• Title/Summary/Keyword: 24-month cycle

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Physics study for high-performance and very-low-boron APR1400 core with 24-month cycle length

  • Do, Manseok;Nguyen, Xuan Ha;Jang, Seongdong;Kim, Yonghee
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.869-877
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    • 2020
  • A 24-month Advanced Power Reactor 1400 (APR1400) core with a very-low-boron (VLB) concentration has been investigated for an inherently safe and high-performance PWR in this work. To develop a high-performance APR1400 which is able to do the passive frequency control operation, VLB feature is essential. In this paper, the centrally-shielded burnable absorber (CSBA) is utilized for an efficient VLB operation in the 24-month cycle APR1400 core. This innovative design of the VLB APR1400 core includes the optimization of burnable absorber and loading pattern as well as axial cutback for a 24-month cycle operation. In addition to CSBA, an Er-doped guide thimble is also introduced for partial management of the excess reactivity and local peaking factor. To improve the neutron economy of the core, two alternative radial reflectors are adopted in this study, which are SS-304 and ZrO2. The core reactivity and power distributions for a 2-batch equilibrium cycle are analyzed and compared for each reflector design. Numerical results show that a VLB core can be successfully designed with 24-month cycle and the cycle length is improved significantly with the alternative reflectors. The neutronic analyses are performed using the Monte Carlo Serpent code and 3-D diffusion code COREDAX-2 with the ENDF/B-VII.1.

Feasibility of combinational burnable poison pins for 24-month cycle PWR reload core

  • Dandi, Aiman;Lee, MinJae;Kim, Myung Hyun
    • Nuclear Engineering and Technology
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    • v.52 no.2
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    • pp.238-247
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    • 2020
  • The Burnable Poison (BP) is very important for all Light Water Reactors in order to hold-down the initial excess reactivity and to control power peaking. The use of BP is even more essential as the excess reactivity increases significantly with a longer operation cycle. In this paper a feasibility study was conducted in order to investigate the benefits of a new combinational BP concept designed for 24-month cycle PWR core. The reference designs in this study are based on the two Korean fuel assemblies; 17 × 17 Westinghouse (WH) design and 16 × 16 Combustion Engineering (CE) design. A modification was done on these two designs to extend their cycle length from 18 months into 24 months. DeCART2D-MASTER code system was used to perform assembly and core calculations for both designs. A preliminary test was conducted in order to choose the best BP suitable for 24-month as a representative for single BP concept. The comparison between the results of two concepts (combinational BP concept and single BP concept) showed that the combinational BP concept can replace the single BP concept with better performance on holding down the initial excess reactivity without violating the design limitations.

An Evaluation of Nuclear Design Characteristics of Duplex Burnable Absorber Rods (이중구조 가연성 독봉의 핵설계 특성 평가)

  • 이대진;김명현;송근우;정연호
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • pp.71-79
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    • 2002
  • Nuclear design characteristics of duplex burnable poison rod were evaluated based on 24 month cycle fuel for Korean Standard Nuclear Plant. A fuel assembly with duplex burnable poison rod was designed for an equivalent assembly to 16 gadolinia BPs. Duplex BP is composed of inner region of natural U-12wt%Gd$_2$O$_3$ and outer shell of 4.95wt%UO$_2$-2wt%Er$_2$O$_3$. In order to compare this duplex option, assemblies with 140 erbia pins were designed as an alternative option. The variation of k-infinitive, rod worth, pin peaking and MTC were compared. Duplex BP had the better neutronic performance than gadolinia BP in all parameters. However, Duplex BP was worse than erbia BP in the aspect of safety.

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