[en] Highlights: • A model of open refrigeration system is developed. • The state of CO₂ has great effect on Refrigeration capacity loss by heat transfer. • Refrigeration capacity loss by remaining CO₂ has little relation to the state of CO₂. • Calculation results are in agreement with the test results. - Abstract: Based on the analysis of the properties of carbon dioxide, an open carbon dioxide refrigeration system is proposed, which is responsible for the situation without external electricity unit. A model of open refrigeration system is developed, and the relationship between the storage environment of carbon dioxide and refrigeration capacity is conducted. Meanwhile, a test platform is developed to simulation the performance of the open carbon dioxide refrigeration system. By comparing the theoretical calculations and the experimental results, several conclusions are obtained as follows: refrigeration capacity loss by heat transfer in supercritical state is much more than that in two-phase region and the refrigeration capacity loss by remaining carbon dioxide has little relation to the state of carbon dioxide. The results will be helpful to the use of open carbon dioxide refrigeration

[en] Taking the Main Steam Isolation Valve (MSIV) of the million kilowatt class pressurized water reactors in China as the examples, the design requirements and structure characteristics of MSIV were introduced in detail, and considering the present situation of the localization of MSIV, the technical difficulties and the key issues during the development were analyzed in-depth, such as the valve design and calculation, the driving device selection, quality assurance of materials, valve sealing performance, and valve prototype qualification. The relevant contents have been verified in the localization of MSIV. (authors)

[en] In this paper, we report a mirror box platform for controlling the beamline mirrors in visual and remote mode at Beijing Synchrotron Radiation Facility (BSRF). The platform is based on Client/Device Server structure and, to ensure the safety, only the clients examined by Server can access the devices. The 3D mirror adjustments and simple ASCII message protocol are designed for implement of the platform control in visual and remote mode. Test results show that the time to update the position status is 0.2 s and the position error in visual control is less than 5%. The performance meets requirements of the mirror box control in BSRF beam lines. By increasing the device drivers in the server and developing programs in the clients, the platform can be used to control the whole beam line. (authors)

[en] As the main stream super pipe is one of important equipment in nuclear power plants, a pipe's mockup must be made by the manufacturers to apply for a manufacturing license. However, there are no detailed requirements for fabricating the mockup in the regulations issued by National Nuclear Safety Administration. Combined with safety review practices, some technical requirements for the main stream super pipe used in improved Generation Ⅱ nuclear power plants are introduced, and some basic requirements for choosing the type of the mockup, quality management, process control, detection and test control and so on are given in his paper so as to provide a reference for applicants and safety technical reviewers. (authors)

[en] It was observed that the focused X-ray spots on the sample had an obvious shift and defocus as the beam currents decreased during the same run cycle at small angle X-ray scattering station, Beijing Synchrotron Radiation Facility (BSRF). A single bent crystal monochromator with a special geometry is proposed to solve those problems, and it meets the experimental requirements of small angle X-ray scattering station. (authors)

[en] The SEBIM safety valve is pilot-operated safety valve refer in particular to overpressure protection for Pressurizer of Nuclear Power Station, it has good stability, structurally complex, high sensitivity, high reliability and perfect function. This paper describes the differences and relationship of preventive maintenance and corrective maintenance of SEBIM safety valve in Nuclear Power Station, and analyzes SEBIM safety valve common cause faults including pilot control valve (R1/R2) leakage fault and over proof with water consumption of serviceability test, and summed up its maintenance and treatment. (authors)

[en] As a method of seismic evaluation, seismic analysis is widely used in the safety evaluation of various equipment in nuclear power plant. At present, because of the different methods of bolt stress checking, the standard used is also different. In this paper, based on ASME and RCC-M standards, the stress evaluation method and evaluation basis are proposed for nuclear grade equipment designed according to different nuclear safety standards and bolts at different positions, which has reference significance for seismic analysis of nuclear grade equipment. (authors)

[en] Most materials exhibit different tensile and compressive strains given the same stress applied in tension or compression. These materials are known as bimodular materials. An important model of bimodular materials is the criterion of positive-negative signs of principal stress proposed by Ambartsumyan. This model is mainly applicable to isotropic materials and deals with the principal stress state in a point. However, due to the inherent complexity of the constitutive relation, FEM based on iterative strategy and analytical methods based on a simplified mechanical model are required. In this paper, we review the basic assumptions of this model and its development, several innovative computational methods, and some important engineering applications. We also discuss the sequent key problems in this field

[en] A vast majority of nonlinear behavior in atmospheric pressure discharges has so far been studied in the space domain, and their time-domain characters are often believed to exact the periodicity of the externally applied voltage. In this paper, based on one-dimensional fluid mode, we study complex nonlinear behavior in the time domain in argon atmospheric dielectric-barrier discharges at very broad frequency range from kilohertz to megahertz. Under certain conditions, the discharge not only can be driven to chaos from time-periodic state through period-doubling bifurcation, but also can return stable periodic motion from chaotic state through an inverse period-doubling bifurcation sequence. Upon changing the parameter the discharge undergoes alternatively chaotic and periodic behavior. Some periodic windows embedded in chaos, as well as the secondary bifurcation occurring in the periodic windows can also be observed. The corresponding discharge characteristics are investigated.

[en] In this paper we analyse the security of a multiple pseudorandom-bit generator based on the coupled map lattice and suggest an improved model. Utilizing the error function attack, the multiple pseudorandom-bit generators which can be realized by the three digitization methods are analysed and the effective key spaces are estimated. We suggest an improved multiple pseudorandom-bit generator with 128-bit secret key, and analyse the key sensitivity and statistical properties of the system. (general)