Radiation-Sensor-Equipped Radio Frequency Identification System

To modernize the management of sensitive nuclear materials, Argonne National Laboratory has developed the ARG-US radio frequency identification (RFID) system for the Packaging Certification Program of the U.S. Department of Energy (DOE), Office of Packaging and Transportation. The system consists of battery-powered RFID tags, a reader network, an application software suite, secured database servers, and storage and transport web applications. The current-generation RFID tags have built-in sensors for seal integrity, temperature, humidity, shock, and battery strength to monitor the state of health of the tagged containers during storage and transportation. Several ARG-US RFID systems, which provide real-time tracking and monitoring capability, have been deployed at selected DOE sites for field testing and application during storage and transportation. To further enhance the system’s capability, a radiation sensor module has been added to the ARG-US RFID tag. The potential benefits of the added radiation sensor module for nuclear materials management can be significant: improved situational awareness; enhanced safety, security, and safeguards; and – just as important – reduced radiation exposure for facility personnel. The incorporated sensor module is a modified, compact, personal dosimeter with a wide detection range for gamma radiation: from ≈10 μR/h to 800 R/hr. A multifunctional carrier board has been designed to process data, initiate alarms, manage power, interface tags, and add future sensors. Benchmark testing with a calibrated Cs-137 source has shown that the integrated tags with dosimeters are functioning as designed. The ARG-US software suite has been modified to process and display the dose rate and cumulative dose, as well as an instant alert/alarm when the detected radiation level exceeds the preset threshold. The cumulative dose can be reset to account for multiple segments of storage and transportation campaigns. The added functionalities of area radiation monitoring, process configuration control and supplemental tamper indication with the dosimeter-enabled tags make the ARG-US RFID system even more potent and versatile for nuclear materials management. INTRODUCTION The ARG-US RFID system consists of battery-powered RFID tags, a reader network, an application software suite, secured database servers, and storage and transport web applications. The current ARG-US RFID tag (MK-II) incorporates five sensors for temperature, humidity, shock, seal integrity, and battery strength. When the system is deployed in the field, the sensor data in the tags are collected autonomously at regular intervals by the Proceedings of 52nd INMM Meeting, Palm Desert, CA, July 17–22, 2011. Work supported by the U.S. Department of Energy, Assistant Secretary, under contract DE-AC02-06CH11357. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. readers and stored in the control computer and the secured database servers. The polling interval can be adjusted depending on applications – from once every few minutes in transport to once every few hours, or longer, in secured storage. Threshold set points can be selected for each sensor, and the tag will issue an alert/alarm instantaneously whenever any sensor threshold is violated. The tag communicates with the reader via a 433-MHz radio wave, with an effective range of >100 m, and no line-of-sight is required. The MK-II tags have a nearly universal form factor that can be easily modified for attachment to different types of drums, as shown in Figure 1. The front of the tag is a plastic chassis that facilitates radio frequency transmission; the back of the tag is a strong metal enclosure with a flange for drum attachment. The piezoresistive seal integrity sensor is concealed and protected under the attachment flange bolt(s) in these applications. Figure 1. MK-II tags mounted on several certified Type-B packagings (from left to right: Models 9975, 9977/9978, ES-3100, and DOT 7A). Figure 2 shows a sample graphical user interface (GUI) screen of the system, called ARG-US OnSite, for monitoring stacked drums in a storage facility. Each symbol represents a drum, with the color indicating the status: green (normal), yellow (warning), and red (alert/alarm). Clicking on a symbol causes the serial and model number of the selected drum to be displayed in the window pane on the right, along with the sensor status and values. (Other drums in the stack can be selected from this pane and the display will change accordingly.) The bottom Figure 2. Sample GUI of ARG-US OnSite for a small storage installation. Note that the drums can be stacked as shown in the right window pane. panes show the current status of drums in storage, historical events, and search functions that can be customized per facility requirements. From submenus of the main GUI (not shown in Figure 2), other pertinent information (e.g., a contents manifest, processing steps, alarm thresholds, auto-collect intervals), as well as detailed sensor history logs, data export, etc. can be entered, viewed, and executed by the user. With regard to developing the ARG-US RFID system for nuclear materials management, the addition of a radiation sensor to the tag has long been considered an important enhancement or milestone. A radiation sensor, in conjunction with other sensors in the tag, can greatly enhance the overall situational awareness in a facility that has a large number of packages. Readings from radiation-sensor-enabled tags can be used to construct a 2-dimensional or even a 3-dimensional map of the radiation dose field in the facility on a real-time basis. Any significant perturbation of the field would generate an instant alert/alarm to supplement the existing facility measures for safety, safeguards, and security. As a result of having this realtime information on the radiation field in the facility, the need for manned surveillance with handheld devices is greatly reduced, and the universally endorsed principle of protection against radiation (as low as reasonably achievable [ALARA]) is achieved. The knowledge and records on dose and dose rates can also be very useful for process control and aging management for long-term storage, down to the item level of the packages. An exhaustive search of candidate radiation sensors for tag incorporation was conducted, and a commercially available personnel dosimeter for gamma radiation was selected. The major advantages of a personnel dosimeter over other possible choices are its compactness, reasonable cost, low power consumption, reliability, acceptance by health-physics professionals, and wide dose-rate operating range, matching the range for nuclear materials monitoring. In the incorporation, the dosimeter casing, external display, control buttons, audio/visual alarm provisions, and battery holder were discarded; only the detector components and the electronic core were retained. According to the manufacturer’s specifications, the selected dosimeter is sensitive to photonic radiation in an energy range of 50 keV to 6 MeV. The dosimeter also has a wide dynamic measurement range for the dose rate, from ≈10 μR/h to 800 R/h, and a dose from 0.1 mR to 1,000 R. DESIGN OF DOSIMETER ADDITION To support the operation of a dosimeter in an ARG-US RFID tag, the following design requirements are considered: (1) ensure secure mounting and easy removal of the dosimeter module if it is not needed, (2) use existing batteries with low power consumption, (3) use versatile communication protocols, and (4) allow room for future expansion of additional sensors. The next-generation ARG-US RFID tag, code named MK-III, has been designed to meet the above requirements. Figure 3 shows a prototype of the MK-III tag with three main electronic boards: dosimeter carrirer board (left), tag controller board (dubbed mother board with antenna, center), and battery supply and management board (right). The dosimeter carrier board can be slid in and out of its compartment and is held securely by two sets of molded alignment tabs. A 20-pin ribbon cable is used for communication with the tag controller board, and a two-pin header connector wire funishes the power from the battery board. The dosimeter board can be removed easily from the MK-III tag, and the tag would function, after slight modification of the software, just like a MK-II tag. Figure 3. MK-III tag with a dosimeter carrier board incorporated in the left compartment. Figure 4 is a block diagram of the dosimeter carrier board that shows how the radiation detector (dosimeter) communicates with the tag control unit in the tag controller board via several communication protocols, as follows: (1) A universal asynchronous receiver and transmitter (UART) RS232 protocol is used between the dosimeter and the micro-controller unit (MCU) on the carrier board. (2) A serial peripheral interface (SPI) protocol is used between the MCU and the tag control unit. (3) An ISO 18000-7 RF protocol is used between the tag control unit and the reader (not shown in Figure 4).