• Title/Summary/Keyword: PWR Nuclear Fuel Assembly

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Study on Characteristics of Sliding Support for Fuel Rod (이동 가능한 연료봉 지지부의 특성 고찰)

  • Song, Kee-Nam;Lee, Sang-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.2
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    • pp.201-206
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    • 2011
  • A spacer grid assembly is one of the most important structural components of the nuclear fuel assembly of a pressurized water reactor (PWR), and it affects the performance of the fuel assembly. The primary design requirement is that the mechanical integrity of the fuel rod should be maintained by the spacer grid assembly during the operation of the reactor. It was known that fretting damage to the fuel rod can be reduced by adjusting the relative moving displacement between the fuel rod and its support. In this study, we used the finite element method to evaluate the characteristics of a sliding support designed to reduce fretting damage of fuel rods.

Improvement of LBW quality of Zircaloy-4 Spacer Grids for PWR Fuel Assembly (경수로 원전연료용 지르칼로이-4 지지격자 레이저용접품질 개선)

  • Kim, Soo-Sung;Song, Kee-Nam;Han, Hyoung-Jun
    • Journal of Welding and Joining
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    • v.24 no.5
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    • pp.22-28
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    • 2006
  • A spacer grid assembly, which is an interconnected array of slotted grid straps and is welded at the intersections to form an egg crate structure, is one of the main structural components of the nuclear fuel assembly for Pressurized Water Reactors (PWRs). The weld quality of spacer grids in PWRs fuel is extremely important for the fuel assembly performance in the nuclear renter. The spacer grid welds are currently evaluated mainly by the metallographic examination although it reveals only cross-points which are welded by the laser beam. This experiment is also to compare the weldability of Zircaloy-4 spacer grids using by the GTA and LB. The effect of node geometries of spacer grids for the GTAW and LBW has been studied and optimum conditions of spacer grid welding have been found. Microstructures and micro-hardness of the GTA and LB welded zones have been also compared.

Possible power increase in a natural circulation Soluble-Boron-Free Small Modular Reactor using the Truly Optimized PWR lattice

  • Steven Wijaya;Xuan Ha Nguyen;Yonghee Kim
    • Nuclear Engineering and Technology
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    • v.55 no.1
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    • pp.330-338
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    • 2023
  • In this study, impacts of an enhanced-moderation Fuel Assembly (FA) named Truly Optimized PWR (TOP) lattice, which is modified based on the standard 17 × 17 PWR FA, are investigated in a natural circulation Soluble-Boron-Free (SBF) Small Modular Reactor (SMR). Two different TOP lattice designs are considered for the analysis; one is with 1.26 cm pin pitch and 0.38 cm fuel pellet radius, and the other is with 1.40 cm pin pitch and 0.41 cm fuel pellet radius. The NuScale core design is utilized as the base model and assumed to be successfully converted to an SBF core. The analysis is performed following the primary coolant circulation loop, and the reactor is modelled as a single channel for thermal-hydraulic analyses. It is assumed that the ratio of the core pressure drop to the total system pressure drop is around 0.3. The results showed that the reactor power could be increased by 2.5% and 9.8% utilizing 1.26/0.38 cm and 1.40/0.41 cm TOP designs, respectively, under the identical coolant inlet and outlet temperatures as the constraints.