Vol.31,

A synchrotron-based proton therapy (PT) facility that conforms with the requirement of future development trend in compact PT can be operated without an energy selection system. This article demonstrates a novel radiation shielding design for this purpose. Various FLUKA-based Monte Carlo simulations have been performed to validate its feasibility. In this design, two different shielding scenarios (3-m-thick concrete and 2-m-thick iron–concrete) are proven able to reduce the public annual dose to the limit of 0.1 mSv/year. The calculation result shows that the non-primary radiation from a PT system without an inner shielding wall complies with the IEC 60601-2-64 international standard, making a single room a reality. Moreover, the H/D value of this design decreases from 2.14 to 0.32 mSv/Gy when the distance ranges from 50 to 150 cm from the isocenter, which is consistent with the previous result from another study. By establishing a typical time schedule and procedures in a treatment day for a single room in the simulation, a non-urgent machine maintenance time of 10 min after treatment is recommended, and the residual radiation level in most areas can be reduced to 2.5 μSv/h. The annual dose for radiation therapists coming from the residual radiation is 1 mSv, which is 20% of the target design. In general, this shielding design ensures a low cost and compact facility compared with the cyclotron-based PT system.

476

The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring (CSR) at the Heavy Ion Research Facility in Lanzhou (HIRFL) has been planned. The CEE is a multi-purpose spectrometer that will be used for various studies on heavy-ion collisions. A multi-wire drift chamber (MWDC) array is the forward tracking detector of the CEE. In this work, GEANT4 simulations were performed for the MWDC forward tracking array with a focus on the track reconstruction algorithm. Combined with the time of flight information, particle identification is achieved. The residue is about 30 μm, while the tracking efficiency is higher than 90 % with the current redundancy. In addition, a prototype of the forward tracking system using three MWDCs was assembled and tested using a high energy proton beam. The firing efficiency of the detector and the reconstruction accuracy of the prototype were derived. The track residue for the protons at about 400 MeV/c is better than 300 μm, meeting the requirements of the CEE. Suggestions for improving the performance of the forward tracking system are given.

372

ATP (adenosine triphosphate) borate ester as a new boron agent for boron neutron capture therapy was tested. It was synthesized via a dehydration reaction induced by heating adenosine triphosphate disodium with boric acid. Next, ATP borate ester pretreatments were assessed to study their effects on cell sensitization from exposure to thermal neutron irradiation emitted by a nuclear reactor. Using cell viability assays (CCK8), survival rates of A549 cells pretreated with or without boron-containing agents, including ATP borate ester and 4-dihydroxyborylphenylalanine (BPA), were measured. One week after feeding an ATP borate ester solution to tumor-bearing nude mice, elemental B content values of tumor muscle and blood were measured using ICP-MS (Inductively coupled plasma mass spectrometry). Meanwhile, other tumor tissue samples were placed in a culture medium, subjected to a 3-min neutron irradiation exposure, and then fixed in formalin 24 h later for dUTP nick end labeling (TUNEL) immunohistochemical staining analysis. Results showed that A549 cell irradiation sensitization (irradiation dose of 0.33Gy) varied with pretreatment. Sensitization values of the ATP borate ester pretreatment group were 1.3–14.1 with boron agent concentrations of 0.3–4.5 mM. Within 1.1–3.4 mM, ATP borate ester showed significantly higher sensitization values than BPA. Meanwhile, TUNEL results demonstrated that apoptosis rates of tumor tissue cells exposed to irradiation after ATP borate ester pretreatment significantly exceeded the corresponding rates for BPA-pretreated cells. In animal experiments, although the distribution ratio of ATP borate ester (tumor tissue/normal muscle, T/N) of 1.2 was not significantly different compared with that of BPA (1.3), the total ATP borate ester concentration in the tumor tissue (0.79 ± 0.05 μg/g) significantly exceeded that of BPA (0.58 ± 0.05 μg/g). Thus, compared with BPA, the greater enrichment of ATP borate ester in tumor tissues permits preferential targeting toward tumor cells for radiation sensitization. Therefore, ATP borate ester is superior to BPA for use in boron neutron capture therapy.

441

To study the adsorption properties of organic functional groups in plant fibres and identify a highly efficient and affordable adsorbent for radioactive wastewater treatment, natural bamboo fibre (NBF) samples were prepared, and the adsorption properties of Eu(III) on NBFs were studied under given experimental conditions. The effects of the pH, solid-to-liquid ratio, background ions, humic acid, contact time, and temperature on the adsorption behaviour of Eu(III) on NBFs were investigated. Adsorption was greatly influenced by pH, and theadsorption curves presented two inflection pointsat pH≈7 and pH≈11. Moreover, while the ionic strength presented a negative effect at pH<7, the high ionic strength favoured adsorption at pH>7. During adsorption on NBFs, the –OH,C–H, O–H, C–O, and C=O were the main adsorption groups. Hydrolysis occurring on the NBF surface caused the adsorption process to become increasingly difficult at pH>7. The maximum adsorption capacity of NBFs was 147.6 mg/g at 308 K, and the adsorption could be described using the pseudo-second-order kinetic model. The adsorption of Eu(III) on NBFs was a spontaneous and endothermic process according to the thermodynamic parameters of the process, and the adsorption thermodynamics could be well described using the Freundlich adsorption model. Therefore, NBFs were determined to be an efficient, inexpensive, and easily disposable sewage treatment material.

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The aim of this study was to determine the attenuation of gamma and X-rays with different energies caused by passage through different materials. To this end, different materials with a range of atomic numbers were chosen to measure gamma and X-ray attenuation coefficients and to explore the mechanisms of interaction of gamma and X-rays with matter of various kinds. It is shown that the attenuation coefficients first decrease and then increase with increase in the radiation (photon) energy. The attenuation of gamma and X-rays passing through materials with high atomic number is greater than that in materials with low atomic number. The attenuation minimum is related to the atomic number of the irradiated materials. The larger the atomic number is, the lower the energy corresponding to attenuation minimum is. Photoelectric and Compton effects are the main processes when gamma rays pass through individual materials with high and low atomic numbers, respectively. Therefore, for radiotherapy and radiation protection, different methods should be considered and selected for the use of gamma and X-rays of different energies for use in different materials.

539

In the present work, the classical Bethe-Weizsäcker (BW) mass formula with five energy terms is revisited and updated. We use the least-squares adjustments on the binding energy of 2497 different nuclides from the last update of the atomic mass evaluation, AME2016 published in March 2017, to provide a new set of energy coefficients of the mass formula. The obtained set of formula coefficients allowed us to reproduce most of the experimental values of the binding energies for each nucleus with A 50. The comparison between the binding energies provided with updated mass formula and those of AME2016 on one hand, and those of previous works, on the other hand, yield relative errors that oscillate between less than 0.05% and 1.5

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In this study, two different designs of liquid metal fast reactor (LMFR) fuel rods wire-wrapped and non-wire-wrapped (bare) are compared with respect to different parameters as a means of considering the optimum fuel design. Nuclear seismic rules require that systems and components that are important to safety must be capable of bearing earthquake effects, and that their integrity and functionality should be guaranteed. Mode shapes, natural frequencies, stresses on cladding, and seismic aspects are considered for comparison using ANSYS. Modal analysis is compared in a vacuum and in lead-bismuth eutectic (LBE) using potential flow theory by considering the added mass effect. A simple and accurate approach is suggested for the determination of the LBE added mass effect and is verified by a manually calculated added mass, which further proved the usefulness of potential flow theory for the accurate estimation of the added mass effect. The verification of the hydrodynamic function (τ) over the entire frequency range further validated the finite element method (FEM) modal analysis results. Stresses obtained for fuel rods against different loading combinations revealed that they were within the allowable limits with maximum stress ratios of 0.25 (bare) and 0.74 (wire-wrapped). In order to verify the structural integrity of cladding tubes, stresses along the cladding length were determined during different transients and were also calculated manually for static pressure. The manual calculations could be roughly compared with the ANSYS results and the two showed a close agreement. Contact analysis methodology was selected and the most appropriate analysis options were suggested for establishing contact between the wire and cladding for the wire-wrapped design grid-independence analysis, which proved the accuracy of the results, confirmed the selection of the appropriate procedure, and validated the use of the ANSYS mechanical APDL code for LMFR fuel rod analysis. The results provided detailed insight for the structural design of LMFR fuel rods by considering different structural configurations (i.e., bare and wire-wrapped) in the seismic loading; this not only provides a FEM procedure for LMFR fuel with complex configuration, but also guides the reference design of LMFR fuel rods.

605

From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt corrosion, fission product attacks, thermal stress, and even combinations of these. In the past few years, synchrotron radiation-based materials characterization techniques have proven to be effective in revealing the microstructural evolution and failure mechanisms of the alloys under surrogating operation conditions. Here, we review the recent progress in the investigations of molten salt corrosion, tellurium (Te) corrosion, and alloy design. The valence states and distribution of chromium (Cr) atoms, and the diffusion and local atomic structure of Te atoms near the surface of corroded alloys have been investigated using synchrotron radiation techniques, which considerably deepen the understandings on the molten salt and Te corrosion behaviors. Furthermore, the structure and size distribution of the second phases in the alloys have been obtained, which are helpful for the future development of new alloy materials.

527

Herein we assess the ¹²⁹I transmutation capability of a 2250-MWt single-fluid double-zone thorium molten salt reactor (SD-TMSR) by considering two methods. One is realized by loading an appropriate amount of ¹²⁹I before the startup of the reactor, and the amount of ¹²⁹I during operation is kept constant by online feeding ¹²⁹I. The other adopts only an initial loading of ¹²⁹I before startup, and no other ¹²⁹I is fed online during operation. The investigation first focuses on the effect of the loading of I on the Th-²³³U isobreeding performance. The results indicate that a ²³³U isobreeding mode can be achieved for both scenarios for a 60-year operation when the initial molar proportion of LiI is maintained within 0.40% and 0.87%, respectively. Then, the transmutation performances for the two scenarios are compared by changing the amount of injected iodine into the core. It is found that the scenario that adopts an initial loading of ¹²⁹I shows a slightly better transmutation performance in comparison with the scenario that adopts online feeding of ¹²⁹I when the net ²³³U productions for the two scenarios are kept equal. The initial loading of ¹²⁹I scenario with LiI = 0.87% molar proportion is recommended for ¹²⁹I transmutation in the SD-TMSR, and can transmute 1.88 t of ¹²⁹I in the ²³³U isobreeding mode over 60 years.

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An investigation using Monte Carlo simulation on a minitype reference radiation (MRR) for the calibration of gamma personal dosimeters is reported. The distributions of dose rate and scattering gamma spectrum are the main simulation objects with the variable physical structures of MRR and the dosimeters as parameters that are to be calibrated. Further, the influences on the reference radiation caused by these parameters are analyzed in detail. This work provides a theoretical basis for better understanding of MRR used for calibration of gamma personal dosimeters. This analysis can help in the development of a calibration technology for such tools based on MRR.

348

Very high frequency (VHF) photocathode guns have excellent performance and are being increasingly selected as electron sources for high repetition rate X-ray free-electron lasers. As a high loaded quality factor cavity, the VHF gun requires high stability in the amplitude and phase of the cavity field. However, the gun is microwave powered by two solid-state power sources through two separate power couplers. The input difference between the two power couplers will influence the stability of the cavity field. To systematically study this influence and obtain measurement formulae, a multi-port VHF gun LCR circuit model is built and analyzed. During the warm-up condition, the cavity structure will be deformed due to the large-scale change in the cavity temperature. Then, the deformation will result in cavity resonant frequency changes. To prevent the mechanic tuner from suffering damages due to the frequent and long-distance movement for correcting the cavity resonant frequency, a self-excited loop (SEL) control system is considered for changing the loop phase and make the loop frequency follow the resonant frequency. In this study, a steady-state model of the VHF gun cavity is built for obtaining the optimal input coupler coefficient and the stability requirement of the forward voltage. Then, the generator-driven resonator (GDR) and SEL control system, which combine with the VHF multi-port modeling, are modeled and simulated. The simulated results show that the SEL system can perfectly operate in the process of condition and warm-up.

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