Above: The Safecast team with the new Pointcast realtime radiation monitor in Koriyama, Fukushima Prefecture.
While the bGeigie and mobile radiation monitoring have been the major focus of Safecast for some time, we have also steadily been building, testing, and deploying a fixed realtime radiation monitoring system which is the first to receive the designation“Pointcast.” There has been a different kind of learning curve associated with this, both in technical terms as well as in the nature of the human partnerships it requires. We indicated the sensors on our web-based map and made the realtime data accessible over a year ago, and as usual we’ve been learning in public. This isn’t a problem for us, it’s one of our most important principles. After deploying quite a few more fixed sensors in recent months and working out some of the bugs and visualization issues, we feel it’s time to call more attention to this system, its purpose, and the feelings and concerns of the people who have agreed to host Pointcast units. This post is the first of several describing the Pointcast system and our observations from an intense few days installing new sensors and conducting maintenance on several others in Fukushima during the recent Golden Week holiday.
What’s it for?
The reason for providing realtime radiation monitoring is simple: people want (and need) to know how radiation levels change over time in the places where they live and work. In most parts of the world this is necessary for basic environmental monitoring, as well as for satisfying the natural curiosity many people have. But in places like Fukushima that have suffered significant radioactive contamination and where there remains some risk of new deposition, it’s more important for people to be able to monitor changes closely. Safecast was established to be an independent source of information, and for people in Fukushima and elsewhere we feel it’s important to provide a reliable means for them to cross-check official data, particularly as decisions are being made regarding the return of people to evacuated areas. We’ll describe people’s motivations for hosting Pointcast sensors in more detail later, but it’s important to keep in mind that we use the “pull” model, and the discussion to install a sensor somewhere begins with an individual or group expressing the desire to have one. A number of our installations in Fukushima are on homes in currently evacuated areas, whose residents wanted to be able to keep tabs on radiation levels while they are away, and to have a way to confirm government statements about how quickly radiation levels have been declining. Outside of Fukushima, we are making Pointcast devices available to environmental groups who feel the need to have monitors near nuclear powerplants, waste sites, and other areas of concern. At several other locations in the US, Japan, and Europe, Pointcast sensors were installed primarily to provide day-to-day monitoring of normal conditions.
Some governments, including Japan’s, provide web-accessible realtime radiation monitoring data to the public. As we noted in a number of previous blog posts, here, and here, for instance, the Japanese government set up approximately 3700 realtime monitoring posts in Fukushima, but because of how they were sited and the lack of transparency of the system overall, many residents do not consider them trustworthy.
Because of technical and contractual fiascos hundreds of monitoring posts in Fukushima are inoperable. On top of this, in February 2016 the government announced that it would move 3000 of the current 3700 monitoring posts from less-contaminated areas in Fukushima into more highly contaminated areas. Government reasoning is that radiation levels have declined in most of the prefecture and have remained essentially unchanged for more than a year, so the density of monitoring coverage can safely be reduced there and increased in areas of more concern closer to Fukushima Daiichi, such as in the towns of Naraha and Minamisoma. We consider such a move to be extremely unwise. We support increasing coverage inside the evacuation zone, but not at the expense of coverage elsewhere. This decision represents reducing rather than increasing the availability of important information about environmental risks. Changing the locations of monitors after several years will make it impossible to make valid long-term comparisons and analysis of changes in radiation levels at specific locations. It will also further damage the credibility of the system itself. Beyond this, it sends a message to the communities that will lose monitors that their concerns are not important. The move is not scheduled to happen until April 2017, so we hope wisdom will prevail and the decision will be reversed before then. It’s precisely because so many poor decisions like this have been made regarding the official monitoring post system that many citizens understandably desire an independent alternative. Pointcast is intended to help fill this need.
The current generation of Pointcast realtime radiation monitor system evolved from earlier Safecast realtime systems built beginning in 2011. That year, with sponsorship from Softbank, and in collaboration with the Keio University “Scanning the Earth” project, we deployed Arduino-based fixed sensors called “NetRad.” These were installed at Softbank stores, with fixed ethernet connections, and the data was displayed on the Yahoo website. By 2012, 300 devices had been deployed in all, but over time as staff changed it became increasingly difficult to get access to the sites for troubleshooting and maintenance. Relatively few remain operational, and Yahoo unexpectedly removed the website two years ago. The major lessons we learned were the importance of having clear access agreements, to avoid partnering with large bureaucratic organizations, and not to depend on 3rd parties for hosting the data.
The next generation, called the nGeigie, used a weatherproof dual-sensor unit made by Medcom called the Hawk 1600, and had improved data communication capabilities, though it still required a fixed ethernet connection at first. About 20 of these were made and successfully installed in Japan and overseas. It became clear, however, that many desired locations in Fukushima and elsewhere would not have ethernet LAN access, so a lot of subsequent development was aimed at providing multiple communication modes, such 3G cellular, WIFI, Bluetooth, or other point-to-point or mesh communications. The sensor components of these systems are basically compatible with the most recent Pointcast communication units, and several have already been upgraded.
Learning from experience, the new Pointcast systems have modular design features making them highly configurable, useable with different sensors and data transmission protocols, and easy to troubleshoot remotely.
Pointcast components installed at Odaka Worker’s Base
What does it consist of?
Each Pointcast installation has a sensor unit and a data communication unit. The sensor unit is intended to be mounted outdoors, while the data communication unit can be mounted either indoors or outdoors. Behind the scenes, the data is stored in the same database as Safecast drive data. Readings can be viewed on our main web-based tilemap as well as at this page. (details below)
The sensor unit currently being used is the Medcom Hawk Radius dual sensor. This is a rugged, well-tested, weatherproof unit that uses the same pancake GM tube and iRover high voltage supply as the bGeigie Nano, providing good equivalency between these fixed sensors and our mobile ones. The pancake provides sensitivity to gamma, beta, and also alpha radiation. The Hawk Radius also incorporates a compensated GM tube inside the case which is sensitive to gamma only; its reading represents the actual gamma dose rate in μSv/hr. Each Pointcast installation provides two data streams, one for each sensor. Both sensors are calibrated for Cs137, and in normal background radiation circumstances should give very similar readings. Because the pancake tube is more sensitive to beta than to gamma, if a strong beta component is present it will read higher than the compensated tube. This should make it possible to distinguish radiation releases from normal background fluctuations more easily.
Pointcast data communication unit
The data communication unit has a compact assembly of circuit boards designed by Safecast volunteers, inside a rugged weatherproof case. External cables connect the unit to a power source, the sensor unit, and a wired LAN if that option is used.
—Main cpu board (bottom layer) : This uses an Arduino Teensy 3.1 for the main processor. A modular design allows the use of fixed ethernet, cellular 3G, WIFI, Bluetooth, or other point-to-point or mesh communications hardware.
— Interface board (middle layer): allows various types of sensors to be connected
— Display (top layer): This large display shows readings for both sensors as well as status information. When placed indoors it makes it possible to easily easily monitor radiation levels outside.
The system runs on DC power, can used with PoE (power-over-ethernet) with an adapter, and also provides means for battery power for uninterrupted monitoring in case of power outages. An integrated SD card stores configuration data as well as measurement data to guard against loss due to communication failure.
The system measures constantly, and uploads the number of counts every 5 minutes (We are testing a more adaptive upload system, which should make it possible to respond quickly after a sudden threshold event). The data is sent to the Safecast database, the same as with drive data (location, time, count). The system stores the data, and it is openly accessible through the Safecast API for further processing and visualization.
Viewing the readings:
Pointcast sensor locations indicated as dots on Safecast tilemap
On the main Safecast web map (aka “Safecast tilemap”), Pointcast sensors are indicated by circular dot icons. The outer ring color indicates the device status: a green ring means the device is online, a dashed grey ring indicates that it is offline. The color of the inner dot indicates the radiation level, using the same color scale as the map itself. Clicking on a dot will cause a small window with two time series graphs to appear showing the readings over the past month. The location of the sensor is given at the top of the window, and the sensor ID number is given in light grey in the background of each graph. Generally the top graph will be for the compensated tube, and the bottom for the pancake tube. At the top of each graph the current reading is given in μSv/hr on the left, and in CPM on the right, in parentheses.
Graphs and detailed information are accessible from the Safecast web map
Clicking “more info” at the bottom left of the graph window will call up the detailed page for that sensor at realtime.safecast.org. (see below)
At realtime.safecast.org, any Pointcast installation can be selected from either a list view (which currently opens by default) or a map view.
Viewing sensors in list view
In the list view, the location of the sensor is given in the far left column, its current status in the far right column, and the latest readings, GPS coordinates, etc., in the columns in-between. Dual-sensor Pointcast installations contain two entries, one for each of the two sensors (older Safecast realtime sensor installations which have not yet been upgraded still have only one). In general, sensor ID numbers ending in “1” indicate a pancake tube, while those ending in “2” indicate a compensated tube. Clicking on a sensor name will call up the detailed page for that sensor.
Viewing sensor status on the map at realtime.safecast.org
Clicking on a dot opens a small window with the most recent reading, from which the detail page can be accessed.
The map view at http://realtime.safecast.org/map/ provides a visual overview of Pointcast locations and their status. A blue dot indicates that the sensor station is currently online, a red dot indicates that it is offline. Clicking on a dot will call up a small window that gives the sensor location and the most recent reading, in CPM and μSv/hr. (at the time of writing, this window does not contain graphs, but new implementations are in the works). Clicking on the sensor name will open the detailed page for that sensor (again, at the time of writing, info for the pancake tube only is displayed, but simple access to both sensors from this window will be provided soon).
Detail page view:
Each sensor (pancake and compensated) has its own detailed info page. This gives the location and ID number, as well as a status indication, at the top, and a map showing the location to the right. The most recent reading is given in bold black letters, in both CPM and μSv/h, with the previous high reading in bold red. A small time series graph of the previous month is to the right of the numerical readings. Clicking on “More sensor data” below the small graph will open the API page for that sensor, through which all the data it has collected can be accessed. Clicking on the graph itself will open a detailed graph window. Actual counts are indicated by small orange crosses, while the simple moving average (SMA) trend line is shown in blue.
Screenshot of detail page view
Detailed time series graph. Orange crosses represent actual counts, blue dots show the trend.
The detailed pages include photos of the installation in most cases, as well as comment fields for inquiries, etc.. Part of the learning curve of establishing a realtime radiation sensor network like this is understanding what kinds of fluctuations in readings are in fact normal, and which ones represent the detection of actual anthropogenic radiation releases. It is well known, for instance, that rainfall washes radon daughters down towards the earth’s surface, resulting in temporary natural spikes in detected radiation. Other apparent anomalies can be caused by technical glitches. One reason we have included comment fields on these pages is so that users who notice changes in radiation levels can point them out and ask for confirmation and clarification. No government-run system we are aware of has a similar feedback system for the public.
So that’s the basic rundown of what the Pointcast realtime radiation monitoring system is about, how it works, and how to use it. Like everything else Safecast does, this system is a constantly evolving work in progress, and we expect the feature set and visualizations to improve over time, but most of the information above should remain valid for a while. While the first sensors that use the “Pointcast” designation are for radiation monitoring, we intend it to refer to an entire category of Safecast stationary sensors, whether for radiation, air, water or anything else. As these new devices are deployed we’ll be describing their features as well.
The next blog posts in this series will describe some of the Pointcast installations we did in Fukushima recently and introduce a few people who have asked us to install them on their homes and places of business.