WO2008051188A2

WO2008051188A2 - Method and apparatus for detection of radioactive material

Info

Publication number: WO2008051188A2
Application number: PCT/US2006/032326
Authority: WO
Inventors: Jerry Bohinc; Dale F. Shapiro
Original assignee: Quintell Of Ohio, Llc
Priority date: 2005-08-19
Filing date: 2006-08-18
Publication date: 2008-05-02
Also published as: WO2008051188A3

Abstract

A radioactive material detection system includes a radiation scanning system and an inertia test apparatus. The radiation scanning system detects the presence of radioactive material in a cargo receptacle. The inertia test apparatus configured to detect mass and moment or of inertia data or mass and rotational inertia data of a cargo receptacle. The inertia test apparatus provides an indication of the presence of shielding within the cargo receptacle.

Description

TITLE OF THE INVENTION [0001] Method And Apparatus For Detection Of Radioactive Material

BACKGROUND OF THE INVENTION

[0002] Embodiments of the present invention relate generally to a method and apparatus for the detection of radioactive material and, more particularly, to a method and apparatus for detecting the presence of shielded and unshielded radioactive material within a container. [0003] There is a growing concern that terrorists or others may at some time in the near future attempt to import into the United States or some other country radioactive or nuclear material which may then be used for the construction of a nuclear weapon for carrying out terrorist objectives. One way of shipping such radioactive or nuclear material is to hide the material among or within seemingly innocuous cargo. For example, such nuclear material could be placed within a standard, sealed cargo container of the type typically employed for shipping cargo by sea, rail, air or by truck. The nuclear material could be positioned within such a sealed cargo container along with other innocuous goods with the container being positioned, for example, within the hold of a large container ship which may be transporting a thousand or more such containers from one location to another. Typically, existing cargo inspection systems are employed either at the port of debarkation or the port of entry for such container ships. Because of the large number of containers which are typically transported by a single large container ship, it is difficult, if not impossible, using the presently available inspection equipment and personnel to thoroughly check each and every container for the presence of any type of contraband, including radioactive or nuclear material. To beef up the inspection equipment and personnel at ports of entry to facilitate a more thorough or detailed inspection of each container is not practical because of the time involved in inspecting each such container and the unacceptable delays in the transport of the containers, as well as potential huge back ups in the loading and unloading of the container ships. [0004] Technologies have been created to scan containers and other cargo receptacles in order to attempt to detect radioactive material within a cargo container or other cargo receptacle. In a typical scanning system, a container is moved through a device that measures radiation on the bed of a truck or on a rail car at a slow continuous speed (e.g., over about a one minute period) or the scanner is moved over the container. However, a problem with scanning technologies is that they have difficulty detecting material that is shielded by lead or other high Z materials. Thus, there can be many false negatives, i.e., radioactive material that is not detected.

[0005] Various embodiments of the present invention overcome the problems associated with the existing container scanning systems by providing a method and apparatus for the detection of shielding within a cargo container or other receptacle and combining that data with scanned or other radiation detection data in order to more accurately identify radioactive material and/or shielded radioactive material.

BRIEF SUMMARY OF THE INVENTION

[0006] Briefly stated, an embodiment of the present invention comprises a radioactive material detection system that includes a radiation scanning system and an inertia test apparatus. The radiation scanning system detects the presence of radioactive material in a cargo receptacle. The inertia test apparatus configured to detect mass and moment or of inertia data or mass and rotational inertia data of a cargo receptacle. The inertia test apparatus provides an indication of the presence of shielding within the cargo receptacle. [0007] Another embodiment of the present invention comprises a radioactive material detection system that includes a radiation scanning system and a rotational inertia test apparatus. The radiation scanning system detects the presence of radioactive material in a cargo receptacle. The rotational inertia test apparatus is configured to detect and rotational inertia data of the cargo receptacle. The rotational inertia test apparatus provides an indication of the presence of radiation shielding within the cargo receptacle to thereby reduce false negatives of the radiation scanning system.

[0008] Another embodiment of the present invention comprises a radioactive material detection system that includes an active radiography scanner and an inertia test apparatus. The active radiography scanner images a cargo receptacle. An inertia test apparatus is configured to detect mass and inertia data of the cargo receptacle. The inertia test apparatus provides an indication of the presence of shielding within the cargo receptacle. [0009] Another embodiment of the present invention comprises a method of detecting shielding within a cargo receptacle. The method includes acquiring image data of the cargo receptacle using an active radiography scanner. Mass and inertia data of the cargo receptacle are detected using an inertia test apparatus. The inertia test apparatus provides an indication of the potential presence of shielding within the cargo receptacle. The image data of the cargo receptacle is analyzed when the inertia test apparatus provides an indication of the potential presence of shielding within the cargo receptacle.

[0010] Another embodiment of the present invention comprises a method of detecting shielding within a plurality of cargo receptacles. The method includes acquiring image data of each of the plurality of cargo receptacles using an active radiography scanner. Mass and inertia data of each of the plurality of the cargo receptacles is detected using an inertia test apparatus. The inertia test apparatus provides an indication of the potential presence of shielding within a particular cargo receptacle. The image data of a particular cargo receptacle is analyzed when the inertia test apparatus provides an indication of the potential presence of shielding within that particular cargo receptacle.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0011] The following detailed description of preferred embodiments of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

[0012] In the drawings:

[0013] Fig. 1 is a functional block diagram of a radioactive material detection apparatus in accordance with a preferred embodiment of the present invention;

[0014] Fig. 2 is a functional block diagram of an inertia test apparatus in accordance with preferred embodiments of the present invention; and

[0015] Fig. 3 is a schematic functional block diagram of a radioactive material detection system in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Referring to the drawings, wherein the same reference numerals are employed for indicating like elements throughout the several figures, there is shown in Fig. 1 , a schematic representation of a radioactive material detection system 10 for detecting the presence of shielded and unshielded radioactive material within a container 12 in accordance with the present invention.

[0017] Cargo containers, box-like containers, cargo receptacles or other objects to be tested 12 are typically transported by truck 14 or railcar (not shown) before being unloaded by a crane 16 onto a ship 100. The container ship 100 is employed for receiving within its hold and, in some cases upon its deck, a plurality of cargo containers 12 generally of a predetermined size of approximately 10 feet by 10 feet by 40 feet. The containers 12 are preloaded with goods to be shipped from one location to another before being loaded onto the container ship 100. Typically, the containers 12 preloaded with the goods to be shipped are sealed before being placed on the container ship 100. The hold of the container ship 100 is sized for receiving a plurality of such containers 12 in a side by side, end to end relationship with other containers 12 being stacked one on top of another to effectively to take advantage of the available space of the container ship 100 for maximum shipping efficiency. The containers 12 are typically made of steel or some other rigid, high strength material in order to provide adequate support for the overlying containers 12 and to adequately protect the goods being shipped within each container 12 from damage which may occur during shipment and the loading/unloading of the containers 12. A typical large container ship 100 may receive one thousand or more containers 12 for shipping from one location to another. As mentioned above, because of the size of the containers 12 and the number of containers 12 on each container ship 100, it is difficult if not impossible to adequately inspect each and every container 12 for contraband, including radioactive material, at the time the containers 12 are being unloaded from the container ship 100 for further transport.

[0018] Embodiments of the present invention provide a method and system for detecting the presence of radioactive or nuclear material within such containers 12 prior to being placed on a container ship 100 (or some other mode of transport).

[0019] The radioactive material detection system 10 includes a radiation scanning system 20 that either actively or passively detects radiation. An active scanning system uses an excitation source to excite the target, such as photons, neutrons or gamma rays, whereas a passive system relies on the occurring energy within the target. The radiation scanning system 20 may include an active scanner or an x-ray or gamma ray imager 22, a passive or active radiation sensing portal 24 and a cargo container identification reader 26. The radiation scanning system 20 may be a VACIS® Inspection System, commercially available from SAIC, San Diego, California. The amount of radiation detected by the passive or active radiation sensing portal 24 may be an amount of intensity or a cumulative value as sensed over a short period of time. The gamma ray imager 22 provides a radiographic image of the internals of a container 12, like an X-ray image, by emitting gamma ray energy on one side of a container 12 and sensing the gamma ray energy that has not been absorbed on the other side of the container 12 as the container 12 move by the imager 24. In the case of an image, the radiation scan data may require interpretation by an analyst, a technician, a trained operator or the like. The cargo container identification reader 26 may be an optical character recognition (OCR) reader, a bar code reader, a radiofrequency identification (RFID) reader, a transponder reader, a receiver or the like.

[0020] The purpose of the radiation scanning system 20 is to detect contraband radioactive or nuclear material (fissile material). Man-made radioactive materials intended for use in medical or industrial applications which may also be legally shipped in cargo containers could also be detected. Thus, the detection by radiation scanning system 20 of the present system could constitute false detection of apparently clandestine fissile material. One way to minimize the occurrence of such false positive detections is by using a separate detector which is sensitive to neutrons, as part of the radiation scanning system 20. The vast majority of naturally occurring radioactive elements and of man-made radioactive isotopes do not emit neutrons whereas fissile materials do emit neutrons.

[0021] Another way of identifying potential false positive detections by the radiation scanning system 20 is by also detecting gamma-ray spectral characteristics. Each radioactive isotope emits gamma rays having an identifiable characteristic energy spectrum. By detecting the gamma ray spectrum, the specific source material can be easily identified. Detection can be registered as a spectral continuum or more simply in properly chosen discreet energy bins. Detectors and associated electronics that register radiation in specific energy windows are commercially available. For example, potassium 40 with an energy peak of about 1.466 Mega electron volts (MEV) can be readily distinguished from other isotopes and particularly from fissile materials having different energy peaks. The specific target material also has its own spectrum, e.g., plutonium has an energy peak of about 0.4137 MEV and weapons grade uranium has an energy peak of about 0.143 MEV are examples of spectral lines of interest for identification respectively. Other naturally occurring and man-made isotopes can be distinguished in the same spectrum of fissile material. The presence of heavy shielding (e.g., "high Z material") the radiation source and the detector can potentially degrade and smear the characteristic spectral lines and thus lessen the usefulness of spectral identification. However, commercially acceptable, legitimately shipped naturally occurring materials, such as potassium, are likely to be uniformly distributed in the cargo containers and not deliberately shielded. Hence, some of the radiation will still reach the detector unobstructed and will thus provide a means of detecting the associated energy spectrum and identifying signature. Man-made radiation sources also have characteristic radiation signatures and ideally will be declared on the shipping manifest to facilitate the occurrence of false positive detections. Thus the spectral analysis contemplated for the system provides clear identification of target radioactive material, as well as clear identification of non-target naturally occurring radioactive isotopes or industrial material radioactivity. Even smeared energy spectrum are typically smeared to lesser energies and thus present a characteristic downward spectral smear that is useful in detection. [0022] Massive deliberate shielding of the interior of all or part of a container 12 remains a potential concern. For such shielding to be most effective, it should contain both gamma and neutron attenuating components. Gamma attenuating materials must be very dense and of a high atomic number, such as lead or a similar dense material. On the other hand, neutron attenuating materials must be of a low atomic weight but of a large volume. The conflicting shielding requirements between gamma radiation and neutrons are impractical in terms of both the container weight and volume constraints. To meet the weight constraints, the high density shielding required for gamma radiation must be concentrated right around the fissile material. This results in a disproportionately high weight to moment of inertia ratio for the container 12. As a result, massive shielding within a container 12 can be detected by measuring the weight to moment of inertia ratio of the container 12. Any container 12 having an unusually high weight to moment of inertia ratio can be indicative of heavy shielding and can be identified for further analysis.

[0023] In the preferred embodiment of the present invention, the radiation scanning system 20 can include any form of active or passive radiation detection which will be interpreted and/or combined with data from an apparatus for detecting shielding in order to minimize false negatives, i.e., little or no radiation data when in fact there is radioactive material present. [0024] One way to overcome problems with detecting shielded radioactive material, is to look for the presence of the shielding material itself within a container 12 as an indicator of possible presence of radioactive material. An effective way to look for the presence of shielded material is to use the gamma ray imager 22 which generates gamma radiation and passes it through a container 12 in order to make an image of the contents of the container 12. High Z material such as the type used for shielding can be imaged and thus detected by the gamma ray image output from the gamma ray imager 22. The full procedure of imaging and analysis can take on the order of 5 minutes or more to complete, where the majority of the time is taken up by the analysis rather than the image data capture. It is desirable to scan or image all containers 12, but only to actually analyze the image data for those which may have some other indication that there is radioactive material and/or the presence of shielding within the container 12. [0025] Another way to look for the presence of shielding inside a container 12 is to use a moment of inertia measurement of the container 12. The radioactive material detection system 10 also includes an inertia test apparatus 30. When the measured moment of inertia of a container 12 varies by a predetermined deviation amount, the inertia test apparatus 30 may determine that heavy shielding is being used within a particular container 12. To preclude degradation of the sensitivity of the radiation scanning system 20 due to massive shielding, the present invention includes equipment 30 for measuring the mass and at least one but preferably three moments of inertia of each cargo container 12 at the port of embarkation, prior to loading the container 12 onto the container ship. Thus, measurement of a threshold mass/moment of inertia concentration can be considered to be a possible detection of a false negative condition. The inertia test apparatus 30 provides an indication of the presence of shielding within a cargo container 12.

[0026] Alternatively, a rotational inertia test may be performed on each container 12 being shipped by the inertia test apparatus 30. The rotational inertia test comprises simply raising one or more edges of the container 12 and measuring the movement and/or acceleration for a given lifting force. The test may be performed along one or more axes. The density of any shielding material may be determined using a simple algorithm along with the measured test data and the total weight of the container 12. The calculation provides an indication of how concentrated the total weight of the container 12 may be - a concentrated weight may be high density shielding (i.e., "high Z material" or the like). Thus, when the measured rotational inertia varies by a predetermined deviation amount, the radioactive material detection system 10 may determine that heavy shielding is being used within a particular container 12. This technique may be used to test for false negatives from the radiation scanning system 20. The inertial data can provide insight into the presence of shielding for any shipping environment during the loading or unloading process including ships, trains, trucks, cars, airline cargo containers and in almost any other shipping environment or non-shipping environment in which details of the contained material may be obscured from observation or might not otherwise be available. [0027] The inertia test apparatus 30 may take advantage of the loading and unloading device, namely the crane or boom 16. Most containers and cargo receptacles 12 are loaded and unloaded using a crane or boom 16 having chains/cables 18 for lifting the containers and cargo receptacles 12. Sensors 28 are installed in contact with the chains/cables 18 or the lifting plate (not shown) to detect force, strain, motion or the like. For example, the sensors 28 may be strain gauges, accelerometers, piezoelectric-elements, semiconductor gauges, vibration detectors, optical detectors or the like. Since the container or cargo receptacle 12 is generally lifted by three- four chains/cable 18, a differential can be detected to gather the moment of inertia or rotational inertia. The dead-weight of the container or cargo receptacle 12 can also be measured using the same or additional sensors 28. Thus, the inertia data can be collected relatively economically during the same process of loading and/or unloading without delaying transport. Alternatively, as shown in Fig. 2, inertia can be measured when stopping on a drive- over weight scale 80 by lifting a corner of the weight platform. The drive-over platform 80 may include both a weighing system 82 and an inertia test system 84. Likewise, a platform 80 designed solely for measuring inertia using an inertia test system 84 may be utilized in a similar manner. The weighing system 82 may simply be a scale as is known in the art. The inertia test system 84 may include a hydraulic lifting arm(s) (not shown) to apply a known or measurable force to a corner or side of the platform 80 and sensors (not shown in detail) to measure the reaction force of the container 12 and truck 14. The sensors for measuring the reaction force may be accelerometers, gyroscopes, strain-gauges, piezoelectric elements or the like. [0028] Generally, moment of inertia or rotational inertia can provide an indication that there is shielding present within a container 12 in a few seconds rather than a few minutes. Inertia testing of the container 12 also does not require analysis by a trained analyst or technician. [0029] Since the goal of radiographic imaging (gamma ray imaging) and inertia testing is to identify potential shielding of nuclear material, a method of asynchronous analysis may be adopted which allows more "coarse" inertia testing to be used to screen particular containers 12 which might then have a higher level of analysis, such as viewing a radiographic (gamma ray) image. Asynchronous analysis means reading or taking data but not analyzing or decoding data initially but waiting to a later time to determine if analysis of the original data should be undertaken. Thus, asynchronous is a method of budgeting and spreading time to other time periods during the in-transit status of the cargo. By using the inertia test data to screen containers 12 in order to decide which radiographic images should be viewed, the throughput of the port can be maintained, as part of the in-transit procedure of the cargo, at a higher level while still maintaining a consistent level of inspection.

[0030] Another way to screen which radiographic images (gamma ray images) need to be reviewed is to place passive radiation sensors 32 on each of the containers 12 while the containers 12 are queuing (i.e., waiting to be loaded onto a container ship 100). Queuing can include the storage yard where containers 12 are kept prior to loading on a ship 100. For example, a passive radiation sensor 32 like those described in U.S. Patent No. 6,891,470 (Bohinc, Jr.), the contents of which are incorporated by reference herein, may be utilized. [0031] Performance of embodiments of the present invention can be further enhanced by utilizing information from the shipping manifest and from other sources relating to the type of contents, the shipper, the destination, prior history of the cargo, etc., in combination with the radiation scanning systems 20 and related components. One example of the use of such information relates to the shipping manifest of known man-made radioactive sources or a threshold concentration of high density material as discussed above. The combination of data from the present invention along with information from other sources improves the probability of the detection of fissile material and minimizes the probability of false positives or false negatives. Thus, embodiments of the present invention include provisions for merging data from various sources to improve true positive detection and to minimize false positives or false negatives.

[0032] Preferably, the information collected from the radioactive scanning system 20 and the inertia test apparatus 30 is sent then to an information processing system 46. In the present embodiment, the information processing system 46 is a computer which includes suitable software to permit analysis of the information signals received from each of the radioactive scanning systems 20 and the inertia test apparatus 30. Preferably, the information processing system 46 includes a database which stores the information collected from the radioactive scanning system 20 and the inertia test apparatus 30 about each container 12 for correlation and tracking. The received information creates a profile of each container 12 including the inertia data and the radioactive scan data so that anomalies and/or high values for both sets of data can trigger a concern or alert about a particular container 12. The information system 46 permits operators to review and interpret the radioactive scan data and make comments in the record for that container 12. Thus, even if the radioactive scan data is not able to trigger an alert while the ship or other vessel 100 is being loaded, the combined, interpreted data may later be used to intercept the ship or vessel 100 before disembarkation from a source port S (Fig. 3), during transit or before unloading at the destination point D (Fig. 3). For example, if an analyst notes that the inertia test data for a particular container is out of parameters, and the radioactive scan data is within parameters, a particular container 12 may be flagged for other action such as a field inspection, a background investigation more intense active scanning or for passive scanning using a system as disclosed in U.S. Patent No. 6,891,470. [0033] Alternatively, a radioactive material detection system 200 includes a remote command center (Fig. 3), as described in U.S. Patent No. 6,965,314 B2, the contents of which are incorporated by reference herein, receives and stores a database of the information obtained from the radioactive material detection system 10 and/or from the information processing system 46. The received information from the radioactive scanning system 20 and the inertia test apparatus 30 about each container 12 permits analysis of the data in combination with other data to facilitate the identification of anomalies or unusual data which is likely to indicate the presence of radioactive material. Software available within the information processing system 46 analyzes the received information from the radioactive scanning system 20 and the inertia test apparatus 30, for the purpose of determining any such anomalies which could indicate the presence of radioactive or nuclear material.

[0034] It will be appreciated by those of ordinary skill in the art that while a particular preferred embodiment of a system for detecting the presence of radioactive material within a ship board container 12 has been described, the basic concepts of the present invention are applicable in other environments. For example, the same basic techniques and technology may be employed in sensing the presence of radioactive or nuclear material in containers 12 being shipped by other methods such as by rail, air, truck, etc. Further, the same techniques could alternatively be employed for detecting the presence of radioactive or nuclear material in a non- container environment such as non-container, bulk shipments or in shipments of smaller packages like boxes or crates. Thus, it will be appreciated by those of ordinary skill in the art that the basic concept of the invention is to combine inertia data about the container or other object to be tested with radioactive scan data for the purpose of detecting the presence of shielded and/or unshielded radioactive material and thereby minimize false negative tests.

[0035] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

CLAIMS We claim:

1. A radioactive material detection system comprising:

a radiation scanning system that detects the presence of radioactive material in a cargo receptacle; and

a moment of inertia test apparatus configured to detect mass and moment of inertia data of the cargo receptacle, the moment of inertia test apparatus providing an indication of the presence of radiation shielding within the cargo receptacle to thereby reduce false negatives of the radiation scanning system.

2. The radioactive material detection system according to claim 1, wherein the moment of inertia test apparatus is integrated into a drive-on platform.

3. The radioactive material detection system according to claim 2, wherein the drive-on platform also includes a scale for weighing the cargo receptacle.

4. The radioactive material detection system according to claim 1, wherein the radiation scanning system includes at least one of an active scanner and a passive scanner.

5. The radioactive material detection system according to claim 1, wherein the moment of inertia test apparatus is integrated into a lifting device.

6. The radioactive material detection system according to claim 1, wherein a mass to moment of inertia ratio exceeds a predetermined value, a sensitivity of the radiation scanning system is increased.

7. The radioactive material detection system according to claim 1, further comprising:

an information processing system that receives radiation scanning data from the radiation scanning system and inertia data from the moment of inertia test apparatus.

8. A radioactive material detection system comprising: a radiation scanning system that detects the presence of radioactive material in a cargo receptacle; and

a rotational inertia test apparatus configured to detect and rotational inertia data of the cargo receptacle, the rotational inertia test apparatus providing an indication of the presence of radiation shielding within the cargo receptacle to thereby reduce false negatives of the radiation scanning system.

9. The radioactive material detection system according to claim 8, wherein the radiation scanning system includes one of an active scanner and a passive scanner.

10. The radioactive material detection system according to claim 8, wherein the rotational inertia test apparatus is integrated into a lifting device.

11. The radioactive material detection system according to claim 8, wherein a mass to rotational inertia ratio exceeds a predetermined value, a sensitivity of the radiation scanning system is increased.

12. The radioactive material detection system according to claim 8, further comprising:

13. A radioactive material detection system comprising:

an active radiography scanner that images a cargo receptacle; and

an inertia test apparatus configured to detect mass and inertia data of the cargo receptacle, the inertia test apparatus providing an indication of the presence of shielding within the cargo receptacle.

14. A method of detecting shielding within a cargo receptacle, the method comprising:

acquiring image data of the cargo receptacle using an active radiography scanner; detecting mass and inertia data of the cargo receptacle using an inertia test apparatus, the inertia test apparatus providing an indication of the potential presence of shielding within the cargo receptacle; and

analyzing the image data of the cargo receptacle when the inertia test apparatus provides an indication of the potential presence of shielding within the cargo receptacle.

15. The method according to claim 14, wherein the active scanner is a radiography scanner.

16. A method of detecting shielding within a plurality of cargo receptacles, the method comprising:

acquiring image data of each of the plurality of cargo receptacles using an active radiography scanner;

detecting mass and inertia data of each of the plurality of the cargo receptacles using an inertia test apparatus, the inertia test apparatus providing an indication of the potential presence of shielding within a particular cargo receptacle; and

analyzing the image data of a particular cargo receptacle when the inertia test apparatus provides an indication of the potential presence of shielding within that particular cargo receptacle.

17. The method according to claim 16, wherein the active scanner is a radiography scanner.