A Study on a Platform to Scan the Earth Information Including Environmental Radiation in the Internet Society Tomoyuki Furutani 1, Keisuke Uehara 2, Pieter Franken 3, Christopher Wang 3, Joe Morros 3 and Jun Murai 4 1 Associate Professor, Faculty of Policy Management, Keio University (Endo 5322, Fujisawa, Kanagawa 252-0882, Japan) E-mail:maunz@sfc.keio.ac.jp 2 Associate Professor, Faculty of Environment and Information Studies, Keio University E-mail:kei@sfc.keio.ac.jp 3 Researcher, Keio University 4 Professor, Faculty of Environment and Information Studies, Keio University In Japan, after the East Japan Great Earthquake on March 11th 2011 and subsequent Fukushima Daiichi Nuclear Power Plant accident, it becomes more and more crucial issues to monitor, visualize and share information on radiation and related environmental phenomena. This study aims (1) to develop a sensor unit to measure radiation air-doses to share data on the Internet, (2) to establish a sensor network system by deploying sensor units in Japan and (3) to build a visualization system via web GIS. As a result, about 300 sensor unites are deployed and air-doses are shown via the WebGIS site in near real time. Key Words : sensor network, spatial information sciences, radiation air-dose, Web GIS, scanning the earth 1. INTRODUCTION In Japan, after the East Japan Great Earthquake on March 11 th 2011 and subsequent Fukushima Daiichi Nuclear Power Plant accident, it becomes more and more crucial issues to monitor, visualize and share information on radiation and related environmental phenomena. After the Fukushima Daiichi NPP accident, public sectors such as MEXT, DOE, MOFA, Agency of Forestries, JAEA have been continuously providing information on radiation air-doses, contamination on soil, river, sea, forest, foods, animals and vegetation via homepages and so on. Not only these kinds of sectors, but also private sectors, volunteer citizens and NPOs have begun to monitor and publish measurement results on radiation air-doses and contamination. Not a few foreigners groups such as Safecast 1) who have academic backgrounds on physics, chemistry, ICT and fabrication has also started monitoring and visualizing radiation and education on radiation measurements for citizens. It can be said that these phenomena have been raised by anxiety of radiation for mankind s health condition. It might be preffered that systems to monitor and visualize environmental information related to risks or critical issues for human life or health including are to be established not only in Japan but also in the worlds. In Japan, so far, monitoring networks regarding atmosphere or earth quakes have been constructed. But it is not always true regarding radiation monitoring as the number of radiation monitoring posts settled by Japanese government is not enough for people to know air-dose levels around their addresses of interests. In this study, therefore, the authors established a system to monitor and publish radiation air-doses in near real time in Japan, especially around Fukushima region. Recently in the matured Internet society, emerging methodologies integrating sensing network technology, digital fabrication and geo-spatial informatics have been established. By employing these methodologies integratedly, it becomes possible to monitor risk events that effect people s life by private sectors or by consumers convenently. - 450 -
This study aims (1) to develop a sensor unit to measure radiation air-doses to share data on the Internet, (2) to establish a sensor network system by deploying sensor units in Japan and (3) to build a visualization system via web GIS. In the following chapter, existing studies of radiation monitoring in the world are to be shown. Research methodologies are indicated in chapter 3. Sensor network units and visualization system are explained in chapter 4 and 5, respectively. In chapter6, impacts caused by the developed system are shown. 2. EXISTING STUDIES Regarding sensor network system on environmental information at fixed points, there exist weather monitoring system by using digital instrument screen and pollen dust monitoring system 2). Weather news co. ltd. has developed such interactive system as to gother and provide weather changes (such as scoll) in the narrow area and cherry brossom situation 3). As for radiation, MEXT of Japan has already deployed monitoring posts around NPP 4) before Fukushima Daiichi NPP accidents, and has increased their numbers in and around Fukushima prefecture after the accident 5) (Fig. 1). Several internet sites provide radiation information that are collected by individuals as maps 6). It can be said that radiation becomes such an environment information that people in Japan would like to know contamination levels of air or soil around their living teritorries. Therefore, the authors considered that monitoring posts have to be deployed not only in the Eastern Japan but also other areas where public monitoring posts have not been deployed. Mobile monitoring of radiation is another popular methology to understand local contamination level or to find hotspots. MEXT has been employing air-borne and car-borne survey to measure radiation in Japan. KURAMA system established by Kyoto University and MEXT is almost the same car-borne survey system which employes NaI scintillator 7). Private voluntary groups such as Safecast 1) has also established methodologies on car-borne survey to measure radiation air-doses by Geiger counter (Inspector Alert) with GPS unit. Major roads in East Japan are covered by Safecast measurements and visualization differes according to map scale. Local communities have started to monitor radiation by themselves with academic specialist s support. For example a local reconstruction comitte in Minamisoma city has been collected air-dose data by using baggy-borne survey in order to provide radiation information on rice fields or on the roads to the residents 8). Fig.1 Graphic user interface example of MEXT s radiation WebGIS service by using monitoring posts (around Fukushima Pref.) - 451 -
3. METHODOLOGIES In this study, the authors purpose to establish a sensor network with more than 300 sensor units deployed in Japan, including the area where the public monitoring posts have not been deployed yet. Therefore, sensor units that are reasonably low price and have accuracies within a certain rainge are to be deployed. Inspector Alert Geiger counters are employed for radiation monitoring, which are produced by International Medcom Co. Ltd. This Geiger counter is mainly used for radiation measurements of surface contamination around the places where radiation dose rates are relatively higher. This device can detect both alpha ray and beta rays that higher sensitivtity are required for monitoring devices, and can also detect gamma rays that have low energy. According to Inspector s specification shown in Table 1, its accuracies to decect radiation are as followings; 15% for 50mR/hr, and 20% for 100mR/h. When people would like to measure small value changes or radiation, it is said that monitoring from 6 to 24 hours is needed for more precise monitoring. Table 1 Specification of Inspector Alert 9) Detector Halogen-quenched Geiger-Mueller tube. Effective diameter 1.75" (45 mm). Mica window density 1.5-2.0 mg/cm2. EXP only: Same detector in anodized aluminum housing with black vinyl grip. 500 volt power supply is located in the probe head. Amphenol Tucal connectors. Operating Range mr/hr:.001 to 100.0, CPM: 0 to 350,000, Total: 1 to 9,999,000 counts, µsv/hr:.01 to 1,000, CPS: 0 to 5,000 Accuracy mr/hr: ±15% up to 50 mr/hr, ±20% up to 100 mr/hr, CPM: ±15% up to 130,000 CPM, ±20% from 130,000 to 350,000 CPM Anti-Saturation Readout holds at full scale in fields up to 100 times the maximum reading Temperature Range -20 to +50 C, -4 to +122 F Power One 9-volt alkaline battery As shown below, the original sensor units are attached to Inspector in a plastic box. It is known that alpha ray, beta ray and gamma ray are disturbed by paper, alminium sheets and lead plates, respectively. In case of this study, it is considered that alpha ray and beta ray are hard to be detected as radiation sensor is covered by a plastic box but gamma ray is mainly detected. The authors basically employed cpm (count per minutes) as a unit in order to show radiation doses by considering Inspector s specification. As people show interests in usv/h as a unit of radiation air-doses after Fukushima Daiichi NPP accident, usv/h is also employed in the developed system. Sivert per hour (Sv/h) itself means impact of radiation for human body per hour and calculated according to count per minutes (cpm) of radiation by using a certain conversion factor. Its conversion factor is a value that is calculated according to energy spectrum by identifying nuclids. In this study, radiation sensor units are installed at the height of 1meter from the ground, so it can be considered that radiation counts regarding gamma ray are mainly measured. Therefore, this study employed a conversion factor only when Cs137 is observed, here 1 usv/h = 310 cpm. Because Inspector has no energy compensation, cpm is the only precise value and usv/h converted by cpm is just used as a reference value. Pachube is employed in order to monitor and share data via Internet. By using Pacube, it becomes possible to share data acquired from sensor units by giving original IDs for them (Fig. 2). Besides, sequential changes of radiation air-doses can be shown in graphs according to one hour, 24 hours, one week and so on. Here, location of sensor unites and measurement values of radiation air-doses are visualized as following. First of all, a database is constructed that manages original ID, logituted, latitude, place name and Pachube ID in a spread sheet. Secondary, coordinates of monitoring posts are converted into.shp file of ArcGIS in order to visualize location of sensor units as geographical points. Thirdly, a web page interface to visualize both location and measurement values is made so that users can know radiation air-doses at a certain sensor unites as graphs by clicking these points. Addresses, longitude, latitude and situation of sensor units (indoor/outdoor and hight) are not published on the web page by considering security of the units and privacies of monitoring partners. ArcGIS server is installed in Windows server 2002 R2 strandard (2.93GHz, 64 bit). Before deploying the sensor units, availability of power supply, place of the plugs and internet environment (wired LAN/WiFi) are confirmed and then monitoring partners to collaborate radiation monitoring are listed up. Sensor units are deployed by mail to these partners. The units are installed both in- and out-doors in this study. This is because the authers considere that not a few people spend many time indoors and are exposed by radiation even in the building s or the houses. - 452 -
4. DEVELOPMENT OF SENSOR UNITS Fig.2 Pachube home page In the sensor units developed in this study, a Geiger counter (Inspector), a build-in computer and a WiFi converters are installed (Fig. 3). Radiation air-doses measured by the Geiger counter is digitalized by arduino, the build-in computer. Ethenet is also mounted in the unit so that air-dose data is send via WiFi converter on WiFi. In case that there is not WiFi environment in the deployed place, data is send via pluged LAN. Internet addresses of the units are basically tagged according to DHCP, but in some cases, static IP address is also used. Picture of the developed sensor unit is shown in Fig. 4. Fig.3 Mechanism of sensor unit employed in the proposed system Fig.4 Sensor unit (Inspector Alert is inside the plastic box) - 453 -
Data set of sensor units is transferred to the original Web GIS server (as explaind in chapter 3) and pachube.com by PUT method of HTTP. Therefore, it is enough for monitoring partnors to prepare internet connecting environment and AC power supply plug. In the future, power supply by using solar panels is planned when more and more out-door sensor units are deployed. About 300 sensor units has been deployed (as of 23 rd March, 2012) from Hokkaido to Okinawa. 5. WEB GIS DATABASE AND VISUALIZATION As shown in Fig. 5 and Fig. 6, the units are mainly installed in Fukushima Prefecture and populated areas. When the users click the monitoring points (shown as orange points named as station ), a graph appeares as shown in Fig. 7. Dislike a graph only interface or PDF maps, WebGIS map has advantages regarding interactiveness and visualization. The users can use zoom-in and zoom-out function of Web GIS so that they can local situation of radiation air-dose monitoring results even when sensor units are located densly. Fig.5 An overview of Web GIS map of the proposed system 10) - 454 -
Top PAPERS Fig.6 A map that shows monitoring posts around Fukushima city (a graph appears when the orange point is clicked) Fig.7 Graphical display shown in the WebGIS 6. IMPACTS OF THE SYSTEM The radiation monitoring system proposed in this study is disclosed since December 2011. As radiation air-doses in the living environment are published on the Web, various opinions and questions have been sent by e-mail. In order to consider risk communication when using sensor network and WebGIS providing radiation monitoring data, the authors would like to discuss the impacts of the proposed system according to these opinions and questions. There are the greatest number of opinions and questions about measurement values and monitoring method as shown following. 455
(1) About measurement values Not a few users have questions about that measurement values are larger or smaller than those monitored by national/local government or by individuals. In the reply to this type of questions, specification and charactoristics of Geiger counter (Inspector) and measurement errors are explained. It is also explained that radiation air-doses by in-door monitoring tend be relatively lower than thouse by out-door monitoring in the areas around evacuation area by Japanese government and be higher than those by out-door monitoring in the other regions. Measurement values could be changed or be unstable before and after the sensor units are replaced. In this case, measurement error effect caused by replacement is explained. (2) About measurement method Several questions are about meaning of in-door monitoring. As the proposed system has employed Geiger-Mueller tube (pancake, acturally), some may think that it s useless to measure in-door radiation air-doses. As indicated in chapter 3, in this case, meaning of in-door measurement is explained as not a few people spend many time in the building or in the rooms. It is also explaind that it is enough to employ GM tube for monitoring changes of radiation air-doses in the long range. (3) Other questions Several medical organizations and school coorperations kindly offered us to become partners of radiation monitoring or to cooperate collaborative survey. As some of the sensor units fail to monitor air-doses, some ask recovery timing. Through these opinions and questions, it is indicated that not a few people in Japan is interested in the proposed system. 7. RESULTS AND FUTURE STUDIES This study aims to establish a monitoring network of radiation air-doses in Japan by integrating sensor network units, digital fabrication technology and WebGIS. About 300 sensor unites are deployed and air-doses are shown via the WebGIS site in near real time. It can be said that the proposed system has an originality from a viewpoint that there exists no radiation monitoring system managed and maintained by private sector. The following issues are still remained to be solved in the future. First of all, several sensor units fail to measure radiation stably. Secondary, as frequently asked question pages are not prepared, some users misunderstand the meaning of provided radiation information. From a viewpoint of risk communication, it might be necessary to prepare to communicate the users via the Web site. It is also crucial matter to deploy sensor network with solar panels in order to increase out-door sensor unites. ACKNOWLEDGMENT: The authors thank to Mr. Masayoshi Son (CEO of SoftBank Co. Ltd.) and Yahoo! Japan because they have financially supported our project. We also thank to ESRI U.S. and ESRI Japan as they kindly helped us to establish ArcGIS server. REFERENCES 1) Safecast, 2010, Available at: http://blog.safecast.org/, Accessed on March 31 st, 2011. 2) LiveE!, 2007, Available at: http://www.live-e.org/en/index.html, Accessed on March 31 st, 2011. 3) Weather News, 2011, Available at: http://weathernews.jp/sakura/, Accessed on March 31 st, 2011. 4) MEXT 2012, Available at: http://radioactivity.mext.go.jp/map/ja/area.html/, Accessed on March 31 st, 2011. 5) MEXT 2011, Available at: http://radioactivity.mext.go.jp/en/, Accessed on March 31 st, 2011. 6) Available at: http://www.nnistar.com/gmap/fukushima.html, Accessed on March 31 st, 2011. 7) Kyoto University Research Reactor Institure 2011, Available at: http://www.rri.kyoto-u.ac.jp/kurama/, Accessed on March 31 st, 2011. 8) Furutani, T., K. Uehara and J. Murai 2012, A study on community-based reconstruction from nuclear power plant disaster - A case study of Minamisoma Ota Area in Fukushima -, Journal of Disaster Research, to be published. 9) International Medcom 2005, Available at: http://medcom.com/downloads/inspector_alert_manual.pdf, Accessed on March 31 st, 2011. 10) Keio Univerisy Scanning the Earth project 2012, Available at: http://ste.sfc.keio.ac.jp/keio/, Accessed on March 31 st, 2011. - 456 -