The 54th Annual Meeting of the Health Physics Society
July 12-16, 2009
Minneapolis, MN

Single Session



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WPM-D - Homeland Security

Room: L100 F/G   2:30 - 5:00 PM

Chair(s): Paul Stansbury , Jim Barnes
 
WPM-D.1   14:30  Using the Inspector1000™ and Falcon5000™ for Demonstrating SNM Safeguards Measurements for the Nuclear Science Merit Badge, Boy Scouts of America Jeff Chapman*

Abstract: The Boy Scouts of America publishes requirements that must be met to achieve a merit badge. Requirements for the Nuclear Science Merit badge are as you might expect: largely based on an understanding of radioactivity, radiation, units, and the use of GM-counters to measure an assortment of naturally radioactive materials and products. What we decided to do recently was to introduce the scouts to the detection of special nuclear material (SNM) and the fundamentals of gamma-ray spectrometry. We used some of the IAEA training principles for safeguards inspectors to demonstrate the use of the spectrometers, showing the scouts how to verify the absence of HEU (high enriched uranium), and the limitations of low-resolution spectrometers compared to germanium spectrometers. This paper will show the results of our work in promoting the nuclear science merit badge in Oak Ridge, and how these new teaching materials will be used in the future.

WPM-D.2   14:45  Cf-252 Characterization for Testing Instrumentation - per Homeland Security Requirements MG Hogue*, Savannah River Nuclear Solutions, LLC ; BM Morgan, Bartlett Nuclear, Inc.

Abstract: The U.S. Department of Homeland Security Domestic Nuclear Detection Office (DNDO) establishes the current American National Standards Institute (ANSI) N42 consensus standards as the initial acceptable performance baseline for radiation detectors. Several of these standards require testing at low levels, typically around 50 µR/h for photon sources. Sources include special nuclear materials, medical radionuclides, naturally occurring radioactive materials (NORM), and industrial radionuclides. While typical characterization methods for calibration and testing are based on measuring current or collecting charge from an ionization chamber, the sensitivity required at low levels leads test developers to consider accurate modeling to guide the testing. This presentation reports on the methods and challenges of Monte Carlo modeling of manufactured, special form sources, including air kerma rate from photons of Am-241, Ba-133, Bi-207, Cd-109, Co-57, Co-60, Cs-137, Sn-113, Th-228, and Y-88, weapons-grade plutonium, 80% enriched uranium, and neutron dose rates from Cf-252. Particular attention is paid to Am-241 and Cf-252. Am-241 primarily emits a photon at low energy, 59.5 keV. This photon is well shielded by the special form encapsulation. This phenomenon is also applicable to the detection of weapons-grade plutonium. Cf-252 modeling is examined particularly for its sensitivity to modeling parameters, such as the neutron spectrum used. This is due to the extreme non-uniformity of dose conversion factors.

WPM-D.3   15:00  Update on the Revision of ANSI/HPS N43.17 Radiation Safety for Personnel Security Screening Systems Using X-ray or Gamma Radiation DF Kassiday*, U.S. Food and Drug Administration

Abstract: The initial version of ANSI/HPS N43.17 was published in 2002. This standard applies to security screening systems in which people are intentionally exposed to ionizing radiation. It provides guidelines specific to the radiation safety aspects of the design, performance, and operation of these systems. A revision was necessary to address new system configurations and operating modes including portals, limited use systems, partial body scanners (for examination of casts etc.), and products that use radioactive material as the radiation source. The following major changes were made with respect to the original standard: 1) The limit on dose to a person screened was changed from a per-scan limit to a per-screening limit. 2) The method of calculating the reference effective dose based on the measured half-value layer was introduced. 3) The user requirements were expanded considerably to cover sufficient administrative and operational controls necessary for limited-use systems. 4) The concept of Ambient Dose Equivalent-Area Product was introduced to deal with partial body scanners. 5) Appropriate equivalent requirements were added for radioisotope-based systems. However, there is consistency of radiation protection between the original standard and the revised standard. All systems complying with the original standard also comply with the present requirements for the general-use category. The final goal of limiting the annual effective dose to members of the public to 0.25 mSv was preserved and applies to all types of systems. A draft of N43.17 revision was submitted to the N43 committee for a vote in October 2008. This presentation will provide an overview of the revisions and expansions of the standard.

WPM-D.4   15:15  Update on the Development of American National Standards Institute N43.16, Radiation Safety for X and Gamma Ray Cargo and Vehicle Security Screening Systems (Up To 10 MeV) C. R. Jones*, U.S. Army Center for Health Promotion and Preventive Medicine ; F. Szrom, U.S. Army Center for Health Promotion and Preventive Medicine; D. F. H. Kassiday, U.S. Food and Drug Administration, Center for Devices and Radiological Health; F. Cerra, National Institute of Standards and Technology (Retired)

Abstract: In late 2003, the American National Standard Institute (ANSI) N43 Committee approved the development of a new standard (ANSI N43.16) dealing with radiation safety aspects for security systems that use ionizing radiation to screen vehicles and cargo containers. The objective of the standard is to provide a consensus standard on radiation safety for such security screening systems (a practice for which there is little specific guidance). The N43.16 standard establishes a system of dose limitation for the system operating crew, bystanders, and inadvertently exposed individuals that is consistent with the recommendations of the National Council on Radiation Protection and Measurements (NCRP). It promulgates specific performance requirements for system design and manufacture, requirements for system installation and initial testing, as well as operational requirements for system users. The standard also provides a general methodology for demonstrating compliance with applicable dose limits and guidance on making radiation measurements around security screening systems. The N43.16 standard is nearly complete and this presentation provides an overview of key elements of the long-anticipated standard.

WPM-D.5   16:00  Establishing an Operational Area Boundary Around Cargo and Vehicle Inspection Systems C. R. Jones*, U.S. Army Center for Health Promotion and Preventive Medicine ; F. Szrom, U.S. Army Center for Health Promotion and Preventive Medicine; D. F. H. Kassiday, U.S. Food and Drug Administration, Center for Devices and Radiological Health; F. Cerra, National Institute of Standards and Technology (Retired)

Abstract: An important radiation protection task associated with cargo and vehicle inspection systems is establishing appropriate boundaries around the system and object being inspected. Outside the boundary, potential radiation doses must be below established dose limits (e.g., the general public limit) and as low as reasonably achievable (ALARA). Several factors complicate this evaluation, including the movement of the radiation source and/or the object being inspected and the variation in security screening sites and duration of operations. Due to the movement of the radiation source and/or object being inspected, the instantaneous dose rate at a given location will vary during a scan, typically on a time scale smaller than the response time of common survey instruments operating in rate mode. Several groups have developed methods, more or less independently, for evaluating the radiation hazards around security screening systems and for establishing appropriate boundaries. This has lead to a variety of methods applicable to specific situations. Although these methods sometimes appear quite different, they are based on the same fundamental principles and differ primarily in the assumptions made. The method described in this presentation is a general approach adapted from the methods used for facility shielding design. It can be adapted to any security screening operation using site and operation specific information. Sample calculations are presented showing how the method is applied and demonstrating its equivalence to alternate methods.

WPM-D.6   16:15  The Challenges of Radiological Scanning of Ship-to-Rail Intermodal PS Stansbury*, Pacific Northwest National Laboratory* ; BA Reichmuth, Pacific Northwest National Laboratory*

Abstract: The U.S Congress has directed U.S. Customs and Border Protection (CBP) to scan 100% of imported cargo for illicit shipments of radiological material and to do so with a minimum impact on the flow of legitimate trade and travel. However, a small percentage of the cargo containers entering the U.S. through a seaport come into the port via ship and leave on a rail car. Such seaports are called intermodal seaports, and typically use straddle carriers (strads) for moving the containers from the ship to the rail. Scanning this cargo presents two interesting challenges. One, the technology being deployed at truck exit gates are effective in scanning containers on chassis but do not address the challenges of a staddle carrier. A strad is wider than a truck and has 10-ft. high massive metal side-panels that would shield a container from detection devices. Two, compared with the linear flow of traffic at a border crossing, the flow of traffic at an intermodal seaport is quite chaotic. Further, driven by economic reasons and schedule pressure, traffic flow within a seaport is usually at the highest possible velocity. Thus there is the challenge of deciding where in the traffic flow to do such scanning in a manner that minimizes impact on the flow of commerce. The SAFE Port Act of 2006 (Pub. L. No. 109-347, to be codified at 6 U.S.C. 921) directed the U.S Department of Homeland Security (DHS) to establish an “Intermodal Rail Radiation Detection Test Center,” hereafter referred to as the Rail Test Center (RTC). DHS’ Domestic Nuclear Detection Office (DNDO) established the RTC at the Port of Tacoma (POT) in September 2007. DNDO is currently using the RTC to test radiological and nuclear threat detection systems associated with the unique environment of intermodal rail scanning while in an operational seaport. Time and motion studies at the intermodal terminals at POT have been conducted on baseline traffic flow and on traffic perturbed by the creation of chokepoints at which radiation scanners could be placed. *Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle under Contract DE-AC05-76RLO 1830.

WPM-D.7   16:30  ITTF/IDOT Radiation Detection Pilot Program William E. Dunn*, PROTECT-US, Inc. ; Thomas E. Korty, Illinois Department of Transportation

Abstract: The Illinois Terrorism Task Force (ITTF) and the Illinois Department of Transportation (IDOT) have undertaken a pilot program of radiation detection technology at a field site near Marshall, Illinois (Marshall Field Site). The ITTF/IDOT effort emphasizes open-road detection (i. e., detection and identification of radioactive materials in vehicles traveling at highway speeds). This presentation describes the results of the pre- and post-deployment testing of the system installed at the Marshall Field Site. Prior to deployment, the proposed radiation detection equipment was tested by staff from the Radiological Assistance Program (RAP Team) at Argonne National Laboratory (ANL). The ANL tests showed that reliable detection and identification of radioactive materials in vehicles moving at speeds up to 40 mph was possible. In May 2007, the radiation detection equipment was installed at the Marshall Field Site. Data collected between May 2007 and November 2008 show that: radioactive materials can be detected and identified at highway speeds under actual field conditions. Many of the detected events can be traced to their origin using knowledge of shipments along the I-70 corridor. A series of tests were conducted at the Marshall Field Site by staff from the Illinois Emergency Agency on 9-Aug-2007. Known radioactive sources were placed in the back of an IEMA Ford Expedition. The vehicle was then driven under the Weaver Road overpass at the posted speed limit of 65 mph and onto the entrance ramp of the weigh station at the posted speed limit of 30 mph. Real-time detection and identification of the sources was performed.

WPM-D.8   16:45  Proposed Design For A Mobile Active Neutron Interrogation System Z. D. Whetstone*, University of Michigan ; T. Zak, University of Michigan; A. L. Lehnert, University of Michigan; K. J. Kearfott, University of Michigan

Abstract: There have been many methods proposed that use a neutron source to search for illicit materials. The active interrogation methods these systems employ generally require neutrons to interact with the materials of interest in a target and then the resulting radiation is subsequently detected. The detector signal is investigated and a determination of whether or not the materials within the target are either illegal or dangerous can be made. Many of these systems employ an isotropic neutron source. However, this allows for any personnel nearby to be exposed to a large flux of neutrons. Furthermore, the neutrons not directed towards the target may interact within the environment and either the original neutrons or their associated secondary radiation may eventually end up in the detectors and contribute undesired information to the detector signal. Both of these problems can be avoided by attaching shadow shields, or “collimators”, to the source and to any detectors in the system. The collimator on the source allows neutrons to emerge less attenuated at a specific solid angle, limiting the neutron flux at other points around the collimator. The detector collimation then insures that only the radiation incident from the direction of the target will be unshielded. By layering low atomic number and high atomic number materials repeatedly, the collimators can be constructed in such a way as to allow for the same shielding efficiency as traditional low atomic number shields, such as water or polyethylene, but in a more compact design. The smaller footprint of an active neutron interrogation system employing the proposed collimation design makes this design a strong candidate for mobile inspections systems. A modular design of the layered collimators has been developed that will allow for relatively easy transportation, construction, and breakdown of the system as well as an ability to adapt the collimation to specific needs based on individual applications.



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