Year
2007
Abstract
As the International Atomic Energy Agency’s Additional Protocol is adopted, an effective screening tool for measuring the fissile content of environmental samples is required. The advantages of neutron activation analysis (NAA) coupled with delayed neutron counting [delayed neutron activation analysis (DNAA)] facilitate analysis of environmental samples, regardless of matrices for nuclear nonproliferation purposes. The technique enhances screening by providing a rapid quantitative method for determining fissile content. Detection and quantification of traces of fissile material is accurate and preparation of samples is simple, because various types of complex matrices such as soil, vegetation, plastic, rock, cloth, and water are analyzed equally well nondestructively [1]. Using DNAA as a screening tool is especially made more evident in the analysis of hot cell swipes due to its efficiency in in both low cost and rapid analysis turnaround time. Fissile materials such as 239Pu and 235U can be made to undergo fission in intense neutron fields. Some of the fission products emit neutrons referred to as \"delayed neutrons\" because they are emitted after a brief decay period following irradiation. Counting those delayed neutrons provides a simple method for determining the total fissile content in the sample [2]. The collaboration between the United States Department of Energy and the Ministry of Science and Technology of the Republic of Korea to strengthen environmental sampling analysis in ROK had been implemented under the PCG (Permanent Coordinating Group) safeguards arrangement. The DNAA technique is one of the collaboration work scopes and the Oak Ridge National Laboratory and the Korea Institute of Nuclear Nonproliferation and Control (KINAC) are working together to advance the technique. Recently, DNAA installation was completed at the High-flux Advanced Neutron Application Reactor (HANARO), which is managed by, Korea Atomic Energy Research Institute (KAERI). The system evaluation tests were performed using standard uranium materials provided by ORNL. This paper introduces the DNAA system configuration and the test-run results achieved through the cooperation.