Our company adapted and improved a multifrequency electromagnetic instrument into a Slingram-400 tool. We utilized our Slingram-400 for the National Radioactive Waste Repository in Bátaapáti (Southwestern Hungary). Our instrument is especially designed for detecting water saturated fracture systems in the subsurface. We carried out a four-month long measurement campaign during winter and spring. We were looking for fractures and fracture system for a possible site for the expanding NRWR. It was the first extensive campaign for our instrument which proved to be a very powerful too, even in very extreme cold weather. Our results gave a solid support for the experts of the NRWR and proved the suitability of our instrument for such purposes.