Annual thorium

Min GR, Edwards RL, Taylor FW, Recy J, Gallup CD, Beck JW (1995) Annual cycles of U/Ca in corals and U/Ca thermometry. Geochim Cosmochim Acta. 59 2025-2042 Moore WS (1981) The thorium isotope content of ocean water. Earth Planet Sci Lett 53 419-426 Moran SB, Hoff JA, Edwards RL, Landing WM (1997) Distribution of Th-230 in the Laborador Sea and its relation to ventilation. Earth Planet Sci Lett 150 151-160 Muhs DR, Simmons KR, Steinke B (2002) Timing and warmth of the Last Interglacial period new U-series evidence from Hawaii and Bermuda and a new fossil compilation for North America. Qrrat Sci Rev 21 1355-1383... 

Total annual intake, in Bq/kg BW, from all sources by a 60-kg person exceeds 66 of lead-210, 166 of polonium-210, 333 of radium-226, 670 of thorium-230, 830 of thorium-228, or 1330 of uranium-238. 

EPA (1984) estimated that about 0.2 Ci of thorium-230 is annually emitted into the air from uranium mill facilities, coal-fired utilities and industrial boilers, phosphate rock processing and wet- process fertilizer production facilities, and other mineral extraction and processing facilities. About 0.084 Ci of thorium-234 from uranium fuel cycle facilities and 0.0003 Ci of thorium-232 from underground uranium mines are emitted into the atmosphere annually (EPA 1984). 

Young WN, Tebrock HA. 1958. The treatment of exposure to thorium and uranium with a chelating agent and supportive measures. Ind Med Surg (Annual Meeting) 27 229-232. 

About one-fifth of our annual exposure to radiation comes from nonnatural sources, primarily medical procedures. Television sets, fallout from nuclear testing, and the coal and nuclear power industries are minor but significant nonnatural sources. Interestingly, the coal industry far outranks the nuclear power industry as a source of radiation. The global combustion of coal annually releases into the atmosphere about 13,000 tons ol radioactive thorium and uranium. Worldwide, the nuclear power industries generate about 10,000 tons of radioactive waste each year. Most of this waste is contained, however, and is not released into the environment. As we explore in Chapter 19, where to bury this contained radioactive waste is a heated issue yet to be resolved. 

NRC has issued an assessment of potential doses to the public associated with the distribution, use, and disposal of exempt products or materials containing low levels of source or byproduct material (Schneider et al., 2001) (see Section 4.1.2.5.2). In a case involving disposal of large volumes of zircon sand produced in processing of zirconium-bearing minerals, the estimated annual dose to a future on-site resident at a disposal site was 100 p.Sv, due to the elevated levels of thorium and uranium. In all other cases, however, the estimated annual dose was substantially less than 10 xSv. Since the volumes of exempt material were large in many cases, this analysis indicates that substantial volumes of waste that contains low levels of radionuclides are potentially exemptible. 

Brunskill GJ, Wilkinson P. 1987. Annual supply of uranium-238, uranium- 234, thorium-230, radium-226, lead-210, polonium-210 and thorium-232 to lake 239 (Experimental Lakes Area, Ontario, (Canada) from terrestrial and atmospheric sources. Can J Fish Aquat Sci 44(Suppl l) 215-230. 

G. van Kaick, A. Karaogjou, A. M. Kellerer (Eds.), Health Effects of Internally Deposited Radionuclides Emphasis on Radium and Thorium, EUR 15877 EN, World Scientific, Singapore, 1995 Standards of Protection against Radiation, Title 10, Code of Federal Regulations, Part 20 (published annually)... 

Koetsier G., Elliott T., and Fruijtier C. (1999) Constrants on diagenetic age disturbance combined uranium-protactinium and uranium-thorium ages of the key Largo Eormation, Florida Keys, USA. 9th Annual V. M. Goldschmidt Conf, pp. 157-158. 

Many Th measurements in the upper ocean indicate that it is mostly dissolved even though thorium is relatively particle-reactive because dissolved thorium grows into secular equilibrium faster than it is depleted by adsorption to particles. To determine an annual particle flux at a given location one would like to sample the ocean at the frequency of the Th half life about one month. This has been done at the Hawaii Ocean Time series (HOT) near Hawaii, and a few of the monthly profiles are presented in Fig. 6.11 (Benitez-Nelson et al, 2001). In this experiment, monthly estimates of the particulate Th flux determined by water column profiles were transformed to carbon fluxes by using measured particulate C Th ratios and compared with the carbon flux from sediment traps. The two different estimates varied by almost a factor of two, with the trap samples being lower. The largest differences were observed during times... 

Table 6.15 summarizes two sources of information on the annual rate of thorium production, by country. The first three columns give the production rate of monazite concentrates for the more recent years of 1976, 1977, and 1978 [El]. We have estimated total thorium production from a typical monazite thorium content of 6 weight percent (w/o). These columns do not include monazite production in the United States or Soviet Union, nor the small production of other thorium minerals. The last two columns give the U.S. Bureau of Mines figures [Ul] for total thorium production in 1973 and an estimate of total thorium production capacity in 1980, if demand were such as to support it. 

The occupational limits for thorium, uranium and some critical decay products are listed in Table 26.1-2. For the chemotoxicity limit of uranium, American and German values for different exposure situations are given. Due to the dominance of the radiotoxicity in the case of thorium, permissible concentration limits are generally based only on the radioactivity. However, former Eastern bloc countries have set a threshold limit for thorium in workroom air (ILO 1980). The annual limit of intake (ALI) will result... 

Acar YB, Gale NJ, Ugaz A, Marks R. (1993). Feasibility of removing uranyl, thorium and radium from kaolinite by electrokinetics. Proceedings of the 19th Annual RREL Hazardous Waste Research Symposium. US Environmental Protection Agency, EPA/600/R-93/040, pp.161-165. 

The evaluated concepts foresee partly different fuel cycles. Rssion reactors can be operated in principle on the basis of eittier a Uranium-Plutonium-cycle or a Thorium-Uranium-cycle, while combinations of these cycles among them or with other reactor concepts than proposed are possible. With t(xja/s nuclear park (comprising mainly LWRs), the world-wide plutonium excess increases annually by about 1001. Besides strategies based on reprocessing like... 

Annual effective doses from ingestion of uranium and thorium radionuclides (UNSCEAR 2000g)... 

---