Present knowledge does not allow for constructing a completely safe industrial facility. Therefore an accident can occur in any facility, including a nuclear power plant. Due to a large quantity of radioactive material present, accidents in nuclear power plants can have significant effects, not only within the facility itself but also in its immediate and distant environment. The master’s thesis develops a method for quantitative human health risk assessment related to nuclear accidents. The new method is called PRONEL. The method is intended for risk assessment of power plants that are located between 40 and 1.300 km away from the selected exposure site. Since these distances are relatively long, only nuclear accidents which included release of the largest quantities of radioactive material have been taken into account. This includes core melt accidents followed by early major containment failure or containment bypass. PRONEL method was applied in assessment of individual risks of nuclear accidents for citizens of Zagreb, Osijek, Rijeka and Split, as well as assessment of collective risk for entire population of the Republic of Croatia. The assessment included 90 power reactors located up to 1.000 km away, and the task was to assess the risks represented by individual power plants, types of power plants and groups of power plants formed on the basis of their distance from selected location. The results have shown that out of four analyzed population centers Osijek is the one with the highest risk. Risks for citizens of Zagreb amount to half of that, while citizens of Rijeka and Split are exposed to four times lower risk than the citizens of Osijek. The greatest contributors to individual and collective risk are power reactors of “eastern” origin, of types VVER-440 V230 and VVER-440 V213. Three nuclear power plants have been identified as generating a risk much higher than the rest. These are Paks NPP in Hungary, Bohunice NPP in Slovak Republic and Kozloduy NPP in Bulgaria. If one would divide the NPPs according to their distance from the exposure site into five groups (<50 km, 50-250 km, 250-500 km, 500-750 km and >750 km), the highest risk for citizens of Zagreb and Rijeka would come from power plants located at distance of 250500 km. For citizens of Osijek, the highest risk would be generated by power plants 50250 km away, and for citizens of Split those power plants that are located at distance of 500-750 km.