Hydrogen Isotope Research Center - Toyama Univ.

Data Base for Tritium Solid Breeding Materials (Li₂O, Li₂TiO₃, Li₂ZrO₃ and Li₄SiO₄) of Fusion Reactor Blankets --- Yoshiaki FUTAMURA

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4. Database for Li₂O

4.5 Irradiation effects

4.5.1 Physical integrity

No.	Data and remark	Fig.	Refs.
1	Fair for 500, 700, 900°C (<3 at. % 6Li burn-up) Fair for 550~1000°C (4 at. % 6Li burn-up)	-	30, 35

4.5.2 Swelling

No.	Data and remark	Fig.	Refs.
1	ΔV/V0, (%) Burn-up at. % 500°C 700°C 900°C 1 –1.0 5.0 6.0 2 –3.5 7.5 6.0 3 –2.8 7.0 6.0	-	30
2	Relationship between the burn-up and the swelling for Li2O.	4.22	6, 30
3	Volumetric swelling of Li2O, Li2ZrO3 and Li4SiO4 at 700°C.	4.23	6, 49
4	Diameter swelling of Li2O, Li2ZrO3 and Li4SiO4 at 500°C, 700°C, 900°C.	4.24	6, 70

4.5.3 Grain growth

No.	Data and remark	Fig.	Refs.
1	Grain growth (μm) at 1 at. % 6Li burn-up 500°C 700°C 900°C 3.5→3.5 3.5→7.0 3.5→17.0	-	36
2	The grain size of irradiated (1% atm.6Li burn-up, 100 full power days) Li2O, Li2ZrO3 and Li4SiO4.	4.25	36

4.5.4 Li transport (g/hr)

No.	Data and remark	Fig.	Refs.
1	W(g/hr)=(29.9/2)F[K·P(H2O)]0.5/P(total)     F=He sweep gas flow rate (mol/hr)     K=[P(LiOH)]2/P(H2O) equilibrium constant for Li2O(s)+H2O(g)→2LiOH(g)     P(H2O) = water vapor pressure in atm.     P(total) = total sweep gas pressure, atm.	-	37, 38
2	Relationship between weight loss of Li2O and temperature.	4.26	37
3	Equilibrium constant for the reaction     Li2O(s)+H2O(g)→2LiOH(g)	4.27	37
4	Burn-up dependence of Li-transfer for Li2O, Li2ZrO3 and Li4SiO4.	4.28	56

4.5.5 Thermal conductivity

No.	Data and remark	Fig.	Refs.
1	Slight decrease due to fast neutron irradiation at low temp.	-	40
Notes1	Thermal conductivity κ=α·Cp·ρ (W/m-K)     α : Thermal diffusivity (m2/s)     Cp : Specific heat (J/g-K)     ρ : Density (g/m3)	-	-

4.5.6 Young's modulus --- No data

4.5.7 Tensile strength --- No data

4.5.8 Compressive strength --- No data

4.5.9 Bending strength --- No data

4.5.10 Tritium diffusivity (cm²/s)

No.	Data and remark	Fig.	Refs.
1	Tritium diffusivity (cm2/s)     D=4.03×10-2exp[–95.1(kJ/mol)/RT]     573≦T≦1173K, R=8.31×10-3 kJ/m-K Single crystal diffusivity decreases with irradiation.	-	41, 30
2	0.857 (mm2/s), 600°C, 80%TD, 6Li 90% enrichment	-	11
3	1.5×10-9 (cm2/s), 600°C	-	33, 44
Notes1	Diffusion coefficient of tritium for Li2O, Li2ZrO3 and Li4SiO4. (Diffusion coefficient of T are shown in the following Appendix 4.5.10.)	4.31	33
Notes2	Lattice diffusion coefficient for lightly irradiated Li2O from Tanjfuji (T), Quanci (Q), and Guggi (G).	4.29	41
Notes3	Lattice diffusion coefficient for Li2O vs. fluence.	4.30	41
Notes4	Summary of Tritium diffusion coef. for Li2O, Li2ZrO3 and Li4SiO4.	4.32	18

Appendix 4.5.10 Diffusion Coefficient of Tritium in Oxide Ceramic Breeder Materials.^{6, 42, 43, 44, 45)}

Material	Neutron fluence (cm-2)	LogD0 (cm2-s-1)	Q (kJ-mol-1)	Temp. range (K)
Li2O	8.1×1016	–4.1±0.5	77.4±5.6	570~690
Li2ZrO3	2.5×1016	–4.9±0.2	75.0±2.2	540~730
Li4SiO4	2.5×1016	–6.7±0.1	43.8±0.9	530~850

4.5.11 Tritium residence time (hr)

No.	Data and remark	Fig.	Refs.
1	τ=exp(2.273×104/T–34.83), He+0.1% He purge     dg = ~16 μm, p=~20%, 593≦T≦773K	-	47
2	Tritium Residence times for Li2O.	4.33	47

4.5.12 Tritium release

No.	Data and remark	Fig.	Refs.
1	Refer to tritium retention and tritium residence time.	-	-

4.5.13 Tritium retention

No.	Data and remark	Fig.	Refs.
1	The amount of tritium retention in Li2O.	4.34	48
2	The amount of tritium retention in Li2O, Li2ZrO3 and Li4SiO4 at 700°C.	4.35	49

4.5.14 Helium retention

No.	Data and remark	Fig.	Refs.
1	Retained / Generated, (%) Burn-up at. % 500°C 700°C 900°C 1 25 25 10 2 14 22 5 3 13 23 7	-	48
2	The amount of Helium retention in Li2O.	4.36	48

4.5.15 After heat (W/cm³)

No.	Data and remark	Fig.	Refs.
1	0.001 W/cm3, 15 MW. yr/m2 fluence, 1-hr cooling, 85%TD     no impurities : tritium retained in breeder.	-	62, 65, 90
2	10-9 W/cm3, 12.5 MW. yr/m2 fluence, 1-hr cooling, 85%TD     no impurities or tritium	-	62, 65, 91

4.5.16 Class C Waste disposal rate

No.	Data and remark	Fig.	Refs.
1	0.2 %, 15 MW. yr/m2 fluence, 10-yr cooling, 85%TD	-	62, 65