Design and performance of an epithermal neutron detector based on PFN.

In this paper, an epithermal neutron detector suitable for the Prompt Fission Neutron (PFN) uranium logging method is designed by Monte Carlo simulation. According to the simulation results, the epithermal neutron detector composed of a 1 mm cadmium (Cd) layer, a 5 mm high-density polyethylene (HDPE) layer, and a 3He tube is sensitive to epithermal neutrons. Through the simulation test of Monte Carlo in formations with different uranium content, the results show that the uranium content in the formation has an obvious linear relationship with E/T, and the detection limit can meet the minimum standard for uranium ore detection. It meets the design expectation and provides a basis for the optimal design of an epithermal neutron detector.

System optimization study of hybrid K-edge/XRF densitometer for uranium-plutonium solution measurement.

In this paper, a comprehensive hybrid K-edge/XRF densitometer (HKED) device model is constructed using MCNP simulation. After the modeling process, a systematic simulation study is conducted to analyze the physical parameters and material selection of KED and XRF. The simulation results reveal that the optimal parameters for the X-ray tube are an X-ray source voltage of 160 kV and a 1 mm Fe filter. The sample should be placed in a vial with an inner diameter of 1.4 cm and an outer diameter of 2 cm. For the KED technique, the determined main parameters are a 1.9 cm Fe filter rod and an inner diameter of 0.08 cm for the collimator. For the XRF technique, the determined main parameters are a 0.01 cm Gd filter and an inner diameter of 0.3 cm for the collimator, with a detector angle of 150°. After selecting appropriate parameters, the average calibration factor Δµ of the KED technique was found to be 3.301 cm2 g-1, with a relative standard deviation (RSD) of 3.36%. Additionally, the comparison between the simulated and calculated values of uranium concentration revealed a minimum measurement error of 0.4%. The minimum detection concentration of KED for uranium solutions is approximately 1 g/L. For plutonium solutions ranging from 0.5 to 20 g/L, linear fitting of the Ka1 net peak area and plutonium concentration showed a coefficient of determination (R2) of 0.999. The detection limit of XRF for plutonium measurement was 2.33✕10-4 g/L. The linear fitting coefficients (R2) of uranium concentration versus K-edge transmission rate and plutonium concentration versus Ka1 net peak area for the hybrid technique in measuring uranium-plutonium mixed solutions are determined as 0.999 and 0.996, respectively, demonstrating the response relationship of the HKED device to uranium and plutonium under different concentrations.