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A trip abroad
Hash Hashemian president@ans.org
In my August column in Nuclear News, I reflected on the importance of ANS’s annual conferences for bringing together our nuclear community at the national level. In September, after speaking at Tennessee’s Nuclear Opportunities Workshop, I focused my NN column that month on the value of state-level conferences.
Also in September, alongside ANS Executive Director/CEO Craig Piercy, I shifted my focus to another key front in nuclear collaboration, the international stage, by attending the General Conference of the International Atomic Energy Agency in Vienna.
The timing of the IAEA’s General Conference could not have been better; it took place the same week the U.S. and U.K. kicked off a new wave of transatlantic partnerships in the nuclear sector between both government and industry. This fortuitous overlapping gave us a timely and concrete reminder of international collaboration’s unparalleled benefits.
The General Conference was an expectedly busy event. To cover as much ground as possible, Piercy and I took turns attending either the U.S. delegation meetings with other countries or the General Assembly of the IAEA, where the American Nuclear Society has a seat among other critical nongovernmental organizations.
We listened to presentations by several of the 180 IAEA member states, including, of course, the United States. Aside from ANS, the U.S. presence at the conference included U.S. Secretary of Energy Chris Wright, NRC Chair David Wright, and DOE Assistant Secretary of Nuclear Energy Ted Garrish.
U.S. representation was further bolstered by an industry delegation that included 65 participants from 32 companies, many of whom used the opportunity to report progress on their plans for the international expansion of their nuclear fleets. Meetings of that industry delegation were coordinated by the Nuclear Energy Institute.
Aside from the main conference, Piercy and I also attended the embedded meetings of the International Nuclear Society Council. INSC exists to facilitate knowledge-sharing and collaboration between 18 different member nuclear societies from around the world.
The INSC meetings within the General Conference brought together the presidents and senior members of those societies to give presentations and explore new opportunities. I made a presentation on the state of nuclear in North America, covering the latest developments and deployments in the U.S. and Canada.
This presentation emphasized the new nuclear lift in the U.S. that is being heavily supported by the Trump administration. I recapped the four executive orders issued by President Trump in May, the recent momentum at the DOE, and how these changes are capitalizing on a broader groundswell in both industry development and public support.
I also pointed out the success of our neighbor Canada in progressing on the first water-cooled small modular reactor in North America using BWRX-300 technology, which was supplied by an American firm and international partners—a perfect symbol of the value of global nuclear collaboration.
In all, I have now represented ANS at the state, national, and international levels, gaining useful insight into the work that needs to be done at each. From this vantage point, it’s clear to me that the path forward from the country to the globe is to, above all else, keep working together and supporting each other to bring about the next age of nuclear.
David Reger, Elia Merzari, Paolo Balestra, Sebastian Schunert, Yassin Hassan, Haomin Yuan, Yu-Hsiang Lan, Paul Fischer, Misun Min
Nuclear Technology | Volume 209 | Number 1 | January 2023 | Pages 90-104
Technical Paper | doi.org/10.1080/00295450.2022.2108688
Articles are hosted by Taylor and Francis Online.
Packed beds play an important role in many engineering fields, with their applications in nuclear energy being driven by the development of next-generation reactors utilizing pebble fuel. The random nature of a packed pebble bed creates a flow field that is complex and difficult to predict. Porous media models are an attractive option for modeling pebble-bed reactors (PBRs), as they provide intermediate fidelity results and are computationally efficient. Porous media models, however, rely on the use of correlations to estimate the effect of complicated flow features on the pressure drop and heat transfer in the system. Existing correlations were developed to predict the average behavior of the bed, but they are inaccurate in the near-wall region where the presence of the wall affects the pebble packing.
This work aims to investigate the accuracy of a porous media model using the Kerntechnischer Ausschuss (KTA) correlation, the most common pressure drop correlation for PBRs compared to the high-fidelity large eddy simulation (LES). A bed of 1568 pebbles is investigated at Reynolds numbers from 625 to 10 000. The bed is divided into five concentric subdomains to compare the average velocity, friction losses, and form losses between the porous media and LES codes. The comparison between the LES simulation and the KTA correlation revealed that the KTA correlation largely underpredicts the form losses in the near-wall region, leading to an overprediction of the velocity near the wall by nearly 30%. An investigation of the form losses across the range of Reynolds numbers in the LES results provided additional insight into how the KTA correlation may be improved to better predict these spatial effects in a pebble bed. These data suggest that the form coefficient near the wall must be increased by 48% while decreasing the form coefficient of the inner bulk region of the bed by 15%. The implementation of these improvements to the KTA correlation in a porous media model produced a radial velocity profile that saw significantly improved agreement with the LES results.
