Monitoring EquipmentAware Electronics RM-80 Geiger-Mueller detector with Fan Filter Aware Electronics Aw-Radw and Aw-graph software running on Windows XP. Interpreting the GraphsNotice that there are three lines for each graph. In the first graph "Last 4 hours" there are fewer data points, so we use interpolation, making a nice smooth curve from limited data. The raw data is colored green to show that the method is interpolation. The magenta line is the same data, but has been "compressed" so that there are only a tenth of the points. This creates an "average" curve that makes it easier to see increase or decrease of the levels. The third curve is red. The red curve attempts to draw a line through the points making it easy to see an upward or downward trend. The last graph also uses this regression method. In the remainder of graphs the red line more closely follows the variations in level of the data. Yellow lines are drawn straight between data points. The magenta line again is an average of the data. There are variations throughout the day and night due to the airflow from underneath the building in through holes in the floor where cables enter the studio control room. There are times that seem unrelated to other events where the levels rise sharply, and then decline. The Fan-Filter unit is located behind the equipment racks near a south-facing window. The Aware RM-80 is attached directly to the filter. The level of radon in this building is lower in winter than summer, and seems to vary with barometric pressure and from day to night. Monitoring Radon GasRadon decays to form several highly radioactive daughter products. Since these daughters are much more radioactive than radon gas itself, detection of these materials is an easy way to determine the presence of radon. Areas with high radon content in the air will also show high quantities of daugher products. When air is drawn through a filter using a small fan the daugher products are filtered out of the air and cling to the filter surface. The detector is close to the filter, so that the radioactivity can be measured. Its a very sensitive method of radon measurement. Its a good idea to test for radon in any living area. Inexpensive kits are available in most hardware stores that accurately measure radon. This is the preferred method. Contact your state's Environmental Protection Agency (EPA) for more information on radon. Where is Radon Found?In the ground, Uranium contained in rocks decays over time creating a chain of daugher products. Radon is one of the elements in this chain. So, radon is released in the ground. If the ground is intact since the half-life of radon is only a few days, most radon turns into other elements right in place, causing no problem. However, if the top layers of soil are removed, then radon can escape directly into the atmosphere. It then is a part of the air we breathe. It can enter a house through the floor if there is no seal. Cracks in a slab floor, or holes in the floor to the under house crawl space can allow radon to enter the living space. How to Remove RadonAnything that can collect small particles can accumulate radon daughter products. The dust on the face of TV's and computer monitors is usually quite radioactive, as the static electricity draws the small particles to the surface. These small particles cling to dust particles and float around the house. The easy answer here is to keep the house clean. A good HEPA filter will remove most all of the danger, but an effective filter can be expensive. Ionic type filters actually make the situation worse! Only certified HEPA filters can eliminate the danger successfully. The best solution is of course to keep as much radon out of the house as possible. This translates to sealing up floors, and venting any under house areas with small fans so that radon cannot accumulate. Educational LinksThe Nuclear Regulatory Commission (NRC) has good information on radiation. Envormental Protection Agency (EPA) for info on radon gas. College Physics Kenneth R. Koehler's great educational site. SLAC Stanford Linear Accelerator...lots of info. PDF-An Intro to Radioactivity excellent writeup by a Physicist. Radioactivity in Nature from Idaho State University.
Special LinksThanks to Bryan Boardman Aware Electronics Corp.