Molten Lead Coolant
The DFR uses lead (not a lead-bismuth eutectic) as coolant, which is somewhat more corrosive than sodium but less aggressive than the eutectic. The DFR’s high operating temperatures of around 1000 °C demand the use of refractory metals (e.g. molybdenum-based alloys) or ceramics or silicon-carbide coated nickel-free heat-resistant alloys. As even at these temperatures, lead reacts far less strongly with water than e.g. sodium, conventional heat recuperators may be employed, though they must be coated on the water side.
Properties of lead at 1000-1100 °C
- thermal capacity [J/(kg*K)]: 140
- heat conductivity (static) [W/(m*K)]: 20…24
- heat transfer coefficient [W/(m2*K)] in the DFR: 30000…40000
- toughness [mPa*s]: 1
Thus at a temperature difference of ca. 200 K between the core’s inlet and outlet and a thermal power of 3 GWth, 115 tons or almost 12 m3 lead must be circulated every second, corresponding to a flow velocity of 2 to 4 meters per second, depending on the distance between tubes.
|Indien||Prüfung||Kein Link, 855/KOLNP/2014|