Sensor deployment is one of the important problems in Wireless Sensor Network (WSN). Deployment affects the coverage of the network especially in critical applications such as in radiation detection. The contributions of this paper are 1) formulating the radiation detection deployment problem in a mathematical form where optimal solutions could be obtained, 2) utilizing one of the famous heuristic algorithms such as Genetic Algorithms (GA) for large scale deployment problems, 3) due to the importance of radiation detection, the paper focus on some of the characteristics of radiation detection problem including the subareas importance and the some of the sensors characteristics such as sensors' sensing and communication, etc. and 3) introducing a GA and Fuzzy logic as a hybrid solution to the problem in order to control the GA crossover and mutation percentages. Although, the concept of the hybrid algorithm is introduced in this paper for sensor deployment, it could be used to solve many other optimization problems. Through a large set of experiments with different problem settings, the efficiency of the proposed algorithms is verified.