Post-Fukushima: Using LabVIEW and CompactRIO to Monitor Radiation
"KURAMA-II would probably have taken one to two months longer to develop if we had not used LabVIEW."
- Dr. Minoru Tanigaki, Division of Quantum Beam Material Science Research Reactor Institute, Kyoto University
Improving an in-vehicle radiometry system by decreasing the number of parts, making the system more compact, automating the measurements, and completing development with a tight deadline so the device could be deployed to assist in the restoration of the Fukushima No. 1 nuclear power plant.
Automating and miniaturizing the existing Kyoto University RAdiation MApping (KURAMA) system using NI LabVIEW system design software and NI CompactRIO hardware. We shortened development time by reusing the original KURAMA software for the KURAMA-II, even though it used different hardware.
Dr. Minoru Tanigaki - Division of Quantum Beam Material Science Research Reactor Institute, Kyoto University
On March 11, 2011, an earthquake in the Pacific Ocean off Japan’s Tohoku region resulted in a tsunami that caused extensive damage to eastern Japan and triggered a series of accidents at the Fukushima No. 1 nuclear reactor plant. Because of this, a need arose to measure in detail the radiation (air dose rate) of Fukushima Prefecture and surrounding regions for the next few decades. A device was also needed immediately to quickly produce precise maps of air dose rates to facilitate a better understanding of issues such as the inhabitants’ state of exposure and scale of environmental contamination. This sparked the development of a system that could carry out cross-sectional air dose rate measurements using data collected from vehicles roaming designated areas and providing a near real-time visualization of the measurements. The resulting device, the KURAMA, was completed in just one week from the start of development, excluding time spent sourcing components.
Figure 1 shows the configuration of KURAMA. A vehicle containing the in-vehicle device travels around the area and continuously measures radiation levels in arbitrary locations. Measurement times and locations are retrieved from the GPS, tagged to the corresponding measurements, and sent to servers through the Internet. A near real-time visualization of the area’s radiation dose distribution is plotted on top of map data with the results. We use a conventional passenger car as the measuring vehicle and a measurer operates the in-vehicle device.
Figure 1: KURAMA’s System Configuration
The in-vehicle device contains a survey meter, an interface box, a GPS unit, a computer, and a 3G mobile router (Figure 2). The survey meter is an off-the-shelf portable set. The GPS unit, computer, and 3G mobile router are also off-the-shelf devices.
Figure 2: KURAMA’s In-Vehicle Device Configuration
The main function of the interface box is digitizing the survey meter’s analog voltage measurement output, for which we use the NI USB-6009 multifunction DAQ device. The software that communicates with the network and associates the measured air dose rates with the corresponding time and location was developed using LabVIEW.
KURAMA functioned as we envisioned and feedback from field tests in Fukushima also spoke well of its practicality, but we still found room for improvement.
Because the KURAMA in-vehicle device is made up of individual components wired together, extensive time and space are needed for its installation and setup. Instead of creating a specialized vehicle, we decided to miniaturize and unify the device to fit into conventional vehicles regularly traveling into all parts of the territory, like local buses or delivery cars.
We also needed to completely automate the measuring and data transmission process to operate without measurers. Lastly, we needed to develop a device for practical use within a short time in immediate response to the grave situation in the Fukushima Prefecture and surrounding regions.
Figure 3 shows the system configuration diagram of KURAMA-II. The biggest change is the in-vehicle device (bottom left of Figure 3), now reduced to just two components—a radiation detector and the CompactRIO control and monitoring system. The original KURAMA interface box and computer were replaced by CompactRIO, which was selected for its compact size and excellent durability (it can even be used as a data collection device in automobiles undergoing crash tests). We incorporated the GPS unit and 3G wireless router, which were independent components in the original KURAMA, into the CompactRIO as a single module. As a result of this setup, we successfully reduced the external dimensions of the device to a mere toolbox size of 34.5 cm by 17.5 cm by 19.5 cm (Figure 4). Also, by installing the software program developed with LabVIEW into the CompactRIO, KURAMA-II is fully automated as long as it remains connected to a power source and it does not require special operation to function.
Figure 3: KURAMA-II’s System Configuration
Furthermore, we completed KURAMA-II in just two months. We greatly reduced development time because the LabVIEW program developed for KURAMA, which had a proven track record of practical use, was directly reused in KURAMA-II, even with a change in hardware configuration.
Figure 4: KURAMA-II’s In-Vehicle Device
LabVIEW has been used in the Kyoto University Research Reactor Institute for around 10 years for applications such as accelerometer control. We were truly able to enjoy the benefits of using LabVIEW in the present development, and we realized a completely new system that can solve problems on-site at a practical level. Features such as the LabVIEW graphical programming method (rather than text-based programming) and ease of task delegation among project members helped us achieve this. If we had not used the graphical system development method, I believe development time would have stretched on for another one to two months.
The KURAMA-II project was adopted by NI Japan’s recovery grant program. As part of the program, NI Japan assisted us with product selection and technical advice.
We are continuing development on KURAMA-II with the goal of transforming it into an even more sophisticated device by further improving the sensitivity of the detector and other functions. We may also receive requests for usability improvements as the device is actually deployed on-site.
Although KURAMA-II is a traveling survey system, we are also exploring its potential in various situations. For example, we are considering a power supply system for a portable survey system that can enter forests, parks, and other areas inaccessible by automobiles to carry out detailed measurements. There is also a need to evaluate more precise positioning methods than those achieved by a conventional GPS.
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