[en] We have developed a scannerless three-dimensional imaging approach that uses a pulsed laser to illuminate a target and an intensified charge-coupled device as the receiver with linearly modulated gain in gated time. The target range is extracted by processing an intensity image with linearly modulated gain and an intensity image with constant gain. Feasibility of the approach is demonstrated by an indoor experiment. Our prototype system can produce 256x256 pixel range images at a 20 Hz frame rate in an outdoor test. The test results indicate that range accuracy is related to the slope coefficient and initial value of the modulated gain.

[en] During the operation, maintenance, decommissioning of nuclear facilities, workers often need to work directly in the radiation environment. Considering the personal dose limit principle in the radiation protection, specific planning is usually carried out prior to the implementation of the work, which requires the radiation protection personnel to obtain the radiation field data of the entire work area. However, due to the number of detectors is limited, the radiation data can only be obtained at a few locations in the radiation area. Hence, it is necessary to select appropriate algorithm to reconstruct the complete radiation field based on these limited radiation data. After studying the accuracy and principle of commonly used reconstruction algorithms, the combination of Empirical Bayesian Kriging algorithm and Least-squares Fitting algorithm is introduced to reconstruct nuclear radiation field based on the sparse measurement data. And after many attempts, the semivariogram type of the Empirical Bayesian Kriging algorithm adopts the whittle detrended, while the model of the Least-squares Fitting algorithm is exponential function. In this method, the two algorithms are responsible for calculating different regions, the radiation field of the region surrounded by the measuring points is interpolated using Empirical Bayesian Kriging algorithm. Then the extrapolation is performed to obtain the radiation field of the outside region with Least-squares Fitting algorithm based on the results obtained in the previous step. To demonstrate the feasibility of this method, the simulation experiment with scattered and sparse measuring data is performed based on a large gradient virtual radiation field, and the average relative error of the reconstructed results is 20.7%. Considering more realistic application, another experiment with sparse data along a certain path is simulated. It shows that the average relative error is 25.1%. The results in this study indicate that the combined method is effective for the reconstruction of large gradient radiation field with sparse measurement data, which is helpful for radiation protection in practical engineering. (author)

[en] The collective dose of nuclear power plant workers mainly comes from the outage period of nuclear power plant. The corrosion activation products deposited in the pipelines and the radiation dose field formed are the main sources of occupational exposure of workers in the nuclear facilities, and the changes of their numerical value also reflect the operating state of the NPP unit. Therefore, it is of great significance to monitor the activity and dose rate contribution changes of radionuclides in key pipelines and points in real time, and which is useful to take necessary protective measures for subsequent maintenance work and reducing the collective dose as much as possible. At present, the nuclear power plant only adopts the dose rate of the maintenance area to implement the corresponding protective measures during the outage period. Some nuclear power plants have implemented the source items investigation during the outage period, and have analyzed the radionuclide activity and dose rate contribution ratio of key pipelines and points in detail. And this work provides a reliable data basis for subsequent source items decontamination and dose reduction. However, during the oxidation operation of the outage period, it is change continuously for the activities of radionuclides at some key points. But there is no relevant instrument to monitor the trend of changes in the radioactivity in the pipeline in real time, which is reserved data blank for the subsequent radiation protection optimization and NPP unit operation evaluation.

[en] The ability to alter magnetic anisotropy values is of technological importance in the application of magnetic ultrahigh-density recording. By capping some other atoms onto the surface of a magnetic thin film or inserting a thin layer between the magnetic film and the substrate, we can change the surface or interface perpendicular magnetic anisotropy and then alter the magnetic properties of the film, such as the spin reorientation transition (SRT), in ultrathin ferromagnetic films. The SRT of face-centered-tetragonal (fct) Fe films grown on Cu(001) substrate is determined by the magneto-optical Kerr effect. We find that the out-of-plane magnetization changes to in-plane induced by a Ni-capping or a Co-inserting layer at 110 K. From the linear relation of the critical thickness of a fct-Fe film with Ni or Co covering when SRT occurs, the 'true' critical thickness of the pure fct-Fe film without coverage or buffer in the absence of structural transformation is obtained by setting the coverage to zero value. The estimated true critical thickness is approximately 4.3 ML for the Ni-capping method and 4.6 ML for the Co-inserting experiment, which are very close to the reported result for the Co-capping experiment.

[en] Highlights: • A facile and efficient strategy is firstly developed for the synthesis of Ru NPs. • Ru NPs are stable and uniform with the controllable sizes from 2.6 to 51.5 nm. • Ru NPs exhibit size-dependent and superior catalytic hydrogenation activity. - Abstract: Ruthenium (Ru) featured with an unusual catalytic behavior is of great significance in several heterogeneous and electro-catalytic reactions. The preparation of tractable Ru nanocatalysts and the building of highly active catalytic system at ambient temperature remains a grand challenge. Herein, a facile strategy is developed for the controllable preparation of Ru nanoparticles (NPs) with the sizes ranging from 2.6 to 51.5 nm. Ru NPs show superior size-dependent catalytic performance with the best kinetic rate constant as high as −1.52 min"−"1, which could far surpass the other traditional noble metals. Ru NPs exert exceedingly efficient low-temperature catalytic activity and good recyclability in the catalytic reduction of nitroaromatic compounds (NACs) and azo dyes. The developed catalytic system provides a distinguishing insight for the artificial preparation of Ru NPs with desired sizes, and allows for the development of rational design rules for exploring catalysts with superior catalytic performances, potentially broadening the applications of metallic NP-enabled catalytic analysis.

[en] Conductive and reflective silver layers on both sides of polyimide films have been prepared by doping silver–ammonia ions into the surfaces of polyimide film, and subsequent solid–liquid interfacial reduction, during which double diffusion of silver ions and newly formed silver crystals occurred between the interfaces of polyimide films and the aqueous reducing surroundings. The newly formed silver nanoparticles could migrate and aggregate onto both sides of substrate films, forming continuous and compact silver layers that result in excellent conductivity, i.e. ∼0.6 and 0.5 Ω/sq on the upside and downside surfaces, respectively. The surface reflectivity could be detected up to 80% on the downside and 90% on the upside surface as well. The effects of the silver contents and reducing conditions on the morphologies and properties have been investigated comprehensively, and the two-side properties differences were discussed. A convictive relationship between the morphologies and properties has been established, providing reliable and general guidance in terms of preparation of inorganic nanoparticles on plastic substrates. This novel and simple strategy can be extended to fabricate many other metal, metal oxide and metal sulfide nanoparticles on plastic substrates, using proper oxidants or sulfions to replace the diverse reductants. The films were characterized by inductively coupled plasma, contact angle measurement, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, four-point probe instrument and ultraviolet spectrophotometry

[en] Background: The standing whole-body counters are widely used for in-vivo measurements, such as ORTEC StandFAST, CANBERRA-FASTSCAN, CIRP-StandWBC. They are mainly designed to quickly and accurately measure internal contamination of radionuclides with medium and high photon energy. The physical phantoms such as BOMAB, IGOR, sBCAM have been used for whole-body counting calibrations. However, these simplified phantoms cannot fully represent all the characteristics of the human body, furthermore, the phantom parameters are based on the reference human body, which cannot represent workers with different body shapes and sizes. To date, there is a lack of understanding about the detection efficiency response as a function of phantom sizes and photon energy.

[en] Full text: As a passive neutron personal dosimeter, CR-39 solid state nuclear track detector is convenient, cheap, insensitive to gamma and beta rays and has strong anti-interference ability and better response to fast neutrons. A method of neutron dose measurement with CR-39 solid state nuclear track detector is established, consisting of detector preprocessing, neutron irradiation, chemical etching and track reading. A performance experiments are carried out on the CR-39 detector according to the international standard ISO21909-1. The results show that the CR-39 solid state nuclear track detector has good repeatability, batch homogeneity, dose linearity, time stability and environmental stability. By adopting the method of adding the polyethylene and boron converter to CR-39 detector, the optimization design is carried out to improve the energy response of fast neutrons and expand the energy detection range. A set of personal neutron dose measurement methods based on the CR- 39 solid track detector has been established by using Monte-Carlo method. To conform the personal neutron dose measurement method, an experimental comparison study is made by using the CR-39 to measure the neutron dose in standard Am-Be, Cf, D2O moderated Cf neutron source radiation field, which the neutron dose distributions were well known. The comparison result shows the deviation of the neutron exposure dose obtained by this measurement method from the actual exposure does not exceed 12%, which has high feasibility and accuracy.

[en] The internal exposure dose estimation formula is E=I·e(g), where I is the intake, and e(g) is the dose coefficient. Therefore, the intake I directly determines the committed effective dose, and the main purpose of internal exposure monitoring is to obtain the value of the intake I by measuring the retention. In order to improve the accuracy of the intake I, a more effective measure is to calibrate the counter to improve the measurement accuracy of the retention. In this paper, a new anthropometric skull phantom has made for skull counter calibration, and carried out calibration of the skull counter. The phantoms’ head circumference of is 56.18cm, the total head height is 23.31cm, the maximum head breadth is 15.76cm, and the maximum head length is 19.23cm. conforms to the reference Chinese male . The phantom consists of bone substitute and soft tissue substitute, the soft tissue substitute is polyurethane, and the hard bone substitute is a mixture of epoxy resin and calcium carbonate. At 46.5keV, the relative deviations between the mass attenuation coefficients of the two tissue equivalent materials and the reference values in the ICRP23 report are 0.86% and -2.98%, respectively. The relative deviation of the mass attenuation coefficient of brain tissue and soft tissue at 46.5KeV is 5.03%, so soft tissue substitute can be used instead of brain tissue. The phantom was made by pouring. The mold is made by 3D printing.

[en] According to IAEA's statistics, currently there are 459 nuclear power reactors in operation in 34 countries and regions around the world, and the global spent fuel inventory is expected to reach 445000 tons by 2020. At present, only one third of the spent fuel is reprocessed and the remaining two-thirds can only be temporarily stored. Spent fuel storage is a necessary part of the nuclear fuel cycle, and the storage Methods: are generally divided into wet storage and dry storage. Wet storage is stored in pools, which has been implemented for more than 40 years. Dry storage usually places spent fuel assemblies in packaged containers to cool by air, which has reached more than 30 years in some countries. According to their own nuclear fuel cycle strategy, nuclear power countries have formulated their own spent fuel management strategy and selected appropriate spent fuel storage technologies for their own countries. In this paper, storage technologies are briefly compared and introduced, as well as the general situation of spent fuel storage in nuclear countries. (authors)