Radon importance

Fig. 17.7), is therefore the nucleus of an atom of a different element. For example, when a radon-222 nucleus emits an a particle, a polonium-218 nucleus is formed. In this case, a nuclear transmutation, the conversion of one element into another, has taken place. Another important difference between nuclear and chemical reactions is that energy changes are very much greater for nuclear reactions than for chemical reactions. For example, the combustion of 1.0 g of methane produces about 52 kj of energy as heat. In contrast, a nuclear reaction of 1.0 g of uranium-235 produces about 8.2 X 10 kj of energy, more than a million times as much. 

Morawska L, Philhps CR (1992) Dependence of the radon emanation coefficient on radium distribution and internal stractnre of the mineral. Geochim Cosmochim Acta 57 1783-1797 Neretnieks I (1980) Diffusion in the rock matrix an important factor in radionuclide retardation J Geophys Res 88 4379-4397... 

Figure 31.2 illustrates the percentages of contribution by each type of radon entry made to a specific group of study houses in the Pacific NW.n Any one house can vary significantly from these figures. However, on a national basis, this is an indication of the relative importance of each of the contributors. 

The key point to remember, in the merits of year-round radon removal, is that there is no guarantee that radon problems will not be present even in the summer months. The radon levels found in individual houses are a complex result of radon source strength, soil transport, the number, size, and location of entry points, weather, and the way the house is operated.2 To be certain of maintaining low radon levels in the house normally requires that an SSD mitigation system works properly 24 h per day, 365 days per year. It is for this reason that durability and system performance are very important considerations. The performance level goal for the system is 100% on-time operation for the life of the building. This requires excellent durability of system components and a reliable means for determining whether the system is fully operational at all times. 

Be sure that applicable codes and standards are followed Begin with the life and safety codes. The intent of this chapter is to reduce the risk resulting from radon, but not in a way that increases other risks. Especially important in this regard are the National Fuel Gas Code,58 National Fire Protection Code (NFPA1), and National Electric Code.59 Also the CABO One and Two Family Dwelling Code32 will be very helpful. There are thousands of code jurisdictions in the United States therefore many issues will have to be dealt with locally. 

The array of proposed standards differ in details, but the approaches are the same in two important ways (a) no account is taken of possible technological or medical advances during the next millennia (b) the level of harm to be avoided in the distant future is miniscule compared to the level of harm that society accepts with a shrug today - for example, the dose of about 2 mSv per year that the average person in the US. now receives from indoor radon, with projected lung cancer fatalities in excess of 15,000 per year. 

The radioactive element is a silvery, shiny, soft metal that is chemically similar to calcium and barium. It is found in tiny amounts in uranium ores. Its radioactivity is a million times stronger that that of uranium. Famous history of discovery (in a shed). Initially used in cancer therapy. Fatal side effects. Small amounts are used in luminous dyes. Radium was of utmost importance for research into the atom. Today its reputation is rather shaky as its decay gives rise to the unpleasant radon (see earlier). In nuclear reactors, tiny amounts of actinium are formed from radium. 

Thus, it is important to simultaneously consider the combination of soil and building characteristics that govern the amount of movement of radon-laden soil gas. 

This inverse relationship between equilibrium factor and "unattached" fraction and their relationship to the resulting dose is important in considering how to most efficiently and effectively monitor for exposure. This inverse relationship suggests that it is sufficient to determine the radon concentration. However, it is not clear how precisely this relationship holds and if the dose models are sufficiently accurate to fully support the use of only radon measurements to estimate population exposure and dose. 

This volume represents a collection of papers that provide a considerable amount of recent results and reflect the current level of scientific understanding of radon related problems. However, with the increased public interest and the resulting increased scientific study, it can be expected that there will be many important new findings and our knowledge of the nature and extent of the indoor radon problem will be greatly expanded in the next few years. 

The dimensionless group Pep is essentially the ratio of the rate of convective transport to the rate of diffusive transport. Similarly, Nr describes the relative importance of radioactive decay to convective flow as a method of removing radon from the soil pores. In the case of Pep >>1/ diffusion can be neglected and the first term in equation (1) drops out. If in addition Nr >>1, then radioactive decay can be neglected as a removal term. If Pep 1, then diffusive radon migration dominates, and the second term in equation (1) can be neglected. 

As noted in Table I, average surface radium concentrations appear to vary by about a factor of 20. This can also be seen from the distributions from the NARR data. Soil permeabilities, on the other hand, have much larger variations, and thus, in principle, may have a greater influence on the spatial variations in average indoor radon concentrations that have been observed. As with the case of surface radium concentrations, the spatial variability of air permeabilities of soils is an important element in developing a predictive capability. 

Factors influencing the production and migration of radon in soils have been examined, and various sources of geographic data have been discussed. Two significant soil characteristics include air permeability and, less importantly, radium concentration. While there are, at present, few opportunities to compare the larger-scale data with on-site field measurements, those comparisons that have been made for both surface radium concentrations and air permeability of soils show a reasonable correspondence. Further comparisons between the aerial radiometric data and surface measurements are needed. Additional work and experience with SCS information on soils will improve the confidence in the permeability estimates, as will comparisons between the estimated permeabilities and actual air permeability measurements performed in the field. 

Another important finding is that simple passive radon monitoring devices, used for short integrating periods, can be very useful in acquiring the data necessary to undertake a national survey for indoor radon. 

Numerous radon and radon decay measurements in houses are now being made by a large number of private and governmental organizations. In order to assure valid and consistent measurements, it is important that proven methods be used following standardized procedures. To address this need, EPA issued "Interim Indoor Radon and Radon Decay Product Measurement Protocols" and established a Radon/Radon Progeny Measurement Proficiency program. 

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