2022 Vol. 39, No. 2
Display Method:
2022, 39(2): 135-153.
doi: 10.11804/NuclPhysRev.39.2022013
Abstract:
The neutron star as a supernova remnant is attracting high attention recently due to the gravitation wave detection and precise measurements about its mass and radius. In the inner core region of the neutron star, the strangeness degrees of freedom, such as the hyperons, can be present, which is also named as a hyperonic star. In this work, the neutron star consisting of nucleons and leptons, and the hyperonic star including the hyperons will be studied in the framework of the relativistic mean-field(RMF) model. Some popular non-linear and density-dependent RMF parametrizations will be adopted to investigate the role of hyperons in a hyperonic star on its mass, radius, tidal deformability, and other properties. Finally, the coupling strengths between mesons and hyperons are also discussed, which can generate the massive hyperonic star with present RMF parameter sets, when the vector coupling constants are strong.
The neutron star as a supernova remnant is attracting high attention recently due to the gravitation wave detection and precise measurements about its mass and radius. In the inner core region of the neutron star, the strangeness degrees of freedom, such as the hyperons, can be present, which is also named as a hyperonic star. In this work, the neutron star consisting of nucleons and leptons, and the hyperonic star including the hyperons will be studied in the framework of the relativistic mean-field(RMF) model. Some popular non-linear and density-dependent RMF parametrizations will be adopted to investigate the role of hyperons in a hyperonic star on its mass, radius, tidal deformability, and other properties. Finally, the coupling strengths between mesons and hyperons are also discussed, which can generate the massive hyperonic star with present RMF parameter sets, when the vector coupling constants are strong.
2022, 39(2): 154-159.
doi: 10.11804/NuclPhysRev.39.2021083
Abstract:
Both the transfer matrix approach and the Wentzel Kramers Brillouin(WKB) approximation are used to calculate the penetrability of\begin{document}$\alpha$\end{document} ![]()
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Both the transfer matrix approach and the Wentzel Kramers Brillouin(WKB) approximation are used to calculate the penetrability of
2022, 39(2): 160-171.
doi: 10.11804/NuclPhysRev.39.2022012
Abstract:
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When a Simple Harmonic Oscillator (SHO) wave function is used as an effective wave function, a very important parameter in the SHO wave function is the effective
2022, 39(2): 172-178.
doi: 10.11804/NuclPhysRev.39.2021046
Abstract:
Following Madey’s calculations on the possible gain induced by stimulated radiation in Free Electron Laser(FEL), we derive the possible maximum gain in laser electron scattering basing on Quantum Electrodynamic(QED) in laser field via introducing the initial state density of laser electron system and the transition rate into a definite final photon state in laser electron scattering. The parameters of laser electron scattering experiments where X-ray or\begin{document}$ \gamma $\end{document} ![]()
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Following Madey’s calculations on the possible gain induced by stimulated radiation in Free Electron Laser(FEL), we derive the possible maximum gain in laser electron scattering basing on Quantum Electrodynamic(QED) in laser field via introducing the initial state density of laser electron system and the transition rate into a definite final photon state in laser electron scattering. The parameters of laser electron scattering experiments where X-ray or
2022, 39(2): 179-187.
doi: 10.11804/NuclPhysRev.39.2021070
Abstract:
In order to reduce beam emittance, improve beam intensity and obtain high quality beam, a stochastic cooling system will be constructed for the high-precision Spectrometer Ring(SRing) in the High-Intensity heavy ion Accelerator Facility(HIAF). The pickup/kicker plays a significant role in the stochastic cooling system and determines its cooling efficiency to a certain extent. The paper discusses the significant function and design specification of the pickup/kicker of the stochastic cooling system, and introduces the concept of shunt impedance. The periodic element slot-ring structure is adopted for the SRing stochastic cooling system, and high frequency structure simulation software(HFSS) is used for modeling and simulation optimization. The effect of slot-ring parameters on shunt impedance of pickup/kicker is studied by sweeping different structural parameters. The simulation results show that the slot-ring structure has high shunt impedance and is suitable for SRing stochastic cooling system. At the same time, considering the flatness of the shunt impedance in the whole operating bandwidth of pickup/kicker, a combination of slot-ring structures of different sizes is proposed to optimize its amplitude flatness. Furthermore, a 16-way power splitter/combiner for the slot-ring structure is designed and fabricated. The measured results show that the combiner/splitter has the performance of a good output amplitude flatness, large isolation, low insertion loss, low voltage standing wave ratio and so on, which meets the requirements of the stochastic cooling system.
In order to reduce beam emittance, improve beam intensity and obtain high quality beam, a stochastic cooling system will be constructed for the high-precision Spectrometer Ring(SRing) in the High-Intensity heavy ion Accelerator Facility(HIAF). The pickup/kicker plays a significant role in the stochastic cooling system and determines its cooling efficiency to a certain extent. The paper discusses the significant function and design specification of the pickup/kicker of the stochastic cooling system, and introduces the concept of shunt impedance. The periodic element slot-ring structure is adopted for the SRing stochastic cooling system, and high frequency structure simulation software(HFSS) is used for modeling and simulation optimization. The effect of slot-ring parameters on shunt impedance of pickup/kicker is studied by sweeping different structural parameters. The simulation results show that the slot-ring structure has high shunt impedance and is suitable for SRing stochastic cooling system. At the same time, considering the flatness of the shunt impedance in the whole operating bandwidth of pickup/kicker, a combination of slot-ring structures of different sizes is proposed to optimize its amplitude flatness. Furthermore, a 16-way power splitter/combiner for the slot-ring structure is designed and fabricated. The measured results show that the combiner/splitter has the performance of a good output amplitude flatness, large isolation, low insertion loss, low voltage standing wave ratio and so on, which meets the requirements of the stochastic cooling system.
2022, 39(2): 188-194.
doi: 10.11804/NuclPhysRev.39.2021047
Abstract:
According to the requirements for the cryogenic vertical measurement system of the Chinese ADS Front-end Demo Linac(CAFe), a 2K superconducting cryogenic vertical measurement control system is designed. One of the main difficulties of the system is to achieve 2K process control in a simple and reliable way, and the other is the control of the pressure in the Dewar during the temperature recovery process. To address these two points, Sequencer, an integrated package in the Experimental Physical and Industrial Control System(EPICS), was used in the paper to implement control of sequential processes such as gas displacement and cavity cooling, enabling easy implementation of multiple process controls. For the temperature recovery process, components such as a Programmable Logic Controller(PLC) are used as the hardware control part, and fuzzy Proportion Integral Differential(PID) a control of the heater is used to stabilize the pressure in the Dewar. The smaller response time and overshoot compared to conventional PIDs ultimately provide a viable and efficient solution to achieve a 2K superconducting cryogenic vertical control system.
According to the requirements for the cryogenic vertical measurement system of the Chinese ADS Front-end Demo Linac(CAFe), a 2K superconducting cryogenic vertical measurement control system is designed. One of the main difficulties of the system is to achieve 2K process control in a simple and reliable way, and the other is the control of the pressure in the Dewar during the temperature recovery process. To address these two points, Sequencer, an integrated package in the Experimental Physical and Industrial Control System(EPICS), was used in the paper to implement control of sequential processes such as gas displacement and cavity cooling, enabling easy implementation of multiple process controls. For the temperature recovery process, components such as a Programmable Logic Controller(PLC) are used as the hardware control part, and fuzzy Proportion Integral Differential(PID) a control of the heater is used to stabilize the pressure in the Dewar. The smaller response time and overshoot compared to conventional PIDs ultimately provide a viable and efficient solution to achieve a 2K superconducting cryogenic vertical control system.
2022, 39(2): 195-200.
doi: 10.11804/NuclPhysRev.39.2021080
Abstract:
In response to the need for monitoring and testing of the neutron absorption performance of the spent fuel pool grid material in the nuclear power plant reactor during the production and use process, we have developed the spent fuel pool grid frame B4C_Al material neutron absorption material detection equipment. In order to reduce the influence of the superthermal neutron background in the detection process, we consider using a magnesium oxide thermal neutron filter to filter out the superthermal neutrons. The neutron transmittance and macroscopic total cross-section of 10 and 5 cm magnesium oxide single crystals were calculated theoretically, and the neutron composition on the surface of the moderator was calculated by Monte Carlo simulation and experimental measurements were carried out. The experimental results show that the neutron transmittance of 10 cm magnesium oxide to the 252Cf neutron source moderated by 8 cm polyethylene is 60.16%, and the relative cadmium ratio is increased by 93.85% compared with that without adding 10 cm of magnesium oxide. At room temperature, magnesium oxide single crystal used as the superthermal neutrons filter of the B4C_Al detection device is feasible.
In response to the need for monitoring and testing of the neutron absorption performance of the spent fuel pool grid material in the nuclear power plant reactor during the production and use process, we have developed the spent fuel pool grid frame B4C_Al material neutron absorption material detection equipment. In order to reduce the influence of the superthermal neutron background in the detection process, we consider using a magnesium oxide thermal neutron filter to filter out the superthermal neutrons. The neutron transmittance and macroscopic total cross-section of 10 and 5 cm magnesium oxide single crystals were calculated theoretically, and the neutron composition on the surface of the moderator was calculated by Monte Carlo simulation and experimental measurements were carried out. The experimental results show that the neutron transmittance of 10 cm magnesium oxide to the 252Cf neutron source moderated by 8 cm polyethylene is 60.16%, and the relative cadmium ratio is increased by 93.85% compared with that without adding 10 cm of magnesium oxide. At room temperature, magnesium oxide single crystal used as the superthermal neutrons filter of the B4C_Al detection device is feasible.
2022, 39(2): 201-205.
doi: 10.11804/NuclPhysRev.39.2021061
Abstract:
Isotope separator on-line of Beijing radioactive ion-beam facility (BRISOL) produces medium and short-lived radioactive isotope beams by irradiating targets with a maxium 200 µA proton beam from a 100 MeV cyclotron. Na and K radioactive ion beams(RIBs) have been generated with CaO and MgO targets at BRISOL. Recentely Al RIB is produced with a SiC target, the beam intensity of 26gAl+ and 23Al+ is 8.7×107 pps and 2.2×102 pps respectively. The SiC target can endure 15 µA proton beam. In this paper, the development of SiC targets and the results of AL RIB on-line production are presented.
Isotope separator on-line of Beijing radioactive ion-beam facility (BRISOL) produces medium and short-lived radioactive isotope beams by irradiating targets with a maxium 200 µA proton beam from a 100 MeV cyclotron. Na and K radioactive ion beams(RIBs) have been generated with CaO and MgO targets at BRISOL. Recentely Al RIB is produced with a SiC target, the beam intensity of 26gAl+ and 23Al+ is 8.7×107 pps and 2.2×102 pps respectively. The SiC target can endure 15 µA proton beam. In this paper, the development of SiC targets and the results of AL RIB on-line production are presented.
2022, 39(2): 206-214.
doi: 10.11804/NuclPhysRev.39.2021027
Abstract:
The pixel detector has been widely used in the inner track detector of high energy particle physics experiments because of its excellent position resolution. With the development of physics experiments, many experiments require detectors and readout electronics to have the capability of high-precision time measurement. To reach the requirement of pixel detectors about the time measurement, a TDC(Time-to-Digital Conversion) ASIC(Application Specific Integrated Circuit) prototype with high event rate processing capability and high precision has been designed. It is expected to be integrated with the front-end readout ASIC of pixel detector as a core component in the future. TDC presented in this paper adopts the combination of coarse and fine measurement, in which the coarse time measurement is based on the counter, and the fine time measurement is implemented by employing the architecture of TAC(Time-to-Amplifier Converter) combined with ADC(Analog-to-Digital Converter). The prototype circuit has been designed based on 130 nm process. TDC has also been simulated, the simulation results indicate that the circuit has the capability processing up to 11 consecutive events in which the time interval between adjacent events is as small as 500 ps, while the bin size of TDC is 2 ps, the DNL (Differential Non-Linearity) is less than 2.8 ps, and the time measurement precision is better than 5 ps RMS.
The pixel detector has been widely used in the inner track detector of high energy particle physics experiments because of its excellent position resolution. With the development of physics experiments, many experiments require detectors and readout electronics to have the capability of high-precision time measurement. To reach the requirement of pixel detectors about the time measurement, a TDC(Time-to-Digital Conversion) ASIC(Application Specific Integrated Circuit) prototype with high event rate processing capability and high precision has been designed. It is expected to be integrated with the front-end readout ASIC of pixel detector as a core component in the future. TDC presented in this paper adopts the combination of coarse and fine measurement, in which the coarse time measurement is based on the counter, and the fine time measurement is implemented by employing the architecture of TAC(Time-to-Amplifier Converter) combined with ADC(Analog-to-Digital Converter). The prototype circuit has been designed based on 130 nm process. TDC has also been simulated, the simulation results indicate that the circuit has the capability processing up to 11 consecutive events in which the time interval between adjacent events is as small as 500 ps, while the bin size of TDC is 2 ps, the DNL (Differential Non-Linearity) is less than 2.8 ps, and the time measurement precision is better than 5 ps RMS.
2022, 39(2): 215-223.
doi: 10.11804/NuclPhysRev.39.2021050
Abstract:
A portable food radiation monitor has been developed and tested. This paper introduced the measurement structure, nuclear signal processing unit and the analysis application program. The nuclear signal processing unit includes anti-aliasing low-pass filter, programmable gain amplifier, high-speed A/D sampling, digital low-pass filter, trapezoidal shaping, pulse amplitude discrimination, and energy spectrum acquisition unit. The analysis application program includes functions for spectral line smooth, spectral peak-seeking, energy calibration, background deduction and activity calculation. The detection efficiency, the correction coefficient and the MDA of 131I have been determined. The calibration coefficient has been used to correct the radioactivity measurement results of 300 mL-food sample. The results show that the measurement error of monitor for 131I radioactivity in the general food is less than 10%, which satisfies the demand of food radioactive measurement.
A portable food radiation monitor has been developed and tested. This paper introduced the measurement structure, nuclear signal processing unit and the analysis application program. The nuclear signal processing unit includes anti-aliasing low-pass filter, programmable gain amplifier, high-speed A/D sampling, digital low-pass filter, trapezoidal shaping, pulse amplitude discrimination, and energy spectrum acquisition unit. The analysis application program includes functions for spectral line smooth, spectral peak-seeking, energy calibration, background deduction and activity calculation. The detection efficiency, the correction coefficient and the MDA of 131I have been determined. The calibration coefficient has been used to correct the radioactivity measurement results of 300 mL-food sample. The results show that the measurement error of monitor for 131I radioactivity in the general food is less than 10%, which satisfies the demand of food radioactive measurement.
2022, 39(2): 224-231.
doi: 10.11804/NuclPhysRev.39.2021042
Abstract:
Precision measurement of the radiation transition properties of highly charged ions are considered not only provides excellent conditions for precise testing of fundamental theoretical models such as strong field QED effects, relativistic effects, and electron correlation effects, but also contributes to many advanced physics research, including isotope shifts, HCI clock, etc. In order to perform precision laser spectroscopy of lithium-like 16O5+ ions to precisely measure the optical transition energy of 2s1/2→2p1/2 and 2s1/2→2p3/2 at the experimental cooler storage ring CSRe in Heavy Ion Research Facility in Lanzhou(HIRFL), a new non-destructive ultraviolet photon detection system has been developed for efficient detection of the forward-emitted ultraviolet photons. This detection system is mainly consisted of a SiC-made parabolic reflector, a MCP(Microchannel Plate) coated with CsI and a high-speed stepper motor. In the high temperature baking environment and ultra-high vacuum experimental conditions at the CSRe, this new detection system enables high-efficiency detection of the de-excitation ultraviolet photons without affecting the normal operation of the ion beams at the storage ring, and the collection efficiency is improved by more than 50 times as compared to the previously installed Channeltron photomultiplier photons detector. This new detection system will not only provide an efficient real-time detection tool for the precision laser spectroscopy of highly charged ions at the CSRe, but also lays a solid foundation for future research on precision laser spectroscopy of heavy ions with higher energies and higher charge state at High Intensity heavy-ion Accelerator Facility(HIAF).
Precision measurement of the radiation transition properties of highly charged ions are considered not only provides excellent conditions for precise testing of fundamental theoretical models such as strong field QED effects, relativistic effects, and electron correlation effects, but also contributes to many advanced physics research, including isotope shifts, HCI clock, etc. In order to perform precision laser spectroscopy of lithium-like 16O5+ ions to precisely measure the optical transition energy of 2s1/2→2p1/2 and 2s1/2→2p3/2 at the experimental cooler storage ring CSRe in Heavy Ion Research Facility in Lanzhou(HIRFL), a new non-destructive ultraviolet photon detection system has been developed for efficient detection of the forward-emitted ultraviolet photons. This detection system is mainly consisted of a SiC-made parabolic reflector, a MCP(Microchannel Plate) coated with CsI and a high-speed stepper motor. In the high temperature baking environment and ultra-high vacuum experimental conditions at the CSRe, this new detection system enables high-efficiency detection of the de-excitation ultraviolet photons without affecting the normal operation of the ion beams at the storage ring, and the collection efficiency is improved by more than 50 times as compared to the previously installed Channeltron photomultiplier photons detector. This new detection system will not only provide an efficient real-time detection tool for the precision laser spectroscopy of highly charged ions at the CSRe, but also lays a solid foundation for future research on precision laser spectroscopy of heavy ions with higher energies and higher charge state at High Intensity heavy-ion Accelerator Facility(HIAF).
2022, 39(2): 232-237.
doi: 10.11804/NuclPhysRev.39.2022004
Abstract:
The electron emission yield of protons with an energy range of 50~250 keV incident on tungsten surface of a target at different temperatures are measured on the 320 kV electron cyclotron resonance ion source(ECRIS) platform of the Institute of Modern Physics, Chinese Academy of Science(IMP, CAS) in Lanzhou. It is shown that the electron emission yield induced by protons with different energies decreases with the increase of target temperature. The results were qualitatively explained by the temperature dependence of the work function. At different target temperatures, the ratio of total electron emission yield to electronic stopping power decreases with the increase of incident ion energy. The ionization competition between electrons in different shells of the target atom is used to explain the experimental results.
The electron emission yield of protons with an energy range of 50~250 keV incident on tungsten surface of a target at different temperatures are measured on the 320 kV electron cyclotron resonance ion source(ECRIS) platform of the Institute of Modern Physics, Chinese Academy of Science(IMP, CAS) in Lanzhou. It is shown that the electron emission yield induced by protons with different energies decreases with the increase of target temperature. The results were qualitatively explained by the temperature dependence of the work function. At different target temperatures, the ratio of total electron emission yield to electronic stopping power decreases with the increase of incident ion energy. The ionization competition between electrons in different shells of the target atom is used to explain the experimental results.
2022, 39(2): 238-244.
doi: 10.11804/NuclPhysRev.39.2021054
Abstract:
To determine the concentration of trace vanadium in saline lake brines, a vanadium pre-purification process is established to reduce the matrix effect of the huge coexisting ions. Two steps, extraction and stripping, are included in the process. The factors affecting the vanadium purification efficiencies are investigated in detail and the optimum conditions are determined to be: vanadium in the solutions was extracted by the organic phase containing 30% D2EHPA (v/v), 20% TBP (v/v) in n-hexane for 30 min at pH 3.0, and then stripped with 3 mol/L H2SO4 for 10 min. Trace vanadium in two natural brine samples are pre-purified using this process and their concentrations are determined by inductively coupled plasma-mass spectrometry (ICP-MS) with sensitivity and limit of detection (LOD) for 51V are 53 171 cps/(µg/L) and 1.88 ng/L, respectively. The standard addition recoveries of the brine samples are ~100% but with small relative standard deviations (RSD<0.6%), indicating that the method can be used to measure the concentration of trace vanadium in natural complicated waters, such as seawater and saline lake brines.
To determine the concentration of trace vanadium in saline lake brines, a vanadium pre-purification process is established to reduce the matrix effect of the huge coexisting ions. Two steps, extraction and stripping, are included in the process. The factors affecting the vanadium purification efficiencies are investigated in detail and the optimum conditions are determined to be: vanadium in the solutions was extracted by the organic phase containing 30% D2EHPA (v/v), 20% TBP (v/v) in n-hexane for 30 min at pH 3.0, and then stripped with 3 mol/L H2SO4 for 10 min. Trace vanadium in two natural brine samples are pre-purified using this process and their concentrations are determined by inductively coupled plasma-mass spectrometry (ICP-MS) with sensitivity and limit of detection (LOD) for 51V are 53 171 cps/(µg/L) and 1.88 ng/L, respectively. The standard addition recoveries of the brine samples are ~100% but with small relative standard deviations (RSD<0.6%), indicating that the method can be used to measure the concentration of trace vanadium in natural complicated waters, such as seawater and saline lake brines.
2022, 39(2): 245-251.
doi: 10.11804/NuclPhysRev.39.2021037
Abstract:
For Swift Heavy Ion(SHI) irradiation, at micro-scale, the incident ions are randomly distributed regardless of beam scanning or defocusing. Recently, this nonuniformity of ion irradiation is becoming critical for the cutting-edge applications of SHIs, i.e., fabrication of high-density microporous membranes, and evaluation of single event effect for the aerospace electronics. In this study, a Monte Carlo(MC) code is developed for simulating the planar distribution of incident ions. Statistically, the predicted distributions of latent tracks and micropores show good coincidence with the direct observations of microporous membranes. According to the simulations, the porosities of membranes are predicted as functions of ion fluences and pore sizes. An empirical formula is proposed for the estimation of effective porosity prior to ion irradiation and chemical etching. Moreover, to evaluate the selectivity of microporous membranes, the probability of multi-pores formation is estimated. A balance between the porosity and selectivity of the membranes is suggested. By employing the MC simulations, uniformity issues of ion irradiation at micro-scale are investigated, whose results may serve as important references for single event effect etc.
For Swift Heavy Ion(SHI) irradiation, at micro-scale, the incident ions are randomly distributed regardless of beam scanning or defocusing. Recently, this nonuniformity of ion irradiation is becoming critical for the cutting-edge applications of SHIs, i.e., fabrication of high-density microporous membranes, and evaluation of single event effect for the aerospace electronics. In this study, a Monte Carlo(MC) code is developed for simulating the planar distribution of incident ions. Statistically, the predicted distributions of latent tracks and micropores show good coincidence with the direct observations of microporous membranes. According to the simulations, the porosities of membranes are predicted as functions of ion fluences and pore sizes. An empirical formula is proposed for the estimation of effective porosity prior to ion irradiation and chemical etching. Moreover, to evaluate the selectivity of microporous membranes, the probability of multi-pores formation is estimated. A balance between the porosity and selectivity of the membranes is suggested. By employing the MC simulations, uniformity issues of ion irradiation at micro-scale are investigated, whose results may serve as important references for single event effect etc.
2022, 39(2): 252-257.
doi: 10.11804/NuclPhysRev.39.2021038
Abstract:
A robust optimization method for computing RBE-weighted dose based on the mixed beam model is proposed to reduce the influence of range and setup uncertainties on dose distribution in carbon-ion radiotherapy. Firstly, a probabilistic robust model was established and the objective function was expressed using the quadratic function. Then two treatment plans were designed regarding to physical absorbed dose and RBE-weighted dose. Finally, the conjugate gradient method was adopted to find the respective optimal solutions so as to make the actual dose distribution across the target volume and organ at risk(OAR) meet the dose requirements as much as possible. The C-shaped model was utilized to evaluate the effectiveness of this method. Compared with the conventional dose optimization method based on the planning target volume(PTV), the robust treatment planning based on physical absorbed dose made\begin{document}$ \Delta {D}_{95{\text{%}} } $\end{document} ![]()
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A robust optimization method for computing RBE-weighted dose based on the mixed beam model is proposed to reduce the influence of range and setup uncertainties on dose distribution in carbon-ion radiotherapy. Firstly, a probabilistic robust model was established and the objective function was expressed using the quadratic function. Then two treatment plans were designed regarding to physical absorbed dose and RBE-weighted dose. Finally, the conjugate gradient method was adopted to find the respective optimal solutions so as to make the actual dose distribution across the target volume and organ at risk(OAR) meet the dose requirements as much as possible. The C-shaped model was utilized to evaluate the effectiveness of this method. Compared with the conventional dose optimization method based on the planning target volume(PTV), the robust treatment planning based on physical absorbed dose made
2022, 39(2): 258-265.
doi: 10.11804/NuclPhysRev.39.2021072
Abstract:
CiADS subcritical reactor used LBE as coolant and closed fuel assembly mixed by wire wrapped. The wire can make the working fluid cross-mixing, enhancing the momentum exchange between coolant in different subchannel. This study generated structured and unstructured mesh by software ANSYS ICEM and STAR-CCM+, analyzed the cross-flow characteristics in CiADS subcritical reactor and investigated the influence caused by using different mesh structure in CFD simulation. The calculation result showed: comparing with unstructured mesh, the cross g between subchannel calculation in structured mesh is closer to the result in LES. The friction factor calculated by structured mesh is closest to the prediction of UCTD formula, and the factor calculated by unstructured mesh is smaller than all empirical formula. In addition, this research refined existed empirical formula, which could predict cross-flow characteristics more accurate. The conclusions provided a new way refining subchannel progress, and provide data support for thermohydraulic design and analysis in CiADS fuel assembly.
CiADS subcritical reactor used LBE as coolant and closed fuel assembly mixed by wire wrapped. The wire can make the working fluid cross-mixing, enhancing the momentum exchange between coolant in different subchannel. This study generated structured and unstructured mesh by software ANSYS ICEM and STAR-CCM+, analyzed the cross-flow characteristics in CiADS subcritical reactor and investigated the influence caused by using different mesh structure in CFD simulation. The calculation result showed: comparing with unstructured mesh, the cross g between subchannel calculation in structured mesh is closer to the result in LES. The friction factor calculated by structured mesh is closest to the prediction of UCTD formula, and the factor calculated by unstructured mesh is smaller than all empirical formula. In addition, this research refined existed empirical formula, which could predict cross-flow characteristics more accurate. The conclusions provided a new way refining subchannel progress, and provide data support for thermohydraulic design and analysis in CiADS fuel assembly.
2022, 39(2): 266-271.
doi: 10.11804/NuclPhysRev.39.2021084
Abstract:
In order to improve the reliability of Residual Heat Removal System(RHRS) in Pressurized Water Reactor nuclear power plant and provide guide and reference for regular overhaul and maintenance of RHRS, the reliability modeling of RHRS was conducted by using fault tree, and the importance index of system components was evaluated. Based on the evaluation results of importance index, an improved scheme of cold standby system with common spare parts is proposed. Dynamic fault tree modeling is adopted and Markov model is used for quantitative analysis. The results show that the reliability of the optimized RHRS is significantly improved.
In order to improve the reliability of Residual Heat Removal System(RHRS) in Pressurized Water Reactor nuclear power plant and provide guide and reference for regular overhaul and maintenance of RHRS, the reliability modeling of RHRS was conducted by using fault tree, and the importance index of system components was evaluated. Based on the evaluation results of importance index, an improved scheme of cold standby system with common spare parts is proposed. Dynamic fault tree modeling is adopted and Markov model is used for quantitative analysis. The results show that the reliability of the optimized RHRS is significantly improved.
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