Nuclear Techniques ›› 2016, Vol. 39 ›› Issue (9): 90403-090403.doi: 10.11889/j.0253-3219.2016.hjs.39.090403

• NUCLEAR ELECTRONICS AND INSTRUMENTATION • Previous Articles     Next Articles

Design and implementation of radioactivity identifying pedestrian portal

HU Yingrui1, LI Xiaoqiang2   

  1. 1. College of Electrical & Information Engineering, Southwest University for Nationalities, Chengdu 610041, China;
    2. The Second Research Institute of Chemical Defense, Beijing 102205, China
  • Received:2016-04-29 Revised:2016-06-10 Online:2016-09-10 Published:2016-09-09
  • Supported by:

    Supported by Fundamental Research Funds for the Central Universities,Southwest University for Nationalities(No.2015NZYQN11)

Abstract:

Background: The SPIR-IDENT(Site Protection Against Intrusion of Radioactive Material)advance spectroscopic pedestrian portal released by MGP company in recent years could detect and identify actual radiological threats in real time,but no similar domestic product with independent property rights exists in China at present.Purpose: This study aims to develop a radioactivity identifying pedestrian portal with independent property rights to enhance the ability of protection against radiological threats,such as intrusion of special nuclear materials or radiological dispersion devices into critical infrastructure.Methods: A 2-L NaI detector is employed to connect with a large scale Field Programmable Gate Array(FPGA)based digital processing system.Digital trapezoidal filter,spectroscopy processing block including spectroscopy composition,smoothing and peak-seeking were implemented in a single FPGA,and a μC/OS-II soft-core was imported to perform digital spectroscopy stabilization,nuclide identification and classification in this FPGA.The spectra processing method was optimized by using hardware multiplier and hardware divider to improve the algorithm speed to satisfy the system requirement.Results: Experimental test shows that the radioactivity identifying pedestrian portal can detect and discriminate radioactive at the distance of less than 1m from the center point of detector within 1 s.The energy resolution is 7.44% @662 keV and the minimum detectable activity is 41.9 kBq.Conclusion: With the large scale embedded FPGA technology and the nuclear pulse digitized processing and shaping technology,a bulk volume NaI detector can be used to implement an effective radioactivity identifying pedestrian portal.

Key words: NaI detector, Embedded FPGA, Isotope identification, Minimum detectable activity

CLC Number: 

  • TL817