Reaktor Serba Guna–Gerrit Augustinus Siwabessy (RSG-GAS) (Multipurpose Reactor–Gerrit Augustinus Siwabessy) is a research reactor located in the Serpong neighborhood of South Tangerang, Banten, Indonesia. The reactor plays an important role in the Centre for Nuclear Industry Development, at Puspiptek, Serpong to serve other supporting laboratories, namely, radioisotope production, nuclear material science, reactor fuel element development, reactor safety, waste treatment, radio-metallurgy and nuclear-mechano laboratories.