Shanghai Institute Of Applied Physics Research Articles

Conservativeness Study on the Seismic Analysis Method for Research Reactor Plant Structure Based on TMSR-LF1

The seismic performance analysis of research reactor plants is crucial for ensuring the safety of the entire reactor system. This paper analyzes the plant structure seismic performance of the 2WMt Thorium Molten Salt Reactor-Liquid Fuel 1 (TMSR-LF1) at the Shanghai Institute of Applied Physics, Chinese Academy of Sciences under the action of frequent earthquakes, fortification earthquakes, and rare earthquakes was analyzed by finite element software PKPM based on the seismic design method of civil code +1°. On this basis, a comparison was made between the seismic responses of structural pushover analysis and elastoplastic time history analysis under the action of rare earthquakes, and the conservatism of these two commonly used methods for elastoplastic analysis was systematically analyzed. The results indicate that the TMSR-LF1 plant structure exhibits well bearing and deformation capacity. It meets the seismic design goal of “no damage under small earthquakes,” “no unrepairable damage under medium earthquakes,” and “no collapse under large earthquakes (using static pushover analysis),” and the critical regions are entirely within the elastic range. Furthermore, the analysis reveals that the elastoplastic time history analysis method produced a significantly higher seismic response than the pushover analysis method, which indicates the conservativeness of the time history method. Therefore, it is recommended to use the elastoplastic time history analysis method to evaluate the seismic performance of research reactor plants under rare earthquake actions. The research in this paper provides important references for the seismic performance analysis of other Class II research reactor plants.

Microstructural evolution of silicon carbide fiber under argon ion irradiation at room temperature

In current work, irradiation-induced microstructural evolution of the Cansas 3303 SiC fiber was investigated. This fiber was irradiated by 1.8 MeV argon ions at room temperature in the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. The ion fluences were 5 × 1014, 1 × 1015, 2.5 × 1015 and 5 × 1015 ions/cm2 corresponding to the maximum doses of 0.27, 0.54, 1.35 and 2.70 displacements per atom (dpa), respectively. Irradiation effects were characterized by using micro-Raman spectroscopy and transmission electron microscopy. The results showed that the Cansas 3303 fiber consists of nanocrystalline SiC grains, carbon packets and carbon ribbons. Irradiation-induced amorphization accompanied with the decrease of SiC grain size was observed in the fiber with the increase of ion fluences. However, SiC grains still remained in this fiber up to the dose of 2.70 dpa. Besides, the reduction of the quantity and size in carbon packets and the annihilation of carbon ribbons in this fiber were also detected.

Numerical Investigation of Freeze Valve Melting Behavior in Molten Salt Reactor using OpenFOAM

Molten Salt Reactor (MSR) used a freeze valve to handle accident conditions when the reactor overheated and the active safety control systems failed. The freeze valve will melt if the reactor core temperature increases and exceeds the freeze valve’s melting temperature. In this research, a numerical investigation of freeze valve melting behavior was conducted. Freeze valve geometry used geometry proposed by Oak Ridge National Laboratory (ORNL) in Molten Salt Reactor Experiment (MSRE) and also used in test loop facility in Shanghai Institute of Applied Physics (SINAP) to develop Thorium Molten Salt Reactor (TMSR). The material used FLiNaK salt (LiF-NaF-KF, 46.5-11.5-42.0 mol %). Numerical calculation performs using OpenFOAM. BuoyantPimpleFoam was used to analyze the heat transfer mechanism. Isothermal phase-change simulated by adding solidificationMeltingSource terms into fvOptions as a flexible framework in OpenFOAM.

Radiation dose distribution of liquid fueled thorium molten salt reactor

A liquid fueled thorium molten salt reactor (TMSR-LF), one of the Generation IV reactors, was designed by the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. This study uses the`rt code to calculate the neutron and gamma dose rate distributions around the reactor. Multiple types of tallies and variance reduction techniques were employed to reduce calculation time and obtain convergent calculation results. Based on the calculation and analysis results, the TMSR-LF1 radiation shield with a 60-cm serpentine concrete layer and a 120-cm ordinary concrete layer is able to meet radiation requirements. The gamma dose rate outside the reactor biological shield was 16.1 mSv h−1; this is higher than the neutron dose rate of 3.71 × 10–2 mSv h−1. The maximum thermal neutron flux density outside the reactor biological shield was 1.89 × 103 cm−2 s−1, which was below the 1 × 105 cm−2 s−1 limit.

Gamma Spectrum Measurement Following the Nuclear Decay

In the present work, the detection systems and the data acquisition methods used in the nuclear decay study in our laboratory at Shanghai Institute of Applied Physics, CAS are introduced. These two detection systems include the low-background anti-Compton spectrometer and the three-parameter (γ-γ-t) coincidence system of HPGe-HPGe detectors, both of which are used to measure the γ rays following the nuclear β- and β++EC decays. In addition, as an example, the detection of γ rays following the β++EC decay of 74As, by using these two spectrometers, is described in detail.

(Invited) High Temperature Steam/CO2 Co-electrolysis Using Solid Oxide Electrolyser Stack at Shanghai Institute of Applied Physics

The high temperature steam/CO2 co-electrolysis using solid oxide electrolyser cell technology is considered to be an important alternative for syngas production with carbon-free process. Previously, the co-electrolysis of steam and CO2 in single cell have been published in Faraday Discussions by our team, and electrolysis parameters have been investigated and optimized systematically. In this paper, we carried out the steam/CO2 coelectrolysis experiment using a 30-cell SOC stack composed of NiO-YSZ/YSZ/GDC/LSCF-GDC with the single cell effective area of 63cm2 (developed by Ningbo SOFCMAN Energy Technology Co., Ltd). The electrochemical performance of stack was investigated through OCV, I-V and long-term stability tests. From OCV and I-V curves, we can see the electrochemical performance of steam/CO2 co-electrolysis is slightly worse than that of steam electrolysis. And stability test was carried out in galvanostatic electrolysis mode (750 oC, 0.25 A/cm2, H2/H2O/CO2= 20/53.33/26.67(molar ratio); H2: 1.645NL/min) for 100hrs, the product of hydrogen electrode was analysis though rotameter and Agilent gas chromatograph 7820 , and the steam and CO2 utilization can be calculated to be 55.38% and 46.33%, respectively. Figure 1

The special nuclear data library CENDL-TMSR for thorium-uranium cycle

Thorium molten salt reactor nuclear energy system (TMSR), which is the fourth generation advanced nuclear energy system, needs more advanced and reliable physical design. The reliability and accuracy of nuclear data has very important impact on the accuracy of nuclear design. According to the requirement of Shanghai Institute of Applied Physics, Chinese Academy of Sciences, China Nuclear Data Center has developed a special nuclear data library CENDL-TMSR for thorium-uranium cycle, which includes evaluated nuclear data library and application libraries for criticality calculation and shielding design of thorium molten salt reactor. In order to verify and validate the reliability and applicability of the CENDL-TMSR, the criticality benchmarking and shielding benchmarking are carried out. The criticality testing results show that the relative errors between calculated k eff and experimental values for most benchmarks are within 0.5%, which indicates that the CENDL-TMSR can be used for physical design of thorium molten salt reactor. The shielding calculation results are consistent with the experimental ones, and the overall performances are better than other evaluated nuclear data libraries.

Design a precise stability controller for high power pulse modulator based on FPGA

Shanghai Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) has been fulfilled the construction assignments and passed the acceptance check at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. The stability of microwave system is one of the major factors to get better beam performance. It is mainly determined by klystron and modulators power supply. The beam voltage stability of pulse modulator, which is the cathode voltage source of the microwave amplifier, is directly affecting the microwave amplitude and phase. The requirement of the microwave stability is 0.04% (rms) for amplitude and 0.05% (rms) for phase tolerance. This paper shows the design considerations of stability improvement and suitable upgrade scheme of the controller for Shanghai SXFEL pulse modulator.

Power losses caused by longitudinal HOMs in 3.9 GHz SHINE cryomodule

Shanghai high repetition-rate XFEL and extreme light facility (SHINE), the first hard XFEL based on a superconducting accelerated structure in China, is now under development at the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. In this paper, power losses caused by trapped longitudinal high order modes (HOM) and steady-state loss generated by untrapped HOMs in 3.9 GHz SHINE cryomodule will be investigated and calculated. Results are presented for power losses of every element in 3.9 GHz cryomodule, caused by HOM excitation in the acceleration RF system of the continues-wave (CW) linac of SHINE.

Neutron flux distribution and conversion ratio of Critical Experiment Device for molten salt reactor research

Critical Experiment Device (cold) was established for research on the physics characteristics of Molten Salt Reactor (MSR) in 1970s, at Shanghai Institute of Applied Physics, China. Neutron flux distribution was measured for different core structures and the conversion ratio of the core containing thorium fuel was determined on the basis of the preliminary criticality experiments. The purpose of this work is to compare the calculated flux distribution and thorium-uranium conversion ratio with the measured results in this device. Calculations were accomplished by using MCNP5 code with nuclear data from ENDF/B-VII.0, ENDF/B-VII.1, JEFF 3.2, JENDL 4.0, CENDL 3.1 and ROSFOND 2010 libraries. The results show that the calculated results are in good agreements with the experimental data. Findings in this work have a great significance to the design and benchmark verification of a cold MSR. However, more hot experiments are needed to study the nuclear properties of the liquid fuel MSR.

Analysis and optimization of high-power pulse transformer for SXFEL

A C-band accelerator structure was used to accelerate electrons at the Shanghai soft X-ray free-electron laser test facility (SXFEL-TF) in Shanghai Institute of Applied Physics (SINAP). The microwave system of this accelerator structure used a 110 MW pulse modulator and a klystron (PV-5050) to provide the power supply. A pulse transformer is a crucial device in a modulator klystron system and plays significant roles in voltage level transformation, matching impedances, and polarity inversion. This study presents the optimization of a high-voltage pulse transformer. The design considerations of reducing flattop ringing and flattop droop, and shortening leading edge are provided. The model simulation, mechanical design, and the relevant experimental results are also presented.

Power losses caused by longitudinal HOMs in 1.3-GHz cryomodule of SHINE

Shanghai high-repetition-rate XFEL and extreme light facility (SHINE), the first hard XFEL based on a superconducting accelerated structure in China, is now under development at the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. In this paper, power losses caused by trapped longitudinal high-order modes (HOM), steady-state loss, and transient loss generated by untrapped HOMs in the 1.3-GHz SHINE cryomodule are investigated and calculated. The heat load generated by resistive wall wakefields is considered as well. Results are presented for power losses of every element in the 1.3-GHz cryomodule, caused by HOM excitation in the acceleration RF system of the continuous-wave linac of SHINE.

Radio-frequency design of a new C-band variable power splitter

A novel variable C-band radio-frequency (RF) power splitter was designed at Shanghai Institute of Applied Physics, Chinese Academy of Sciences. Using three RF impedance combiners, an H-bend, and an RF polarizer, this new power splitter is much more compact than a traditionally designed splitter, which comprises three 3-dB hybrids. The parameters were optimized to achieve good matching and minimize reflection. Here, the RF design of the new C-band variable power splitter is presented.

Design, RF measurement, tuning, and high-power test of an X-band deflector for Soft X-ray Free Electron Lasers (SXFEL) at SINAP

Abstract An X-band transverse-deflecting structure is a crucial RF unit for bunch-length measurement conducted at the Shanghai Soft-X-ray Free Electron Laser Facility (SXFEL) at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. The target of this prototype deflector is to operate at 30 MW to have a deflection of 10 MV/structure to realize 20-fs resolution in a full-size structure (0.6 meters long, used on user facility of SXFEL), which satisfies the requirement of the linac beam size measurement at 840 MeV. The program was started in 2010 focusing on X-band deflectors, including design, fabrication, and RF measurement. The electrical tuning of the deflector was successfully done using a unique “cage”-type bead. Recently, a high-power test was conducted at KEK on the first prototype deflector. The high-gradient features at the nominal gradient was proven, but the further increase of power and pulse width was limited at 45 MW with a 173-ns pulse width due to approaching the feasible limit of the modified pointing vector value 5 MW/mm2. In this final stage, frequent breakdowns near the badly brazed point occurred and further conditioning had to be suspended owing to limited available time.

Performance of an electron linear accelerator for the first photoneutron source in China

A compact 15.0-MeV, 1.5-kW electron linear accelerator (LINAC) was successfully constructed to provide an electron beam for the first photoneutron source at the Shanghai Institute of Applied Physics, Shanghai, China. This LINAC consists of five main parts: a thermal cathode grid-controlled electron gun, a pre-buncher, a variable-phase-velocity buncher, a light-speed accelerating structure, and a high-power transportation beamline. A digital feedforward radio frequency compensator is adopted to reduce the energy spread caused by the transient beam loading effect. Furthermore, a real-time electron gun emission feedback algorithm is used to keep the beam stable. After months of efforts, all the beam parameters successfully met the requirements of the facility. In this paper, the beam commissioning process and performance of the LINAC are presented.

The preliminary neutronics analysis for a 10 MW molten salt reactor with solid fuel

The 10 MW MSR-SF is a type of Pebble-bed Fluoride-salt-cooled High-temperature Reactors (PB-FHRs) and was designed by the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). The CAS planned to construct it around 2020 as the initial step with the expectation of a larger 100 MW PB-FHR. The PB-FHRs are composed of randomly distributed fuel pebbles consisting of randomly distributed TRISO coated particles, which is known as the feature of stochastic double heterogeneity. In this work, an explicit modeling method is adopted to consider the stochastic double heterogeneity and the code Serpent is used to execute the Monte Carlo neutron transport calculation. Moreover, the regular lattice method will introduce non-negligible bias in the neutronics analysis for the PB-FHR, while the exact explicit method can provide more reliable results. Therefore, the accurate three-dimensional power distribution of the 10 MW MSR-SF is obtained with the code Serpent based on the explicit modeling approach. The power peaking factor of the 10 MW MSR-SF is small and reasonable.

Design a high power pulse transformer for c-band klystron modulator

Shanghai soft X-ray Free Electron Lasers (SXFEL) used C-band accelerator structure to accelerate electrons at SINAP (Shanghai Institute of Applied Physics). 50MW C-band klystron and 110MW modulator are used to provide power supply for accelerator structure. In order to meet the modulator-klystron demands, a reliable and stable high power pulse transformer is indispensable. In this paper, the key design points for the high voltage pulse transformer are presented. The methods of shortening rise time and diminishing flattop droop are highlighted.

Criticality Properties and Control Rod Worth of the Critical Experiment Device for MSR Research

Zero-power experiments are very important parts in design verification for all reactor types. In the 1970s, in China, at the Shanghai Institute of Applied Physics (then, Shanghai Institute of Nuclear Research), a Critical Experiment Device (cold) was established for research on the physics characteristics of the molten salt reactor (MSR), and a series of zero-power experiments was successfully performed; related experimental results were obtained later. The device consisted mainly of graphite moderator and powdered BeF2 – UF4 / ThF4 fuel and could achieve a maximum power of 200 W. The current work is focused on criticality properties with various core configurations and fuel arrangements of this device and the worths of the cadmium rods used in the device. Evaluations on the agreement of calculation results with experimental data showed good results. Discrepancies between the calculation results and the experimental data might be primarily caused by the simulated outermost fuel element positions not being exactly the same as the experimental arrangements and the unmodeled instruments used in the experiments. The findings in this work can be considered a step of verification of simulation methods and calculations for a cold MSR.

Numerical study of tritium transport characteristics in Thorium Molten Salt Reactor with Solid Fuel (TMSR-SF)

Abstract Tritium control is one of the most key issues for the development of Molten Salt Reactor (MSR). The tritium transport characteristics in 2MWth Thorium Molten Salt Reactor-Solid Fuel (TMSR-SF) proposed by Shanghai INstitute of Applied Physics (SINAP) is studied in this paper. Three works are conducted: Firstly, an integrated numerical model is established, including tritium production, adsorption, diffusion, corrosion and permeation. Secondly, the Tritium trAnsPort chAracteristics analysiS code (TAPAS) for TMSR-SF is developed and benchmarked. The results prove the fidelity and accuracy of TAPAS. Finally, the distributions of the key variables including TF, T2 and Cr2+ in TMSR-SF system at both steady and transient state are obtained. In addition, some methods for tritium mitigation are evaluated by TAPAS. Numerical results show that tritium can be efficiently removed from the molten salt via graphite absorption. The amount of T2 at steady state is two orders of magnitude more than TF. Tritium permeation can be prevented by increasing 7Li enrichment and reducing redox potential. Tungsten or similar low-permeability material is a candidate for tritium barrier when covered on the surface of the heat exchanger wall. This work provides some valuable considerations for the tritium control in the MSR.

The Scanning Magnets for Proton Therapy Designed by SINAP

A new proton therapy scanning system for the treatment of cancer has been accomplished at the Shanghai Institute of Applied Physics (China). It is mainly comprised of two separate dipole magnets, which have been fabricated and now are under commission. According to the design requirements, we have confirmed the dimensions of the magnets and optimized the local and integrated field quality. The static electromagnetic field analysis has been completed in OPERA 3D, including the spatial distribution and interference of the magnetic fields, the optimization of the pole, the verification of the scanning scope. The dynamic behaviors of the two dipole magnets were analyzed respectively and approaches to reduce the effects of the eddy currents were integrated into the design. In addition, the static and dynamic magnetic field measurements were finished. Compared with the simulated magnetic fields, the measurement results indicate that the design of the scanning magnets reaches the design targets. All the specific design results of the scanning magnets are concluded in this paper.