Design of the Coal PGNAA Device by MOCA Program

Prompt gamma neutron activation analysis (PGNAA) is a method for quantitative analysis of multiple elements, which is applied in the analysis of coal, concrete, and solid mine. For the purpose of coal PGNAA study, experiment in lab is necessary. But, restricted by the situation of lab, infinite coal material is impracticable. So, designing a coal PGNAA experimental device to stand of the process of PGNAA of bulk coal and achieve the goal of radiation protection is very practical. Monte Carlo is a kind of mature method, by which can simulate the transportation of neutrons and the process of the interaction of particles and material, and calculate the complicate-constructed nuclear incidents. So, using the Monte Carlo method to design experiment of nuclear reactor is common. This research used a special Mont Carlo program-MOCA to design a coal PGNAA experimental device to reach the aim of promoting the PGNAA technique. Firstly, the field distribution of ²⁵²Cf neutron source which was used in PGNAA common was constructed with MOCA. Then, by simulating the neutron field formed by ²⁵²Cf neutron sources in bulk of coal and polyethylene, the relationship curves of neutron flux and its distance from the source were obtained. Based on the principles of infinite coal material and radiation protection, according to the curves obtained in the previous work, an experimental coal PGNAA device was designed. Finally, the PGNAA experiments of seven different components of coal material were carried out with the device. The spectrums from lab experiment showed element characteristic peaks obviously and quantitative analysis results with good linear. The successful experiment proved that the device was designed reasonably, and MOCA program was an effective method in the study process of coal PGNAA and could be used more in the further.