP behavior (Severe 
accident type sequences), 
VERCORS/VERDON programs
CEA – VERCORS/VERDON loops:
Accurate ST quantification (FGR
and FPR kinetics by gamma 
spectrometry)
Accurate Temperature 
measurements
All the FP behavior available, but 
very high temperature (up to 
fuel relocation) 
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
VERDON
Pontillon, Y. et al., NUCLEAR ENGINEERING AND DESIGN, 2010, 240,1843
Page 8
MERARG vs VERCORS (2/3)
Y. Pontillon et al.(DEC)
Most of the analytical programs focusses: 
On all FP behavior (Severe 
accident type sequences), 
VERCORS/VERDON programs
CEA – VERCORS/VERDON loops:
Accurate ST quantification (FGR
and FPR kinetics by gamma 
spectrometry)
Accurate Temperature 
measurements
All the FP behavior available, but 
very high temperature (up to 
fuel relocation) 
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
Typical VERCORS/VERDON
thermal sequence
G. Ducros, et al., Nuclear Engineering and Design, vol. 208, no. 2, pp. 191–203, 2001.
Page 9
MERARG vs VERCORS (3/3)
Y. Pontillon et al.(DEC)
FP behavior (I and Cs) in LOCA type thermal scenario ? 
Methodology used:
First, one focuses on the results 
obtained up to 1200°C (VERCORS 
series) for Fission Gases
Then, one checks the consistencies 
with those of the GASPARD 
program (Fission Gases)
Finally, determine the 
corresponding volatile FPs 
source term
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
This determination is made 
easier because a direct 
comparison can be done:
The same fuel rod has been 
tested in the two programs (6 
cycles UO2 at 72 GWd/t)
Page 10
Results (1/3)
Y. Pontillon et al.(DEC)
FG behavior up to 1200°C (Kinetics), UO2 at 72 GWd/t
VERCORS:
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
GASPARD:
0
500
1000
1500
2000
2500
0,00E+00
2,00E-03
4,00E-03
6,00E-03
8,00E-03
1,00E-02
1,20E-02
1,40E-02
1,60E-02
1,80E-02
 12:00  13:00  14:00  15:00  16:00  17:00  18:00  19:00  20:00
T
e
m
p
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r
a
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(
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)
F
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.
Durée
133Xe
85Kr
Début de délocalisation
Température
Kr85
Xe133
Start of gas releases at around 500-600°C,
greater amplitude for 85Kr than for 133Xe at 700-
800°C),
The second burst release around 1,100-1,200°C 
with significantly greater amplitude for the 85Kr
in relation to the 133Xe,
 
Cinétique de relâchement : GASPARD A2-0 J08
0.0E+00
2.0E+12
4.0E+12
6.0E+12
8.0E+12
1.0E+13
1.2E+13
1.4E+13
1.6E+13
1.8E+13
0 50 100 150 200 250 300
durée (minutes)
a
t
/
s
/
g
0
200
400
600
800
1000
1200
1400
T
e
m
p
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r
a
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u
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e
 
(
°
C
)
Xe133 (X1000) at/s/g
Kr85 at/s/g
Température Kr85
Xe133 x 1000
Exactly the same behavior
Page 11
Results (1/3)
Y. Pontillon et al.(DEC)
FG behavior up to 1200°C (Kinetics), UO2 at 72 GWd/t
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
Consistent with other results
Page 12
Results (2/3)
Y. Pontillon et al.(DEC)
FG behavior up to 1200°C (released fraction), UO2 at 72 GWd/t
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
VERCORS GASPARD
Temperature Kr(85), % Xe(133), % Kr(85), % Xe(133), %
1000°C 7,4 0,8 6,2 0,6
1200°C 12,7 1,8 11,6-12,2 1,7-2,1
Very good consistency between 
the results obtained thanks the 
two programs
Page 13
Results (3/3)
Y. Pontillon et al.(DEC)
FG and FP behavior up to 1200°C (released fraction), UO2 at 72 
GWd/t
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
 
VERCORS Tests 
FGR (85Kr, 6 
cycles 
specimen, %) 
FGR (133Xe, 6 
cycles 
specimen, %) 
FPR (137Cs, 6 
cycles 
specimen, %) 
FPR (131I, 6 
cycles 
specimen, %) 
(0,2°C/s / 1000°C) 
RT6 7.4 0.8 0.04 0.25 
(0.2°C/s / 1200°C) 
RT6 12.7 1.8 0.47 0.56 
(end of the test, 2200°C) 
RT6 ~100 ~100 100 100 
(0,2°C/s / 1000°C) 
RT8 10.4 0.7 0.08 0.18 
(0,2°C/s / 1200°C) 
RT8 11.5 1.0 0.45 0.35 
(end of the test, 2200°C) 
RT8 ~100 ~100 100 100 
 
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Page 14
Results (3/3)
Y. Pontillon et al.(DEC)
FG and FP behavior up to 1200°C (released fraction), UO2 at 72 
GWd/t
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
 
VERCORS Tests 
FGR (85Kr, 6 
cycles 
specimen, %) 
FGR (133Xe, 6 
cycles 
specimen, %) 
FPR (137Cs, 6 
cycles 
specimen, %) 
FPR (131I, 6 
cycles 
specimen, %) 
(0,2°C/s / 1000°C) 
RT6 7.4 0.8 0.04 0.25 
(0.2°C/s / 1200°C) 
RT6 12.7 1.8 0.47 0.56 
(end of the test, 2200°C) 
RT6 ~100 ~100 100 100 
(0,2°C/s / 1000°C) 
RT8 10.4 0.7 0.08 0.18 
(0,2°C/s / 1200°C) 
RT8 11.5 1.0 0.45 0.35 
(end of the test, 2200°C) 
RT8 ~100 ~100 100 100 
 
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Very low I and Cs releases (less than 0,6 %)
Page 15
Results (3/3)
Y. Pontillon et al.(DEC)
FG and FP behavior up to 1200°C (released fraction), UO2 at 72 
GWd/t
TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
 
VERCORS Tests 
FGR (85Kr, 6 
cycles 
specimen, %) 
FGR (133Xe, 6 
cycles 
specimen, %) 
FPR (137Cs, 6 
cycles 
specimen, %) 
FPR (131I, 6 
cycles 
specimen, %) 
(0,2°C/s / 1000°C) 
RT6 7.4 0.8 0.04 0.25 
(0.2°C/s / 1200°C) 
RT6 12.7 1.8 0.47 0.56 
(end of the test, 2200°C) 
RT6 ~100 ~100 100 100 
(0,2°C/s / 1000°C) 
RT8 10.4 0.7 0.08 0.18 
(0,2°C/s / 1200°C) 
RT8 11.5 1.0 0.45 0.35 
(end of the test, 2200°C) 
RT8 ~100 ~100 100 100 
 
S
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In good consistency with what one can extract from literature: the temperature limit at which I and Cs can 
become mobile 1, the diffusion coefficient of gaseous and volatile species in nuclear ceramics 2
1) J-P Hiernaut et al., 
JNM 377 (2008) 313-
324; C. Ronchi, High 
Temperature 2007, 
Vol 45, n°4, pp 552-
571; I. Johnson et al., 
JNM 154 (1988) 67-
73
2) J. A. Turnbull et 
al., JNM 1982 107 
168-184; W. H. 
Hocking et al., JNM 
294 2001 45-52; D. 
Roudil et al., Material 
research society 
symposium 
proceeding Vol 824; 
S. G. Prussin et al., 
JNM 154 1988 25-37; 
C. T. Walker et al., 
JNM 393 (2009) 212-
213
Page 16
Conclusion/Perspectives
Y. Pontillon et al.(DEC)TOPFUEL, FUEL REACTOR PERFOMANCE MEETING, September 30th – October 4th, 2018
This paper first focuses on the global characteristics of the
GASPARD and VERCORS programs
The VERCORS results regarding high burn up UO2 fuel are discussed
and compared to those of GASPARD
Thanks to the quasi identical results obtained for FG between
GASPARD and VERCORS, indications on volatile fission product
releases are then given.
The global released fraction is very low for I and Cs, i.e. less than
0.6% up to 1200°C
 Enlarge the FP data in LOCA type transient: all the VERCORS and
VERDON tests.
Funding: EdF and Framatome (GASPARD), IRSN and EdF (VERCORS)
Page 17Y. Pontillon, G. Ducros (DEC)Restricted use to the DEN Scientific Committee (20/10/2014)
Thanks you,
Any questions ?


New Insight on Volatile Fission Products (I and Cs) release from high burnup UO2 fuel under LOCA type conditions

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New Insight on Volatile Fission Products (I and Cs) release from high burnup UO2 fuel under LOCA type conditions

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