The Experts below are selected from a list of 5334 Experts worldwide ranked by ideXlab platform

Mamoru Ishii - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of blowdown event in a pwr type small Modular Reactor
    Nuclear Technology, 2019
    Co-Authors: Guanyi Wang, Shanbin Shi, Yikuan Yan, Zhuoran Dang, Xiaohong Yang, Mamoru Ishii
    Abstract:

    AbstractAs one of the future directions of nuclear energy development, small Modular Reactor (SMR) designs meet the demands of safety, sustainability, and efficiency by eliminating circulating pump...

  • experimental study on accident transients and flow instabilities in a pwr type small Modular Reactor
    Progress in Nuclear Energy, 2017
    Co-Authors: Guanyi Wang, Shanbin Shi, Yikuan Yan, Xiaohong Yang, Mamoru Ishii
    Abstract:

    Abstract Experimental study on natural circulation flow instabilities is of great importance for the safety analysis in a PWR-type SMR, especially for accident scenarios such as loss of coolant accident (LOCA) and loss of heat sink accident (LOHS). In this study, an experimental natural circulation facility was built by scaling down from a typical PWR-type SMR. The scaling ratios were derived from non-dimensional field and constitutive equations of the drift flux model. The test facility has a height of 3.44 m with an operating pressure limit of 1.0 MPa. Two kinds of tests, the blowdown test and cold-blowdown test were performed. The blowdown test was designed to simulate the low pressure phase (

  • modeling of flashing induced flow instabilities for a natural circulation driven novel Modular Reactor
    Annals of Nuclear Energy, 2017
    Co-Authors: Shanbin Shi, Mamoru Ishii
    Abstract:

    Abstract An analytical study based on frequency domain analysis is presented on the flashing-induced flow instability in a natural circulation test facility, which was designed to investigate the flow instability for a BWR-type novel Modular Reactor (NMR). To address the flashing phenomena at low pressure conditions, such as initial startup transients or accidents, the liquid enthalpy change in the P-T diagram due to reduced hydrostatic head in the riser or chimney was treated as an axially uniform heat flux. Based on the drift flux model, the system transfer function was obtained through small perturbations about the steady state in the frequency domain. The D-partition method was used to determine the neutral stability boundary in the dimensionless stability plane, which was constituted of the subcooling number and phase change number. From the frequency domain analysis, the flashing stability boundary and the density wave oscillations boundary could be predicted. Some parametric studies had been performed on the system pressure and the inlet flow resistance coefficients in the stability analysis. The results showed that the flashing stability boundary was more sensitive to the system pressure than the density wave oscillations. In addition, the theoretical stability boundaries were benchmarked against the experimental stability boundaries from quasi-steady state tests. Although the general stability boundary agreed well with the experiments, certain discrepancies still existed due to the assumptions of thermal equilibrium in current study. In the future, the thermal non-equilibrium conditions including subcooled boiling will be taken into account in the flashing induced stability analysis.

  • a core design study for a small Modular boiling water Reactor with long life core
    Nuclear Technology, 2016
    Co-Authors: W S Yang, Shanbin Shi, Mamoru Ishii
    Abstract:

    This paper presents the core design and performance characteristics of the Novel Modular Reactor (NMR-50), a 50-MW(electric) small Modular Reactor. NMR-50 is a boiling water Reactor with na...

  • a core design study for a small Modular boiling water Reactor with long life core
    Nuclear Technology, 2016
    Co-Authors: W S Yang, Shanbin Shi, Mamoru Ishii
    Abstract:

    AbstractThis paper presents the core design and performance characteristics of the Novel Modular Reactor (NMR-50), a 50-MW(electric) small Modular Reactor. NMR-50 is a boiling water Reactor with natural-circulation cooling and two layers of passive safety systems that enable the Reactor to withstand prolonged station blackout and loss of ultimate heat sink accidents. The main goal in the core design is to achieve a long-life core (~10 years) without refueling for deployment in remote sites. Through assembly design studies with the CASMO-4 lattice code and coupled neutronics and thermal-hydraulic core analyses with the PARCS and RELAP5 codes, a preliminary NMR-50 core design has been developed to meet the 10-year cycle length with an average fuel enrichment of 4.75 wt% and a maximum enrichment of 5.0 wt%. The calculated fuel temperature coefficient and coolant void coefficient provide adequate negative reactivity feedbacks. The maximum fuel linear power density throughout the 10-year burn cycle is 18.7 kW/...

Yonghee Kim - One of the best experts on this subject based on the ideXlab platform.

  • truly optimized pwr lattice for innovative soluble boron free small Modular Reactor
    Scientific Reports, 2021
    Co-Authors: Xuan Ha Nguyen, Seongdong Jang, Yonghee Kim
    Abstract:

    A novel re-optimization of fuel assembly and new innovative burnable absorber (BA) concepts are investigated in this paper to pursue a high-performance soluble-boron-free (SBF) small Modular Reactor (SMR), named autonomous transportable on-demand Reactor module (ATOM). A truly optimized PWR (TOP) lattice concept has been introduced to maximize the neutron economy while enhancing the inherent safety of an SBF pressurized water Reactor. For an SBF SMR design, the 3-D centrally-shielded BA (CSBA) design is utilized and another innovative 3-D BA called disk-type BA (DiBA) is proposed in this study. Both CSBA and DiBA designs are investigated in terms of material, spatial self-shielding effects, and thermo-mechanical properties. A low-leakage two-batch fuel management is optimized for both conventional and TOP-based SBF ATOM cores. A combination of CSBA and DiBA is introduced to achieve a very small reactivity swing (< 1000 pcm) as well as a long cycle length and high fuel burnup. For the SBF ATOM core, safety parameters are evaluated and the moderator temperature coefficient is shown to remain sufficiently and similarly negative throughout the whole cycle. It is demonstrated that the small excess reactivity can be well managed by mechanical shim rods with a marginal increase in the local power peaking, and a cold-zero shutdown is possible with a pseudo checker-board control rod pattern. In addition, a thermal-hydraulic-coupled neutronic analysis of the ATOM core is discussed.

  • Truly-optimized PWR lattice for innovative soluble-boron-free small Modular Reactor
    'Springer Science and Business Media LLC', 2021
    Co-Authors: Xuan Ha Nguyen, Seongdong Jang, Yonghee Kim
    Abstract:

    Abstract A novel re-optimization of fuel assembly and new innovative burnable absorber (BA) concepts are investigated in this paper to pursue a high-performance soluble-boron-free (SBF) small Modular Reactor (SMR), named autonomous transportable on-demand Reactor module (ATOM). A truly optimized PWR (TOP) lattice concept has been introduced to maximize the neutron economy while enhancing the inherent safety of an SBF pressurized water Reactor. For an SBF SMR design, the 3-D centrally-shielded BA (CSBA) design is utilized and another innovative 3-D BA called disk-type BA (DiBA) is proposed in this study. Both CSBA and DiBA designs are investigated in terms of material, spatial self-shielding effects, and thermo-mechanical properties. A low-leakage two-batch fuel management is optimized for both conventional and TOP-based SBF ATOM cores. A combination of CSBA and DiBA is introduced to achieve a very small reactivity swing (

  • impacts of an atf cladding on neutronic performances of the soluble boron free atom core
    International Journal of Energy Research, 2020
    Co-Authors: Xuan Ha Nguyen, Seongdong Jang, Yonghee Kim
    Abstract:

    The impacts of various ATF (accident tolerant fuel) claddings on neutronic performances of pressurized water Reactor fuel assembly and soluble‐boron‐free small Modular Reactor autonomous transportable on‐demand Reactor module (ATOM) are investigated. There are two ATF cladding concepts which are evaluated here: (a) Coating Zircaloy‐4 cladding with thin layer of Cr or Cr alloys; (b) High‐strength and oxidation‐resistant claddings: SS‐304 and FeCrAl. A minor modification of burnable absorber loading in the ATOM core is proposed to adopt the selected ATF cladding and maintain the core performances.

  • an advanced core design for a soluble boron free small Modular Reactor atom with centrally shielded burnable absorber
    Nuclear Engineering and Technology, 2019
    Co-Authors: Xuan Ha Nguyen, Chihyung Kim, Yonghee Kim
    Abstract:

    Abstract A complete solution for a soluble-boron-free (SBF) small Modular Reactor (SMR) is pursued with a new burnable absorber concept, namely centrally-shielded burnable absorber (CSBA). Neutronic flexibility of the CSBA design has been discussed with fuel assembly (FA) analyses. Major design parameters and goals of the SBF SMR are discussed in view of the Reactor core design and three CSBA designs are introduced to achieve both a very low burnup reactivity swing (BRS) and minimal residual reactivity of the CSBA. It is demonstrated that the core achieves a long cycle length (∼37 months) and high burnup (∼30 GWd/tU), while the BRS is only about 1100 pcm and the radial power distribution is rather flat. This research also introduces a supplementary reactivity control mechanism using stainless steel as mechanical shim (MS) rod to obtain the criticality during normal operation. A further analysis is performed to investigate the local power peaking of the CSBA-loaded FA at MS-rodded condition. Moreover, a simple B4C-based control rod arrangement is proposed to assure a sufficient shutdown margin even at the cold-zero-power condition. All calculations in this neutronic-thermal hydraulic coupled investigation of the 3D SBF SMR core are completed by a two-step Monte Carlo-diffusion hybrid methodology.

  • An advanced core design for a soluble-boron-free small Modular Reactor ATOM with centrally-shielded burnable absorber
    Elsevier, 2019
    Co-Authors: Xuan Ha Nguyen, Chihyung Kim, Yonghee Kim
    Abstract:

    A complete solution for a soluble-boron-free (SBF) small Modular Reactor (SMR) is pursued with a new burnable absorber concept, namely centrally-shielded burnable absorber (CSBA). Neutronic flexibility of the CSBA design has been discussed with fuel assembly (FA) analyses. Major design parameters and goals of the SBF SMR are discussed in view of the Reactor core design and three CSBA designs are introduced to achieve both a very low burnup reactivity swing (BRS) and minimal residual reactivity of the CSBA. It is demonstrated that the core achieves a long cycle length (∼37 months) and high burnup (∼30 GWd/tU), while the BRS is only about 1100 pcm and the radial power distribution is rather flat. This research also introduces a supplementary reactivity control mechanism using stainless steel as mechanical shim (MS) rod to obtain the criticality during normal operation. A further analysis is performed to investigate the local power peaking of the CSBA-loaded FA at MS-rodded condition. Moreover, a simple B4C-based control rod arrangement is proposed to assure a sufficient shutdown margin even at the cold-zero-power condition. All calculations in this neutronic-thermal hydraulic coupled investigation of the 3D SBF SMR core are completed by a two-step Monte Carlo-diffusion hybrid methodology. Keywords: Small Modular Reactor, Soluble-boron-free (SBF), Centrally-shielded burnable absorber (CSBA), ATOM, Serpent-COREDA

Xuan Ha Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • truly optimized pwr lattice for innovative soluble boron free small Modular Reactor
    Scientific Reports, 2021
    Co-Authors: Xuan Ha Nguyen, Seongdong Jang, Yonghee Kim
    Abstract:

    A novel re-optimization of fuel assembly and new innovative burnable absorber (BA) concepts are investigated in this paper to pursue a high-performance soluble-boron-free (SBF) small Modular Reactor (SMR), named autonomous transportable on-demand Reactor module (ATOM). A truly optimized PWR (TOP) lattice concept has been introduced to maximize the neutron economy while enhancing the inherent safety of an SBF pressurized water Reactor. For an SBF SMR design, the 3-D centrally-shielded BA (CSBA) design is utilized and another innovative 3-D BA called disk-type BA (DiBA) is proposed in this study. Both CSBA and DiBA designs are investigated in terms of material, spatial self-shielding effects, and thermo-mechanical properties. A low-leakage two-batch fuel management is optimized for both conventional and TOP-based SBF ATOM cores. A combination of CSBA and DiBA is introduced to achieve a very small reactivity swing (< 1000 pcm) as well as a long cycle length and high fuel burnup. For the SBF ATOM core, safety parameters are evaluated and the moderator temperature coefficient is shown to remain sufficiently and similarly negative throughout the whole cycle. It is demonstrated that the small excess reactivity can be well managed by mechanical shim rods with a marginal increase in the local power peaking, and a cold-zero shutdown is possible with a pseudo checker-board control rod pattern. In addition, a thermal-hydraulic-coupled neutronic analysis of the ATOM core is discussed.

  • Truly-optimized PWR lattice for innovative soluble-boron-free small Modular Reactor
    'Springer Science and Business Media LLC', 2021
    Co-Authors: Xuan Ha Nguyen, Seongdong Jang, Yonghee Kim
    Abstract:

    Abstract A novel re-optimization of fuel assembly and new innovative burnable absorber (BA) concepts are investigated in this paper to pursue a high-performance soluble-boron-free (SBF) small Modular Reactor (SMR), named autonomous transportable on-demand Reactor module (ATOM). A truly optimized PWR (TOP) lattice concept has been introduced to maximize the neutron economy while enhancing the inherent safety of an SBF pressurized water Reactor. For an SBF SMR design, the 3-D centrally-shielded BA (CSBA) design is utilized and another innovative 3-D BA called disk-type BA (DiBA) is proposed in this study. Both CSBA and DiBA designs are investigated in terms of material, spatial self-shielding effects, and thermo-mechanical properties. A low-leakage two-batch fuel management is optimized for both conventional and TOP-based SBF ATOM cores. A combination of CSBA and DiBA is introduced to achieve a very small reactivity swing (

  • impacts of an atf cladding on neutronic performances of the soluble boron free atom core
    International Journal of Energy Research, 2020
    Co-Authors: Xuan Ha Nguyen, Seongdong Jang, Yonghee Kim
    Abstract:

    The impacts of various ATF (accident tolerant fuel) claddings on neutronic performances of pressurized water Reactor fuel assembly and soluble‐boron‐free small Modular Reactor autonomous transportable on‐demand Reactor module (ATOM) are investigated. There are two ATF cladding concepts which are evaluated here: (a) Coating Zircaloy‐4 cladding with thin layer of Cr or Cr alloys; (b) High‐strength and oxidation‐resistant claddings: SS‐304 and FeCrAl. A minor modification of burnable absorber loading in the ATOM core is proposed to adopt the selected ATF cladding and maintain the core performances.

  • an advanced core design for a soluble boron free small Modular Reactor atom with centrally shielded burnable absorber
    Nuclear Engineering and Technology, 2019
    Co-Authors: Xuan Ha Nguyen, Chihyung Kim, Yonghee Kim
    Abstract:

    Abstract A complete solution for a soluble-boron-free (SBF) small Modular Reactor (SMR) is pursued with a new burnable absorber concept, namely centrally-shielded burnable absorber (CSBA). Neutronic flexibility of the CSBA design has been discussed with fuel assembly (FA) analyses. Major design parameters and goals of the SBF SMR are discussed in view of the Reactor core design and three CSBA designs are introduced to achieve both a very low burnup reactivity swing (BRS) and minimal residual reactivity of the CSBA. It is demonstrated that the core achieves a long cycle length (∼37 months) and high burnup (∼30 GWd/tU), while the BRS is only about 1100 pcm and the radial power distribution is rather flat. This research also introduces a supplementary reactivity control mechanism using stainless steel as mechanical shim (MS) rod to obtain the criticality during normal operation. A further analysis is performed to investigate the local power peaking of the CSBA-loaded FA at MS-rodded condition. Moreover, a simple B4C-based control rod arrangement is proposed to assure a sufficient shutdown margin even at the cold-zero-power condition. All calculations in this neutronic-thermal hydraulic coupled investigation of the 3D SBF SMR core are completed by a two-step Monte Carlo-diffusion hybrid methodology.

  • An advanced core design for a soluble-boron-free small Modular Reactor ATOM with centrally-shielded burnable absorber
    Elsevier, 2019
    Co-Authors: Xuan Ha Nguyen, Chihyung Kim, Yonghee Kim
    Abstract:

    A complete solution for a soluble-boron-free (SBF) small Modular Reactor (SMR) is pursued with a new burnable absorber concept, namely centrally-shielded burnable absorber (CSBA). Neutronic flexibility of the CSBA design has been discussed with fuel assembly (FA) analyses. Major design parameters and goals of the SBF SMR are discussed in view of the Reactor core design and three CSBA designs are introduced to achieve both a very low burnup reactivity swing (BRS) and minimal residual reactivity of the CSBA. It is demonstrated that the core achieves a long cycle length (∼37 months) and high burnup (∼30 GWd/tU), while the BRS is only about 1100 pcm and the radial power distribution is rather flat. This research also introduces a supplementary reactivity control mechanism using stainless steel as mechanical shim (MS) rod to obtain the criticality during normal operation. A further analysis is performed to investigate the local power peaking of the CSBA-loaded FA at MS-rodded condition. Moreover, a simple B4C-based control rod arrangement is proposed to assure a sufficient shutdown margin even at the cold-zero-power condition. All calculations in this neutronic-thermal hydraulic coupled investigation of the 3D SBF SMR core are completed by a two-step Monte Carlo-diffusion hybrid methodology. Keywords: Small Modular Reactor, Soluble-boron-free (SBF), Centrally-shielded burnable absorber (CSBA), ATOM, Serpent-COREDA

Shanbin Shi - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of blowdown event in a pwr type small Modular Reactor
    Nuclear Technology, 2019
    Co-Authors: Guanyi Wang, Shanbin Shi, Yikuan Yan, Zhuoran Dang, Xiaohong Yang, Mamoru Ishii
    Abstract:

    AbstractAs one of the future directions of nuclear energy development, small Modular Reactor (SMR) designs meet the demands of safety, sustainability, and efficiency by eliminating circulating pump...

  • experimental study on accident transients and flow instabilities in a pwr type small Modular Reactor
    Progress in Nuclear Energy, 2017
    Co-Authors: Guanyi Wang, Shanbin Shi, Yikuan Yan, Xiaohong Yang, Mamoru Ishii
    Abstract:

    Abstract Experimental study on natural circulation flow instabilities is of great importance for the safety analysis in a PWR-type SMR, especially for accident scenarios such as loss of coolant accident (LOCA) and loss of heat sink accident (LOHS). In this study, an experimental natural circulation facility was built by scaling down from a typical PWR-type SMR. The scaling ratios were derived from non-dimensional field and constitutive equations of the drift flux model. The test facility has a height of 3.44 m with an operating pressure limit of 1.0 MPa. Two kinds of tests, the blowdown test and cold-blowdown test were performed. The blowdown test was designed to simulate the low pressure phase (

  • modeling of flashing induced flow instabilities for a natural circulation driven novel Modular Reactor
    Annals of Nuclear Energy, 2017
    Co-Authors: Shanbin Shi, Mamoru Ishii
    Abstract:

    Abstract An analytical study based on frequency domain analysis is presented on the flashing-induced flow instability in a natural circulation test facility, which was designed to investigate the flow instability for a BWR-type novel Modular Reactor (NMR). To address the flashing phenomena at low pressure conditions, such as initial startup transients or accidents, the liquid enthalpy change in the P-T diagram due to reduced hydrostatic head in the riser or chimney was treated as an axially uniform heat flux. Based on the drift flux model, the system transfer function was obtained through small perturbations about the steady state in the frequency domain. The D-partition method was used to determine the neutral stability boundary in the dimensionless stability plane, which was constituted of the subcooling number and phase change number. From the frequency domain analysis, the flashing stability boundary and the density wave oscillations boundary could be predicted. Some parametric studies had been performed on the system pressure and the inlet flow resistance coefficients in the stability analysis. The results showed that the flashing stability boundary was more sensitive to the system pressure than the density wave oscillations. In addition, the theoretical stability boundaries were benchmarked against the experimental stability boundaries from quasi-steady state tests. Although the general stability boundary agreed well with the experiments, certain discrepancies still existed due to the assumptions of thermal equilibrium in current study. In the future, the thermal non-equilibrium conditions including subcooled boiling will be taken into account in the flashing induced stability analysis.

  • a core design study for a small Modular boiling water Reactor with long life core
    Nuclear Technology, 2016
    Co-Authors: W S Yang, Shanbin Shi, Mamoru Ishii
    Abstract:

    This paper presents the core design and performance characteristics of the Novel Modular Reactor (NMR-50), a 50-MW(electric) small Modular Reactor. NMR-50 is a boiling water Reactor with na...

  • a core design study for a small Modular boiling water Reactor with long life core
    Nuclear Technology, 2016
    Co-Authors: W S Yang, Shanbin Shi, Mamoru Ishii
    Abstract:

    AbstractThis paper presents the core design and performance characteristics of the Novel Modular Reactor (NMR-50), a 50-MW(electric) small Modular Reactor. NMR-50 is a boiling water Reactor with natural-circulation cooling and two layers of passive safety systems that enable the Reactor to withstand prolonged station blackout and loss of ultimate heat sink accidents. The main goal in the core design is to achieve a long-life core (~10 years) without refueling for deployment in remote sites. Through assembly design studies with the CASMO-4 lattice code and coupled neutronics and thermal-hydraulic core analyses with the PARCS and RELAP5 codes, a preliminary NMR-50 core design has been developed to meet the 10-year cycle length with an average fuel enrichment of 4.75 wt% and a maximum enrichment of 5.0 wt%. The calculated fuel temperature coefficient and coolant void coefficient provide adequate negative reactivity feedbacks. The maximum fuel linear power density throughout the 10-year burn cycle is 18.7 kW/...

Yikuan Yan - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of blowdown event in a pwr type small Modular Reactor
    Nuclear Technology, 2019
    Co-Authors: Guanyi Wang, Shanbin Shi, Yikuan Yan, Zhuoran Dang, Xiaohong Yang, Mamoru Ishii
    Abstract:

    AbstractAs one of the future directions of nuclear energy development, small Modular Reactor (SMR) designs meet the demands of safety, sustainability, and efficiency by eliminating circulating pump...

  • experimental study on accident transients and flow instabilities in a pwr type small Modular Reactor
    Progress in Nuclear Energy, 2017
    Co-Authors: Guanyi Wang, Shanbin Shi, Yikuan Yan, Xiaohong Yang, Mamoru Ishii
    Abstract:

    Abstract Experimental study on natural circulation flow instabilities is of great importance for the safety analysis in a PWR-type SMR, especially for accident scenarios such as loss of coolant accident (LOCA) and loss of heat sink accident (LOHS). In this study, an experimental natural circulation facility was built by scaling down from a typical PWR-type SMR. The scaling ratios were derived from non-dimensional field and constitutive equations of the drift flux model. The test facility has a height of 3.44 m with an operating pressure limit of 1.0 MPa. Two kinds of tests, the blowdown test and cold-blowdown test were performed. The blowdown test was designed to simulate the low pressure phase (