in-pile behaviour of lithium metatitanatein exotic-9nrg/mmi 13th workshop on ceramic breeder blanket...
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NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 1
In-pile behaviour of lithium meta titanate in EXOTIC-9
A.J. Magielsena, J.B.J. Hegemana, M.J.M. Peetersa, J.G. van der Laana, J.D. Lulewiczb, M.P. Stijkela
a NRG Petten, the Netherlands, b CEA Saclay, France
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 2
MOM !
In-pile behaviour of lithium meta titanate in EXOTIC-9
A.J. Magielsena, J.B.J. Hegemana, M.J.M. Peetersa, J.G. van der Laana, J.D. Lulewiczb, M.P. Stijkela
a NRG Petten, the Netherlands, b CEA Saclay, France
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 3
Outline• Scope of work• Objectives EXOTIC-9/1 • Rig layout & design• Material loading• In-pile operation• Tritium release characterisctics• Status & outlook
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 4
Scope of work• Tritium inventory is major item in the safety case for a fusion power
plant: breeding blanket should be designed for minimal inventory:– Fast tritium release up to end-of-life burn-up– Increase the lower value of breeder temperature, and reduce
large low temperature zones
• Tritium breeders under development in EU for HCPB concept:– Li4SiO4 base, new manufacturing process explored– Li2TiO3 base, stretched to smaller & denser pebble, to enhance
effective 6Li density
• Present EFDA HCPB test programme is also addressing effects of pebble-bed thermo-mechanics (e.g. in HICU)
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Objectives for EXOTIC*-9/1Tritium release characteristics of latest Li2TiO3 supplied by
CEA• differential inventory from in-pile transients• post-irradiation inventory measurements
• Co-irradiation of small piggy back samples, – New technology OSi samples for post irradiation microscopy and inventory
measurements– OSi with 20% 6Li– MTi with 30% 6Li
• Secundary: Permeation though Eurofer-97 and demonstration of in-situ oxidation for permeation reduction
*EXtraction Of Tritium In Ceramics
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 6
Design (1)EXOTIC-9/1 T-release capsules
• Annular breeder pebble-bed, modest radial temperature gradient, 120 mm stack height
• Triple containment for safety • Integrated tritium monitoring.• Electrical heaters, for large
variation in temperature transients(300-500 C)
• Purge gas (He + 5000 ppm - 10 ppm H2 or pure He, all 6.0 quality)
• Eurofer-97 tube permeation rateobtained simultaneously
• Demonstration of in-situ oxidation for permeation reduction
EXOTICEXOTIC--8/98/9
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Design (2)
A B C D E F G H I
1 Be Be Be Be Be Be Be Be 1 Be F Fuel element
2 F F F D2 F F2 F H2 2 Be
3 F F C3 F E3 F G3 F 3 I3 CR Control rod
4 F CR F CR F CR F H4 4 Be
5 F F C5 F E5 F G5 F 5 I5 Be Reflectorelement
6 F CR F CR F CR F H6 6 Be
7 F F C7 F E7 F G7 F 7 Be E5 Experiment
8 F F F D8 F F8 F H8 8 Be
9 Be Be Be Be Be Be Be Be 9 Be Hx EXOTIC
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 8
Test matrix and loadingCeramic materials:1. Same as 4, approx. 1.2 g2. Li4SiO4 20 % 6Li enr. (FZK, OSi00/2-3-c),
0.2 g3. Li4SiO4 nat 6Li enr. (FZK, OSi03/1-3 ), 0.2 g
4. Li2TiO3 nat 6Li enr. CEA, CTI 273 Ti 1100 CTI), approx. 12.8 g
5. Li2TiO3 , 29,5 % 6Li enr. (CEA, CTI 1233 Ti 1100 CEA), 0.2 g
6. Same as 4, approx 1.2 g
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 9
table 1 Characteristics of irradiation specimens after assembly of the test elements
bulk material
Piggyback 1
Piggyback 2
Piggyback 3
Piggyback4
Material Li2TiO3 Li2TiO3 Li4SiO4 Li4SiO4 Be Supplier CEA CEA FZK FZK FZK(NGK)NRG ID NRG 130 NRG 131 NRG 129 NRG132 NRG 2010 6Li enrichment 7.5 % 30% 7.5 % 20 % -- measured density (g·cm-3) by He pycnometry technique
3.280 3.246 2.34 not meas. not meas.
open porosity (%) 1.7 2 3.5 not meas. not meas. closed porosity (%) 5.3 5.8 2.7 not meas. not meas. Smear density (g·cm-3) 1.84 1.84 1.44 1.44 not meas. Theoretical density (g·cm-3) 3.43 3.43 2.25 not meas. not meas. Weight (g) 12.8 0.2 0.2 0.2 0.2 Pebble diameter (mm) 0.6-0.8 0.6-0.8 0.25-0.63 not meas. 0.85-1 grain size (μm) 1-3 1-4 not meas. not meas.
Material loading (1)
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Material loading (2)
Li2TiO3, CTI 273 Ti 1100 CTI nat 6Li (NRG 130)
Li2TiO3, CTI 1233 Ti 1100 CEA, 30% 6Li (NRG
131)
FZK, OSi-03/1-3 nat 6Li Li4SiO4 (NRG 129)
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Rig assembly
irradiation experiment near completion of assembly
Second containment with heater element ~ 5 m
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 12
Beryllium piggy-back
NGK pebbles (0.2 g, NGK 1.0 batch 2003) of diameter 0.85- 1 mm fitted in mini tube, tube loaded to sleeve inside stainless steel support of ceramic bed
to
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 13
In-pile tritium release (1)
1st Cycle: 05-04
0
100
200
300
400
500
600
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28Time (days)
Tem
pera
ture
(C)
0
0.2
0.4
0.6
0.8
1
1.2
IC s
igna
l (a.
u.)
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 14
In-pile tritium release (2)Cycle 05-07
0
100
200
300
400
500
600
0 5 10 15 20 25time (days)
Tem
pera
ture
(C)
0.0
0.7
1.4
2.1
2.8
3.5
4.2
IC s
igna
l (a.
u.)
High inventory build-up
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 15
Effect of purge gas composition
First cycles results suggest:• Surface process (desorption) seems not rate determining• Bulk diffusion is apparently rate determining
0.0
0.5
1.0
1.5
2.0
13.5 14 14.5 15 15.5
time (days)Tr
itium
rele
ase
rate
(mC
i/min
)
0.1 % H2 (ref gas)
1.0 % H2 0.1 % H2 (ref gas)
Later cycle (05-07)
0
100
200
300
400
500
600
0 5 10 15 20 25time (days)
Tem
pera
ture
(C)
0.0
0.8
1.6
2.4
3.2
4.0
4.8
Triti
um re
leas
e ra
te (m
Ci/m
in)
Temperature
Tritium release rate
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Tritium residence time from temperature transients
At steady state: Tritium generation rate (G) = Tritium release rate
The surface area represents the difference in inventory: ΔI = I2 - I1
The difference in tritium residence time is calculated from: Δτ = τ2 - τ1 = ΔI / G
GI
=τ
Tritium residence time (τ):
I = tritium inventory (mCi)G = tritium production rate (mCi/min)
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 17
Tritium release of Li2TiO3 pebbles in E-9/1
Li2TiO3-extruded (E-9/1)
0.1
1
10
100
1000
1.20 1.30 1.40 1.50 1.60 1.70
Temperature (1000/T(K))
Tritr
ium
Res
iden
ce ti
me
(hou
rs)
cycle_04cycle_05cycle_06cycle_07cycle_09cycle_10fit
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 18
Tritium release & microstructureEXOTIC-Capsule E-8/2 E-8/9 E-8/1 E-8/7 E-8/7 E-8/9 E-8/5 E-9/1
CEA CEA CEA CEA CEA CEA CEA CEAsinter spinel agglom agglom extrus extrus extrus-
sinterextrus-spheroid-sinter
pellets crushed bar pebbles pebbles pebbles pebbles pebbles pebbles4.0 - 9.5 0.8 - 1.2 0.7 - 0.9 0.6 - 1.2 1.1 - 1.5 0.9 - 1.2 1.1 - 1.5 0.6 - 0.8
83 90 84 84 89 94 87 931 - 2 ? 1.5 - 2 1 - 2 1.5 - 2.5 1-2.5 1 - 2.5 1 - 315 ? 10 11 6 ? 7 1.72 ? 6.5 4.8 5 ? 5.7 5.3
0.8 1 1.3 1.3 - 4.8 6.4 12.2
Closed porosity
Residence time at 500 C
Size pellets / pebbles
Grain sizeDensity of pebble
Open porosity
Supplier
Fabrication
Shape
Tritium residence time increases with amount of closed porosity
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 19
Comparison with EXOTIC-8 results
0.1
1
10
100
1000
1.15 1.25 1.35 1.45 1.55 1.65 1.75Temperature (1000/T(K))
Triti
um R
esid
ence
Tim
e (h
ours
)
E-8/5; extruded; TD= 87; OP= 7
E-8/1;agglomerated; TD= 84; OP= 10
E-8/2; sintered pellets; TD= 83; OP= 15
E-8/7; extruded; TD= 89; OP= 6
E-8/7; agglomerated; TD= 84; OP= 11
E-8/9; extruded; TD= 94
E-9/1; extruded; TD= 93; OP= 1.7
E-8/9; spinel; TD= 90
0
2
4
6
8
10
12
14
16
18
20
0 5 10 15Tau in hrs (at 500 C)
Por
osity
OpenClosedTotal porosityLinear (Total porosity)Linear (Closed)Linear (Open)
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 20
Permeation in first few days …
1st Cycle: 05-04
0
100
200
300
400
500
600
0 2 4 6 8Time (days)
Tem
pera
ture
(C)
0
0.2
0.4
0.6
0.8
1
1.2
IC s
igna
l (a.
u.) IC-1
50 x IC-2
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 21
Status & outlook• EXOTIC-9/1 now in 6th cycle, continues to Spring 2006; the
experiments runs well with no instrumentation failures• Significant inventory built up is observed in the latest high density
MTi pebbles, attributed to high closed porosity and low fraction ofopen porosity
• P.I.E. starts mid 2006: post-irradiation inventories and microscopy• In-situ oxidation of Eurofer-97 containment in Cycle 05-10, should
provide evidence for effective permeation reduction – This is ongoing for a week: water vapour saturated purge gas through seconsd
containment, with tube at about 400 C. This will be continued for another 2 or 3 weeks, depending on actual effect
• Consequences for breeder material and its specification development will be addressed soon (TBM scope & timing), including a.o. low temperature irradiation effects
NRG/MMI 13th Workshop on Ceramic Breeder Blanket Interactions 22
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