In Vietnam, nuclear physics is a fundamental part of the national curriculum for physics. However, due to a lack of experimental apparatus (detectors, radioactive sources, etc) at most of the schools, the majority of students do not have opportunities to experience the phenomena behind the concepts. Moreover, safety is another major concern when conducting experiments on radioactive materials. We have developed a system of remote-controlled detector which allows students and teachers to conduct radioactive experiments safely. The system is assembled from many accessible components with reasonable prices such as Geiger-Müller counter, Arduino board, distance sensor, Wi-Fi transceiver receiver model board and stepper motor, etc. These components are widely available in the market.