Li4SiO4values describe: Li₄SiO₄ pebbles
Fusion, private
What it enables
Inside the vessel, materials must also make fuel: lithium ceramic pebble beds breed tritium, beryllide pebbles multiply neutrons.
Status and pusher
Pebble bed mockups irradiated and thermally cycled in EU and Japan programs; pushed by HCPB-class blanket designs.
Watch out
Tritium release kinetics and pebble crushing set the design margins.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated.
Provisional provenance: EUROfusion and international fusion materials programmes.
Wet cleaning
| Recipe | not applicable: hygroscopic and reactive |
|---|
| Forbidden | moisture, absolutely |
|---|
| Limit | tritium release kinetics, not cleanliness |
|---|
Vacuum and outgassing
| Outgassing, unbaked (10 h) | insufficient data |
|---|
| Outgassing, baked | insufficient data |
|---|
| Vapour pressure | lithium loss at high temperature |
|---|
Temperature
| Metallurgical limit | service 300–900 °C |
|---|
Thermal
| Thermal conductivity | ~2 W/m·K |
|---|
| Melting / softening | 1250 °C |
|---|
Mechanical
| Strength | pebble crush strength |
|---|
| Elongation | nil |
|---|
| Density | 2.4 g/cm3 |
|---|
Engineering
| Corrosion | hygroscopic |
|---|
| Joining | pebble bed |
|---|
| Process notes | breeds the tritium the machine burns |
|---|
| Availability and cost | programme quantities |
|---|
Grades
| Li4SiO4 pebbles | EU reference breeder |
|---|
| Li2TiO3 pebbles | Japanese reference, better stability |
|---|
| Be12Ti beryllide | multiplier with lower swelling than Be metal |
|---|
Sources · 1
- EUROfusion breeding blanket program
← The Matter