Vol.24,

Although conventional radiotherapy remains to be one of the most useful treatments for cancer, it is not the best strategy to maximize the effects on the tumors and minimize the damage to the surrounding tissues due to its physical and biological characteristics. Synchrotron radiation (SR) with uniquely physical and biological advantages may represent an innovative approach for cancer treatment. In recent years, SR-based photon activation therapy, stereotactic synchrotron radiation therapy and micro-beam radiation treatment have been developed, and the results of in vitro and in vivo experiments are very promising. It is necessary to understand the physical and radiobiological principle of those novel strategies before the approach is applied to the clinic. In this paper, we summarize the advances of SR in terms of physical, radiobiological advantages and its potential clinical applications. With the successful operation of shanghai synchrotron radiation, good opportunities in China have been provided for investigations on the treatment of cancer with synchrotron radiation.

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As a third generation light source, Shanghai Synchrotron Radiation Facility (SSRF) has up to 140 beam position monitors (BPM) installed to monitor the beam dynamics on its storage ring. Once the operation mode is chosen, the betatron functions are determined. Since the sinusoidal betatron oscillation is the dominant component of the transverse motion, these BPMs can be used to measure the motion to get the betatron functions. Three methods are compared to calculate the phase advance among the BPMs in this paper, aiming to find one or more feasible ways to check the beam optics in SSRF. Some experiments have also been made to verify the practicality of the phase information.

508

Identification and characterization of L-, D- and DL- penicillamine were demonstrated by Terahertz time-domain spectroscopy (THz-TDS). To understand the physical origins of the low frequency resonant modes, the density functional theory (DFT) was adopted for theoretical calculation. It was found that the collective THz frequency motions were decided by the intramolecular and intermolecular hydrogen bond interactions. Moreover, the quantification of penicillamine enantiomers mixture was demonstrated by a THz spectra fitting method with a relative error of less than 3.5%. This technique can be a valuable tool for the discrimination and quantification of chiral drugs in pharmaceutical industry.

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447

³⁶Cl is one of the most interesting nuclides in accelerator mass spectrometry (AMS) measurements. The application of ³⁶Cl has been widely applied in various fields. All most all of ³⁶Cl AMS measurements at natural isotopic concentrations have yet been performed at tandem accelerator with 5 MV or higher terminal voltage. The measure improvement of ³⁶Cl and other medium heavy isotopes performed at 3 MV in AMS facilities is one of the hottest topics in AMS measurements. In order to increase the suppression factor of ³⁶S, the energy loss straggling and angular straggling of ³⁶Cl and ³⁶S ions in various counter gases (P10, isobutane and propane) were investigated. Some groundwater samples were measured with energy of 32 MeV, and the results were in good agreement with the result obtained with ion energy of 72 MeV. The results indicate that the approximate detection limit of ³⁶Cl in 3 MV AMS facility is ³⁶Cl/Cl=1×10^-14, and the uncertainty is 30% when the sample with isotopic ration ³⁶Cl/Cl≈10^-13.

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VME system of the Resistive Plate Chamber (RPC) electronics for the Daya Bay Reactor Neutrino Experiment is described in this paper. A 9U VME RPC trigger module (RTM) is designed to process coincidence signals coming from front end cards (FECs), to generate local triggers and send them to FECs to select the hit data from RPC detector, to report trigger information to a master trigger system and receive cross triggers from the master trigger system. Another 9U VME readout module is designed to collect data from all FECs, to send out configurations to FECs, and to transmit collected hit data to the data acquisition system via VME bus. Test results prove that the VME system is capable of treating a maximum data rate (2.2 MB·s^-1), without data loss.

448

Control rod is a primary control part of emergency control and power regulation in nuclear reactor. The main application of it is to control fast change of the reactivity. The theoretical analysis for the worth of control rod is necessary in the stage of design. Based on design requirements, some results are calculated. Firstly, control rod worth with different density of neutron absorber is calculated by MCNP here. Secondly, the study of integral and differential control rod worth is presented in this paper while the control rod is inserted into reactor core and total worth of three rods with different positions are also calculated. Finally, the effect of the axial and radial neutron flux in reactor core which is caused by the control rods is simulated. The simulation results of the control rods meet design requirements for TMSR.

489

Studies on the self-leveling behavior of debris bed are crucial for the assessment of core-disruptive accident (CDA) occurred in sodium-cooled fast reactors (SFR). To clarify this behavior over a comparatively wider range of gas velocities, a series of experiments were performed by injecting nitrogen gas uniformly from a pool bottom. Current experiments were conducted in a cylindrical tank, in which water, nitrogen gas and different kinds of solid particles, simulate the coolant, vapor (generated by coolant boiling) and fuel debris, respectively. Based on the quantitative data obtained (mainly the time variation of bed inclination angle), with the help of dimensional analysis technique, a set of empirical correlations to predict the self-leveling development depending on particle size, particle density and gas injection velocity was proposed and discussed. It was seen that good agreement could be obtained between the calculated and experimental values. Rationality of the correlations was further confirmed through detailed analyses of the effects of experimental parameters such as particle size, particle density, gas flow rate and boiling mode. In order to facilitate future analyses and simulations of CDAs in SFRs, the obtained results in this work will be utilized for the validations of an advanced fast reactor safety analysis code.

453

As primary separators in pressurized water reactors (PWRs), cyclone separators separate most of the water from vapor-water two-phase mixture, which is important to the safety and economics of nuclear power plants. To improve the performance of cyclone separators, we tested new structures in this study, e.g. porosity and inclined angle of the separator wall. Under different structures, separation efficiency and pressure drop were studied theoretically and experimentally. Results show that each of the structural parameters has an effect on separator performance, but none of the trends is monotonically in experimental ranges. Besides separator structures, the comprehensive performance is also determined by flow patterns. From segregated to homogeneous flow, the separation ability decreases. The separation efficiency is about 5% higher at 20° inclined angle when the superficial velocities are 0.012 and 16 m·s^-1 for the liquid and gas, respectively. The separation efficiency is only 91% without an impeller, while it is up to 100% at the same superficial velocities of air and water, 16 and 0.015 m·s^-1, respectively. Based on the study, it is promising to understand deeply the separation mechanism and further to provide data for designing large-scaled separators for advanced pressurized water reactors.

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