[en] The physical design of the 270 degree C double achromatic bending magnet system is introduced for 14 MeV medical electron standing wave linac. The optical path design of the system is calculated by the code TRANSPORT. Meanwhile, the double achromatism conditions are derived from the transport theory, as a result they agree very well. From magnetic field of the magnet calculated by the POISSON program, the magnetic field strength of the magnet center and the field distribution of the good field region both satisfy the design request. The influence of fabrication error and misalignment of magnet on beam envelope is also considered here

[en] One of the most important controlled parameters of thermal power units is the boiler drum water level. Disturbances of feed water flow rate could cause instability of the drum water level. This study proposes the Gray correlation compensation (GCC) control technology for the Boiler feed water pump turbine (BFPT) to solve this problem. Simulation results indicate that the GCC controller outperforms the traditional proportional-integral-derivative controller when it encounters different disturbances. Furthermore, the GCC controller can rapidly switch to the high-pressure steam source to ensure that the drum water level is in the secure range during steam source switching of the BFPT

[en] Metallographic and hydrogen content analysis and autoclave corrosion test for irradiated Zircaloy-4 sample of different heat-treatment show that Zircaloy-4 specimens with water-quench at 1030℃ possesses the best corrosion resistance in the neutron fluence of (4∼7) × 10²¹ n/cm², it is accordant with the same rule of non-irradiated specimens with the same heat-treatment. No difference of corrosion weight gain is found on three kinds of specimens with difference heat-treatment effect. The hydride disperse uniformly in three kinds of specimens matrix. There is no obvious distinction of hydrogen content in samples through different heat-treatment. (authors)

[en] In order to expand the nuclear power in energy and desalination, increase competitiveness in global nuclear power market, many developed countries with strong nuclear energy technology have realized the importance of Small Modular Reactor (SMR) and initiated heavy R and D programs in SMR. The Advanced Small Pressurized Water Reactor (ASPWR) is characterized by great advantages in safety and economy and can be used in remote power grid and replace mid/small size fossil plant economically. This paper reviews the history and current status of SMR and ASPWR, and also discusses the design concept, safety features and other advantages of ASPWR. The purpose of this paper is to provide an overall review of ASPWR technology in western countries, and to promote the R and D in ASPWR in China. (authors)

[en] Beam tests (on table) of 14 MeV medical electron standing wave LINAC (linear accelerator) prototype have been fulfilled satisfactorily. The 270 degree bending magnet system is a key component of this machine which is designed by using TRANSPOR-EM/PC code and POISSON code. 270 degree bending magnet prototype combined with 14 MeV electron standing wave linear acceleration tube is under beam test. Experimental results show that electron beams in an energy range of 6∼14 MeV and different initial emittances are exposed to achromatic and focus action. When transported into target position beam current intensity is 3.5 mA at 15.1 MeV. Beam fleck diameter is about 2 mm. These above results demonstrate that performances of bending magnet system satisfy radiotherapy condition requirements of 14 MeV medical LINAC

[en] There was a great deal of fission product generated in U0₂ fuel during irradiation and the accumulation of fission product during irradiation induced swelling of U0₂ fuel, which has seriously influence on the operational characteristics of fuel elements.. Micro zone composition analysis for fission product of U0₂ fuel has been received much global attention. In this paper, research statuses of micro zone composition analysis results for fission product in U0₂ fuel were investigated. The radial distribution of fission product in U0₂ pellet and research methods were described to supply technique supporting for the researches of subsequent related field. (authors)

[en] The effects of nuclide types, emissivity orders, and active area changes on the emissivity response of the surface contamination meter were studied. The results show that all the measurement results cannot be calibrated directly using the calibration factors given on the verification certificate before making the corresponding calibration coefficient table. Determine the boundary of the polluted area through patrol survey and accurate measurement, and calculate the area of the polluted area. By comparing the relationship between the area of the polluted area and the detector window and the uniformity of the polluted area, it is determined to use a single measurement or multiple multi-point measurements, and select the corresponding formula to calculate the surface emissivity or surface activity of the polluted area. (authors)

[en] Objective: This study was performed to determine the feasibility of liver tumor motion prediction based on back propagation(BP) neural network. Methods: A liver cancer patient was scanned using X-ray volume imaging, and all breath motion figures were recorded.The tumor was located using an iodized oil mark.The mark motion track was gathered through image processing. A BP model was established based on the marked track. This model was used for tumor prediction. The results were compared with the true mark track. Results: Accurate prediction of liver tumor was achieved via BP neural network, with a deviation of less than 1 pixel. However, the predicted value was less accurate at the peak of the breath motion curve, with a deviation of less than 2 pixels. Conclusions: BP neural network is proposed as a new approach for liver tumor motion prediction. This network is beneficial to enhance the accuracy of liver stereotactic body radiation therapy and real-time adaptive radiation therapy. The proposed approach could be applied clinically. (authors)

[en] Micro-milling is widely used as a method for machining of micro-parts with high precision and efficiency. Taking the nickel-based single-crystal superalloy DD98 as the research object, the crystal characteristics of single-crystal materials were analysed, and the removal mechanism of single-crystal micro-milled parts was described. Based on molecular dynamics, a simulation model for nickel-based single-crystal superalloy DD98 micro-milling was established. Based on the response surface method of central composite design, the influences of spindle speed, feed rate, and milling depth on the surface roughness were examined, and a second-order regression model of the DD98 surface roughness was established. Using analysis of variance and the residuals of the model, a significant influence on surface roughness was found in the following order from large to small: Feed rate, spindle speed, and milling depth. Comparisons were conducted between the micro-milling experimental values and the predicted model values for different process parameters. The results show that the model fit is relatively high, and the adaptability is good. Scanning electron microscopy analysis of the micro-milling surfaces was performed to verify the slip and the removal mechanism of single-crystal materials. These results offer a theoretical reference and experimental basis for micro-milling of single-crystal materials

[en] In a coupled laser system, the dynamics of the receiving laser is investigated when two separate transmitting lasers are injected into the receiving laser with different coupling strengths. It is shown that the phenomenon of preference of chaotic synchronization appears under appropriate coupling conditions. The receiving laser will entrain the pulses of either one or both transmitting lasers when the coupling is strong while it keeps its own dynamics when the coupling is weak.