摘要
高温气冷堆是具有第四代反应堆特征的重要堆型,石墨材料作为高温气冷堆中的重要结构材料和慢化剂,其性能对反应堆的设计、运行和维护具有重要意义.针对高温、大载荷条件下石墨摩擦系数测量方法的局限性,该文提出了高温气冷堆用石墨材料摩擦系数测量方法并设计了实验装置,通过模拟高温气冷堆堆芯内的环境参数,确定了石墨摩擦系数测量方法和数据处理方法.实验装置外壳使用不锈钢制造,内部由隔热砖构成腔体并填充保温棉,用石墨加热棒加热,由力传感器采集推进力和拉回力数据,计算摩擦力和摩擦系数.结果表明,该测量方法能够稳定并准确地获得石墨摩擦系数数据,为高温气冷堆相关数值模拟和设计改进提供数据支撑.
Abstract
[Objective]High-temperature gas-cooled reactors(HTGRs),a key component of fourth-generation nuclear reactors,are attracting considerable global interest.Graphite materials,serving as crucial structural materials and moderators in HTGRs,play a substantial role in reactor design,operation,and maintenance.A particular area of focus is the tribological properties of graphite.[Methods]In response to the limitations of existing methods used for measuring the friction coefficient of graphite at high temperatures,pressures,and load conditions,a new method has been proposed in this article.This method relies on a self-designed graphite-based device,which simulates the environmental parameters within the core of an HTGR,thereby allowing the measurement of the coefficient of friction of graphite materials.The graphite material used in this study is BG80,which fulfills the requirements of HTGRs well.Gas atmospheres of the measurement tests comprised helium and nitrogen.The gases were used separately to achieve different atmospheric conditions.The temperature range of the device can be changed from 25℃to 1 300℃,which includes normal and ultrahigh temperatures as well as those reached during accidents in HTGR power plants.The load range of the device is 0～30 kg,which is close to the load experienced by graphite materials in the reactors.The device can be internally heated by a self-designed graphite heater powered by direct current.Further,the temperature of the device can be well controlled using an auxiliary system.The device shell is made of stainless steel,with a cavity constructed from insulating bricks and filled with insulation cotton to maintain the temperature.Graphite rods are used for heating,and force sensors are used to collect data on pushing and pulling forces,which are used to accurately calculate the friction force and coefficient of friction.Data processing involves measuring frictional forces via a sensing device when pushing forces are applied at a fixed rate under a given temperature and atmospheric condition as well as under a given load in the normal direction.To mitigate measurement errors,differences between pushing,pulling,and normal loading forces are used for data analysis.Then,linear regression is employed to determine the coefficient of friction from the measured forces.[Results and Conclusions]The results demonstrate that the measurement method can stably and accurately obtain data on the coefficient of friction of graphite materials.In addition,generally,when the displacement is greater than 5 mm,the coefficient of friction begins to stabilize during subsequent displacement processes.Concurrently,when the temperature is>500℃,the coefficient of friction in helium significantly decreases compared to that below 500℃.The results of this study provide support for the numerical simulations and design improvements of HTGRs.
维普
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