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The CYCIAE-230 cyclotron is a proton beam accelerator dedicated to cancer therapy. The low-level radiofrequency (LLRF) system of CYCIAE-230 cyclotron is designed based on the previous LLRF systems which have been successfully commissioned for CYCIAE-100 and CYCIAE-14 cyclotrons. This design includes four feedback control loops, namely, tuning loop, amplitude loop, phase loop, and balance loop. The LLRF system for CYCIAE-230 cyclotron have the same amplitude, phase, and tuning loops as the previous designs. Meanwhile, the balance loop makes the LLRF system stand out. It is enabled after the amplitude loop is closed and controls the homogeneity of the accelerating fields of the four cavities. From the bird view of the control system of the cyclotron, the LLRF system is an embedded control unit which communicates with the program logical controller with Profibus-DP (Distributed Peripherals). In this paper, the desktop experiment has been performed with a small-scale copper cavity with low power. This small-scale cavity has an unloaded quality factor ( Q 0 ) of around 7800 and has push–pull and push–push resonate modes, which are the characteristic parameters of the cavities of CYCIAE-230 cyclotron. The design and performance of the LLRF system were discussed based on the desktop experiment results in this paper.

The CYCIAE230 is a low-current, compact superconducting cyclotron designed for proton therapy. The Radio Frequency system consists of four RF cavities and applies second harmonic to accelerate beams. The driving power for the cavity system is estimated to be approximately 150 kW. The LLRF controller is a self-made device developed and tested at low power using a small-scale cavity model. In this paper, the resonator systems of an S.C. cyclotron in history are reviewed. Contrary to those RF systems, the cavities of the CYCIAE230 cyclotron connect two opposite dees. Two high-power RF windows are included in the system. Each window carries approximately 75 kW RF power from the driver to the cavities. Thus, the RF system for the CY-CIAE230 cyclotron is operated in driven push–pull mode. The two-way amplifier-coupler-cavity systems are operated with approximately the same amount of RF power but 180° out of phase compared with each other. The design, as well as the technical advantage and limitations of this operating mode, of the CYCIAE230 cyclotron RF system is analyzed.

We in this study investigated the role of lncRNA NR2F2-AS1 in prostate carcinoma (PC). We showed that NR2F2-AS1 was upregulated in PC and positively correlated with CDK4. In PC cells, NR2F2-AS1 overexpression led to upregulated, while NR2F2-AS1 siRNA silencing led to downregulated CDK4. Follow-up study revealed that high levels of NR2F2-AS1 and CDK4 in PC tissues were closely correlated with the poor survival of PC patients. Cell proliferation data showed that NR2F2-AS1 overexpression led to increased, while NR2F2-AS1 siRNA silencing led to proliferation rate of PC cells. Moreover, NR2F2-AS1 also showed positive effects on cell cycle progression. In addition, CDK4 overexpression reduced the effects of NR2F2-AS1 siRNA silencing. Therefore, NR2F2-AS1 positively regulates CDK4 to promote cancer cell proliferation in PC.

In AP1000 plant, the Automatic Depressurization System (ADS) 1–3 stages operate to discharge the high-temperature and high-pressure steam from the Reactor Coolant System (RCS) primary side to the large heat sink tank In-containment Refueling Water Storage Tank (IRWST) in accidental conditions. The key equipment’s specific shape and arrangement lead to the complicate flow and heat transfer characteristics in IRWST. In the present work, an overall scaled IRWST&ADS sparger experiment has been built up. The thermocouples matrix, flowmeters, pressure transmitters, heat flux sensors, Particle Image Velocimetry (PIV) technique, and high speed camera are employed for the measurements of the key thermal and flow parameters. The local steam jets condensation phenomena as well as the overall flow and thermal behavior are investigated. The experimental results indicate that the thermal stratification phenomenon is obvious in IRWST. The criteria of Richardson Number and Stratification Number are utilized to predict and evaluate the thermal stratification extent, respectively. An improved ADS arrangement design is further proposed to reduce the thermal stratification. Moreover, the multi-holes lumped “steam condensation column” is modeled with characteristic parameters, then the steam condensation heat transfer coefficient range in chugging condensation process is estimated. The experimental results provide practical engineering application reference for the effective operation of the passive safety system in AP1000 plant.

As a driven accelerator, the CYCIAE-100 cyclotron is designed by China Institute of Atomic Energy for the Beijing Radio Ion-beam Facility project. The cyclotron RF system is designed to use two RF power sources of 100 kW to drive two half-wavelength cavities respectively. Two Dee accelerating electrodes are kept separately from each other inside the cyclotron, while their accelerating voltages are maintained in phase by the efforts of LLRF control. An analog–digital hybrid LLRF system has been developed to achieve cavity tuning control, dee voltage amplitude and phase stabilization etc. The analog subsystems designs are focused on RF signal up/down conversion, tuning control, and dee voltage regulation. The digital system provides an RF signal source, aligns the cavity phases and maintains a Finite State Machine. The digital parts combine with the analog functions to provide the LLRF control. A brief system hardware introduction will be given in this paper, followed by the review of several major characteristics of the digital control in the 100 MeV cyclotron LLRF system. The commissioning is also introduced, and most of the optimization during the process was done by changing the digital parts.

TRIUMF’s ARIEL pre-buncher is powered by a sawtooth waveform which is the combination of 11.79 MHz, 23.57 MHz and 35.36 MHz harmonics. To upgrade the existing analog and digital hybrid LLRF control system, reduce the hardware cost, and achieve more flexible control of the system, an FPGA based digital daughter board is designed. The generation, control, and regulation of these three harmonics are all incorporated digitally inside a single FPGA. To reduce the number of RF interfaces on the motherboard, the new daughter board is designed to control the amplitude and phase of the sawtooth waveform with one channel ADC and DAC. To lock the output phase of the sawtooth waveform to the reference signal, a digital phase-locked loop is designed to lock all three harmonics to the external reference signal. The related work, including the system design of the LLRF control system and the development of the digital phase-locked loop, are presented in this paper.

The Beijing Radioactive Ion-beam Facility project is being constructed by BRIF division of China Institute of Atomic Energy. In this project, a 100 MeV high intensity compact proton cyclotron is built for multiple applications. The first successful beam extraction of CYCIAE-100 cyclotron was done in the middle of 2014. The extracted proton beam energy is 100 MeV and the beam current is more than 20 μA. The RF system of the CYCIAE-100 cyclotron includes two half-wavelength cavities, two 100 kW tetrode amplifiers and power transmission line systems (all above are independent from each other) and two sets of Low Level RF control crates. Each set of LLRF control includes an amplitude control unit, a tuning control unit, a phase control unit, a local Digital Signal Process control unit and an Advanced RISC Machines based EPICS IOC unit. These two identical LLRF control crates share one common reference clock and take advantages of modern digital technologies (e.g. DSP and Direct Digital Synthesizer) to achieve closed loop voltage and phase regulations of the dee-voltage. In the beam commission, the measured dee-voltage stability of RF system is better than 0.1% and phase stability is better than 0.03°. The hardware design of the LLRF system will be reviewed in this paper.

The five-beam three-component laser Doppler velocimetry (LDV) is applied to investigate the turbulent flow in a 6 × 6 rod bundle installed with simple grid spacers. LDV measurement has been conducted at four cross sections downstream a grid spacer at five Reynolds numbers ranging from 6600 to 70,300. The flow evolution downstream of the grid spacer is demonstrated through the comparison of the axial mean velocity and Root Mean Square (RMS) velocity at the three cross sections downstream of the grid spacer. All the three components of the flow velocity are measured in the selected subchannels at the outlet cross section of the rod bundle which is dedicated to provide more information on the turbulence statistics in the rod bundle flow. Remarkably high ratio of axial normal stress to the turbulent kinetic energy, v v ¯ / k , is observed even in the subchannel center, which indicates that the turbulence in the rod bundle is anisotropic. Comparing experiment results at the five Reynolds numbers, the low Reynolds number effect is found in the case with Re = 6.6 × 103. The experiment results also imply that the Reynolds number effect in the tight-lattice bundle is weak compare to that in the loose one.

The five-beam three-component laser Doppler system is operated in the three-beam two-component mode to measure the 3 × 3 bundle flow with simple grid spacer. Experiment has been conducted at Re = 15,200 and 29,900. According to the experiment result, the root mean square (RMS) of axial velocity fluctuation shows large value in the gap and the near-wall region of the edge sub-channel which is induced by the axial velocity gradient. Significant intensity of lateral velocity fluctuation is observed which indicates the strong lateral mixing in a 3 × 3 rod bundle. Through the correlation analysis coherent structures have been observed in the gap region. The spectral analysis shows that the LDV measurement complies to the Komogorov spectrum law, f−5/3, well. The low-frequency peak spectral density of the axial velocity fluctuation has been observed in the gap region connecting sub-channels with velocity difference. The performance of the SSG model and the baseline Reynolds stress model are investigated based on the experiment result. The models predict higher axial velocity in the interior sub-channel and lower in the edge and corner ones than the experiment result. Large discrepancy between the calculated and measured axial flow velocity is resulted from failure in calculating the strong negative u ′ w ′ ¯ in the gap region connecting different sub-channels.

Test 7 intermediate-break loss-of-coolant accident (IBLOCA) with 13% break at cold leg was conducted in OECD/NEA ROSA-2 Project using Large Scale Test Facility (LSFT). In this test, auxiliary feedwater was assumed to fail and all safety injection was injected only into the intact loop. Core started to dryout when break valve opened. Liquid level in the core dropped rapidly before loop seal clearing (LSC). ATHLET Mod 2.1 Cycle A was used in the post-test analyses of this LSTF experiment. A basis model with two primary coolant loops, one group steam generator U-tube, and three channels in core was built to simulate this test. One dimension finite critical flow model was employed to simulate a nozzle type break with an over predicted result. The major calculated parameters were compared with the test data, and the overall trend of the test was well calculated by the code, it reveals that ATHLET model could predict such IBLOCA with reasonable results.Copyright © 2013 by ASME

A model of Passive Residual Heat Removal Heat Exchanger (PRHR HX) and In Containment Refueling Water Storage Tank (IRWST) in AP1000 had been scaled by power-volume theory. FLUENT code analysis for the characteristic of thermal stratification phenomenon and natural convective of the scaled model was performed for 2000s of transients to investigate the temperature field distributions and flow field distributions in IRWST. As for the numerical experiment, the distributions had been achieved at different times. The centralized layout of PRHR HX, which looks like a circle in a section, makes the temperature of fluid outside tubes higher at the location that closer to the upper of the circle in the horizontal tube section and closer to the center of the circle in the vertical tube section, and there may appear nuclear boiling. Then temperature difference between the tube side and fluid side is smaller, causing the heat exchanger efficiency is worse at these locations. In order to improve the heat transfer effect of PRHR HX, two schemes had been proposed. First, increase horizontal section length and shorten the vertical section length. Second, Flat layout replaces centralized layout. These models were established and simulated by FLUENT. Heat transfer coefficients of “C-tubes” were comparative analyzed to study which kind of the heat transfer effect was better. It contributes to provide some references for improving the heat transfer effect of PRHR HX.

COSINE (COre and System INtegrated Engine for design and analysis) is the software platform for nuclear power plant design and analysis being developed in China, which contains three thermal-hydraulics codes and three physics codes in the first phase of this project. Three thermal-hydraulics codes in COSINE are sub-channel code, system analysis code, and containment analysis code. Separate experiments data and integral experiments data are needed to validate the models and analyze the uncertainty of these codes. Some data are obtained from international database and organizers. At the same time, an experiment plan has been made by SNPSDC to meet the COSINE thermal-hydraulics codes validation requirements. In the 1st phase of this plan, eight separate effects facilities are being constructed to get some valuable data from January 2011 to December 2014, and the test contents has been programmed. The facilities, contents and the schedules of the tests of COSINE validation experiment plan-I are detailed in this paper.Copyright © 2013 by ASME

Uncertainties are addressed in the special context of assessing and managing risks from rare, severe-consequence hazards. Risk Oriented Accident Analysis Methodology (ROAAM) is used to analyze uncertainties during severe accidents analysis in nuclear power plants. In-vessel Retention (IVR) is one of the mitigations for severe accidents which will cause core damage. By external reactor vessel cooling (ERVC), the integrity of the reactor vessel is preserved. The success criterion for IVR is the local heat flux on the wall of lower head is less than the critical heat flux (CHF). This paper analyzes the uncertain parameters which decide the mitigation to be successful or fail. Two bounding structures and 4 molten pool steady states are defined. And the success probability of IVR is evaluated with a molten pool heat transfer model. Then the effectiveness of IVR-ERVC under the two bounding structures is evaluated.Copyright © 2010 by ASME

Change of wavelength in a CSOM (confocal scanning optical microscope) can be used as a depth scanner without any mechanical movement so as to improve the quality of sectional images in a CSOM. This paper puts forward such a new CSOM system.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new design of an optical coordinate transformation system (OCTS) is proposed. This OCTS is accurate within the linear term ofthc spatial frequency of input pattern.

Compared with traditional SDF MSF'' our new technique has greatly reduced the recorded information to the same goal in one piece. And that follows the bigmning work of a new pattern recognition system which has higher reliabilty with lower precisive treatment.