Vol.27,

In this study, concentrations of tritiated water (HTO) and non-exchangeable organically bound tritium (NE-OBT) and the NE-OBT/HTO ratios were determined in soil around Qinshan Nuclear Power Plant (NPP), Zhejiang, China, and their vertical profile and spatial distribution were investigated. Results showed variations in both the HTO and NE-OBT concentrations in the vertical profile. The HTO concentrations generally decreased firstly and then increased with the increasing depths, but the trend was not significant. The NE-OBT concentrations in the surface soils (0-5cm) were considerably lower than those in the deep soils (5-25cm) at all the sites. The NE-OBT/HTO ratios also show a variable vertical profile, initially increasing and then decreasing with increasing soil depth. Both the HTO and NE-OBT concentrations decreased with the increasing distance to the HWRs in deep soil layers (5-25cm), revealing that the released tritium from the NPP affected the spatial distribution.

444

Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor (TMSR-LF1) was calculated by ORIGEN-S with an updated cross section library generated by TRITON in SCALE 6.1.3 code system. The results show that the tritium production rate and normalized tritium production rate of TMSR-LF1 are 8.90×10¹¹ Bq/d and 4.45×10¹¹ Bq/(MW·d), respectively. The environmental impact of tritium was analyzed via PC-CREAM 08 with an assumed 36% release rate of tritium referring to the molten salt reactor experiment (MSRE). During normal operations, the maximum tritium concentration is 1.4 Bq/m³ under normal condition, and the corresponding individual dose to the public is about 1 μSv/a; under extreme conditions, the maximum concentration and corresponding individual doses are 11.8 Bq/m³ and 9 μSv/a, respectively. Ingestion is the main exposure pathway and accounts for 62% of the total dose. Of this, 35% is from organically bound tritium (OBT).

795

Thorium as a suitable fertile with higher natural resources in comparison with uranium resources has been remarkably considered by different nuclear energy user countries in the last decades. Its prominent features such as suitable possibility for power flattening of a nuclear reactor, applicable breeder blanket to produce ²³³U fissile as well as neutron leakage prevention from a nuclear core has caused its application as power flatter, breeder material or other aimed utilizations be evaluated by the researches. In the present study, neutronics of a modeled CANDU 6 loaded with ThO₂ and UO₂ fuel rods has been computationally studied. The study aimed at reprocessing of burned ThO₂ seeds at CANDU 6 reactor to recover the total produced uranium, which is to be going under another compound fuel cycle. The obtained results showed all the core reactivity coefficients are sufficiently negative. The modeled core 949 GWd burn-up concluding in 99.99% depletion of ²³⁵U initial loads. 18.38 kg of ²³³U produced in the burnt ThO₂ fuel after 1 year burn-up time. In addition, 31.84 kg of ²³⁹Pu produced in the UO₂ spent fuel rods after the burn-up time. After a proposed cooling time, about 50.01 kg of ²³³U will be available in the spent ThO₂ fuel.

460

An analysis of the neutron activation and shutdown dose rates was performed for the EAST high-power deuterium neutral beam injector test facility (EAST NBITF) by using the multiparticle transport code FLUKA 2011.2. Also, the neutron and neutron-induced gamma spectra of the facility’s vacuum vessel were evaluated. The results identified the major radionuclides ⁹⁹Mo, ⁶⁵Ni, ⁵⁸Co, ⁵⁶Mn, and⁵¹Cr for the vacuum vessel and the primary nuclide ⁶⁴Cu for both the ion dump and the calorimeter. The simulated results indicated that, when the EAST NBITF operates within the design parameters of deuterium energy 80 keV, current 50 A, and pulse 100 s, the neutron intensity will achieve 10¹¹n/s with no radiation safety problems after the EAST NBITF shuts down for 1 h.

496

Calculation of the neutron noise induced by fuel assembly vibrations in two pressurized water reactor (PWR) cores has been conducted to investigate the effect of cycle burnup on the properties of the ex-core detector noise. An extension of the method and the computational models of a previous work has been applied to two different PWR cores to examine a hypothesis that fuel assembly vibrations cause the corresponding peak in the auto power spectral density (APSD) increase during the cycle. Stochastic vibrations along a random two-dimensional trajectory of individual fuel assemblies were assumed to occur at different locations in the cores. Two models regarding the displacement amplitude of the vibrating assembly have been considered to determine the noise source. Then, the APSD of the ex-core detector noise was evaluated at three burnup steps. The results show that there is no monotonic tendency of the change of the APSD of ex-core detector, however, the increase of APSD occurs predominantly for peripheral assemblies. When assuming simultaneous vibrations of a number of fuel assemblies uniformly distributed over the core, the effect of the peripheral assemblies dominate the ex-core neutron noise. This behaviour was found similar in both cores.

432

The underground nuclear power plant (NPP) makes full use of land resources, reduces costs, makes better use of its passive safety, and avoids radioactivity release into the atmosphere in a serious nuclear accidents. In this paper, for obtaining comprehensive and integrated analyses on this new NPP design, we introduce four kinds of underground NPP designs, analyze the feasibility of each design from various aspects, and use the multiple criteria decision analysis (MCDA) method to choose the best option.

719

Multi-group cross-section library is the basic condition for lattice calculation, which provides the necessary nuclear data parameters. The multi-functional lattice code SONG ^[1], ^[2] is developed to adapt to the research demands of different types of new reactors, especially the fourth generation (GEN-IV) reactors ^[3], ^[4]. The corresponding multi-group cross section library of SONG (SONGLIB) is well designed with much effort considering the next generation reactors’ new feature in material, spectrum, burnup depth, etc. Therefore, the burnup chain ^[5], energy group structure ^[6], and reaction path should be specially considered. The library SONGLIB is processed, with the Evaluated Nuclear Data File (ENDF), nuclide data auxiliary processing code NJOYBAT ^[1], and library management code MANLIB ^[1]. A series of verification work of SONGLIB is then carried out, and the calculated results are satisfied.

499

Thermal mixing and stratification phenomena may occur during the loss of a coolant accident (LOCA) or main steam line break accident (MSLB) in the containment of a Passive Containment Cooling System (PCCS), or in the suppression pools in BWR. However, the present study pays insufficient attention to the thermal stratification phenomena in the containment of small modular reactors (SMR). In this paper, an investigation on the mixing and thermal stratification phenomena caused by the plumes or buoyant jets in SMR containments was carried out. The experiments were both conducted under non-adiabatic and adiabatic conditions for a steel containment. In each condition, two key parameters, inlet temperature, and flow rate were tested by controlling variables to identify their influence on the thermal stratification phenomenon. The visualization experiments illustrated the jet mixing and stratification development. The experiment results were compared with the numerical computation and they reached a good agreement.

719

Accelerator-based neutron sources could outstandingly compete with the reactor-based ones, which are widely used for research aims and radioisotope production. Spallation neutron sources are used by many research centers. In this work, the potential of natural uranium spallation target irradiated by low-energy protons for production of an external neutron source was investigated. MCNPX code was used to model the spallation target. The results showed using 30 MeV protons of 100 µA current a neutron flux in order of 10⁷ n/s.cm² leaks from an optimized-dimension target. Different physical models available in the computational code do not result in significant relative discrepancies for neutron yield and deposited heat calculations. Water with a velocity of 0.6 m/s can be used as coolant of the spallation target to keep the surface temperature under 100 ˚C at atmosphere pressure.

605

Fertile fuel, such as thorium or depleted uranium, can be bred into fissile fuel and burnt in a breed-and-burn (B&B) reactor. Modeling a full core with fertile fuel can assess the performance of a B&B reactor with exact quantitative estimates, but costs too much computation time. For simplicity, performing the recently developed neutron balance method with a zero-dimensional (0-D) model can also provide a reasonable result. Based on the 0-D model, the feasibility of the B&B mode for thorium fuel in a fast reactor cooled by sodium was investigated by considering the (n, 2n) and (n, 3n) reaction rates of fuel and coolant in this work, and compared with that of depleted uranium fuel. Afterwards, the performance of the same thorium-based fuel core, but cooled by helium, lead-bismuth, and FLiBe, respectively, is discussed. It is found that the (n, 2n)&(n, 3n) reactions should not be neglected for the neutron balance calculation for thorium-based fuel to sustain the B&B mode of operation.

526

A 325 MHz superconducting half-wave resonator (HWR) has been designed with β=0.51. Three shapes of the inner conductors (racetrack, ring-shape and elliptical-shape) were optimized to decrease the peak electromagnetic fields and minimize the dissipated RF power on the cavity walls. In order to suppress the operation frequency shift caused by fluctuations of the helium pressure and maximize the tuning ranges, the frequency shifts and mechanical properties were studied on the electric and magnetic areas. The helium vessel was designed to keep the mechanical structure as robust as possible.

479

A new X-ray absorption fine structure (XAFS) data-collection system based on the Experimental Physics and Industrial Control System software environment has been established at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility. The system provides for automatic sequential analysis of multiple samples for continuous high-throughput (HT) measurements. Specifically, 8 sample pellets are loaded into an alumina holder, and a high-precision two-dimensional translation stage is programmed to switch these samples automatically for collecting the XAFS spectrum of each sample in sequence. Experimenters implement HT measurements via a graphical user interface developed with Control System Studio. Finally, the successful operation of the HT XAFS system is demonstrated by running experiments on two groups of copper-ceria catalysts, each of which contains 8 different powder samples.

426

In this paper, we present a novel design scheme of temperature-jump (T-jump) area for microfluidic device. Numerical simulation and experimental research of thermal characteristics of the solution in microchannels is completed. Numerical simulation of the temperature-jump microchannel is analyzed to study the heat transfer characteristics by comparing performance of three proposed configurations. Calculation of the power requirement is discussed in the dimensional design of microheater. Temperature sensitive fluorescent dye is applied to investigate the temperature field of microchannel heated by a designed microheater. It is found that the T-jump microfluidic can provide rapid heating for solutions with strong convection heat transfer ability.

650

The recent increasing use of γ-ray industrial computed tomography (γ-ray ICT) in various fields has induced greater attention to its performance as well as to considerations of radiation safety. It is understood that radiation protection planning cannot be sacrificed for the sake of CT image quality during the design, manufacture, and layout of γ-ray ICT systems. In the present work, we describe a typtical γ-ray ICT system in brief, and, based on experience and pertinent examples, we propose design requirements for ensuring the radiation safety of the sealed radioactive source, source container, and workspace. The design examples and dose rate measurement results illustrate that the proposed design standards are reasonable, feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-ray ICT systems. This paper discussed the predominant measures associated with the radiation protection of γ-ray ICT systems in accordance with the pertinent Chinese standards. In addition, based on experience and pertinent examples, the design requirements for ensuring the radiation safety of a sealed radioactive source, source container, and workspace were defined in detail. The design examples and dose rate measurements conducted in conjunction with a γ-ray ICT system and workspace employing the proposed design standards have illustrated that the proposals provided in this paper are reasonable, feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-ray ICT systems.

705

The radiation shielding efficiency of material depends upon photon attenuation, exposure buildup factors and neutron removal capacity. A newly developed Pb-free gadolinium based glasses in compositions (80-x)B₂O₃-10SiO₂-10CaO-xGd₂O₃ (where x = 15, 20, 25, 30 and 35 mol%) had completely been investigated for their shielding efficiency with Geant4 simulation for mass attenuation coefficients and neutron total macroscopic cross section and by calculating exposure buildup factors. The exposure buildup factors for photon energy from 0.015 to 15 MeV had been calculated up to 40 mean free paths using five factors Geometric Progression method. The mass attenuation coefficients of the Pb-free glasses were simulated for energies from 223 to 2614 keV and compared with the possible available experimental results. The neutron shielding efficiency of these glasses was discussed by calculating neutron total macroscopic cross section for energies from 1 eV to 14.1 MeV. Present investigations are found to be very useful for applications in nuclear engineering.

644

A Monte Carlo method to study the response of portable detector to terrestrial gamma ray is proposed. This method is based on two-stage Monte Carlo simulation. First, the probability distributions of the phase space coordinates of the events that are most likely to be detected are reconstructed at the phase space shell level. The phase space shell is a closed surface enclosing the detector. The detector response to events originating from the phase space shell is then studied. The full absorption spectra as well as the partial absorption spectra are obtained for natural radionuclides uniformly distributed in the ground. For validation, this method is applied to a HpGe portable detector previously studied. The previous study is based on a semi-empirical model. Good agreement is achieved when we compare the full energy peak efficiencies and the total in-situ spectra obtained by the two methods. As an application, the effective depth of the activity of the ¹³⁷Cs artificial radionuclide in the soil is determined from the low-energy part of the total in-situ spectrum.

510

A Levenberg-Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks (the 583-keV peak of ²⁰⁸Tl, the 609-keV peak of ²¹⁴Bi, and the 662-keV peak of ¹³⁷Cs) using an in situ NaI (Tl) scintillation spectrometer. The algorithm, in addition, was compared with a genetic algorithm used for multiple deconvolution. The three fitted peak areas (583, 609 and 662 keV) were calculated from the measured gamma-ray spectra obtained from a simulation experiment in which a ¹³⁷Cs source was buried at different soil depths (from 18 to 38 cm). The application of the Levenberg-Marquardt algorithm yielded similar results compared to the genetic algorithm. A lack-of-fit test showed that the fitting is good when the instrumental noise levels were estimated from replicated analyses. The relative fitting error of the total net area and the residual standard deviation were within 5% and 0.04, respectively, and the goodness of the fitting was better than 0.98. While the methods used in this paper give high performance, the results may lead to incorrect estimation when the signal-to-noise ratio is smaller than −30 dB. This study is useful for the determination of radioactive specific activity of ¹³⁷Cs by in situ spectrometry.

625

In gamma camera and single-photon emission computerized tomography (SPECT), the collimator removes most photons. Here, a gamma camera without collimator utilizes a specific arrangement of detectors. Instead of bending beams (like a lens) or directing beams (by parallel hole collimator), changes are created in detectors’ field of view (FOV), so that each detector’s FOV looks different from others. Simulation proved this theory, with 98 detectors (2cm ×1.41cm) arranged in a zigzag manner for Monte Carlo simulation. A radioactive source with energy of 140 keV was situated on the detectors’ faces. Sixty projections, each 3° (0–179°) apart, were simulated by Monte Carlo N-Particle (MCNP) 4C code, rotating detectors around a radioactive point. The band containing the radioactive source is clearly visible in each projection. Counts obtained after simulation in different projections were reconstructed, and point source location emerged correctly. Simulation of gamma camera with zigzag arrangement of detectors and MCNP-4C code demonstrated that one could string the space and determine radioactive source by image reconstruction without using collimators, solely through these special detectors’ distribution.

526

The NaI(Tl) scintillation detector has a number of unique advantages, including wide use, high light yield, and its low price. It is difficult to obtain the decomposition of instrument response spectrum because of limitations associated with the NaI(Tl) scintillation detector’s energy resolution. This paper, based on the physical process of γ photons released from decay nuclides, generating an instrument response spectrum, uses the Monte Carlo method to simulate γ photons with NaI(Tl) scintillation detector interaction. The Monte Carlo response matrix is established by different single energy γ-rays with detector effects. The Gold and the improved Boosted-Gold iterative algorithms have also been used in this paper to solve the response matrix parameters through decomposing tests, such as simulating a multi-characteristic energy γ-ray spectrum and simulating synthesized overlapping peaks γ-ray spectrum. An inversion-decomposition of the γ instrument response spectrum for measured samples (U series, Th series and U-Th mixed sources, among others) can be achieved under the response matrix. The decomposing spectrum can be better distinguished between the similar energy characteristic peaks, which improve the error levels of activity analysis caused by the overlapping peak with significant effects.

568

The applications of carbon ion beam in tumor therapy have attracted more attention in recent years. Monte Carlo simulation is an important approach to obtain accurate radiotherapy parameters. In this work, a 400 MeV/u carbon ion beam incident on water phantom was simulated with Gate/Geant4 tools. In methods, the authors set up a carbon ion beam source according to the experiment parameters of Haettner E, defined the geometries and materials, set up the physics processes, and designed the means of information collection. In results, the authors obtained the longitudinal dose distribution, the lateral dose distribution, and the relative uncertainty of dose. The dose contributions of all kinds of fragments were calculated detailedly, and compared with the Francis Z’s results. This work is helpful for people’s understanding of the dose distributions produced by carbon ion beam and fragments in water. The simulation method is also significative for radiotherapy treatment planning of carbon ion beam, and it is easy to extend. For obtaining a special result, we may change the particle energy, particle type, target material, target geometry, physics process, detector, etc.

721

Low-mass vector meson (ρ, ω, and ϕ) production at forward rapidity in p+p and d+Au collisions at sNN = 200 GeV is studied within the framework of a multiphase transport model (AMPT). Detailed investigations, including the transverse momentum and the rapidity dependence of low-mass vector meson production in the AMPT model show that the hadron interaction process is important for a quantitative description of the ρ and ω data. But for the ϕ meson, the strange quark production in the AMPT model with the string melting scenario describes the data reasonably well, while the default AMPT model under predicts the data. The N(ϕ)/N(ρ+ω) ratio from the AMPT model with the string melting scenario perfectly describes the data in p+p collisions. For the d+Au collisions, an increased trend of this ratio vs. transverse momentum and the number of participants is observed from the AMPT model. Our results indicate that a precise measurement of the N(ϕ)/N(ρ+ω) ratio in d+Au and Au+Au collisions will shed more light on the strangeness production and its dynamics in Quark Gluon Plasma.

597

Copper-64 is a radioisotope of medical interest that could be used for positron emission tomography imaging and targeted radiotherapy of cancer. In this work, we investigated the possibility of producing the ⁶⁴Cu isotope through a ⁶⁵Cu(γ,n) reaction using high-intensity γ-beams produced at the Extreme Light Infrastructure - Nuclear Physics facility (ELI-NP). The specific activity for ⁶⁴Cu was obtained as a function of target geometry, irradiation time, and electron beam energy, which translates into γ-beam energy. Optimized conditions for the generation of ⁶⁴Cu isotopes at the ELI-NP were discussed. We estimated that an achievable saturation specific activity is of the order of 1–2 mCi/g for thin targets (radius 1–2 mm, thickness 1 cm) and for a γ-beam flux of 10¹¹ s^-1. Based on these results, the ELI-NP could provide great potential for the production of some innovative radioisotopes of medical interest in sufficient quantities suitable for nuclear medicine research.

591

Palladium nanoparticles (Pd NPs) were fabricated by using insulin amyloid fibrils (INSAFs) as biotemplates. Atomic force microscopy measurements showed that ultra-small Pd NPs were well adsorbed and dispersed on surfaces of INSAFs. X-ray photoelectron spectroscopy confirmed the partial reduction of Pd ion into metallic Pd(0) probably due to the presence of Cys groups on surface of the insulin fibrils. The electrochemical performance of Pd/INSAFs to reduction of H₂O₂ was further evaluated by cyclic voltammetry (CV). The remarkably high electrocatalytic activity, low detection limitation and excellent stability make the Pd/INSAFs a promising bio-nanoelectrocatalyst.

659

We investigated the properties of strange quark matter in an external strong magnetic field with both confinement and leading-order perturbative interactions considered. It was found that the leading-order perturbative interaction can stiffen the equation of state of magnetized quark matter, while the magnetic field lowers the minimum energy per baryon. By solving the Tolman-Oppenheimer-Volkoff equations, we obtain the internal structure of strange stars. The maximum mass of strange stars can be as large as 2 times the solar mass.

607

The data for neutron-induced reactions is indispensable in a lot of applications of nuclear science and technologies. All reaction cross sections, angular distributions, energy spectra, and double differential cross sections of neutron, proton, deuteron, triton, and alpha-particle emissions are consistently calculated and analyzed for n+²³Na reactions at incident neutron energies below 200 MeV, based on nuclear theoretical models. The calculated results are compared with the experimental data and the evaluated data in the ENDF/B-VII, JENDL-4.0, and JEFF-3.2 libraries. In most cases, the calculated results describe the corresponding experimental data well. At the resonance energy region, evaluated experimental data are adopted to fit to the resonance structures.

647

Soil salinity can limit plant growth and productivity. The cultivation of tolerant varieties is convenient and cost-effective for making good use of the saline soils. The sweet sorghum plant has a high tolerance for saline alkaline soils. The KF1210-3 and KF1210-4 early-maturity mutants of sweet sorghum were obtained via carbon ion irradiation. The study assesses the productivity of three sweet sorghum cultivars (KF1210-3, KF1210-4, and KFJT-CK) which were grown in intermediate (4.6 dSm⁻¹) and high (11.9 dSm⁻¹) soil salinity. The sweet sorghum grown in the soil salinity of 4.6 dSm⁻¹ produced 50.00–57.30% greater fresh weight than that in the soil salinity of 11.9 dSm⁻¹, while the difference was not as obvious among the dry biomass of the three sweet sorghum cultivars. Moreover, the Brix degree of the sweet sorghum grown in the soil salinity of 11.9 dSm⁻¹ was greater than that grown in the soil salinity of 4.6 dSm⁻¹. The heavy ion irradiation experiment is of great significance in screening plant mutants, improving environmental conditions, and assessing the productivity. This process, in turn, aids in the understanding of the effects of the biochemical and physiological mechanisms of salt stress.

436

Radiometric analysis of soil samples, collected from northern alluvial sediment plains between rivers Ravi and Chenab, have been carried out. Activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and the artificial radionuclide ¹³⁷Cs were estimated by using high purity germanium detector (HPGe). Subsequent values of activity concentrations were used to find terrestrial absorbed dose rate and annual effective doses received by resident of area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were found to be 45.0±1.3, 59.6±2.8, 613.8±20.0 and 4.0±0.2 Bq kg^-1 respectively. Terrestrial absorbed dose rate and annual effective dose received by public was found 85.1 nGy h^-1 and 0.5 mSv respectively. The activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs and resulting doses obtained for the current study were compared with data available in literature and with international standards.

588