[en] Radioisotopes have been used in a wide variety of industrial applications since the early 1950s. At DSM, a Dutch chemicals and materials group, the first applications were introduced around 1955. These applications mainly concerned on-line density measurements for process-control purposes. Besides process control, the following main applications of radioisotopes can be distinguished: (i) Column scanning: a technique using sealed ⁶⁰Co, ¹³⁷Cs and ²⁵²Cf sources for on-line troubleshooting in distillation columns and other process equipment; this technique allows investigations to be performed at very short notice, saving production time and therefore money. (ii) The radiotracer technique: used as a tool for troubleshooting, for flow measurements, for determining process parameters and for in-line corrosion studies. Short-lived radionuclides typically used in this field are 56Mn, 24Na, 82Br, 113mIn, 81mKr and 99mTc; (iii) Neutron activation analysis based on the k₀-standardization method. The NAA technique, which was originally introduced for trace element analysis in high-purity silica, has evolved into a key analytical technique at DSM Research besides ICP-MS, ICP-AES and other sophisticated in-house methods