Underwater vehicle is designed to ensure the security of country sea boundary, providing harsh requirements for its power system design. Conventional power sources, such as battery and Stirling engine, are featured with low power and short lifetime. Micronuclear reactor power source featured with higher power density and longer lifetime would strongly meet the demands of unmanned underwater vehicle power system. In this paper, a 2.4 MWt lithium heat pipe cooled reactor core is designed for micronuclear power source, which can be applied for underwater vehicles. The core features with small volume, high power density, long lifetime, and low noise level. Uranium nitride fuel with 70% enrichment and lithium heat pipes are adopted in the core. The reactivity is controlled by six control drums with B4C neutron absorber. Monte Carlo code MCNP is used for calculating the power distribution, characteristics of reactivity feedback, and core criticality safety. A code MCORE coupling MCNP and ORIGEN is used to analyze the burnup characteristics of the designed core. The results show that the core life is 14 years, and the core parameters satisfy the safety requirements. This work provides reference to the design and application of the micronuclear power source.
Fiber reinforced polymer rebars have advantages of light weight, high tensile strength and excellent corrosion resistance. However, researches showed that [1-2], the low elastic modulus of FRP rebar resulting in a larger deflection than steel reinforced concrete beam in equivalent condition. Therefore, it is crucial to control the deflections in serviceability limit states. Three GFRP reinforced concrete beams were tested with four-point bending, deducing the cracking moment formula of the FRP reinforced beam. Then, Bischoff model is adopted to calculate the deflection, and reaching a good agreement with the experimental results. We recommend Bischoff model to evaluate the immediate deflections.
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