Heat exchanger

The heat exchanger is a building that converts reactor heat into 500°C steam for steam turbines. It consumes 10 MW of heat and outputs steam at a rate of about 103 steam per second, making it the key intermediate between nuclear heat and electrical power generation.

In practical terms, one heat exchanger takes in water and turns it into very hot steam, raising the fluid from the normal 15°C input temperature to 500°C output temperature. Because steam turbines consume 60 steam per second and produce 5.82 MW when fed 500°C steam, one heat exchanger can support a little over one and a half turbines at full output. The exchanger’s output is also often expressed as about 10.3 water per second consumed, since steam is produced from water at a 10:1 ratio.

A useful way to think about the exchanger is that it is effectively an energy-to-steam converter. Its 10 MW heat consumption corresponds to heating the working fluid by 50,000 unit-°C per second in total. Spread across the full temperature rise to 500°C steam, this yields the familiar production rate of roughly 103 steam/s.

In a nuclear power setup, heat exchangers are usually placed so that they can draw heat directly from heat pipes connected to reactor heat. Their job is to maintain a steady supply of 500°C steam for turbines, which then convert that steam into electricity. Since the exchanger’s output is fixed by its heat consumption, the main bottlenecks in a steam power block are usually heat supply, water supply, and steam distribution rather than the exchanger itself.

A few practical points follow from its throughput:

• One exchanger produces enough steam for a bit more than 1.5 steam turbines.
• The exchanger’s output is based on 500°C steam; lower-temperature steam would not match the turbine figures used above.
• Because it consumes 10 MW of heat, multiple exchangers can be chained to scale nuclear power output as long as enough reactor heat is available.
• Its water demand is modest compared with its steam output, at about 10.3 water/s per exchanger.

Overall, the heat exchanger is the central thermal conversion building in nuclear power generation, turning reactor heat into the high-temperature steam required by turbines.