Abstract. Uranium silicides are envisaged as potential nuclear materials for the next generation. U 3 Si is featured by the high actinide density and the better thermal conductivity relative to UO 2 . To properly and safely utilize nuclear materials, it is crucial to understand their chemical and physical properties. First-principles in theory is mostly used to analyze the point defect structures for uranium silicides nuclear fuels. The lattice parameters of U 3 Si and USi 2 are calculated and the stability of different types of point defects are predicted by their formation energies. The results show that silicon vacancies are more prone to be produced than uranium vacancies in β-USi 2 matrix. The most favorable sites of fission products are determined in this work as well. According to the current data, rare earth elements cerium and neodymium are found to be more stable than alkaline earth metals strontium and barium in a given nuclear matrix. It is also determined that in USi 2 crystal lattice fission products tend to be stabilized in uranium substitution sites, while they are likely to form precipitates from the U 3 Si matrix. It is expected that this work may provide new insight into the mechanism for structural evolutions of silicide nuclear materials in a reactor as well as to provide valuable clues for fuel designers.

An implementation method of a power supply on-chip (PSOC) was presented for low power digital integrated circuit (IC) applications in this paper. The PSOC consists of a main power supply and a backup low power dissipation power supply, which is featured of micro-standby power consumption and fast switching. The PSOC was designed according to the design rules of SMIC 0.18μm CMOS process and validated both through simulation and silicon verification. The active area is about 0.035mm2 in fact. Post-layout simulation results indicate that output voltage of the PSOC is regulable in the range of 1.52~2.5V as input voltage is in the range of 2.0~3.6V, in which output of the main power supply is regulable in the range of 1.75~ 1.84V. The maximum quiescent current of main power supply is 16.23μA, while the maximum quiescent current of standby power is only 0.552μA. Experimental results indicate that the PSOC is capable of providing energy for the system digital IC implementation. Its power switching time is less than 148μs at the load capacitance of CL =56nF.