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Molten salt reactor MSR

A molten salt reactor (MSR) uses molten fluoride or chloride salt as coolant and graphite, or none in fast-spectrum designs as moderator. 0 are operating worldwide, totalling 0.0 GW gross, out of 4 units of this type on record.

Operating
0
0.0 GW gross
Under construction
0
Planned
4
Retired
0
Fuel salt Clean salt Steam Corefuel dissolvedin the coolant Intermediateexchanger Steamgenerator Turbineto grid Three loops
The fuel is the coolant. Near atmospheric pressure, so there is no stored energy to drive a rupture.

The fuel is dissolved into the coolant itself, so the core is a circulating liquid rather than an array of solid rods. Operating near atmospheric pressure at 600–700 °C removes the stored energy that drives a pressurised reactor's worst accidents, and a freeze plug that melts on loss of power can drain the core to passively cooled tanks. Against that: the salt is corrosive, the fission products travel with it, and no commercial unit has yet operated. Every entry in this family is a first-of-a-kind.

Advantages
  • Fuel dissolved in the coolant means no fuel fabrication in the conventional sense and no cladding to fail
  • Near-atmospheric pressure removes the stored energy that drives a pressurised reactor's worst accidents
  • A freeze plug that melts on loss of power can drain the core passively to cooled tanks
  • High outlet temperature gives good efficiency and process heat potential
  • Gaseous fission products can be removed continuously rather than accumulating in the fuel
Drawbacks
  • Fluoride and chloride salts are corrosive, and long-term materials data is thin
  • Fission products circulate through the whole primary loop, so the entire circuit is highly radioactive
  • No commercial unit has ever operated; every design is first-of-a-kind
  • Most designs need HALEU
  • Online salt chemistry processing is an unproven industrial operation
Design basis
CoolantMolten fluoride or chloride salt
ModeratorGraphite, or none in fast-spectrum designs
Fuel formFuel dissolved in the salt, or TRISO in a salt coolant
Typical enrichment5–20% U-235, often HALEU

Model lines

ModelOperatingUnits on record
Thorcon — 2
SSR-W — 1
MSR-100 — 1

Sources