Vol.23,

The front end light-blocked components of the third generation of synchrotron radiation facility, which are subjected to high heat load, are cooled with flowing water through the cooling channels. The convective heat transfer coefficient and the flow resistance (or pressure drop) are two important parameters for evaluating the heat transfer performance of the cooling channels and should be strictly quantified. In this research, two typical bent cooling channels in Shanghai Synchrotron Radiation Facility (SSRF) were modeled and their in-pipe turbulent flows were simulated. The two criteria obtained under different channel water velocities met the SSRF technical requirements. To reduce the total pressure drop, arc transitions were proposed to replace the right angle transitions in the cooling channels. At the same time, an experiment was performed to measure the convective heat transfer coefficient of a typical bent channel unit. The experimental results were in good agreement with the simulation ones.

409

The dipole magnet of the China Spallation Neutron Source (CSNS) Rapid-cycling Synchrotron (RCS) will be operated at a 25 Hz sinusoidal alternating current which causes severe vibration. The vibration will influence the long-term safety and reliable operation of the dipole magnet. By taking the dipole magnet and magnetic measurement girder as specific model system, a method for analyzing and studying the dynamic characteristic of the system is put forward by combining theoretical calculation with experimental testing. This paper established the mechanical model of the system, and the top six step natural frequency and vibration mode were obtained through theoretical modal analysis (ANSYS). Then according to testing modal analysis, the natural frequency, damping ratios and vibration mode of the system structure were obtained too. The theoretical modal analysis results coincide with the experimental testing results. Besides, the 6th step natural frequency is close to the exciting frequency of the magnet, so the resonance phenomenon may take place at the actual working conditions. The dynamic characteristic data of the structure can provide an analysis basis for the further study and the formal dipole magnet girder optimal design of RCS.

318

A program based on MATLAB 7.0 platform was developed to locate characteristic peak position and calculate net area of characteristic peak. The formula for the calculation of relative standard deviation of net peak area by Sterlinski's method was found excellent in searching single peaks and resolving overlapping peaks in high resolution gamma-ray spectrum. Gaussian function fitting method using Levenberg-Marquardt algorithm was applied to calculate net area of peaks. A standard test spectrum supplied by the IAEA in 1995 was analyzed by the program and another two widely used commercial software. The analysis results show the program was superior to the latter two in searching single peaks and resolving overlapping peaks. The optimized fitting indexes are found between 0.962 and 0.996, which shows that the program adopted is feasible and accurate for extracting the net peak area in high resolution gamma-ray spectra.

383

The distribution characteristics of the neutron field in cement was simulated using the MCNP code to comply with the requirements of an online Prompt Gamma Neutron Activation Analysis system. Simulation results showed that the neutron relative flux proportion reduced with increasing cement thickness. When the cement thickness remains unchanged, the reduced proportion of thermal neutrons increases to a small extent, but the epithermal, intermediate, and fast neutrons will decrease according to the geometric progression. H element in the cement mainly affects the reduction of fast neutrons and other single-substance elements, e.g., O, Ca, ⁵⁶Fe, Si, and Al. It also slows down the reduction of the fast neutrons via inelastic scattering. O contributes more than other elements in the reduction of fast neutrons. Changing the H content affects the thermal, epithermal, intermediate, and fast neutrons, while changing the Ca, Fe, and Si contents only influences the thermal, epithermal, and intermediate neutrons; hence, there is little effect on the reduction of fast neutrons.

375

The total macroscopic removal cross sections, deposited energies and the absorbed doses of three new shielding composites loaded with specific boron-rich slag, boron concentrate ore and boron mud of China for ²⁵²Cf neutron source were investigated by experimental and Monte Carlo calculation. The results were evaluated by boron mole numbers per unit volume in composites. The half value layers of the composites were calculated and compared with that of Portland concrete, indicating that ascending boron mole numbers per unit volume in the composites can enhance the shielding properties of the composites for ²⁵²Cf neutron source.

427

^99mTc-3PRGD₂ is a new SPECT radiotracer for several tumor imaging with high uptake where integrin α_vβ₃ is highly expressed. This pilot study was to assess the safety, biodistribution and radiation dosimetry of ^99mTc-3PRGD₂ in healthy volunteers. The 10 healthy male volunteers were injected with ^99mTc-3PRGD₂ (786.7±55.8 MBq, 19.1–24.2 mCi). Baseline measurements of vital signs, laboratory safety tests and 12-lead electrocardiogram were recorded before and after injection. Blood and urine samples were collected and radiation counts were obtained at various time points. Whole-body scans and ROIs of identified organs were used for visual analysis and estimating the radiation dosimetry. No adverse reactions were found during the study. ^99mTc-3PRGD₂ exhibited a rapid clearance from the blood with less than 45% of the initial dosage at 10 min after injection and gradual increasing radioactivity in urine with (52.9±6)% of original dose at 1440 min. The whole-body imaging showed high radioactive accumulation in bladder. And the highest ^99mTc-3PRGD₂ uptake was found in the kidneys (3.50×10⁻² mSv/MBq). The ^99mTc-3PRGD₂ exhibited good pharmacokinetic properties and little radiation burden. This study showed that ^99mTc-3PRGD₂ would be a safe and attractive SPECT agent in clinic applications.

606

To study and analyze reconstruction parameters in ^99mTc-Trodat-1 SPECT (Tomography Emission- Computed Single-Photon) brain semi-quantitative analysis, and the outlined methods of ROIs (regions of interests). The ^99mTc-trodat-1 SPECT brain imaging was processed, and the ROIs were outlined four times from December 2009 to July 2011. The results for each method were analyzed and compared to improve our experience. There was no statistically significance between the outlined number of pixel in both sides of the cerebellum and the ratio of the radioactive counts. From LEHR and FAN beam collimator, the average ratio became better with increasing the outlining method, especially the fourth time. It could be estimated that striatum mean volume (±SD) was (39.51±9.54 ml, in the range of 19.97–51.98 mL) and mean weight (±SD) was (44.09±10.64 g in the range of 22.28–58.01 g). The details of image processing and data analysis should not be ignored to outline appropriate methods, and withstand the repetitive inspection. The total striatum was outlined and its volume and weight was analyzed.

392

For modern particle physics experiments, trigger-less data acquisition (DAQ) system has been put into practice because of the need of reaction multiplicity and trigger flexibility. In such new DAQ systems, global synchronized clock plays an important role because it affects the granularity of time slice and precision of reference clock. In this paper, a novel synchronized clock distribution method is proposed. With the help of modulation technique, master clock module distributes system clock to each slave module. To synchronize slave clocks, the propagation delay is adjusted and the clock phase is aligned by an FPGA chip automatically. Furthermore, an ADC- based method is proposed to evaluate the performance of multi-module clock synchronization simultaneously. The experiments of a prototype system show that slave clocks can be synchronized less than 100 ps over 150 m range. The proposed method is simple and flexible, and it can be used in trigger-less DAQ system and other applications of clock distribution preciously.

330

Hydrogen combustion in a nuclear power plant may threaten the integrity of some important systems and components. In this paper, the effect of hydrogen combustion in the primary pump compartment is analyzed by different initial hydrogen concentration and igniter locations using Computational Fluid Dynamics method. The results show that the combustion is confined to a limited area without pump damage at about 6.6% hydrogen volume fraction. Once igniting the hydrogen, the combustion affects the whole compartment at the 12% hydrogen volume fraction. The stress caused by the great temperature gradient or high temperature may damage the primary pump. Igniters at the lower location accelerate the combustion process and cause a threat to the pump integrity.

459

Based on nuclear power plant (NPP) best-estimate transient analysis with RELAP5 / MOD3 code, the reactor point kinetics model in RELAP5 / MOD3 code is replaced by the two-group, 3-D space and time dependent neutron kinetic model, and two-fluid model is replaced by drift flux model. A coupled three-dimensional physics and thermal-hydrodynamics model is used to develop its corresponding computing code, thus simulating natural circulation of single-phase flow for the PWR. In this paper, we report the forward and reverse flow distribution in the inverted U-tubes of the steam generator (SG) under some typical operating conditions in the natural circulation case, and analyze the influence of main coolant pump resistance on the forward and reverse flow distribution. The calculation results show that, the pressure drop between SG inlet and outlet plenum decreases, and the SG inlet and outlet mass flow decrease with an increased main coolant pump resistance, but net mass flux of reverse flow in inverted U-tubes, and the ratio of mass flow in all reverse flow tubes to that of main coolant pipeline increase, meanwhile, the secondary steam load is invariable in this process.

347