The creation of the Radiation Sensor Board has been motivated by the nuclear disaster in Fukushima after the unfortunate earthquake and tsunami struck Japan. We want to help authorities and security forces to measure the levels of radiation of the affected zones without compromising the life of the workers. For this
The design of the sensor board is open hardware and the source code is released under GPL.
The Libelium Team. April 2011.
The idea is simple, each node acts as an autonomous and wireless Geiger Counter. It measures the number of counts per minute detected by the Geiger tube and send this value using ZigBee and GPRS protocols to the control point. The system is powered with high-load internal batteries what ensures a lifetime of years.
With this technology radiation measurements can be known in real time without compromising the life of the security corps members as they do not have to be inside the security perimeter in order to activate the Geiger counters. The information is extracted automatically and sent wirelessly to the Gateway of the network.
Prevention and Control Radiation Sensor Network
The Prevention and Control Radiation Sensor Network is formed by dozens of sensor devices deployed in the surroundings of the nuclear power plant and reaching the closest cities. Sensor nodes are installed in street lights and
Emergency Radiation Sensor Network
If a radiation leakage occurs in a place where there is not a previously installed radiation sensor network, an emergency deployment can be done in just a couple of hours. Security
There are two different usages of the Radiation Sensor Board. The first one is explained in a different article, the second one is treated here.
- USB Geiger Counter: It can be used as a personal Geiger Counter being powered by a USB connection though the Arduino board. It is a cheap and easy way for personal users to monitor specific objects and certain places near home. More info here.
- Wireless and Autonomous Geiger Counter: This is the usage described in the current article using the Waspmote platform. The idea of this technology is double, on the one hand this technology allows to to monitor as a prevention procedure the surroundings of a nuclear power plant along with the closest cities autonomously without the need of human intervention, and on the other hand it let us quickly deploy emergency control points when a radioactive leakage happens.
The sensor node is composed by:
How the Radiation Sensor Network works
Waspmote has a cyclic behaviour. It sleeps most of the time in order to save battery. At specific
If the values are above the security threshold defined, as well as being sent through the ZigBee network they are also directly transmitted to the security corps by an SMS alarm with the GPRS radio or event directly sent to the Internet via a TCP/IP socket.
Along with the value extracted from the Geiger counter, Waspmote adds also the GPS information (latitude, longitude) in order to give the exact location of the radiation source.
Types of Radiation
There are three types or radioactive particles, Alpha, Beta and Gamma which are generated in the nuclear power plants.
Alpha radiation consists of positively (+2) charged particles emitted from the nucleus of an atom in the process of decay. These particles are also very dense which, with their strong positive charge, precludes them from penetrating more than an inch of air or a sheet of paper. Because of this, Alpha particles are not a serious health hazard, except when they are emitted from within the body as a result of ingestion, for instance, when their high energy poses an extreme hazard to sensitive living tissue.
A weak form of ionizing radiation detectable on some models of Geiger counters, typically those that incorporate a thin mica window at one end of the Geiger -Mueller tube.
Beta radiation consists of negatively charged (-1) particles emitted from an atom in the process of decay. These particles are relatively light and can penetrate somewhat better than an Alpha particle, though still only through a few millimetres of aluminium at best. If ingested, Beta radiation can be hazardous to living tissue. A relatively weak form of ionizing radiation detectable on many Geiger counters, generally dependent on the thickness of the Geiger-Mueller tube wall or the existence of a window at the end of the tube.
Gamma radiation represents one extreme of the electromagnetic spectrum, particularly that radiation with the highest frequency and shortest wavelength. (That same spectrum also includes the more familiar X-rays, ultraviolet light, visible light, infrared rays, microwaves, and radio waves, listed in order of decreasing frequency and increasing wavelength from Gamma rays.) Gamma rays can pass through virtually anything, and are effectively shielded or absorbed only by materials of high atomic weight such as lead. Gamma rays are produced naturally by the sun and other bodies in outer space, their transmission to earth being known as “cosmic radiation”. A very powerful and potentially very dangerous type of ionizing radiation detectable on virtually all Geiger counters.
Certain minerals that make up part of the earth containing the radioactive elements Uranium and/or Thorium also emit Gamma rays. This, along with the cosmic radiation (Gamma rays which come from the sun and other stars), combine to produce the “background count” of a Geiger counter. This might typically be in the range of 15 to 60 counts per minute, but will vary depending upon your location on the earth, your altitude, and the efficiency of the Geiger counter. The background count should always be factored in or “subtracted” from the overall reading derived from a specific radioactive source.
Common background radiation goes from 0.041μSv/h to 0.081μSv/h (3650 – 7200μSv/year).
Sources: Wikipedia, Blacksmith Institute, Geigercounters.com
In the video the sensor board is tested using Vaseline Glass which has been previously highly charged using ultraviolet light. This radioactivity level lasts only a couple of minutes but is enough to see how the irradiated Beta and Gamma particles are detected.
Particles detected by the Radiation Sensor Board
The Geiger tube
From counts per minute to Servants
The formula which passes from
For example, the conversion
- LDN-712 : 120 * 0.00233 = 0.27μSv/h
- SBM-20 : 120 * 0.00277 = 0.33μSv/h
You can get just the Radiation Sensor Board in order to integrate your own Geiger tubes or buy it in a “ready to use” pack along with the Geiger tube already soldered.
If you are interested in purchase information, please contact us.