Nuclear cogeneration of heat and power
In a conventional power plant, heat produced during the generation of electricity is often lost. In a cogeneration plant, however, it is recovered for use in industry and even homes. It is estimated that the cogeneration of heat and power (CHP) can increase the energy efficiency level to about 90 %. High-temperature, gas-cooled nuclear reactors (HTRs) can generate steam conditions comparable to conventional CHP plants. As they are well suited to CHP, EU-funded researchers joined their efforts to provide technical support to a nuclear CHP concept promising to deliver large-scale power and heat to industries without using fossil fuels. The aim of the ARCHER (Advanced high-temperature reactors for cogeneration of heat and electricity R&D) project was to extend European HTR and Very-HTR technologies by incorporating recent advancements. This initiative involved collaboration between European and international partners from Asia, the United States and South Africa. ARCHER partners assessed the coupling of nuclear cogeneration to industrial processes. A suitable cogeneration coupling case study was selected based on real user data from an oil refining and petrochemical complex. From this coupling study, it was concluded that an HTR cogeneration plant can support industrial sites requiring process steam at temperatures up to 600 °C. An added benefit of the HTR is the outstanding safety aspects. Focussed R&D and modelling studies were performed to provide even more insight of the system’s behaviour under accident conditions. The experimental work on ingress and dust mobilization for example resulted in a significant extension of the current knowledgebase and understanding of the system. Research and development efforts also targeted HTR fuels and high-temperature materials. State-of-the-art post-irradiation examination of HTR fuel pebbles and surrogate particles provided valuable insights into fuel performance codes. In addition, the behaviour of HTR fuel waste was examined under long-term disposal conditions. Materials, like graphite, for the reactor core that have reached a level of maturity were considered for the development of a demonstrator. Project scientists also made recommendations for nickel-based materials for use in high-temperature heat exchangers. An intermediate heat exchanger mock-up was developed to validate a design for the extension of the application of HTRs to higher temperatures. There are currently few alternatives to fossil fuel combustion for industrial power production in the EU. ARCHER results confirm that there is no technical impediment to the development of nuclear CHP. Although specific studies depending on the deployment site and configuration are necessary, the validity and viability of nuclear cogeneration coupled to industrial processes has been demonstrated.
Keywords
Cogeneration of heat and power, nuclear reactors, high-temperature, fossil fuels, graphite