Gamma-ray spectrometry is a highly sophisticated process of measuring and evaluating sample activity. The results of this technique are only as good as the procedures applied. In order to obtain signicant data, it is necessary to use a detector properly calibrated according to its application and use the correct reference materials and standards. The Joint Research Project MetroMETAL Ionising Radiation Metrology for the Metallurgical Industry (European Metrology Research Programme EMRP) has the goal to create "reference standards for composite steel, cast steel, slag and fume dust containing a known activity of some radionuclides (60Co, 137Cs, 192Ir, 226Ra and 241Am) considered as potential contaminants" that are "prepared in geometries/matrices that match the industrial environments for which they are designed". Prototypes of those standards are sent to the participating partners for evaluation. Part of the tasks of this project is the comparison of Monte Carlo codes for eciency and activity simulation in order to gain insight into their respective strengths and weaknesses. In that respect it is necessary to design a detector image for the use of Monte Carlo codes in radiation transport. In the course of this work a functioning and validated detector model has been created and tested by comparing simulated peak eciencies to the experimentally found values of the participating laboratories. The results of the intercomparisons are presented in this work. The goal of MetroMETAL is to provide recommendations on future measurement protocols, standards and methods in the metallurgical industry. Another application, where a properly calibrated detector is necessary, is the monitoring of environmental radiation levels. In that respect sediment samples taken at two hydroelectric power plants located on the Danube river are evaluated. Ongoing measurements establish a baseline for present and future reference. This is particularly relevant for assessment of radiation levels after accidents and understanding of environmental transport and distribution of radioactive material.