Integrated Primary and Special Nuclear Material Alarm Resolution

Abstract

The present specification discloses methods for inspecting an object. The method includes scanning an object in a two-step process. In the primary scan, a truck or cargo container (container) is completely scanned with a fan beam radiation, the transmitted radiation is measured with an array of detectors, and the transmission information and optionally the fission signatures are analyzed to determine the presence of high-density, high-Z and fissionable materials. If the container alarms in one or more areas, the areas are subjected to a secondary scan. This is done by precisely repositioning the container to the location of the suspect areas, adjusting the scanning system to focus on the suspect areas, performing a stationary irradiation of the areas, and analyzing the measured feature signatures to clear or confirm the presence of SNM.

1 . An inspection system for inspecting an object using radiation comprising:
 an X-ray source for generating and transmitting X-ray radiation;   a collimator positioned in front of said X-ray radiation source wherein said collimator comprises two vertical structures defining a vertical slit through which said transmitted X-ray radiation is directed and a plurality of horizontally movable members positioned in front of said vertical slit, wherein said plurality of horizontally movable members each have a first configuration where they block more of the transmitted radiation from passing through the vertical slit and a second configuration where they block less of the transmitted radiation from passing through the vertical slit;   a detector array for detecting a portion of transmitted radiation passing through said object; and   a controller, wherein said controller is programmed to cause at least a portion of said horizontally movable members to move depending upon a mode of operation.   
     
     
         2 . The inspection system of  claim 1  wherein said mode of operation is a first stage scanning mode and wherein, in response to the first stage scanning mode, the controller causes each of said plurality of horizontal members to be positioned to block an equivalent portion of said vertical slit. 
     
     
         3 . The inspection system of  claim 1  further comprising a processor, wherein said processor is adapted to analyze said detected radiation to determine a presence of high-density or high atomic number materials. 
     
     
         4 . The inspection system of  claim 3 , wherein said processor is adapted to determine whether to conduct a second scan based upon said determination of a presence of high-density or high atomic number materials. 
     
     
         5 . The inspection system of  claim 3 , wherein said processor is adapted to determine a location of a suspect area containing a presence of high-density or high atomic number materials. 
     
     
         6 . The inspection system of  claim 5 , wherein said controller is adapted to reposition said X-ray radiation source based upon the location of the suspect area, rotate the X-ray radiation source so that a center axis of the X-ray radiation source is aligned with a center axis of the suspect area, or cause an area external to, but proximate to, said suspect area to be scanned to generate a background signal and wherein said processor subtracts said background signal from a signal generated by scanning the suspect area. 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . The inspection system of  claim 3  further comprising a second stage scanning system comprising:
 a second X-ray source for generating and transmitting X-ray radiation; 
 a second collimator positioned in front of said X-ray radiation source wherein said second collimator comprises two vertical structures defining a vertical slit through which said transmitted X-ray radiation is directed and a plurality of horizontally movable members positioned in front of said vertical slit, wherein said plurality of horizontally movable members each have a first configuration where they block more of the transmitted radiation from passing through the vertical slit and a second configuration where they block less of the transmitted radiation from passing through the vertical slit; and 
 a second detector array for detecting a portion of transmitted radiation passing through said object. 
 
     
     
         10 . The inspection system of  claim 9 , wherein said processor is adapted to determine a location of a suspect area containing a presence of high-density or high atomic number materials and wherein said controller is adapted to reposition said second X-ray radiation source or a portion of the plurality of horizontally moveable members of the second collimator based upon the location of the suspect area. 
     
     
         11 . (canceled) 
     
     
         12 . A method for inspecting an object using an inspection system comprising the steps of:
 conducting a first scan wherein said first scan causes a fan beam of radiation to be transmitted through the object, detecting transmitted radiation using at least one detector array, an conducting, via a processing system, a first analysis of transmitted radiation data to determine a presence of high-density and high atomic number materials;   determining whether to conduct a second scan based upon said first analysis;   repositioning at least a portion of the inspection system relative to a detected location of at least one suspect area;   performing a stationary irradiation of said at least one suspect area;   measuring radiation signatures; and   analyzing the measured radiation signatures to clear or confirm the presence of high-density and high atomic number materials in the at least one suspect area.   
     
     
         13 . The method of  claim 12 , wherein the scanning radiation comprises a single energy or multi-energy x-ray source having an energy of approximately 9 MV. 
     
     
         14 . The method of  claim 13 , wherein the x-ray source is a neutron source and is coupled with a neutron production target such as deuterium or beryllium to produce a mixed x-ray and neutron beam. 
     
     
         15 . (canceled) 
     
     
         16 . The method of  claim 12 , wherein the at least one detector array for detecting transmitted radiation is spectroscopic and the determination of the high-Z material is based on the spectral analysis. 
     
     
         17 . The method of  claim 12  wherein the processing system analyzes fission signatures to determine a presence of fissionable materials. 
     
     
         18 . The method of  claim 12 , wherein the delayed gamma rays are measured with at least one of a plastic or a liquid scintillator. 
     
     
         19 . The method of  claim 12 , wherein the prompt neutrons are measured with a threshold-activation detector such as a fluorocarbon-based detector. 
     
     
         20 . The method of  claim 12 , wherein the delayed neutrons are measured with neutron detectors. 
     
     
         21 . The method of  claim 12 , wherein said step of repositioning at least a portion of the inspection system relative to a detected location of suspect areas includes collimating the fan beam vertically, using at least one horizontally moveable section, to transmit the radiation directed towards the area of interest. 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . The method of  claim 12 , wherein an area close to the at least one suspect area is scanned and the background is subtracted from the signal obtained from scanning the area of interest. 
     
     
         25 . A method for inspecting an object using radiation comprising:
 generating and transmitting radiation produced by a source;   collimating said radiation, using a vertical collimator, to produce a fan-beam of radiation;   detecting a portion of transmitted radiation passing through said object, using a first detector array;   detecting fission signatures using a second detector array;   moving the object relative to the detection system, using a conveyor mechanism;   analyzing scan data and issuing a high-Z alarm where a high-Z material is present, using a processor;   repositioning at least a portion of the inspection system relative to a detected location of at least one suspect area;   performing a secondary stationary irradiation of said at least one suspect area;   measuring fission signatures; and   analyzing the measured fission signatures to clear or confirm the presence of high-Z materials, using a processor.   
     
     
         26 . The method of  claim 25  wherein said vertical collimator comprises horizontal members to block at least a portion of the fan beam not directed to the alarming object during a secondary scan.