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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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The journey of the U.S. fuel cycle
Craig Piercycpiercy@ans.org
While most big journeys begin with a clear objective, they rarely start with an exact knowledge of the route. When commissioning the Lewis and Clark expedition in 1803, President Thomas Jefferson didn’t provide specific “turn right at the big mountain” directions to the Corps of Discovery. He gave goal-oriented instructions: explore the Missouri River, find its source, search for a transcontinental water route to the Pacific, and build scientific and cultural knowledge along the way.
Jefferson left it up to Lewis and Clark to turn his broad, geopolitically motivated guidance into gritty reality.
Similarly, U.S. nuclear policy has begun a journey toward closing the U.S. nuclear fuel cycle. There is a clear signal of support for recycling from the Trump administration, along with growing bipartisan excitement in Congress. Yet the precise path remains unclear.
Bilge Yildiz, Katherine J. Hohnholt, Mujid S. Kazimi
Nuclear Technology | Volume 155 | Number 1 | July 2006 | Pages 1-21
Technical Paper | Fission Reactors | doi.org/10.13182/NT06-A3742
Articles are hosted by Taylor and Francis Online.
Hydrogen production using high-temperature steam electrolysis (HTSE) supported by a supercritical CO2 (SCO2) recompression Brayton cycle that is directly coupled to an advanced gas-cooled reactor (AGR) is proposed in this paper. The system features and efficiency are analyzed in a parametric fashion. The analysis includes the influence of the major components' performance and the component integration in a proposed plant layout. The configuration, HTSE-SCO2-AGR, with thermal recuperation from the product gas streams and an intermediate heat exchanger between the turbine exit and the feedwater stream is found to offer excellent thermal efficiency, operational flexibility, and expected cost. The HTSE average process temperature is 900°C, and the hydrogen pipeline delivery pressure is assumed to be 7 MPa for the evaluation of the plant performance. The reactor exit temperature and the SCO2 cycle turbine inlet temperature are the same as those for the SCO2 recompression cycle design: 550 to 700°C. The 900°C at the HTSE unit, which is higher than the reactor exit temperature, is achieved with recuperative and electrical heating. HTSE is assumed to operate within 80 to 90% voltage efficiency at 1 atm to 7 MPa of pressure. A parametric analysis of these operating conditions shows that the system can achieve 38.6 to 48.2% low heating value of net hydrogen production energy efficiency. The extensive experience from commercial AGRs, the compactness of the SCO2 power conversion system, and the progress in the electrolysis cell materials field can help the economical development of a future recuperative HTSE-SCO2-AGR. The major research and development needs for this plant concept are materials processing for the durability and efficiency of the HTSE system, the design update of the AGR with advanced materials to resist high-pressure CO2 coolant, thermal hydraulics of CO2 at supercritical pressures, and detailed component design for system integration.
