Search

Summary: The three‐dimensional non‐isothermal model of anode‐supported planar solid oxide fuel cell was established. In order to reduce the temperature rise of SOFC in the process of operation and improve the output performance of the stack, this paper studied and compared the operation of SOFC in four different flow modes. The study found that the flow mode has a great influence on the temperature distribution of the SOFC stack. In co‐flow, the temperature increases continuously along the channel length. In the case that oxygen and hydrogen of each cell are in co‐flow, by reversing the flow direction between adjacent cells, the temperature rise of the SOFC stack along the channel direction can be reduced by 26 K, which decreases from 41.2 K to about 15 K. At the same time, the output current density and power density of the SOFC stack are also improved to some extent. [ABSTRACT FROM AUTHOR]

Summary: High‐quality diamond intrinsic layer was epitaxially grown on a IIb‐type boron‐doped diamond substrate. The quality of the epitaxy layer was evaluated by Raman spectroscopy and cross‐polarizer images and compared with other samples. The dark current of the diode was analyzed, revealing a rectification ratio as high as 2 × 109 at ±7 V. Current‐voltage characteristics of the converter under the irradiation of different americium‐241 activity sources were investigated. A maximum total conversion efficiency (ηtotal) of 1.41%, short‐circuit current (Isc) of 6.68 nA/cm2, and open‐circuit voltage (Voc) of 1.06 V from the diamond alpha‐voltaic battery were obtained under the irradiation of an americium‐241 source with a source activity of 8.85 μCi/cm2. The trend for the battery parameters with the increase in the activity of the americium‐241 source was clarified. Parameters Isc and Voc increase with the increase in the radioactive source activity. The ηtotal increases with the increase in the source activity but fluctuates in a certain activity interval with an increase in the fill factor, and then decreases with the increase in radioactive source activity. The research results are significant for the design of nuclear batteries. Highlights: Diamond Schottky alpha‐voltaic battery with high quality intrinsic layer was fabricated;The quality of the intrinsic layer was analyzed by Raman microscopy and cross‐polarizer images, and compared with other samples;The variation of battery parameters with the increase in radiative source activity was explained. [ABSTRACT FROM AUTHOR]

Summary: To improve both safe operation and high resource utilization in nuclear power, we propose and investigate the concept of an accelerator‐driven ceramic fast reactor (ADCFR). This reactor type has the potential to operate continuously throughout a 40‐year core life, without fuel shuffling or supplementation. The ADCFR consists of a high‐power superconducting linear accelerator, a gravity‐driven dense granular spallation‐target, and a ceramic fast reactor. The performance of the ADCFR was assessed by using a neutron‐physics simulation, thermal calculations, and a characteristic analysis. The results show that the peak position for the neutron spectrum in the ADCFR is at about 0.1 MeV. This means that it falls with the fast neutron spectrum, and it can convert loaded nuclear fertile material into fissile fuel. Using a burnup simulation, the ideal effective multiplication‐factor (Keff) was calculated by using a combination of subcritical (accelerator‐driven) and critical modes. In 40 year of operation, Keff is obtained from the initial 0.98 to the peak ~1.02 and then to ~0.99. Different granular coolant materials were selected to compare neutron performance. In breeding, the differences are relatively small. The thermal calculation indicates that heat transfer performance of granular makes it possible to meet the required specifications in theory. Finally, the corresponding characteristics, with regard to the 2‐phase coolant, ceramic materials, nuclear safety performance, operation modes, economics, and range of applications were analyzed. Accelerator‐driven ceramic fast reactors can achieve very high levels of inherent safety, good breeding performance, high power‐generation efficiency, and high flexibility in wide range of applications. [ABSTRACT FROM AUTHOR]