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Two steps forward for U.K. advanced nuclear
This week, two significant announcements have emerged from the United Kingdom’s advanced reactor sector.
On June 14, Rolls-Royce, the United Kingdom National Nuclear Laboratory, and the Japan Atomic Energy Agency announced that they had signed two trilateral memorandums of cooperation to collaborate on “advanced modular reactor (AMR) technology, specifically high-temperature gas-cooled reactors (HTGR), and the coated particle fuel these reactors will use.”
Separately, on June 16, Bellevue, Wash.–based TerraPower announced that its Natrium reactor design has been formally submitted for U.K. regulatory review. The company also announced the formation of a new subsidiary, TerraPower UK Ltd.
Joseph L. Bottini, Sabrina Hammouti, David Ruzic, Caleb S. Brooks (Univ of Illinois)
Proceedings | Advances in Thermal Hydraulics 2018 | Orlando, FL, November 11-15, 2018 | Pages 440-448
Boiling heat transfer is an effective method for transferring heat from system components, enabling high heat transfer rates from minimal surface superheats. While it is effective, two-phase heat transfer offers added complexities to single-phase heat transfer caused by the addition of deformable interfaces, dissimilar fluid properties, and phase transition. The critical heat flux (CHF) marks the upper limit of safe operation for many boiling heat transfer systems, and its prediction is essential to ensure safe operation. While much effort has been devoted to studying boiling heat transfer and CHF, the characteristics of the surface, such as wettability and roughness, influence the boiling heat transfer, but are not well understood. Heat transfer surfaces of varying wettability and roughness have been prepared, characterized, and subjected to flow experiments up to CHF to study the role the surface properties have in flow boiling heat transfer. The surfaces were prepared using a high-power laser to texture the surface altering the wettability and roughness. Increasing the roughness and decreasing the wettability are found to have competing effects on both the boiling curves and the CHF points. The onset of nucleate boiling (ONB) points are delayed for the lesswetting surfaces, and the CHF value is lower. An increase in roughness for the textured surface causes earlier ONB and increases CHF, but the CHF values are lower than for the original, polished surface. The roughness and wettability are demonstrated to be influential properties on both the boiling heat transfer and the CHF point, and are not well captured by the existing CHF models.