Key factors affecting the thermal performance of annular fuel elements in LFR

Abstract

BackgroundThe key factors affecting the thermal performance of the lead-cooled fast reactor (LFR) annular fuel are very important to improve the core power density of LFR.PurposeThis study aims to analyze those key factors and provide guidance for improving reactor core power density.MethodsFirstly, one quarter thermal analysis model of typical annular fuel element of lead cooled fast reactor was established, followed by the thermal resistance analysis of typical LFR annular fuel element to evaluate the key factors affecting its thermal performance. Secondly, four indicators, i.e., the temperature difference between the coolant outlet inside and outside the channel, the maximum temperature of annular fuel pellet, the position of adiabatic surface and the temperature difference between the inner and outer cladding, were used as evaluation criteria to analyze the influence of various factors on the thermal performance of the annular fuel element.ResultsThe thermal resistance analysis results show that the key factors affecting the thermal performance of LFR annular fuel element are gas gap width, cladding thickness and flow distribution ratio. Evaluation and analysis results indicate that temperature difference of coolant and the maximum temperature of annular fuel pellet can be significantly reduced by increasing the flow distribution ratio whilst slightly increasing the width of the outer gas gap and reducing the width of the inner gas gap can reduce the coolant outlet temperature difference and the average temperature difference between the inner and outer cladding. Changing the cladding thickness has no significant effect on the thermal performance of annular fuel element.ConclusionsStudying the key factors that affect the thermal performance of the LFR annular fuel has importance value for optimal design of the LFR core.

Keywords

• lfr
• annular fuel
• thermal performance
• key influencing factors