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International Atomic Energy Agency, 2014, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, STI/PUB/1578 (July 2014) Typically exposure to radon and its progeny accounts for half of an individual’s radiation dose, making it the single largest contributor. This radon comes from the ground, with exposure affected by factors such as local geography, building construction, and lifestyle. Radon levels in the air range from about 4 to 20 Bq/m 3. Indoor radon levels have attracted a lot of interest since the 1970s and in USA they average about 55 Bq/m 3, with an EPA action level of 150 Bq/m3. Levels in Scandinavian homes are about double the US average, and those in Australian homes average one fifth of those in USA. Levels up to 100,000 Bq/m 3 have been measured in US homes. In caves open to the public, levels of up to 25,000 Bq/m 3 have been measured.A Japanese study on 3000 residents living in an area with 60 Bq/m 3 radon near Misasa hot springs showed no health difference. The ICRP recommends keeping workplace radon levels below 300 Bq/m 3, equivalent to about 10 mSv/yr.
In the USA, 858 million tonnes of coal was used in 2013 for electricity production. With an average content of 1.3 ppm uranium and 3.2 ppm thorium, US coal-fired electricity generation in that year gave rise to 1100 tonnes of uranium and 2700 tonnes of thorium in coal ash. In Victoria, Australia, some 65 million tonnes of brown coal is burned annually for electricity production. This contains about 1.6 ppm uranium and 3.0-3.5 ppm thorium, hence about 100 tonnes of uranium and 200 tonnes of thorium is buried in landfill each year in the Latrobe Valley.Earlier IAEA recommendations for the classification of exempt waste ( i.e. beneath low-level, and therefore not requiring any special facilities for disposal) are between 10 Bq/g and 1 MBq/g for 'moderate amounts'– depending on the radionuclide in question and the chances of public exposure ( Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, IAEA July 2014), however in practice categorization of waste is strongly determined by where the waste comes from. The list of isotopes that contribute to natural radiation can be divided into those materials which come from the ground (terrestrial sources – the vast majority) and those which are produced as a result of the interaction of atmospheric gases with cosmic rays (cosmogenic).
Exposure to radon is a problem in certain mining activities, notably uranium mining, and good ventilation must be assured so as to keep occupational exposure down, and levels must be monitored. Radioactive materials which occur naturally and where human activities increase the exposure of people to ionising radiation are known by the acronym 'NORM'. The largest producers of tantalum are Australia and Africa, most niobium comes from Brazil. Rare Earth Elements
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Language - this is for primary school-children, and they can wait to use mild profanity like 'Gordon-Flipping-Bennet.' That's very annoying. With increased uranium prices the uranium in ash becomes significant economically. In the 1960s and 1970s, some 1100 tU was recovered from coal ash in the USA.The feasibility depends on grade and the composition of the ash – high acid consumption makes recovery uneconomic. Over the years there have been many occasions when it was asserted that coal-fired power stations emitted more radioactivity into the environment (from NORM) than was released anywhere in the nuclear fuel cycle. While having some basis in fact, the claim is generally not correct now where deployment of emission reduction technology– scrubbers, filters and flue gas desulphurization– acts to capture solids from this material.More volatile Po-210 and Pb-210 still escape. In China, coal-fired power plants are a major source of radioactivity released to the environment and thus contribute significantly to enhanced NORM there. (Wu et al in NORM VII)
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