Vol.27,

Under normal water chemistry (NWC) conditions, the oxygen and hydrogen peroxide produced by water radiolysis in the coolant of boiling water reactors (BWRs) can lead to intergranular stress corrosion cracking (IGSCC) in the constituent materials of plant components. This fact has led to the wide-scale adoption of hydrogen water chemistry (HWC) in the nuclear industry to counteract these effects. This study seeks to characterize the metallic composition and the surface properties of the constituent materials of plant components in order to determine their effects on the accumulation of chalk river unidentified deposits (crud) on fuel rods in the BWR Unit-1 of the Kuosheng Nuclear Power Plant in Taiwan. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used to calculate the concentrations of surface crud and gamma spectrometry was used to determine the radioactivity of the corrosion products, as well as their axial distribution across the surface of the fuel rods. X-ray diffraction (XRD) analysis and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) were used to identify the crystalline phase and morphology of the crud as irregular shapes and flakes. The amount of crud deposited during the fourth fuel cycle exceeded that of the third fuel cycle due to extended burn up time. Our analytical results indicate that the implementation of HWC had no significant effect on the characteristics of subsequent crud deposits.

394

This paper proposes a design of passive cooling system for CPR1000 spent fuel pool (SFP). Our design can effectively manage the SFP temperature not to exceed 80℃. Then the transient analysis of the CPR1000 SFP with designed passive cooling system is carried out in station blackout (SBO) accident by the best-estimate thermal-hydraulic system code RELAP5.The simulation results show that to maintain the temperature of CPR1000 SFP under 80℃, the numbers of the SFP and air cooling heat exchangers tubes are 6627 and 19086 respectively. The height difference between the bottom of the air cooling heat exchanger and the top of the SFP heat exchanger is 3.8m. The number of SFP heat exchanger tubes decreases as the height difference increases; while the number of the air cooling heat exchanger tubes increases. The transient analysis results show that after the SBO accident, a stable natural cooling circulation is established. The surface temperature of CPR1000 SFP increases continually until 80℃, which indicates that the design of the passive air cooling system for CPR1000 SFP is capable of removing the decay heat to maintain the temperature of the SFP around 80℃ after losing the heat sink.

414

The activity levels of long-lived radionuclides in minerals have received more and more concern for the public health. The inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the content of uranium and thorium in 60 mineral samples collected from 16 mines of seven provinces in China. The contents of uranium and thorium ranged 0.17±0.04 μg·g⁻¹ to 15.3±2.39 μg·g⁻¹ and 0.19±0.04 μg·g⁻¹ to 19.6±7.56 μg·g⁻¹, respectively. The highest levels of U and Th contents were found in aluminum ore, whereas the lowest in antimony and copper ores.

320

The stochastic point kinetics equations with a multi-group of delayed neutrons, which are the system of a couple stiff stochastic differential equations, are presented. The analytical exponential model is used to solve the stochastic point kinetics equations in the dynamical system of the nuclear reactor. This method is based on the eigenvalues and corresponding eigenvectors of the coefficient matrix. The analytical exponential model calculates the mean and standard deviations of neutrons and precursor populations for the stochastic point kinetics equations with step, ramp, and sinusoidal reactivities. The results of the analytical exponential model are compared with published methods and the results of the deterministic point kinetics model. This comparison confirms that the analytical exponential model is an efficient method for solving stochastic stiff point kinetics equations.

414

A numerical simulation study was performed to clarify the thermal mixing characteristics of coolant in the core bottom structure of the High Temperature Gas-Cooled Reactor (HTR). The flow field and temperature field in the hot gas chamber and the hot gas duct of the HTR was obtained based on the commercial Computational Fluid Dynamics (CFD) program. The numerical simulation results showed that the helium flow with different temperatures in the hot gas mixing chamber and the hot gas duct mixed intensively, and the mixing rate of the temperature in the outlet of the hot gas duct reached 98%. The results indicated many large-scale swirling flow structures and strong turbulence in the hot gas mixing chamber and the entrance of the hot gas duct, which were responsible for the excellent thermal mixing of the hot gas chamber and the hot gas duct. The calculated results showed that the temperature mixing rate of the hot gas chamber decreased only marginally with increasing Reynolds number.

438

In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the "Porous Media Model" (PMM) for nuclear reactor analysis. In the conventional approach, whole reactor core simplifies to a single porous medium and also, the resistance coefficients that are essential to using this model are constant values. These conditions impose significant errors and restrict the applications of the model for many cases, including accident analysis. In this article, the procedures for calculating the coefficients are modified by introducing a practical algorithm. Using this algorithm will result in obtaining each coefficient as a function of mass flow rate. Furthermore, the method of applying these coefficients to the reactor core is modified by dividing the core into several porous media instead of one. In this method, each porous medium comprises a single fuel assembly. PMM with these two modifications is termed "multi-region PMM" in this study. Then, the multi-region PMM is introduced to a new CFD-based thermo-hydraulic code that is specifically devised for combining with neutronic codes. The CITVAP code, which solves multi-group diffusion equations, is the selected as the neutronic part for this study. The resulting coupled code is used for simulation of natural circulation in a MTR. A new semi-analytic method, based on steady-state CFD analysis is developed to verify the results of this case. Results demonstrate considerable improvement, compared to the conventional approach.

436

313

The integrated gradient of a quadrupole will be deviated by a close neighboring sextupole, and this is called the effect of fringe field interference. Using the Lie algebra techniques, an analytical expression for the betatron tune shift due to this effect has been derived. The process doesn’t depend on the supposition of the thin-lens quadrupoles. It can be used to estimate the tune shift differences between the designed lattice and the one including the fringe field interference. More generally, the method can be applied to other kinds of fringe field interference.

418

Bromate (BrO3−) is a disinfection byproduct in drinking water, and its removal is very difficult especially at low levels. ⁶⁰Co gamma-rays were used to remove BrO3− in aqueous solution in this study. The effects of absorbed doses, BrO3− initial concentration, gas saturation, pH value, and coexisting anions (Cl^-, NO₃^-, SO₄^2- and HCO₃^-/CO₃^2-) on BrO3− reduction were evaluated. After 4.0-kGy irradiation of, air-equilibrated solution of 30.7 μg/L BrO3−, the residual BrO3− was 8.3 μg/L, which is below the maximum contaminant level of drinking water. The BrO3− reduction rate increased with the dose, in the order of N₂ > air > O₂ > N₂O atmosphere under similar conditions. The results also show that high pH favored the BrO3− removal. According to the experimental results, it can be concluded that the efficiency of decomposing BrO3− by reactive species followed the order of aq−>>HO2.>O2−.. Coexisting Cl^-, HCO₃^-/CO₃^2- and SO₄^2- ions have little effect on BrO3− removal, whereas NO₃^- can inhibit its removal as a result of competition with BrO3− for ⋅e_aq^-.

343

The radiation-induced degradation of 4-nitrophenol (4-NP) was performed in combination with a Fenton reagent, H₂O₂, and TiO₂ nanoparticles to investigate the synergetic effects of radiolytical degradation combined with other advanced oxidation processes. The experimental results indicated that the degradation efficiency of 4-NP was 87.5%, 57.4%, and 41.0% at a dose of 20 kGy when its initial concentration was 100, 200, and 350 mg/L, respectively. Radiation combined with H₂O₂, the Fenton method, and TiO₂ remarkably increased the degradation efficiency of 4-NP, showing the synergetic effects. Radiation may enhance the biodegradability of 4-NP, suggesting that it has the potential to be used as a pretreatment method in combination with the biological method for the treatment of industrial wastewater containing toxic organic pollutants. Major intermediates during the 4-NP degradation process were identified and a possible degradation pathway was tentatively proposed.

292

The feasibility of adsorption and the adsorption behavior of radon on a nanomaterial-based zeolitic imidazolate framework-8 (ZIF-8) adsorbent was investigated. Grand canonical Monte Carlo simulation and four-channel low background α/β measurement were performed to examine the adsorption kinetics of this adsorbent. Results demonstrated that ZIF-8 is a good adsorbent of radon. Therefore, this adsorbent can be used to significantly reduce the hazardous effects of radon on occupational radiation workers.

454

The sensitivity of cancer cells to radiation therapy varies based on cell cycle phase. Here we evaluated the differences between X-ray and carbon ion irradiation with respect to cellular radiosensitivity and cancer cycle arrest in the breast cancer cell line, MCF-7. The cell survival rate, cell cycle distribution and presence of apoptosis were measured by clonogenic assay and flow cytometry. BRCA1 and p21 protein levels were analyzed by western blot, and the levels of human telomerase reverse transcriptase (hTERT) mRNA expression and telomere length were detected with real time polymerase chain reaction. The results show a significant dose-dependent effects on survival rate, apoptosis and protein levels in the carbon ion group of MCF-7 cells. Decreased proliferation was not observed at 2 Gy X-ray irradiation. There were significant differences in cellular cycle arrest, apoptosis percentages and BRCA1 and p21 protein expression between X-ray and heavy ion groups. The results indicated that increasing of BRCA1 and p21 expression, and attenuation of hTERT gene expression induced by heavy ion irradiation in MCF-7 cells might relate to mechanism of cellular radiosensitivity in G₂/M arrested phase.

301

A non-destructive instrumental neutron activation analysis with high resolution gamma-ray spectrometry of long-lived radionuclides was developed and used for measurement of trace element contents in samples of bone to determine health and diseases. Using this method, the silver (Ag), cobalt (Co), chromium (Cr), iron (Fe), mercury (Hg), rubidium (Rb), antimony (Sb), selenium (Se), and zinc (Zn) mass fractions were estimated in bone samples from 27 patients with intact bone (12 females and 15 males, aged from 16 to 49 years) who had died from various non-bone related causes, mainly unexpected traumas, and from 5 patients with chondroma (2 females and 3 males, 15 to 42 years old), obtained from open biopsies or after operation. The reliability of the differences in the results between intact bone and bone affected by chondroma was evaluated by a parametric Student’s t-test and a non- parametric Mann-Whitney U-test. It was found that in the bone affected by chondroma, the mean mass fractions of Co, Cr, Fe, Se, Sb, and Zn were significantly higher than in normal bone tissues. In the neoplastic bone, many correlations between trace elements found in the control group were no longer evident. This work revealed that there is a significant disturbance of the trace element metabolism in bone affected by chondroma.

312

A general model for skeletal dosimetry in mice is presented. Geometrical constructs were made for four general regions in the mouse skeleton, and dose factors for ⁹⁰Sr and ⁹⁰Y were calculated using the MCNP Monte Carlo transport code. Then, an overall skeletal dose factor for the whole skeleton was derived based on the individual values and the fraction of the total skeleton that they were assumed to represent. The whole skeleton average values were 1.56×10^-11 Gy/dis for ⁹⁰Sr and 1.74×10^-11 Gy/dis for ⁹⁰Y.

404

Radio genetic therapy which combines gene therapy with radiotherapy, has shown promising results in cancer treatment. In this study, an oncolytic adenovirus-based gene therapy system regulated by radiation was constructed to improve the cancer curative effect. This gene therapy system incorporated the radiation-inducible early growth response gene (Egr-1) promoter and the anticancer gene tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). To confirm the antitumor effect of Ad-ET combined with ¹²C⁶⁺ ion irradiation, the survival and apoptosis fraction of tumor cells HT1080 and normal cells MRC-5 in combination treatment were detected by CCK-8 assay and FACS analysis. Then the expression levels of TRAIL gene and protein were tested by real-time PCR and western blotting. The results show that ¹²C⁶⁺ ion irradiation could induce cell growth inhibition and apoptosis by activating the TRAIL gene expression in tumor cells, while exhibiting no obvious toxicity to the normal lung cell line MRC-5. The results also demonstrate that use of an oncolytic adenovirus-based radiation-inducible gene therapy system together with ¹²C⁶⁺ ion irradiation could cause synergistic antitumor effect specifically in tumor cells but not in normal cells. The results indicate that the novel radio genetic therapy could potentiate radiation treatment by improving the safety and efficiency of monotherapy, and provide theoretical support for clinical application of combination treatment.

381

The objectives of this study are to evaluate the dosimetric impact of hip prosthesis using ELEKTA linac X-rays and compare dose perturbations of metallic and non-metallic hip prostheses. The local dose distributions of typical hip prostheses were calculated for 4, 8, and 15 MV beams by Geant4. Three prosthesis materials were selected in calculation to reveal the relation between material type and local dose perturbations of prostheses. Furthermore, the effect of nominal energy on prosthesis perturbation was also discussed and analyzed. Taking the calculated dose to the hip joint as reference, considerable differences were observed between prostheses and hip joints. In the prosthesis shadow region, the relative dose decreasing was up to 36%, 21%, and 16% for the Co-Cr-Mo alloy, titanium alloy, and ceramic prostheses, respectively. In backscattering region, the relative dose increasing was about 1%–7%. Overall, the results show that the dose perturbation effect of prostheses was mainly determined by material type, nominal energy, and density. Among these typical hip prostheses, ceramic prosthesis introduces the lowest dose perturbations.

406

Estrogens as a kind of steroidal sex hormone are widely used in humans, especially quinestrol (QS), dienestrol (DS), and norethindrone (NET, 19-nor-17-alpha-ethinltestoster-one) which cannot be completely degraded after application. Steroidal estrogens at low concentration pulling into environment can disturb the normal biological function of wide life and thus lead to great threat to humans. So it is important to explore its degradation mechanism and its behavior in the environment. In this study, we investigated the oxidation or reduction system under gamma-irradiation for reducing estrogenic activity in the aqueous solutions as well as degradation kinetics, its byproducts and yield of transformation by different analytical methods such as GC-MS and HPLC. Gamma irradiation could effectively degrade estrogens in aqueous solution. The degradation reaction of estrogens could be depicted by first order reaction kinetics. The total organic carbon of solution decreased with an increasing absorbed dose with the order: quinestrol > norethindrone > dienestrol. The toxicity of the three estrogens was declined after irradiation. Mono- and quadric-hydroxylated intermediates as well as organic acids were formed after Gamma irradiation.

308

Nanomaterials and nanotechnology have great potential in the biological and biomedical field. Recent studies reveal that many nanomaterials possess antibacterial activities. While most of these studies focus on the ability of nanomaterials to inhibit the growth of pathogenic bacteria in vitro, few of them test the effects of nanomaterials on intestinal commensal bacteria. Here, we report that TiO₂ nanoparticles (10, 50 and 100 nm in size) can inhibit the growth of Drosophila intestinal commensal bacteria in vitro. This activity depends on the dosage or size, but is independent of the photocatalytic activity of TiO₂ nanoparticles. Surprisingly, dietary TiO₂ nanoparticles of the same dosage fail to display similar effects in Drosophila larvae or adults. These flies show a normal amount of intestinal commensal bacteria, as well as a normal developmental cycle, energy store, and locomotor activity. These results imply that the antibacterial effect of TiO₂ nanoparticles differs in vitro and in vivo.

323

341

With extensive use of flash-based field programmable gate arrays (FPGAs) in military and aerospace applications, single event effects (SEEs) of FPGAs induced by radiations have been a major concern. In this paper, we present SEE experimental study of a flash-based FPGA from Microsemi ProASIC3 product family. The relation between the cross section and different linear energy transfer (LET) values for the logic tiles and embedded RAM blocks (BRAMs) are obtained. The results show that the sequential logic cross section depends not too much on operating frequency of the device. And the relationship between 0→1 upsets (zeros) and 1→0 upsets (ones) is different for different kinds of D-flip-flops (DFFs). The devices are not sensitive to SEL up to a LET of 99.0MeV·cm²/mg. Post-beam tests show that the programming module is damaged due to the high-LET ions.

364

A novel full-digital integrator has been developed for the magnetic diagnostics in HL-2A. Based on the pipeline processing of the field programmable gate array (FPGA) and high speed PCI extensions for Instrumentation (PXI) platform, the digital integrator has realized octal-channel 10 kHz real time integration and data transmission. In order to reduce the integration drift, a 24-bit analog-to-digital converter (ADC) and simple analog processing circuits are applied for high precision sampling, while certain correction algorithms are used to minimize the drift. With simple and highly integrated circuits and high performance digital processor, the digital integrator is of high stability and functional expansibility which greatly simplifies the operation procedure. The digital integrator has been tested in the plasma discharge experiments, and the experimental results have confirmed that the drift performance and accuracy of the digital integrator could fully meet the requirements of HL-2A.

329

To meet the needs of signal alignment between the transmitter and receiver in a quantum key distribution (QKD) system, we put forward a TDC-GPX based synchronization scheme, which is based on high precision time measurement. We send a low-frequency repeat optical pulse synchronized with associated quantum signals on the receiver’s side by using a Time-Digital-Convertor (TDC) module, the time intervals between quantum signals, and synchronization signals measured and converted to corresponding temporal orders to complete the synchronization. We state the principle of the synchronization scheme in detail and then verify it in an actual QKD test bed. The test results show that our TDC-GPX based synchronization can obtain a time resolution better than 100 ps, and the proposed scheme shows full feasibility for an actual QKD system.

334

We report on the temperature dependence of single event upsets in the 215 to 353 K range in a 4M commercial SRAM manufactured in a 0.15 μm CMOS process, utilizing thing film transistors. The experimental results show that temperature influences the SEU cross-section on the rising portion of the cross-section curve (such as the chlorine ion incident). SEU cross-section increases 257% when the temperature increases from 215 to 353 K. One of the possible reasons for this is that it is due to the variation of upset voltage induced by changing temperature.

349

A prompt gamma neutron activation analysis (PGNAA) setup was developed for heavy metal detection in aqueous solutions with a 300 mCi ²⁴¹Am-Be neutron source and a 4 × 4 inch (diameter × height) BGO detector. In the present work, heavy metals, including Mn, Cu, Ni, Cr and Zn, were measured by the setup. The minimum detectable concentrations of Mn, Cu, Ni, Cr and Zn were 246.6, 391.2, 218.1, 301.5 and 2804.1ppm, respectively. The minimum detectable concentration of each element and the linearity response between the characteristic peak counts and elements concentrations have been studied. And the results showed that all heavy metals had a good linear relationship between characteristic peak counts and concentrations.

340

High energy dual-energy X-ray Digital Radiography (DR) imaging is mainly used in the material recognition of cargo inspection. We introduce the development history and principle of the technology and describe the data process flow of our system. The system corrects original data to get a dual-energy transparence image. Material categories of all points in the image are identified by the classification curve, which is related to the X-ray energy spectrum. For the calibration of classification curve, our strategy involves a basic curve calibration and a real-time correction devoted to enhancing the classification accuracy. Image segmentation and denoising methods are applied to smooth the image. The image contains more information after colorization. Some results show that our methods achieve the desired effect.

460