Year
2009
Abstract
Currently the potential to use nuclear or radioactive materials as a weapon has became a matter of internationally grave concern. Various measures have been taken to combat such threats. In this regard, the detection of illicit trafficking and transport of nuclear and radioactive materials is an essential component for the overall strategy of preventing and detecting such threats. Fixed radiation portal monitors (RPMs) have been deployed at border, seaport, airport and key traffic checkpoints as a preventive measure. However, the RPMs usually are large and heavy and can not easily be moved to different locations. A terrorist using nuclear or radiological weapons could circumvent the RPMs because it is fixed. On the other hand, secret screening at a roadside can be more effective for inspecting any suspected container or vehicle. Due to these reasons, a detection system easy to move from place to place and complementary to the RPMs – a mobile radiation detection system - is required. We have developed a mobile radiation detection system consisting of some radiation detectors (two He-3 gas detectors for neutron detection, two plastic scintillation detectors and one NaI for gamma ray detection), a data acquisition system, a GPS(Global Positioning System), a mobile unit(SUV) and an operation software. Field tests using various radioactive sources (Ba-133, Cs-137, Co-60, Cf- 252) were conducted to analyze the performance of the developed mobile radiation detection system. The test results showed that 50 µCi Ba-133, 50 µCi Cs-137, 20 µCi Co-60, and 4.4 µCi Cf-252 could be detected at speeds of up to 30 km/hr in traffic lane 1, 30 km/hr in traffic lane 2, 60 km/hr in traffic lane 3, and 60 km/hr in traffic lane 2, respectively. The mobile radiation detection system developed will contribute to defending public health and safety and the environment by detecting vehicles smuggling illegally nuclear or radioactive material.