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1 Glossary Activity - The rate of disintegration (transformation) or decay of radioactive material. The units of activity are the curie (Ci) and the becquerel (Bq). Source: United States Nuclear Regulatory Commisison Definitions Last revised Wednesday, August 02, 2006 Alpha Particle - One of the particles emitted in radioactive decay. It is identical with the nucleus of the helium atom and consists, therefore, of two protons plus two neutrons bound together. A moving alpha particle is strongly ionizing and so loses energy rapidly in traversing through matter. Natural alpha particles will traverse only a few centimeters of air before coming to rest. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 57th Edition, CRC Press, Boca Raton, Florida (1976). Anion - A negatively charged ion. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 57th Edition, CRC Press, Boca Raton, Florida (1976). Anion exchange resin - An insoluble organic polymer containing cation groups that attract and hold anions present in a surrounding solution in exchange for anions previously held. Source: Answers.com - encyclodictionalmanacapedia Beta Particle - One of the particles which can be emitted by a radioactive atomic nucleus. It has a mass about 1/1837 that of a proton. The negatively charged beta particle is identical with the ordinary electron, while the positively charged type (positron) differs from the electron om having equal but opposite electrical properties. The emission of an electron entails the change of a neutron into a proton inside the nucleus. The emission of a positron is similarly associated with the change of a proton into a neutron. Beta particles have no independent existence inside the nucleus, but are created at the instant of emission. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). Coincidence Summing - A process where the signal from two or more gamma rays emitted by a single decay of a single radionuclide occur within the resolving time of the detector end up being recorded together as a single event so that the recorded event is not representative of the original decay. Typically causes counts to be lost from the full energy peaks, but may also cause addition 1

2 to the full energy peaks. Coincidence summing is a function of the sample-to-detector geometry, and the nuclide's decay scheme. It is not a function of the overall count rate. Source: Canberra Glossary Concentration - The amount of a substance in weight, moles, or equivalents contained in unit volume. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 57th Edition, CRC Press, Boca Raton, Florida (1976). Curie - A unit of radioactivity, equal to the amount of a radioactive isotope that decays at the rate of disintegrations per second. Source: Answers.com encyclodictionalmanacapedia Decay - The spontaneous transformation of one radioactive nuclide into a daughter nuclide, which may be radioactive or may not, with the emission of one or more particles or photons. The decay of N 0 nuclides to give N nuclides after time t is given by N= N 0 exp(-λt), where λ is called the decay constant or the disintegration constant. The reciprocal of the decay constant is the mean life. The time required for half of the original nuclides to decay (i.e., N=½ N 0 ) is called the half-life of the nuclide. The same terms are applied to elemental particles that spontaneously transform into other particles. For example, a free neutron decays into a proton and an electron. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). Decimal multiples and submultiples of SI units: SI prefixes Factor Prefix Symbol Factor Prefix Symbol = (10 3 ) 8 yotta Y 10-1 deci d = (10 3 ) 7 zetta Z 10-2 centi c = (10 3 ) 6 exa E 10-3 = (10 3 ) -1 milli m = (10 3 ) 5 peta P 10-6 = (10 3 ) -2 micro µ = (10 3 ) 4 tera T 10-9 = (10 3 ) -3 nano n 10 9 = (10 3 ) 3 giga G = (10 3 ) -4 pico p 10 6 = (10 3 ) 2 mega M = (10 3 ) -5 femto f 10 3 = (10 3 ) 1 kilo k = (10 3 ) -6 atto a 2

3 Factor Prefix Symbol Factor Prefix Symbol 10 2 hecto h = (10 3 ) -7 zepto z 10 1 deka da = (10 3 ) -8 yocto y Source: Guide for the Use of the International System of Units (SI) NIST Standard Reference Database 146 Inquiries or comments: Feedback Online: May Last update: March 2004 Decay Series or Radioactive Series - (nuclear physics) A succession of nuclides, each of which transforms by radioactive disintegration into the next until a stable nuclide results. Also known as decay chain; decay family; decay series; disintegration chain; disintegration family; disintegration series; radioactive chain; radioactive decay series; series decay; transformation series. Source: Answers.com encyclodictionalmanacapedia U-238 SERIES Uranium 238 (percent abundance = 99.27%) Half-life: 4.49 x 10 9 years Bone and kidney, chemical toxicity probably more important due to its low specific activity. Radiotoxicity of 238 U about the same as 234 U. EPA method for total Uranium. Also EPA method 908.1, fluorometric. Soluble complexes are formed under oxidizing conditions especially when carbonates are present. Secondary enrichment can occur when reducing conditions cause the uranium to precipitate out. This leads to elevated 226 Ra. 238 U, 234 Th, 234 U, and 230 Th usually behave as a group. Thorium 234 half-life: 24.1 days 3

4 Relatively short half-life allows it to decay in place before being taken up by the bones. Extremely insoluble. Thorium may be more soluble in the presence of high concentrations of organic material. Carbonate aquifers, Basaltic aquifers, and quartise/sandstone aquifers have low thorium concentrations. May end up in solution via alpha recoil. Protactinium 234 half-life: 1.18 minutes Uranium 234 (percent abundance =.006%) half-life: 2.48 x 10 5 years Bone and kidney, chemical toxicity probably more important due to its low specific activity. Radiotoxicity of 238 U about the same as 234 U. EPA method for total Uranium. Also EPA method 908.1, fluorometric. Soluble complexes are formed under oxidizing conditions especially when carbonates are present. Secondary enrichment can occur when reducing conditions cause the uranium to precipitate out. This leads to elevated 226 Ra. 238 U, 234 Th, 234 U, and 230 Th usually behave as a group. Thorium 230 half-life: 8.0 x 10 4 years The long half-life of this isotope makes it a possible concern, activity is probably higher than that of 232 Th due to alpha recoil. Bone seeker. EPA tentative method Extremely insoluble. Higher natural abundance than uranium, thus in the absence of secondary enrichment of uranium, 228 Ra (progeny of 232 Th) can be higher than 4

5 226 Ra. Thorium may be more soluble in the presence of high concentrations of organic material. Carbonate aquifers, Baslatic aquifers, and quartise/sandstone aquifers have low thorium concentrations. May end up in solution via alpha recoil. Radium 226 half-life: 1622 years bone sarcomas and head carcinomas EPA method Little relationship between levels of 222 Rn and 226 Ra. Radium does not form any soluble complexes. Alpha recoil can enhance 226 Ra concentrations in water. Radon 222 half-life: 3.82 days Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer. EPA tentative method Little relationship between levels of 222 Rn and 226 Ra. Granite aquifers have the highest radon concentrations. Radon is chemically inert and is not transported great distances from its source. Polonium 218 half-life: 3.05 minutes Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer. The immediate progeny of 222 Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away. Lead 214 5

6 half-life: 26.8 minutes Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer. The immediate progeny of 222 Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away. Bismuth 214 half-life: 19.7 minutes Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer. The immediate progeny of 222 Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away. Polonium 214 half-life: 1.6 x 10-4 seconds Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer. The immediate progeny of 222 Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away. Lead 210 6

7 half-life: 22 years Accumulates in the bone, its short-lived progeny, 210 Bi then decays in place. It's a beta emitter, thus reducing its dose. EML/HASL method Pb-01. Large concentrations of Rn in water could lead to detectable levels of 210 Pb. Lead 210 may become regulated in the future. Bismuth 210 half-life: 5.0 days 210 Pb accumulate in the bone, its short-lived progeny, 210 Bi then decays in place. It's a beta emitter, thus reducing its dose. Polonium 210 half-life: days The long half-life of this isotope makes it a possible concern, distributed in soft tissues as well as the bones. EML/HASL method Po-01 and Po-02 Large concentrations of 222 Rn could lead to detectable levels of 210 Po. In systems that have elevated 210 Po, 222 Rn is also elevated. In situations where 222 Rn is elevated and there is no 210 Po, it is believed to be due to adsorption of both the 210 Pb and 210 Po. Elevated 210 Po is associated with significant sulfide concentrations and ph's around 6. Polonium 210 may become regulated in the future. TH-232 SERIES Thorium 232 half-life: 1.39 x years 7

8 The long half-life of this isotope makes it a possible concern, although due to alpha recoil the activity of 230 Th is probably higher. EPA tentative method Extremely insoluble. Higher natural abundance than uranium, thus in the absence of secondary enrichment of uranium, 228 Ra (progeny of 232 Th) can be higher than 226 Ra. Thorium may be more soluble in the presence of high concentrations of organic material. Carbonate aquifers, Baslatic aquifers, and quartise/sandstone aquifers have low thorium concentrations. Radium 228 half-life: 5.75 years Two to three times more radiotoxic than 226 Ra. EPA method Radium does not form any soluble complexes. Since the percent abundance of thorium is higher than that of uranium, 228 Ra can be greater than 226 Ra Actinium 228 half-life: 6.13 hours Radium 228 is determined by measuring 228 Ac and then back calculating to 228 Ra. Reaches secular equilibrium in six hours. Thorium 228 half-life: 1.9 years EPA tentative method Extremely insoluble. Higher natural abundance than uranium, thus in the absence of secondary enrichment of uranium, 228 Ra (progeny of 232 Th) can be higher than 226 Ra. Thorium may be more soluble in the presence of high concentrations of organic material. Carbonate aquifers, Baslatic aquifers, and quartise/sandstone aquifers have low thorium concentrations. May end up in solution via alpha recoil. 8

9 Radium 224 half-life: 3.64 days Radiotoxicity is believed to be small because of the short half of 224 Ra and progeny. EPA method Measures all alpha emitting radium isotopes. New Jersey method is specific for 224 Ra. Activity is often equal to two times greater than 228 Ra. Since the parent is thorium the 224 Ra activity is usually unsupported, 224 Ra/ 228 Ra ratios greater than one are probably due to alpha recoil. This isotope may become regulated in the future. Should look at systems with high 228 Ra. If 224 Ra is present in the water supply the alpha activity may vary depending on when the sample is analyzed.> Radon 220 half-life: 54.5 seconds Decays through a series of short lived alpha emitting progeny, so it would have similar health consequences as 222 Rn if it were present. Can be mathematically calculated by doing the New Jersey method for 224 Ra. Radon is chemically inert and is not transported great distances from its source. Polonium 216 half-life: seconds Can be mathematically calculated by doing the New Jersey method for 224 Ra. Lead 212 half-life: 10.6 hours 9

10 Can be mathematically calculated by doing the New Jersey method for 224 Ra. Bismuth 212 half-life: 60.5 minutes Can be mathematically calculated by doing the New Jersey method for 224 Ra. Polonium 212 half-life: 3.1 x 10-7 seconds Uranium 235 SERIES Uranium 235 (percent abundance = 0.72%) half-life 7.13 x 10 8 years Bone and kidney, chemical toxicity probably more important due to its low specific activity. Radiotoxicity of 238 U about the same as 234 U. EPA method for total Uranium. Also EPA method 908.1, fluorometric. Soluble complexes are formed under oxidizing conditions especially when carbonates are present. Secondary enrichment can occur when reducing conditions cause the uranium to precipitate out. This leads to elevated 226 Ra. 238 U, 234 Th, 234 U, and 230 Th usually behave as a group. Thorium 231 half-life 25.6 hours 10

11 Extremely insoluble. Protactinium 231 half-life 3.43 x 10 4 years Actinium 227 half-life 22.0 years Thorium 227 half-life 18.6 days Radium 223 half-life 11.1 days Radiotoxicity is believed to be small because of the short half of 223 Ra and progeny 11

12 EPA method Measures all alpha emitting radium isotopes. Radon 219 half-life 3.92 seconds Polonium 215 half-life 1.83 x 10-3 seconds Lead 211 half-life 36.1 minutes Bismuth 211 half-life 2.16 minutes 12

13 Thallium 207 half-life 4.79 minutes Neptunium SERIES activities from series members are insignificant due to the extremely low concentrations of 237 Np found in nature. Source: Wisconsin State Laboratory of Hygiene Environmental Health Division Radiochemistry Unit - Decay Chains for Naturally Occurring Isotopes Dose / Exposure Units Roentgen (R) The roentgen is a unit used to measure a quantity called exposure. This can only be used to describe an amount of gamma and X-rays, and only in air. One roentgen is equal to depositing in dry air enough energy to cause 2.58E-4 coulombs per kg. It is a measure of the ionizations of the molecules in a mass of air. The main advantage of this unit is that it is easy to measure directly, but it is limited because it is only for deposition in air, and only for gamma and x rays. Rad (radiation absorbed dose) The rad is a unit used to measure a quantity called absorbed dose. This relates to the amount of energy actually absorbed in some material, and is used for any type of radiation and any material. One rad is defined as the absorption of 100 ergs per gram of material. The unit rad can be used for any type of radiation, but it does not describe the biological effects of the different radiations. Rem (roentgen equivalent man) The rem is a unit used to derive a quantity called equivalent dose. This relates the absorbed dose in human tissue to the effective biological damage of the radiation. Not all radiation has the same biological effect, even for the same amount of absorbed dose. Equivalent dose is often expressed in terms of thousandths of a rem, or mrem. To determine equivalent dose (rem), you multiply absorbed dose (rad) by a quality factor (Q) that is unique to the type of incident radiation. 13

14 Source: Idaho State University - Radiation Related terms This page will be updated periodically. Last update : 11/25/2006 Electron-volt (symbol ev) A unit of energy equal to the work done on an electron in moving it through a potential difference of one volt. It is used as a measure of particle energies although it is not an SI unit. 1 ev = X joule Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). Gamma Ray - A photon or high-energy quantum emitted from the nucleus of a radioactive atom. Gamma rays are the most penetrating of the three common types of radiation (the other two are alpha particles and beta particles) and are best stopped by dense materials such as lead. Source: Canberra Glossary Gram - One thousandth of a kilogram. The gram is the fundamental unit of mass in c.g.s units and was formerly used in such units as the gram-atom, gram-molecule, and gram-equivalent weight, which have now been replaced by the mole. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). Gravimetric - Of or relating to measurement by weight. Source: Answers.com encyclodictionalmanacapedia Half-life - The time required for half of the nuclei in a sample of a specific isotopic species to undergo radioactive decay. Source: Answers.com encyclodictionalmanacapedia 14

15 Ingrowth the production of progeny due to the decay of the parent Source: Wisconsin State Laboratory of Hygiene Ionizing Radiation has many practical uses, but it is also dangerous to human health. Both aspects are discussed below. Ionizing radiation is either particle radiation or electromagnetic radiation in which an individual particle/photon carries enough energy to ionize an atom or molecule by completely removing an electron from its orbit. If the individual particles do not carry this amount of energy, it is impossible for even a large flood of particles to cause ionization. These ionizations, if enough occur, can be very destructive to living tissue, and can cause DNA damage and mutations. Examples of particle radiation that are ionizing may be energetic electrons, neutrons, atomic ions or photons. Electromagnetic radiation can cause ionization if the energy per photon, or frequency, is high enough, and thus the wavelength is short enough. The amount of energy required varies between molecules being ionized. X-rays, and gamma rays will ionize almost any molecule or atom; Far ultraviolet, near ultraviolet and visible light are ionizing to some molecules; microwaves and radio waves are non-ionizing radiation. Source: From Wikipedia, the free encyclopedia Isotope - (1) One of several nuclides having the same number of protons in their nuclei, and hence belonging to the same element, but differing in the number of neutrons and therefore in 15

16 mass number A, or in energy content (isomers). For example 12 6C, 13 6C, and 14 6C are carbon isotopes. Small quantitative differences in chemical properties exist between isotopes or orientation. Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). Isotopic tracer - An isotopic tracer, (also "isotopic marker" or "isotopic label"), is used in chemistry and biochemistry to help understand chemical reactions and interactions. In this technique, one or more of the atoms of the molecule of interest is substituted for an atom of the same element, but of a different (often radioactive) isotope. Because the atom has the same number of protons, it will behave in almost exactly the same way chemically as other atoms in the compound, and with few exceptions will not interfere with the reaction under investigation. The difference in the number of neutrons, however, means that it can be detected separately from the other atoms of the same element. Mass spectrometry can also be used with this technique, since mass spectra recorded with sufficiently high resolution can distinguish among isotopes based on the different masses resulting from the different number of neutrons. Source: Answers.com encyclodictionalmanacapedia Natural abundance - The relative abundance of an isotope in nature compared to other isotopes of the same element is relatively constant. The Chart of the Nuclides presents the relative abundance of the naturally occurring isotopes of an element in units of atom percent. Atom percent is the percentage of the atoms of an element that are of a particular isotope. Atom percent is abbreviated as a/o. Source: Nuclear Power Fundamentals Integrated Publishing P.O. Box 129 Port Richey, FL USA Nuclide - A species of atom distinguished by the constitution of its nucleus. The nuclear constitution is specified by the number of protons, Z; number of neutrons, N; and energy content. (Or, by the atomic number, Z; mass number A(= N + Z) and atomic mass). Source: Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). 16

17 Picocurie - One trillionth (10-12 ) of a curie. Planchet - A small shallow metal container in which a radioactive substance is deposited for measurement of its activity Source: Answers.com encyclodictionalmanacapedia Precipitation - The process of separating a substance from a solution as a solid. Source: Answers.com encyclodictionalmanacapedia Radioactivity - The spontaneous disintegration of certain atomic nuclei accompanied by the emission of alpha-particles (helium nuclei), beta-particles (electrons), or gamma-radiation (shortwave electromagnetic waves). Natural radioactivity is the result of the spontaneous disintegration of naturally occurring radioisotopes: most radioisotopes can be arranged in three radioactive series. The rate of disintegration is uninfluenced by chemical changes or any normal changes in their environment. However, radioactivity can be induced in many nuclides by bombarding then with neutrons or other particles. Adapted From:Weast, R. C., CRC Handbook of Chemistry and Physics, 70th Edition, CRC Press, Boca Raton, Florida (1990). Random Summing - A process where the signal from two or more separate decays of the same radionuclide or different radionuclides that occur within the resolving time of the detector end up being recorded together as a single event so that the recorded event is not representative of the original decays. Typically causes counts to be lost from the full energy peaks. Random summing is a function of the overall count rate, or the activity of the sample being measured. Source: Canberra Glossary Resolution The ability of a spectroscopy system to differentiate between two peaks that are close together in energy. Thus, the narrower the peak, the better the resolution capability. Measured as FWHM. Source: Canberra Glossary Self Absorption Absorption of the photons emitted by the radioactive nuclides in the sample by the sample material itself. Source: Canberra Glossary 17

18 Shielding Reduction of radiation by interposing a shield of absorbing material between any radioactive source and a person, work area, or radiation-sensitive device. Source: United States Nuclear Regulatory Commisison Last revised Monday, June 23, 2003 Spectrometer - An instrument which separates radiation into energy bands (or, in a mass spectrometer, particles into mass groups) and indicates the relative intensities in each band or group. See, for example, Figure 2. Source: EP-95 ON THE MOON WITH APOLLO 16 18