thorium concentration average

Th – Thorium - GTK

Th – Thorium Introduction Thorium is a member of the actinide series of elements, along with U and the human-made elements such as Pu. The element has an atomic number of 90, an atomic mass of 232, one main oxidation state (+4) and one naturally occurring isotope (232Th). Like U, …

Thorium - World Nuclear Association

The most common source of thorium is the rare earth phosphate mineral, monazite, which contains up to about 12% thorium phosphate, but 6-7% on average. Monazite is found in igneous and other rocks but the richest concentrations are in placer deposits, concentrated by wave and current action with other heavy minerals. ...

Concentrations of uranium and thorium isotopes in uranium ...

The alpha-emitting isotopes of uranium and thorium were determined in the lungs of 14 former uranium miners and in soft tissues and bones of three miners and two millers. These radionuclides were also determined in soft tissues and bones of seven normal controls. The average concentrations in pCi/kg ...

Concentration levels of radon in mines, industries and ...

While the concentration of thorium-232 in the environment are comparable or higher than that of uranium-238, the relatively shorter half-life (56 seconds) of radon-220 compared to radon-222 with half-life (3.82 days), makes radon- ... This means that the average radon concentration levels and effective exposure doses to the entire population ...

Thorium and uranium isotopes in seawater and sediments ...

The procedure used for determining the laboratory chemical efficiency for the extraction of thorium is discussed below. The uranium isotopic ratios were obtained by alpha spectroscopy [4] from THORIUM AND URANIUM ISOTOPES IN SEAWATER AND SEDIMENTS 103 isolates of this first portion and the data are presented in table 1.

Magnesium-Thorium Alloy (ca. 1980s)

Mag-thor has had a variety of applications (e.g., in missiles, spacecraft, tanks), but its primary use is in the manufacture of aircraft parts, especially engines. According to NUREG-1717, the average concentration of thorium in these alloys was about 1.7%.

TENORM Policy Revision Draft Overview - colorado.gov

(2) The tailings or wastes produced by the extraction or concentration of uranium or thorium from ore processed primarily for its source material content, including discrete surface wastes resulting from uranium or thorium solution extraction processes (underground ore bodies depleted by

The thorium, uranium and zirconium concentrations in ...

The Thorium, Uranium and Zirconium Concentrations in Bauxites and Their ... Concentration of thorium and uranium during the processing of bauxite 35 Radioactivity of aluminum metal 40 ... contain greater amounts of thorium and uranium than the average crustal rocks. The …

Toxicological Profile for Thorium - Agency for Toxic ...

Thorium Isotopic Concentration in Three Occupational Cases and the General Population of ... ATSDR's Toxicological Profile for Thorium was released in 1990. In order to update the literature in this ... an average thorium lung burden of 0.30 Bq (8.11 pCi) …

NRC: 10 CFR Appendix B to Part 20--Annual Limits on Intake ...

Nov 01, 2018· The monthly average concentrations for release to sanitary sewers are applicable to the provisions in § 20.2003. The concentration values were derived by taking the most restrictive occupational stochastic oral ingestion ALI and dividing by 7.3 x 10 6 (ml).

Occurrence of thorium - Wikipedia

Thorium is found in small amounts in most rocks and soils.Soil commonly contains an average of around 6 parts per million (ppm) of thorium. Thorium occurs in several minerals including thorite (ThSiO 4), thorianite (ThO 2 + UO 2) and monazite.Thorianite is a rare mineral and may contain up to about 12% thorium …

Uranium (U) Toxicity: What are the Standards and ...

May 06, 2009· A TWA is the "average" exposure in any 8-hour work shift of a 40-hour work week. The PEL is the TWA concentration to which it is believed that nearly all workers may be repeatedly exposed, day after day, without adverse effect.

Radiometric Map of Australia provides new insights into ...

In Australia, the airborne-measured average concentration of uranium in exposed regolith and bedrock (to a depth of around 30 centimetres) based on the new radioelement data is 1.1 ppm. Uranium occurs in two main valence states: U 4+ and U 6+.

NUCLEAR REGULATORY COMMISSION - westvalleyfactsofwny.org

The average activity concentration of radioactive material that may be buried under this option in the case of natural thorium (Th-232 plus Th-228) is 50 pCi/gm, if all daughters are present and in equilibrium; for enriched uranium it is 100 pCi/gm if the uranium is soluble and 250 pCi/gm if insoluble; for depleted uranium it is 100 pCi/gm if ...

Atlas of Natural Radiation - REMon - European Commission

Data of Thorium concentration in rock samples have been collected from scientific literature. These data have been used to estimate the average value of Thorium concentration in bedrock for each geological unit. This map has been developed on a country-by-country basis and could easily be improved if more data were made available.

MINERAL MAKEUP OF SEAWATER - web.stanford.edu

ELEMENT: MOLECULAR WEIGHT: PPM IN SEAWATER: MOLAR CONCENTRATION: Chloride: 35.4: 18980: 0.536158: Sodium: 23: 10561: 0.459174: Magnesium: 24.3: 1272: 0.052346: Sulfur ...

Uranium-238 and thorium-232 series concentrations in soil ...

On the other hand, taking into account that uranium and thorium are always present in soil, their gamma radiation causes external exposures with the consequent absorbed doses. Radon gas accumulates in indoor air. The average dose that many populations receive …

6 EQUATIONS OF RADIOACTIVE DECAY AND GROWTH

6.6 RADIOACTIVE DECAY SERIES If a radioactive nuclide is situated in the Chart of Nuclides far from the stability line (for the light elements at Z=N), the daughter nucleus after radioactive decay may be radioactive as well. In nature this occurs with the heavy nuclides in the uranium and thorium decay series (Chapter 12).

Determination of thorium, uranium, and potassium elemental ...

A comprehensive study was conducted to determine thorium, uranium and potassium elemental concentrations in surface soils throughout the accessible area of Cyprus using high-resolution γ−ray spectrometry. A total of 115 soil samples was collected from all over the bedrock surface of the island based on the different lithological units

Original Scientific Paper Precipitation and Hydrolysis of ...

concentration of the precipitation components influence the formation of various complexes. In this work the effect of pH upon the formation of precipitates in the system thorium nitrate—ammonium oxalate has been investigated keeping the concentration of thorium nitrate constant (1.25 mM) while syste-

Experimental studies of thorium ion implantation from ...

The average thorium concentration in the subsurface area determined by the mean Laser Phys. Lett. 15 ... It can be seen from the figure that the thorium concentration in the subsurface area concerned increases as the number of laser pulses increases, while the Th4f-line position does not change.

Determination of Radium-228 in Natural Waters

a thorium-rich area, and the amount of radium-228, as expected, was considerably greater in the Brazilian samples than in the United States samples. The average concentration of radium-228 in the Brazilian foods was about 10 times that of radium-228 in the American foods. The Ra22S/Th228 in biological materials was al­

Radionuclides in the Ocean - seawater, sea, depth, oceans ...

Radioactivity in the Ocean The partial inventory of natural radionuclides in sea water in Table 1 (see page 22) amounts to 1–2 × 10 22 Bq, without including the uranium daughters or the 232 Th series nuclides. Human-made nuclides in the ocean have been estimated to be 85 × 10 15 Bq directly dumped, 1.5 × 10 18 Bq from fallout, and 1 × 10 17 Bq from reprocessing plant effluent.

Thorium - Wikipedia

Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately hard, malleable, and has a high melting point.

Economics of Thorium and Uranium Reactors - …

Economics of Thorium and Uranium Reactors. In February 2012, the Nuclear Regulatory Commission (NRC) approved a license for two new nuclear reactors in Georgia. This was the first time a new nuclear reactor has been commissioned since 1978. 1. The reactor to be used is the AP1000 built by Westinghouse, a 1154 MWe

Uranium and Thorium Determination in Water Samples …

Uranium and Thorium Determination in Water Samples Taken along River Kura 82 Uranium and thorium was determined at the mass numbers of 238 and 232 respectively using Bi-209 as internal standard. The main purpose of the study is to measure the level of uranium and thorium in water samples taken along river Kura. 2. Materials and Methods