⚡ Chapter 7: Other Thermodynamic Cycles Associated with Nuclear Reactors
Beyond Electricity: Cogeneration, Desalination, Hydrogen
- Combined Cycles:
- Brayton (gas) + Rankine (steam) → 60% efficiency (e.g., Areva’s GT-MHR He-N₂).
- Desalination:
- Multi-effect distillation, multi-stage flash, reverse osmosis.
- Steam savings: Up to 3x less consumption.
- Hydrogen Production:
- Steam methane reforming (chemical equilibrium modeling).
- High-temperature electrolysis (HTE, 800-1000°C).
- Nuclear Cogeneration:
- Overall efficiency > 80% (e.g., Gösgen NPP → 54 MW process steam).
Highlight: Areva’s Antares project → 58.9% overall efficiency!
Abstract
This chapter examined nuclear thermodynamic cycles other than those used for conventional electricity generation. Combined cycles integrate Brayton topping cycles with Rankine bottoming cycles, achieving efficiencies exceeding 60% through optimal heat recovery. The pinch method systematically optimizes Heat Recovery Steam Generators (HRSG), demonstrated through dual-pressure helium-steam configurations reaching 48.73% efficiency and the Areva GT-MHR He-N₂ combined cycle achieving 47% efficiency with 65.6% exergy efficiency. Supercritical CO₂ combined cycles are explored, including sCO₂-sCO₂ and sCO₂-NH₃ variants. Seawater desalination technologies are detailed, covering single and multiple effect distillation, multi-stage flash systems, reverse osmosis, and mechanical vapor compression reducing steam consumption by factor of three. Hydrogen production methods include steam methane reforming modeled through complex equilibrium calculations and high-temperature electrolysis (HTE) operating at 800-1000°C with detailed thermodynamic modeling. Nuclear cogeneration applications demonstrate overall efficiencies exceeding 80%, exemplified by the Gösgen NPP supplying 54 MW process steam, the Areva Antares project achieving 58.9% overall efficiency, and PWR-coupled desalination maintaining 31.19% efficiency while producing 40 kg/s freshwater through thermocompression ejectors.