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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Latest News
New report lays out path to U.S. nuclear energy dominance
The new report “How America Can Achieve Nuclear Energy Dominance,” from the Working Group on U.S. Nuclear Energy Dominance, outlines a plan of action for the Trump administration that includes deploying new nuclear reactors, developing domestic supply chains, promoting nuclear exports, reforming regulations, and developing the workforce.
Working group chair Todd Abrajano said, “We welcome the Trump administration’s bold moves to kick-start the U.S. nuclear energy sector, but we recognize that President Trump’s executive orders alone can’t achieve our goals.”
Muhammad Ishaq, Muhammad Zaman, Muhammad Ilyas, Alam Nawaz Khan Wardag, Mansoor H. Inayat
Nuclear Science and Engineering | Volume 198 | Number 12 | December 2024 | Pages 2382-2402
Research Article | doi.org/10.1080/00295639.2024.2328967
Articles are hosted by Taylor and Francis Online.
Innovative reactor designs like small modular reactors (SMRs) have the potential to operate in a natural circulation (NC) boiling mode, but this mode introduces flow oscillations that pose a risk to nuclear safety. Therefore, it is essential to investigate the effects of various parameters on these oscillations. This study focuses on predicting the operational behavior of the Integral PWR-type SMR Test Rig (iPSTR) when operating in NC and subcooled boiling conditions. The iPSTR replicates an NC boiling loop with a vertical heater, vertical cooler configuration, high-temperature and high-pressure conditions, and nonuniform diameter structure. Using the RELAP5 model, thermal-hydraulic simulations were performed to anticipate how varying degrees of inlet subcooling affects parameters such as mass flow rate and void fraction, with experimental data used to validate the model’s accuracy. This investigation covers a range of process conditions, including system pressures from 5 to 20 bars, core input power varying from 8.5 to 14.5 kW, and degrees of inlet subcooling from 1 to 49 K. The results reveal that increasing input power leads to higher average mass flow rates, while at a constant system pressure, higher input power stabilizes flow rates at higher degrees of inlet subcooling. Moreover, reduced and more consistent oscillation amplitudes and frequencies at higher core power result at more elevated system pressure, enhancing the safety of the iPSTR facility.