Vol.29,

The two-tailed comet assay (2T-comet assay) is a method for simultaneously evaluating DNA single-strand breaks (SSBs) and double-stand breaks (DSBs). In the present study, the endonuclease DNaseI and hydrogen peroxide were used to induce DSBs and SSBs in bone marrow mononuclear cells (BMMNCs) from mice, and the damaged DNAs were assessed with a 2T-comet assay. The results demonstrated that this method can detect and discriminate between BMMNC DNA SSBs and DSBs simultaneously. Using this method, we studied DNA damage in BMMNCs from female BALB/c mice after total body irradiation with X-rays and carbon ions. The results indicated that these two types of radiation induced serious DNA damage in BMMNCs in a dose-dependent manner. The DNA damage induced by carbon ions was more severe than that induced by X-rays at the same dose, and a high dose of carbon ion radiation was more likely to cause death in mice. The DSBs and SSBs induced by X-rays were the highest on the 3^rd day post-IR. For carbon ion radiation, DSBs were the most serious on the 3^rd day, while SSBs were more obvious on the 3^rd day and 13^th day post-IR. The ratio of DSBs/SSBs was clearly related to the different types of radiation.

339

A new polyglycerol phthalate extractant was prepared and characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H NMR) spectroscopy, and thermogravimetric analysis (TGA). A preliminary study of the extraction of long-lived (⁹⁰Sr and ^152+154Eu) and short-lived (⁹⁰Y) radionuclides by polyglycerol phthalate was performed. The influence of different diluents, concentration of the acid, type of acid, and various interfering ions was explored. The stripping of ^152+154Eu radionuclide was studied by using different acid solutions and it was found that sulfuric acid was the ideal acid for this purpose. Furthermore, ^152+154Eu was extracted from the fission products (⁹⁰Sr) and the extraction% of ⁹⁰Sr was found to improve in the presence of interfering ions.

343

While the high-energy radiation effects on polypropylene, which are crucial for the cable industry for nuclear power plants, have been thoroughly studied, the property changes of PP at low-dose-rate electron-beam irradiation are far from elucidated. Herein, the influence of electron-beam irradiation on the structure and properties of PP were examined. The static EB irradiation conditions were 1.2 MeV at a low dose rate of 20 kGy/h to achieve absorbed doses ranging from 45, to 60, 100, and 200 kGy. The molecular structure was first evaluated by measuring the carboxyl index and the relative radical concentrations via Fourier transform infrared spectroscopy (FT-IR) and electron spin resonance (ESR), respectively. Mechanical, differential scanning colorimetric (DSC), and rheological tests were carried out to further investigate the changes in the properties (tensile, crystalizing, and viscoelastic properties) of irradiated PP, which showed good agreement with the structural analysis results. We found that radio-oxidative degradation (chain scission) was predominant, which can be due to the low dose rate facilitating oxygen diffusion into the PP matrix during electron-beam irradiation.

311

Solvent extraction is an important process in the nuclear fuel cycle. Tributyl phosphate (TBP) diluted with dodecane is commonly used as a solvent for extracting heavy metals from a nitric acid medium. Studies on the hydrodynamics of a single drop, which is the smallest mass transfer entity, are required for better understanding of the complex mass transfer and phase separation phenomena that occur in extraction equipment. In this study, drop formation at nozzles is studied using 30%TBP-dodecane as the dispersed phase and dilute nitric acid as the quiescent continuous phase. Experiments are carried out to determine the drop diameter, jetting velocity, drop detachment height and drop formation time for various dispersed phase velocities, nozzle diameters (1.91 mm, 3.04 mm, and 4.88 mm), and nitric acid concentrations (0.01N, 1N, 3N). Drop formation is captured using high speed imaging, which enables quantification of drop size, onset of jetting, drop detachment height, and drop formation time. Experimental data are used to propose correlations for predicting drop diameter and minimum jetting velocity. The correlations are found to be very accurate with average absolute relative errors of 5.23% and 2.9%, respectively.

458

Phosphorylurea molecules, which are bidentate organophosphorous compounds containing both phosphoryl and carbonyl groups, are considered efficient extractants for UO₂². This study aims to explain the complexation of UO₂²⁺ with carbamoylphosphoramidic acid (CPO), a simple model for phosphorylurea, for ligand design for uranium recovery from seawater using density functional theory calculations (DFT), natural bond order analysis (NBO), and the quantum theory of atoms in molecules (QTAIM). The results showed that, when CPO acts as a monodentate ligand, the affinity of phosphoryl for UO₂²⁺ is stronger than that of carbonyl, and CPO coordinates to UO₂²⁺ through the phosphoryl oxygen atom. When CPO serves as a bidentate ligand, both the phosphoryl and carbonyl oxygen atoms connect to UO₂²⁺, and the U–O(carbonyl) bond plays a more important role than the U–O(phosporyl) bond in the interaction between UO₂²⁺ and CPO. This paradox may be caused by the significant charge transfer from the U–O(carbonyl) π bond orbital to the C–N σantibond orbital of the bidentate CPO. The NH spacer between the phosphoryl and carbonyl groups could ensure the delocalization of the electron system of the molecule. The bidentate binding motif is favored by entropy and opposed by enthalpy, while the monodentate binding motif is favored by enthalpy and opposed by entropy. Ultimately, the bidentate binding motif is more favorable than the monodentate one. As expected, the interaction between UO₂²⁺ and the deprotonated CPO is stronger than that between UO₂²⁺ and the neutral CPO. Comparing the interaction between UO₂²⁺ and CPO with that between UO₂²⁺ and N-phenylcarbamoylphosphoramidic acid (PhCPO), formed by replacing one hydrogen atom from the terminal nitrogen atom of CPO with a phenyl group, the phenyl substituent at the terminal nitrogen atom of PhCPO shows a slightly negative effect on the interaction between UO₂²⁺ and PhCPO.

385

The deexcitation of single excited ¹¹²Sn nuclei at T = 1–30 MeV is simulated using the isospin-dependent quantum molecular dynamics (IQMD) model and GEMINI model. The fragmentation mechanism, critical behavior, and kinematic characteristics are investigated within these two models. The results show that the IQMD model can be applied to the analysis of fragmentation processes, critical points, and slope temperature extraction. The results of IQMD are generally consistent with experimental 〈M_IMF〉- Z_bound data. However, GEMINI can reproduce the experimental data better than IQMD for isotopic distributions.

339

Lorentz force velocimetry (LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field (ExMF). Two types of ExMFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet (PM) and another generated by an electromagnet (EM) on the order of 2 T. Two forces, including the magneto-static force between the ExMF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition, ExMFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for an LFV device to operate normally under a moderate ExMF. However, the magneto-static force will account for a high proportion of the measured force, thus inhibiting the normal LFV operation, if the ExMFis too high.

335

The kinetic freeze-out temperatures, T₀, in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are extracted by four methods: i) the Blast-Wave model with Boltzmann-Gibbs statistics (the BGBW model), ii) the Blast-Wave model with Tsallis statistics (the TBW model), iii) the Tsallis distribution with flow effect (the improved Tsallis distribution), and iv) the intercept in T = T₀ + am₀ (the alternative method), where m₀ denotes the rest mass and T denotes the effective temperature which can be obtained by different distribution functions. It is found that the relative sizes of T₀ in central and peripheral collisions obtained by the conventional BGBW model which uses a zero or nearly zero transverse flow velocity, β_T, are contradictory in tendency with other methods. With a re-examination for β_T in the first method, in which β_T is taken to be ~(0.40±0.07)c, a recalculation presents a consistent result with others. Finally, our results show that the kinetic freeze-out temperature in central collisions is larger than that in peripheral collisions.

534

Fast beam profile measurement is important in fast beam dynamic behavior investigations. A bunch-by-bunch beam size measurement system, which is presently used to measure horizontal profile, has been developed at the Shanghai Synchrotron Radiation Facility (SSRF) and is capable of measuring bunches within a separation of 2 ns. The system is based on a direct-imaging optical system and high-speed photomultiplier array detector. A high-bandwidth linear signal amplifier and acquisition module have also been designed to process bunch-by-bunch multi-channel signals from the detector. The software resampling technique and principal component analysis (PCA) method were developed to obtain the synchronized data and enhance the signal-to-noise ratio. The fast injection of transients was successfully captured and analyzed. Moreover, the bunch-by-bunch positions and sizes exhibited strong oscillation after the injection at the horizontal betatron oscillation frequency of the SSRF storage ring, and this demonstrated the bunch-by-bunch measurement capability of our system.

489

A new linac injector CSR-LINAC for the Cooler Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR) is proposed to improve the performance of the HIRFL. As a key component of the CSR-LINAC, the 108.48 MHz radio frequency quadrupole (RFQ) is under design at the Institute of Modern Physics (IMP). Heavy ions with mass-to-charge ratios of 3 ~ 7 will be accelerated from 4 keV/u to 300 keV/u by the RFQ. In the beam dynamics design, the New Four-Section Procedure (NFSP) is adopted to improve the transmission efficiency and obtain a compact structure. In this paper, a transmission efficiency of 98.0% in the 3.07 m long cavity was obtained. The Interdigital H-type (IH) structure is employed because of its mechanical stability and high shunt impedance. The RF performance of the cavity is investigated by the electromagnetic simulation. The optimized results of the electric field to meet the beam dynamics requirements is presented in this paper.

408

A balanced optical microwave phase detector (BOMPD) based on a 3×3 coupler is presented. This system was developed to extract ultra-low-jitter microwave signals from optical pulse trains emitted by mode-locked Er-fiber lasers, and synchronized microwave and laser systems. We demonstrate that the BOMPD achieves a precision of synchronization of less than 100 femtoseconds of timing jitter. The experimental setup can be applied to the soft X-ray free electron laser (SXFEL) located on the campus of the Shanghai synchrotron radiation facility. A microwave signal with a 2.856 GHz frequency is extracted from a 238 MHz mode-locked Er-laser, with an absolute timing jitter of 34 fs in the 10 Hz to 10 MHz frequency offset range. In addition, the microwave and 238 MHz optical pulse signals are synchronized with a relative timing jitter of 16 fs at the same frequency offset range.

462

This paper presents a neutronics design of a 10 MW ordered-pebble-bed fluoride-salt-cooled high-temperature experimental reactor. Through delicate layout, a core with ordered arranged pebble bed can be formed, which can keep core stability and meet the space requirements for thermal-hydraulics and neutronics measurements. Overall, objectives of the core include inherent safety and sufficient excess reactivity providing 120 effective full power days for experiments. Considering the requirements above, the reactive control system is designed to consist of 16 control rods distributed in the graphite reflector. Combining the large control rods worth (about 18000–20000 pcm), molten salt drain supplementary means (-6980 to -3651 pcm) and negative temperature coefficient (-6.32 to -3.80 pcm/K) feedback of the whole core, the reactor can realize sufficient shutdown margin and safety under steady state. Besides, some main physical properties, such as reactivity control, neutron spectrum and flux, power density distribution, and reactivity coefficient have been calculated and analyzed in this study. In addition, some special problems in molten salt coolant are also considered, including ⁶Li depletion and tritium production.

370

In this study, we aimed to determine the accumulations of ²¹⁰Po and ²¹⁰Pb in soil and lichen samples in Köprübaşı. The Köprübaşı district is home to the largest uranium deposits in Turkey. To date, there has been no study recorded in the literature related to ²¹⁰Po and ²¹⁰Pb depositions in lichens in Köprübaşı. Six different lichen species (Cladonia convoluta, Parmelina tiliacea, Physcia stellaris, Pleurosticta acetabulum, Xanthoparmelia conspersa and Xanthoria parietina) as well as soil samples were collected from seven sampling locations around Köprübaşı. Lichens were used as biomonitors for ²¹⁰Po and ²¹⁰Pb deposition. The ²¹⁰Po and ²¹⁰Pb activity concentrations were measured in all the samples by alpha spectrometry. The activity concentrations in the lichen samples ranged from 64 to 577 Bq.kg^-1 with an average of 266 Bq.kg^-1 for ²¹⁰Po and from 78 to 565 Bq.kg^-1 with an average of 333 Bq.kg^-1 for ²¹⁰Pb. The activity ratios of ²¹⁰Po/²¹⁰Pb ranged from 0.80 to 1.99. In the lichen species, the mean ²¹⁰Po activity values varied from 154 Bq.kg^-1 in Pleurosticta acetabulum to 390 Bq.kg^-1 in Xanthoparmelia conspersa. The range of the mean ²¹⁰Pb activity was between 153 Bq.kg^-1 in Cladonia convoluta and 378 Bq.kg^-1 in Parmelina tiliacea. In the soil samples, ²¹⁰Po and ²¹⁰Pb activity concentrations were ranged from 14 to 1268 Bq.kg^-1 and from 19 to 1113 Bq.kg^-1, respectively. While the values of ²¹⁰Po and ²¹⁰Pb measured in the lichen samples are comparable with those of the literature, the results of ²¹⁰Po and ²¹⁰Pb in the soil taken from the uranium mine are higher than the results of the literature studies.

336

In order to pursue high-precision beam position measurements for free-electron laser (FEL) facilities, a cavity beam position monitor (CBPM) is employed to measure the transverse position that can meet the requirement of position resolution at a sub-micrometer or even nanometer scale. However, for the pill-box cavity BPM, crosstalk between the cavities will have an effect on the accurate measurement of beam position. To reduce the effect of crosstalk on CBPM performance and ease the measurement of the isolation between the cavities, the cavities with a slight difference in resonant frequency were designed and applied in the Dalian Coherent Light Source (DCLS) and Shanghai Soft X-Ray Free-Electron Laser (SXFEL) facilities. Furthermore, two methods, the principal component analysis (PCA) method and the method of harmonic analysis, are proposed in this paper to evaluate the crosstalk. The results demonstrate that the two methods are feasible in evaluating the crosstalk between the cavities.

477

X-ray fluorescence microtomography (μXFCT) is a nondestructive analytical technique and has been widely used to nondestructively detect and quantify the elemental composition and distributions in samples. Usually, synchrotron radiation X-rays are used for μXFCT, due to its high flux density. In this paper, a laboratory-source-based μXFCT system was developed, in which a polycapillary lens is employed to focus the X-ray beam and improve the flux density. The maximum likelihood expectation maximization (MLEM) algorithm was used to reconstruct the computed tomography (CT) slices at a limited number of projections. The experimental results demonstrated that the developed system could reveal the elemental distribution inside the test sample, with an elemental sensitivity of 1000 ppm.

609