The objective of this study is to contribute efforts to identifying the characteristics and operation reason of known or clandestine nuclear facility. To achieve this purpose is by means of chemical analysis of various samples from process line and surrounding environment. It is possible to assume that the information of the qualitative and quantitative nuclear activities can be obtained by chemically verifying the various samples discharged from specific nuclear facility. Therefore, these techniques may be helpful to identify the presence of undecleared facilities, to detect the falsified operating data and to verify the accounting data. Am-241 dating method is available to detect the actions to conceal the diversion strategy by falsifying operation data of plutonium production facility. Low level counting systems have been used as environmental monitoring in the neighborhood of nuclear facilities, and it is important to optimize experimental conditions (to reduce system background and to improve detection efficiency) for more accurate measurement. These optimized conditions may be useful in establishing low background counting system and counting room. (Author).