Design and tests for the HTR-10 control rod system

The 10 MW High Temperature Gas-cooled Reactor-Test Module (HTR-10) was brought to criticality in December of 2000. The control rod system discussed in this paper is a part of the HTR-10 to control the reactivity of the core. The stepping motor as the motive power source contributes to simplify the control rod drive mechanism. The sprocket wheel device, an actuator of the control rod, is more suitable for the HTR-10 than other possible designs. A magnetic damper is used to limit the emergency insertion speed of the control rod. Significantly useful information is derived from solution to the lubrication problem under the conditions of high temperature, high radiation, and the inert helium atmosphere. This paper also covers the philosophy behind the design and descriptions of the control rod system and the performance tests.