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Office of Homeland Security & Emergency Coordination
Radiation Safety Division (RSD)
United States Department of Agriculture

Glossary

A

A1
A2
Accelerator Produced Radioactive Material
Activity
Agreement State
ALARA
Alpha
ALI
Analytic X-Ray Equipment
Annual Limit on Intake
ANSI
Ash analysis
Associate User
Atomic Number
AU

B

Background
Baggage and Parcel Inspection Systems
Becquerel (Bq)
Beta
Bioassay
Bone Densitometer
Bremsstrahlung
Bq
Byproduct Material

C

Cabinet X-Ray Equipment
Calibration Source
Chart of Nuclides
Check Source
CFR
Ci
Class - 7
Closeout Survey
Comprehensive Guidance and Requirements
Contained Source
Contamination
Controlled Area
CPM
Curie (Ci)

D

Decay
Decay-in-storage
Declared Pregnant Worker
Decommissioning Survey
Diffractometer
Dose
Dose Equivalent
Dosimeter
Dosimetry
DOT
DPM

E

ECD
Electron
Electron Capture Detector (ECD)
Environmental Protection Agency
Exposure

F

FDA
Field Study
Form-3
Food and Drug Administration

G

Gamma
Gamma Counter
Geiger-Mueller
Giga
GM
Gray (Gy)

H

Half-life
HazMat Labels
Health Physicist
HP
Human Use Study

I – J

Incineration
Ionization
Ionizing Radiation
Irradiator
Isotope
Isotope Room

K – L

Kilo

Lab Survey
Laboratory Cabinet X-Ray Unit
Large Animal
Leak Test
License
Limited Quantity
Liquid Scintillation Counter
Location Radiation Protection Officer (LRPO)
LSC

M

Mass Number
Material License (see license)
Mega
MeV
Micro
Milli
Minimum Detectable Activity (MDA)

N

NaI Detector
Nano
Naturally Occurring Radioactive Materials (NORM)
NCRP
Neutron
NRC
Nuclear Gauge
Nuclear Regulatory Commission
Nuclide
NUREG

O – P – Q

Occupational Dose
Office of Homeland Security and Emergency Coordination (OHSEC)

Permit (Radiation Source Permit)
Permit Holder
Photon
Pico
Portable X-Ray Fluorescence Analyzer (XFA)
Possession Limits
Proton

R

Rad
Radiation Area
Radiation Safety Committee
Radiation Safety Division (RSD)
Radiation Source
Radiation Source Permit (Permit)
Radiation Worker
Radioactive Material License (see license)
Radioactive Decay
Radioactive Material
Radioactive waste
Radioactivity
Radio-isotope
Radio-labeling
Rad-type
RAM
Rem
Responsible User
Restricted Area
RQ - Reportable Quantity
RSC
RSMS
RSO

S

Sealed Source
SI
Sievert (Sv)
Small Animal
Sodium iodide detector
Special Form
Special Use Studies

T

Terra
Ti
TLD
Transport Index
Trefoil
Type-A Package

U – V – W

UN Number
Unsealed Radioactive Materials
Unrestricted Area

Waste
Waste broker
Waste stream

X – Y – Z

X-ray
X-ray Fluorescence Analyzer
X-ray Producing Equipment
X-ray Tube


 

A1

A1 is the activity limit of special form radioactive material that can be packaged and shipped in a Type A package. DOT establishes the A1 value for each radio-isotope. The values of the A1 quantity arise through transport accident conditions with release of the sealed source but no dispersal of its radioactive content. Table of A1 and A2 values

 

A2

A2 is the activity limit of normal form radioactive material that can be packaged and shipped in a Type A package. DOT establishes the A2 value for each radio-isotope. The values of the A2 quantity arise through transport accident conditions with release and dispersal of all of the radioactive content. Table of A1 and A2 values

 

Accelerator Produced Radioactive Material

Radioactive material that has been made radioactive through interactions in a cyclotron or linear accelerator.

 

Activity

Activity is the rate of decay of radioactive material, observed as the emission of radiation particles (alpha, beta, photon, or neutron) from the atomic nucleus, indicating nuclear events. Activity is measured in units of :

  • becquerel (bq),
  • curie (ci), and
  • disintegrations per minute (DPM).

Some conversions factors:

1 becquerel = 1 nuclear disintegration / second.
1 curie = 3.7 x 1010 becquerel.
1 giga-becquerel = 27 milli-curies
1 DPM = 60 becquerel
1 micro-curie = 2,220,000 DPM

 

Agreement States

An agreement state is a state that has entered into an agreement with the Nuclear Regulatory Commission (NRC) giving it authority to regulate radioactive material within its borders, except for nuclear power plants and Federally controlled sites.

 

ALARA

"As Low As is Reasonably Achievable”, a Health Physics philosophical doctrine, to keep radiation doses lower than legal requirements.

 

ALI

"Annual Limit on Intake

 

Alpha

Alpha radiation is a highly ionizing form of particle radiation with a low penetration depth. Alpha particles (named after and denoted by the first letter in the Greek alphabet, α) consist of two protons and two neutrons bound together into a particle, identical to a helium nucleus. Alpha particles are positively charged, and can be deflected by a magnetic field. They can be stopped by a few centimeters of air, a sheet of paper, or by the outer dead layer of skin. When isotopes emitting alpha particle are ingested, they are far more dangerous than their half-life or decay rate would suggest.

 

Analytic X-ray Equipment

Analytic x-ray equipment is used in laboratory settings in research and industry, to make microscopic measurements and examinations of chemical compounds and sample materials on an atomic or nuclear scale. The intense beam of low-energy x-rays produced by analytical x-ray equipment can cause serious injuries. The x-ray fluorescence (spectroscopy) analyzer and the diffractometer are examples of analytic equipment.

 

Annual Limit on Intake

The annual limit on intake is the limit that the NRC places on the amount of radioactive material that a radiation worker can take into their body over the course of a working year. These values have been calculated for several radioisotopes and are listed in …

10 CFR 20 Appendix B Tables , Table 1 ALI values for occupational dose …

The ingestion of one ALI gives a dose of 5 rem. Regulations require that the total external and internal radiation dose to a worker not exceed 5 rem in one year.

 

ANSI

American National Standards Institute

 

Ash analysis

Ash residues remaining after radioactive waste has been incinerated is analyzed to determine radioactive material content. If radioactive materials are detected in the ash, the ash is treated as radioactive waste. If no radioactive materials are detected, the ash can be disposed of using normal ash disposal procedures.

 

Associate User

An associate user is a person listed on the Permit who is authorized to work with radiation sources under the Permit Holder’s supervision. The Permit Holder must be the supervisor of the associate users listed on the Permit.

 

Atomic Number

The protons in the nucleus and the orbiting electrons, hold each other in balance, and are always equal in number. This number is the atomic number. The atomic number identifies each element. Each element has a name, which represents the atomic number. The elements can be numerically organized in the Periodic Table. Because the elements are number variations that fit into slots in this table, we know that they have all been discovered, and that there will not be any new ones, except perhaps, at the very end.

AU

Associate user

 

Background

Background radiation means radiation from cosmic sources; naturally occurring radioactive material, including radon; and global fallout as it exists in the environment from the testing of nuclear explosive devices or from past nuclear accidents.

 

Baggage and Parcel Inspection Systems

X-ray equipment used at airport baggage screening and security points. Security applications range from screening baggage at airports to systems used to inspect trucks entering the United States.

 

Becquerel (Bq)

A unit of activity.

1 becquerel = 1 nuclear disintegration / second.
1 curie = 3.7 x 1010 becquerel
1 giga-Becquerel = 27 milli-Curies

 

Beta

Beta radiation consists of particles of ionizing radiation also known as beta particles or beta rays. Beta particles (named after and denoted by the second letter in the Greek alphabet, β) are high-energy, high-speed electrons emitted by certain types of radioactive nuclei such as potassium (K-40). Beta particles are negatively charged, and can be deflected by a magnetic field. The production of beta particles is termed beta decay. An unstable atomic nucleus with an excess of neutrons may undergo beta decay, where a neutron is converted into a proton and an electron. Although the beta particles given off by different radioactive materials may vary in energy, most beta particles can be stopped by a few millimeters of aluminum.

 

Bioassay

Bioassay (radiobioassay) means the determination of kinds, quantities, and locations of radioactive material in the human body, whether by direct measurement (in vivo counting) or by analysis and evaluation of materials excreted or removed from the human body.

 

Bone Densitometer

A densitometer is a diagnostic x-ray device that measures bone mineral density. It is based on “dual-emission x-ray absorptiometry.” It is also called a DXA scan, (previously known as a DEXA scan). The patient is exposed to two x-ray beams of different energies. When soft tissue absorption is subtracted out, the bone mineral density can be determined. The DXA scan is typically used to diagnose and follow osteoporosis, low bone density. It should not be confused with a bone scan, which diagnoses disorders of the bones such as infections, fractures, or tumors. A DXA scan radiation dose is approximately 50 milli-Rems, which is less than the amount of radiation that one receives on a roundtrip flight from California to New York.

 

Bremsstrahlung

"Braking radiation" is electromagnetic radiation, in the form of x-rays, produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus. Bremsstrahlung has a continuous spectrum, which becomes more intense and shifts toward higher frequencies when the energy of the accelerated particles is increased. Bremsstrahlung is often used in the more narrow sense to describe radiation from beta particles stopped in matter. Bremsstrahlung radiation may be formed if dense material is used to shield a high energy beta-emitter, such a lead shield for Phosphorus (P-32).

Bq

Becquerel

 

Byproduct Material

Byproduct material is material that has become radioactive as a result of fission reactions in a nuclear reactor. Byproduct material is regulated by the Nuclear Regulatory Commission or Agreement States.

 

Cabinet X-ray Equipment

Cabinet x-ray equipment includes laboratory cabinet equipment, and baggage and parcel inspection systems. This type of equipment is typically regarded as low hazard.

 

Calibration Source

A calibration source is a contained source that is exempt from NRC licensing consideration due to its low activity. These sources are typically used to calibrate laboratory gamma or liquid scintillation counters.

 

Chart of Nuclides

A chart of nuclides is a graph in which one axis represents the number of neutrons and the other represents the number of protons in an atomic nucleus. Points are plotted on the graph where real nuclides are known to exist. This system of ordering nuclides offers insight into the characteristics of isotopes.

 

Check Source

A check source is a contained source that is exempt from NRC licensing considerations due to its low activity. This means that such sources will not be tracked on a Permit or other official radioactive inventory. Check sources are typically used to monitor portable survey instrument performance. Although not officially tracked, the control of all exempt check sources is required. Therefore, such sources should not be casually given or thrown away. When maintained for routine use, they should be securely locked in storage. When they are no longer useful, they should be transferred to the manufacturer or a radioactive waste broker.

 

CFR

Code of Federal Regulations

 

Ci

Curie

 

Class – 7

Under DOT rules, class – 7 is the hazardous materials classification for radioactive material.

 

Closeout Survey

A closeout survey is the final survey of a laboratory room or space, listed on a unsealed isotope Permit before removing the room from the Permit, and releasing it from Radiation Safety Division surveillance, for unrestricted use.

 

Comprehensive Guidance and Requirements

The “Comprehensive Guidance and Requirements” are the USDA Radiation Safety Division’s official policy documents specifying the Permit Holder obligations for each of the following rad-types: unsealed isotopes, irradiators, nuclear gauges, ECDs, portable x-ray fluorescent analyzers, and x-ray producing equipment. The RSD “Comprehensive Guidance and Requirements” documents supersede the “Permit Use Conditions.”

 

Contained Source

A contained source is a source containing radioactive materials where the materials are enclosed or contained to prevent dispersion. Examples of contained sources are plastic plates or discs impregnated with radioisotopes, electron capture detector foils, and sealed sources.

 

Contamination

The uncontrolled dispersal of radioactive material where it is unwanted. The contamination potential is greater for radioactive material that is dissolved in a liquid, broken into pieces, or crushed into dust.

 

Controlled Area

An area where access to is limited or controlled by the Permit Holder or location management for reasons of security.

 

CPM

Counts per minute. This is the unit of measurement of a counting detector, before considerations of background, counting efficiency, and geometry.

 

Curie (Ci)

A unit of activity. A Curie is defined as the activity in 1 pure gram of Radium (Ra-226)..

1 curie = 3.7 x 1010 Becquerel
1 giga-Becquerel = 27 milli-Curies

 

Decay

Radioactive decay, a process of spontaneous nuclear transformation in the nucleus of an atom with the subsequent emission of radiation, and change of an unstable nucleus into a more stable isotope or a different element.

 

Decay-in-storage

Decay-in-storage is a method of handling radioactive material that has a short half-life. Radioactive isotopes with a half-life of 120 days or less may be disposed of as non-radioactive waste after being held for decay for at least 10 half lives.

 

Declared Pregnant Worker

A woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception for purposes of radiation dose estimates.

 

Decommissioning Survey

A decommissioning survey certifies that all unsealed radioactive material has been removed from a building and that unsealed radioactive material is no longer being used in the building. A decommissioning survey is conducted by inspectors from the Radiation Safety Division, which involves the review of closeout survey records and radioactive material disposal records, as well as visual inspections, meter surveys, and on-site contamination surveys of the laboratories and storage areas where unsealed radioactive material was used. The decommissioning process verifies and documents that no evidence of any radioactive contamination was found, nor that of any remaining radioactive material or sources, and that all reference warning signs and labels regarding radioactive material have been removed and disposed of. Decommissioning refers to unsealed isotopes and to individual buildings and may not necessarily apply to all work with radioactive material at a given location.

 

Diffractometer

A diffractometer is an instrument for analyzing the structure of a material from the scattering pattern produced when a beam of x-ray radiation interacts with it. This scattered pattern is called diffraction. A diffractometer consists of an x-ray source and a detector. X-ray diffraction yields the atomic structure of materials by the scattering of x-rays through the electrons of the individual atoms in the sample. X-ray scattering techniques can reveal information about the crystallographic structure, chemical composition, and physical properties of materials ranging from simple inorganic solids to complex compounds, such as proteins. A diffractometer can also be used to identify unknown substances, by comparing diffraction data against a database. These x-ray systems are designed for use in a laboratory setting.

 

Dose

Radiation energy deposited in matter. Dose was originally defined in units of rads. Dose is also now defined in units of grays, which is an SI (metric) formulation.

1 gray is equal to a dose of 1 Joule / kilogram
1 gray = 100 rads
1 rad = 10 milli-grays

 

Dose Equivalent

Radiation energy deposited in human tissue, and normalized for the sensitivity of the tissue to different types of radiation. Often, when the normalizing factor is 1, the dose equivalent is the same as dose. Dose equivalent was originally defined in units of rem. Dose equivalent is also now defined in units of sieverts, which is an SI (metric) formulation.

1 sievert is equal to a dose equivalent of 1 Joule / kilogram
1 sievert = 100 rem
1 rem = 10 milli-sievert

 

Dosimeter

A device to determine dose from ionizing radiation.

 

Dosimetry

Dosimetry is the study, measurement, method of measurement, or instrument of measurement of radiation dose. Dosimetry often refers to the personnel badge that people may wear to measure and monitor their dose. It may also refer to the status of wearing such a badge, dose history, or the records where dose history is maintained. More specifically, radiation dosimetry is the calculation of the absorbed dose in tissue resulting from exposure to ionizing radiation. Radiation dose refers to the amount of energy deposited in matter and its biological effect on living tissue, and should not be confused with activity measured in units of curie or becquerel. Exposure to a radioactive source will give a dose which depends on the activity, time of exposure, energy of the radiation emitted, distance from the source, and shielding.

 

DOT

United States Department of Transportation

 

DPM

Disintegrations per minute. This is a unit of activity, derived from detector measurements in CPM. Conversion of CPM to DPM involves consideration of instrument counting efficiency, background, and geometry.

60 DPM = 1 becquerel
1 micro-Curie = 2,220,000 DPM

 

ECD

Electron Capture Detectors

 

Electron

The electron is a subatomic particle with a negative electric charge and a mass that is far smaller than a proton or a neutron. The electron revolves around the nucleus of an atom, in numbers equal to the number of protons in the atomic nucleus, which is also the atomic number. The interaction of electrons among atoms is what forms chemical bonds. The disturbance of electrons in orbit around a nucleus is what causes x-ray radiation. Low energy free electrons are considered ions of charge. However, high-energy, high-speed electrons emitted by certain types of radioactive nuclei such as potassium (K-40) are called beta particles, or beta radiation.

 

Electron Capture Detector (ECD)

An electron capture detector (ECD) is a device used in a gas chromatograph to detect trace amounts of chemical compounds in a sample. Typically, it contains a 10 milli-curie nickel (Ni-63) metal foil.

Chromatography is a set of laboratory techniques for the separation of mixtures. A gas chromatograph is used in analytic chemistry for separating and analyzing compounds that can be vaporized without decomposition. It can measure the purity of a sample or separate the different components of a sample, determining relative amounts. The ECD used in a gas chromatograph detects electron-absorbing samples such as halogen compounds. A radioactive beta emitter, nickel (Ni-63), is a component of an ECD. The beta particles ionize a gas, which causes a background current to flow in the ECD circuitry. If a sample absorbs some of the negative electron ions (a process called ionizing electron capture) the current is reduced. The current fluctuation therefore reveals the presence of the sample components.

Environmental Protection Agency (EPA)

The U.S. Environmental Protection Agency (EPA) is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress. It has the responsibility of maintaining and enforcing national standards under a variety of environmental laws, in consultation with state and local governments. Within the EPA, there is an Office of Air and Radiation.

 

Exposure

A measurement of ionization in air, of x-ray radiation and low to medium energy gamma radiation. Exposure cannot be measured for other kinds of radiation. Units of exposure are given in Roentgens. The concept of exposure is older than dose, and is considered scientifically obsolete; however, it is still often used. The term exposure is sometimes used imprecisely as a synonym for dose.

 

FDA

United States Food and Drug Administration

 

Field Study

A field study using unsealed isotopes involves selectively distributing radioactive material in the environment. A protocol for a special use field study must be reviewed and approved by the RSC, as well as the Nuclear Regulatory Commission (NRC).

Form-3

NRC Form-3 “Notice to Employees” consists of questions and answers about the NRC and its responsibilities, the employee’s responsibilities, and instructions to employees as to how to report safety concerns and violations of NRC rules. At locations where radioactive material is stored or used, this form is required to be prominently posted where employees can see it.

 

Food and Drug Administration

The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services, one of the federal executive departments. The FDA regulates food safety, tobacco products, dietary supplements, prescription and over-the-counter drugs, vaccines, biopharmaceuticals blood transfusions, medical devices, electromagnetic radiation emitting devices, veterinary products, and cosmetics.

 

Gamma

Gamma radiation (named after and denoted by the third letter in the Greek alphabet, γ) is high energy electromagnetic radiation released from an unstable nucleus, as it becomes more stable, after the decaying nucleus has emitted either alpha or beta radiation. This type of radiation is predicted from the electromagnetic theory of radiation. However, such radiation has observed characteristics of particles, like the other kinds of radiation, and is said to consist of photon particles, having neither mass nor electric charge. These highly energetic photons are deeply penetrating and difficult to stop. They can be attenuated by thick layers of material, where stopping power of the material depends mostly on its total mass.

 

Gamma Counter

Standard laboratory equipment that measures gamma radiation emitted by a radionuclide. Samples are placed in vials, that move along a track inside a shielded detector, set to measure specific energy windows characteristic of the particular isotope. Due to the heavy shielding of the detector, a gamma counter often is not portable. In principle, the gamma counter is like a scintillation detector except that a scintillation crystal such as sodium idodide (NaI) surrounds the sample. The gamma rays interact with the crystal, are absorbed, and produce light.

 

Geiger-Mueller detector

A tube that measure activity; it consists of electrodes, filled with a low-pressure inert gas and a halogen gas. The walls of the tube form a cathode while the anode is a wire passing up the center of the tube with a potential difference of several hundred volts, but no current flowing. When ionizing radiation passes through the tube, gas molecules are ionized. The tube's electrodes accelerate the ions towards the cathode and the electrons towards the anode. The ion pairs further ionize the gas, creating an avalanche of charged particles. This results in a short, intense pulse of current which ‘cascades” from the negative electrode to the positive electrode and is measured or counted. These current pulses are processed in a count-rate meter that produces a readout on a scale, and an audible sound. GM measurements do not relate easily to dose-rate. But GM detectors can be calibrated for dose-rate, when working with specific, known isotopes.

 

Giga

Metric prefix, meaning times 1,000,000,000 (billion)

 

GM

Geiger-Mueller detector

 

Gray (Gy)

The SI unit of absorbed dose. One gray is equal to an absorbed dose of 1 Joule / kilogram or 100 rads.

 

Half-life

The time it takes for ½ of a number of unstable atoms to decay. Half-life is a physical property of radioactive isotopes, and is different for each isotope. It can range from seconds to billions of years. It cannot be calculated or predicted, but can only be determined by empirical measurement.

 

HazMat Labels

Hazardous Materials labels are required by the DOT to be placed on Type-A packages containing radioactive material, intended for transport or shipment. Radioactive HazMat labels are white or yellow diamond shaped labels that list radionuclide and activity, and the package transport index.

 

Health Physicist

Radiation Safety Scientist

 

HP

Health Physicist

 

Human Use Study

A human use study involves the uptake of radioactive material in a human subject. A human use protocol must first be reviewed and approved by the US Food and Drug Administration (FDA) Radioactive Drug Research Committee or other Institutional Review Board before it can be submitted to the Radiation Safety Division. The human use application must include an approval from the USDA Human Use Committee.

 

Incineration

Incineration is the disposal of radioactive waste through incineration. An incineration program must be approved according to the NRC guidance “Information Required for Commission Approval of Treatment or disposal by Incineration” dated January 1, 1991. Incinerators must be approved as required by Federal, state, and local authorities.

 

Ionization

The removal of electrons from atoms and molecules. This is a process that can alter chemical properties and chemical reactions.

 

Ionizing Radiation

A classification of radiation harmfulness according to its ability to cause ionization. Radiation with sufficiently high energy can ionize atoms, causing electrons to be stripped (or 'knocked out') from an electron shell, which leaves the atom with a net positive charge. Ionization disrupts chemical bonds, which can damage cells and cellular DNA, as well as generating toxic chemicals which interfere with cellular metabolism.

 

Irradiator

A device used to expose a wide range of samples to gamma radiation for a variety of purposes. The source of the radiation is typically a cobalt (Co-60) or cesium (Cs-137) sealed source. The radioactive source is completely contained in lead shielding, which is an integral part of the irradiator equipment. The activity of the irradiator source can be in the thousands of Curies. Together with the shielding, the irradiators can weigh thousands of pounds.

 

Isotope

A weight variation of atoms of a single element resulting from the different number of neutrons in atoms of the same element. The element name together with the sum of its protons and neutrons identifies the isotope, for example Carbon-14. Isotopes may be radioactive or stable. However, the term isotope is often used to indicate radioactive material.

 

Isotope Room

A room that appears on an unsealed isotope Permit, where unsealed radioactive material may be used or stored, and which is subject to required lab surveys, and which must be tracked by the Radiation Safety Division until a final close-out survey is done.

 

Kilo

Metric prefix, meaning, times 1,000 (thousand)

 

Lab Survey

Evaluation of radiological conditions and potential hazards. Surveys are required when it is reasonable to evaluate a radiological hazard and when necessary to comply with the regulations. Surveys are also used to plan work in areas where radioactive material will be used.

 

Laboratory Cabinet X-ray Unit

A laboratory cabinet x-ray unit is a system with an x-ray tube installed in a shielded enclosure intended to contain the item being irradiated. The enclosure protects people from the area of x-ray exposure. Shielding surrounds the volume exposed to x-rays and the shielding is an inherent part of the system. Cabinet x-ray systems are primarily used for industrial quality control inspections.

 

Large Animal

For purposes of unsealed isotope special use studies, a large animal is a fully grown adult animal with a weight greater than 10 kilo-grams (about 22 pounds).

 

Leak Test

A leak test is a test that consists of rubbing a source, or the surfaces near a source, with filter paper to see if any radioactive material is leaking from the source. In USDA, irradiators, nuclear gauges, electron capture detectors, x-ray fluorescence analyzers, and any other sealed source (except for very small sources, which are exempt) are required to be leak tested every six months. The Radiation Safety Division will provide the Permit Holder with a leak test sheet and a leak test filter paper. The Permit Holder is expected to have the leak test done and returned to RSD for evaluation and reporting results.

 

License

The document issued by the Nuclear Regulatory Commission authorizing the U.S. Department of Agriculture to possess and use radioactive materials at USDA facilities throughout the United States.

 

Limited Quantity

Under DOT rules, a limited quantity of radioactive material means the quantity per package which is excepted from requirements for Type-A packaging, labeling, marking (except for the UN identification number), and shipping papers, provided that

  • the package surface dose-rate does not exceed 0.5 milli-rem / hour;
  • the packaging bears the marking “Radioactive”;
  • the package does not contain fissile material.

The limited quantity can be calculated for each isotope by dividing the A1 values by 1,000 or by dividing the A2 values by 1,000 for solids, and 10,000 for liquids or gasses.

 

Liquid Scintillation Counter

A liquid scintillation counter is standard laboratory equipment for measuring radiation from beta-emitting nuclides. Samples are suspended in a "cocktail" containing a solvent, with small amounts of other additives known as fluors, scintillants, or scintillators. Beta particles emitted from the sample transfer energy to the fluors which then emit light. In this way, each beta emission results in a pulse of light. The samples are placed in small glass or plastic vials that are loaded into the liquid scintillation counter. The counter has photomultiplier tubes which detect the light pulses. Liquid scintillation counters often contain an external standard reference that contains cesium (Cs-137) or radium (Ra-226). These sealed sources are the responsibility of the instrument's manufacturer when the instrument is surplused.

 

Location Radiation Protection Officer (LRPO)

An individual that has been designated to provide advice and assistance regarding the USDA Radiation Safety Program at a location. An LRPO must be designated at locations that have more than one Permit Holder. However, all locations are encouraged to designate an LRPO. There is an LRPO representative on the Radiation Safety Committee.

 

LSC

Liquid scintillation counter

 

Mass Number

The mass number is the sum of the protons and neutrons found in the nucleus of an atom. An isotope is a weight variation of an atom of a single element, and is identified by the element name along with the mass number. The number of neutrons in the nucleus of an isotope can be found by subtracting the atomic number (the number of protons) from the mass number (the number of protons and neutrons).

 

Material License

The document issued by the Nuclear Regulatory Commission authorizing the U.S. Department of Agriculture to possess and use radioactive materials at USDA facilities throughout the United States.

 

Mega

Metric prefix meaning, times1,000,000 (million)

 

MeV

Mega electron volt (1 million electron volts). This is a unit of energy for particle or electromagnetic radiation. For example, (cesium) Cs-137 emits gamma radiation of 0.662 MeV, and (phosphorus) P-32 emits a 1.7 MeV Beta particle

 

Micro

Metric prefix meaning a millionth

 

Milli

Metric prefix meaning a thousandth

 

Minimum Detectable Activity (MDA)

The smallest amount of activity that can be quantified for comparison with regulatory limits.

 

NaI detector

Sodium iodide detector

 

Nano

Metric prefix meaning a billionth

 

Naturally Occurring Radioactive Materials (NORM)

Radioactive materials present in the earth's crust. This includes potassium (K-40), Uranium, Thorium, and Radon.

 

NCRP

National Council on Radiation Protection and Measurements

 

Neutron

The neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons. The number of protons in a nucleus is the atomic number and defines the type of element the atom forms. The number of neutrons is the neutron number and determines the isotope of an element. Neutron radiation is a kind of ionizing radiation which consists of free neutrons. Neutrons may be emitted from any number of different nuclear reactions. Free neutrons readily pass through most material, but interact enough to cause biological damage. Neutron radiation is considered to be the most severe and dangerous radiation available. Neutrons can travel great distances, but can be shielded by hydrogen rich material. The most effective shielding materials are water, polyethylene, paraffin wax, or concrete, where a considerable amount of water molecules are chemically bound to the cement.

 

NRC

United States Nuclear Regulatory Commission

 

Nuclear Gauge

A nuclear gauge (also called a nuclear density gauge, a soil moisture gauge, or a moisture density gauge) is a tool used for civil construction that measures soil density or soil water content. Nuclear gauges are also used for industrial, mining, and scientific purposes. In USDA, nuclear gauges are used for building roads and dams, and for collecting scientific data on soil water content in agricultural and forestry settings. For measuring soil density, a radioactive source emits gamma radiation into soil, and a sensor measures the radiation that is reflected by the soil. The source of the gamma radiation is typically a cesium (Cs-137) sealed source of about 8 to 10 milli-Curies. For measuring water density, the radioactive source emits neutrons and then measures the returning scattered neutrons. The source of the neutron radiation is typically americium (Am-241) source, in combination with the element beryllium, typically a source of about 40 to 50 milli-Curies.

 

Nuclear Regulatory Commission

The Nuclear Regulatory Commission (also called, the NRC) is an independent agency of the US government. It is the Federal regulator of radioactive material, established by the Energy Reorganization Act of 1974, from the United States Atomic Energy Commission, with headquarters located in Rockville, MD.

The NRC:

  • oversees agreement states programs;
  • issues licenses in non-agreement states;
  • regulates all nuclear power plants;
  • issues licenses to Federal agencies in all states.

Numerous special inspection teams, with many different specialties, routinely conduct inspections at various licensee sites, including USDA sites

 

Nuclide

A nuclide is an atomic species characterized by the constitution of its nucleus
Isotopes and elements are nuclides. Nuclides can be graphically represented in a chart of nuclides.

 

NUREG

Nuclear Regulatory Commission (NRC) consolidated guidance about materials licenses, gives detailed information about what information to include when applying for various kinds of NRC licenses. These documents are also helpful in understanding compliance issues with currently operating licenses.

 

Occupational Dose

The dose received by an individual in the course of employment in which the individual's assigned duties involve exposure to radiation.

 

Office of Homeland Security and Emergency Coordination (OHSEC)

OHSEC is the management office for the Radiation Safety Division. It provides Departmental government-wide initiatives pertaining to physical security, emergency programs, personnel and document security, continuity of operations, and continuity of government. OHSEC also provides security management of USDA's Headquarters facilities in the National Capital Region and 24/7 operations center support to USDA national emergency response and program operations. OHSEC also supports the USDA radiation safety program.

 

Permit (Radiation Source Permit)

The document issued by the Radiation Safety Division authorizing a USDA employee to possess and use radioactive materials or x-ray producing equipment at USDA locations.

 

Permit Holder

Any USDA employee whose training and experience have been reviewed and approved by the Radiation Safety Division, who is named on the Permit, and who uses or directly supervises the use of radioactive material or x-ray producing equipment. Only the Permit Holder and the associate users listed on the Permit are authorized to acquire, possess, store, or use radioactive material or x-ray producing equipment.

 

Photon

The existence of gamma and x-ray radiation was predicted from the electromagnetic wave theory of radiation. However, such radiation has observed characteristics of particles and is said to consist of photon particles, having neither mass nor electric charge.

 

Pico

Metric prefix, meaning, trillionth

 

Portable X-Ray Fluorescence Analyzer (XFA)

X-ray fluorescence is the emission of characteristic "secondary" (or fluorescent) x-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in geochemistry, forensic science and archaeology. Portable x-ray fluorescence analyzers should not be confused with analytic laboratory x-ray equipment where the target material being analyzed is usually bombarded by electronically produced x-rays. Portable x-ray fluorescence analyzers may contain one or more radioactive sources that bombard the target with gamma radiation. An XFA may contain one or more of the following radioactive isotopes in quantities up to 50 milli-Curies: Cadmium (Cd-109), Iron (Fe-55), Americium (Am-241).

 

Possession Limits

The possession limit for an unsealed isotope is the amount of radioactive material listed on a Permit, that a Permit Holder is allowed to possess in an active inventory.

 

Proton

The proton is a subatomic particle with a positive electric charge and a mass slightly smaller than that of a neutron. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in a nucleus is the atomic number and defines the type of element the atom forms. Protons do not normally exist free of an atomic structure, since free protons soon pick up an electron and become neutral hydrogen, which may then react chemically.

 

Rad

The conventional unit of absorbed dose. One rad equals an absorbed dose of 0.01 Joule / kilogram or 0.01 gray.

 

Radiation Area

Radiation area means an area, accessible to individuals, in which radiation levels are greater than 5 milli-rem per hour at one foot from the radiation source or from any surface that the radiation penetrates.

 

Radiation Safety Committee (RSC)

The RSC is a policy making committee that meets quarterly, in various places. It is required by the NRC license, and represents USDA agencies using radioactive materials. The RSC establishes policies and reviews program compliance.

 

Radiation Safety Division (RSD)

The Radiation Safety Division is the operational office of the USDA radiation safety program. As a Department level office, it interacts with agencies through Permits that it issues to agency employees. The Radiation Safety Division works with agencies in managing the Permit Holder’s program activities that involve the use of radioactive material and x-ray equipment. The RSD periodically sends inspectors to the Permit Holder locations. RSD also provides guidance and direction regarding radiological emergency preparedness programs through the USDA Office of Homeland Security and Emergency Coordination (OHSEC) and through agency emergency response offices.

 

Radiation Source

A source of ionizing radiation, either from radioactive materials or electronic x-ray equipment.

 

Radiation Source Permit (Permit)

The authorizing document issued by the Radiation Safety Division to allow a USDA employee to possess and use radioactive materials or x-ray producing equipment.

 

Radiation Worker

An individual who, in the course of employment, is assigned duties in a restricted area involving exposure to radiation or radioactive materials.

 

Radioactive Material License (see license)

 

Radioactive Decay

A process of spontaneous nuclear transformation in the nucleus of an atom with the subsequent emission of radiation, and change of an unstable nucleus into a more stable isotope or a different element.

 

Radioactive Material

Matter that emits radiation from the nucleus of its atoms. (from byproduct material)

 

Radioactive Waste

Radioactive waste is what is left over from the use of radioactive materials. During research and chemical analysis, test tubes, bottles, tubing and process equipment come into contact with the radioactive material. This material must be segregated as radioactive waste. If laboratory animals are injected with radioactive material for research purposes, the animal carcasses containing the radioactive material become radioactive waste and must be handled appropriately. Other examples of radioactive waste are contaminated protective clothing and gloves, wiping rags, mops, filters, equipment, and tools. Small quantities of radioactive chemicals which are left over from an experiment, or which are no longer needed can also be classified as radioactive waste.

 

Radioactivity

The emission of radiation from the nucleus of atoms.

 

Radio-Isotope

Any radioactive material.

 

Radio-labeling

Radio-labeling is a technique for tracking the passage of a sample of substance through a system. It is used in chemistry and biochemistry to help understand chemical reactions and interactions. A compound is "labeled" by substituting a radioactive atom of the compound in place of a stable atom of the same element. With this substitution in effect, the radioactive atom will behave in the same way chemically as other like atoms in the compound, and will not interfere with the reaction under investigation. When these radioactive atoms are later detected in a different part of the system, they are known to have come from the originally labeled substance.

 

Rad-type

A business term used in the Radiation Safety Division office to designate different kinds of radiation sources. The RSD rad-types are: unsealed isotopes, irradiators, nuclear gauges, ECDs, portable x-ray fluorescent analyzers, and x-ray producing equipment.

 

RAM

Radioactive material

 

Rem

The conventional unit of dose equivalent. One rem equals a dose equivalent of 0.01 Joule / kilogram or 0.01 sieverts.

 

Responsible User

This is the USDA term, used in the past, for a “Permit Holder.” Other organizations may use similar terms, such as “Principle Investigator.”

 

Restricted Area

An area, access to which is limited by the Permit Holder or by location management for the purpose of protecting individuals from undue risks from exposure to radiation and radioactive materials.

 

RQ - Reportable Quantity

Abbreviated as RQ, the EPA has set transportation threshold activity limits for isotopes that, if exceeded, must be indicated at the end of the Proper Shipping Name, both on the paperwork, and on the exterior of the package. The limit for americium (Am-241) is 10 milli-Curies. Since a moisture density gauge may have an americium (Am-241) source greater than than 10 milli-Curies, the designation, RQ, must sometimes be shown.

 

RSC

Radiation Safety Committee

 

RSMS

Radiation Safety Management System, the RSD web-based database.

 

RSO

Radiation Safety Officer

 

Sealed Source

A contained source that has been constructed and tested to pass specific accident conditions without the release of radioactive material.

 

SI

The French phrase, systeme internationale, which means, international system of weights and measures, previously known as the metric system.

 

Sievert (Sv)

The SI unit of the quantity expressed as dose equivalent. One sievert equals a dose equivalent of 1 Joule / kilogram or 100 rem.

 

Small Animal

For purposes of unsealed isotope general use, a small animal is a fully grown adult animal with a weight not more than 10 kilo-grams (about 22 pounds).

 

Sodium Iodide detector

A common and useful scintillating material, with traces of thallium, that is used as a detector to measures ionizing radiation. The sensor, called a scintillator, consists of a transparent crystal, that fluoresces when struck by ionizing radiation. A photomultiplier tube measures the light from the crystal. The photomultiplier tube is attached to an electronic amplifier and other electronic equipment to count and quantify the amplitude of the signals produced by the photomultiplier. When a charged particle strikes the scintillator, a flash of light is produced. The association of a scintillator and photomultiplier with the counter circuits forms the basis of the scintillation counter apparatus.

 

Special Form

Special form radioactive material is either an indispersible solid radioactive material or a sealed capsule containing radioactive material.

 

Special Use Studies

Special use studies include:

  • Human Use
  • Large Animal Use
  • Field Studies

For unsealed isotopes, a general research protocol is required for routine program activities. Some protocols for special uses of unsealed isotopes require the approval of the USDA Radiation Safely Committee (RSC) as well as approval from other sources.

 

Terra

Metric prefix meaning, times 1,000,000,000,000 (trillion)

 

Ti

Transport index

 

TLD

Thermoluminescent dosimeters

 

Transport Index

The radiation dose-rate in milli-Rem per hour measured at 1 meter from the Type-A package surface, rounded up to the nearest tenth. The Ti appears on the HazMat Yellow-II or Yellow-III label and on the on the Shipper’s Declaration

 

Trefoil

The three-bladed radiation warning symbol. It first appeared at the University of California Radiation Laboratory in Berkeley in 1946, improvised to represent activity radiating from an atom. The color combination of magenta on yellow was first used at Oak Ridge National Lab in 1948. By the late 50s, ANSI standards and federal regulations had codified the version of the warning sign used today. Present regulations also permit the use of black as a substitute for magenta (a deep purple-red).

 

Type-A Package

Type A packaging is packaging that is designed to withstand DOT specified water spray, drop, puncture, and crash tests. A Type-A package is required for shipping radioactive materials when the radioactivity inside the package does not exceed the A1 or A2 values. Type-A packaging, is specified to withstand normal transportation conditions and minor accidents only.

 

UN Number

UN numbers are four-digit numbers that identify hazardous materials in the framework of international transport. In case of a transportation accident involving hazardous material, the UN number provides quick information to emergency responders. UN numbers are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods. They are published as part of their Recommendations on the Transport of Dangerous Goods. These recommendations have been adopted by the US Department of Transportation (DOT).

For a nuclear gauge, the UN number is UN3332. It should appear on the carrying case and transportation papers as: UN3332, class – 7, Radioactive Material, Type A package, special form.

For unsealed isotopes in normal form, shipped in excess of exempt quantities, the UN number is UN2915, It should appear on the Type-A package and transportation papers as: UN2915 class – 7, Radioactive Material, Type A package, non special form

For unsealed isotopes in normal form, shipped in exempt limited quantities, the UN number is UN2910. The package should me marked “radioactive material,” but there is no requirement to list the UN number.

 

Unsealed Radioactive Materials

Radioactive materials that are in a liquid, powder or granular form, and can be easily dispersed through routine laboratory procedures. Unsealed radioactive material (also called isotopes) refers to radioactive chemicals used in laboratory research for their tagging, labeling, tracing, radiation, or decay properties. Unsealed radioactive material is also variously referred to as (radio-) isotopes, (radio-) nuclides, byproduct material, licensed material, or activated material.



Unrestricted Area

An area, access to which is neither limited or controlled by the Permit Holder or by location management.

 

Waste (see radioactive waste)

 

Waste broker

A company that is licensed to transfer radioactive waste to licensed radioactive waste disposal or treatment facilities.

 

Waste stream

Waste with common properties managed in a similar manner is called a waste stream. Radioactive waste should be segregated into an appropriate waste streams for processing and disposal. Some examples of waste streams are: decay-in-storage, sewer disposal, incineration, waste broker transfer.

 

X-rays

X-ray radiation is a form of high frequency electromagnetic radiation, also characterized as high energy photon particles, usually called, x-rays. X-rays are produced when electrons undergo energy level transitions as they orbit the atomic nucleus. Since an x-ray tube can induce this process, x-rays are regarded as electronically produced radiation, which can be generated, controlled, and stopped according to the electrical voltage applied to the x-ray tube.

 

X-ray Fluorescence Analyzer

X-ray fluorescence is the emission of characteristic "secondary" (or fluorescent) x-rays from a material that has been excited by high-energy x-rays or gamma rays. The phenomenon is used in an x-ray fluorescence (spectroscopy) analyzer for chemical analysis, particularly in the investigation of metals, glass, ceramics, and building materials, and for research in geochemistry, forensic science, and archaeology. For laboratory equipment, the target material being analyzed is usually bombarded by electronically produced x-rays. This equipment should not be confused with portable x-ray fluorescent analyzers, which contain radioactive sources.

 

X-ray Producing Equipment

X-ray radiation is a form of high frequency electromagnetic radiation, also characterized as high energy photon particles, usually called, x-rays. X-rays can be electronically produced when an x-ray tube is turned on and electronically activated. Turning the equipment off stops the production of x-rays. X-ray radiation is the same kind of radiation as gamma radiation, but generated by a different process and discovered and named under different circumstances. The two types of radiation are now usually distinguished by their origin: x-rays being electronically produced and emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus as the result of radioactivity. X-rays do not have anything to do with radioactive material; therefore, they are not regulated by the NRC. In USDA, x-ray producing equipment includes a wide range of equipment types such as:

  • Diagnostic equipment
  • Laboratory Cabinet x-ray units
  • Fluorescence analyzer
  • Diffractometer
  • Baggage and parcel inspection systems
  • Bone Densitometers.

X-ray Tube

An x-ray tube is a vacuum tube that produces x-rays. They are used in x-ray machines. The x-ray tube has a cathode, which emits electrons into the glass-enclosed vacuum and an anode to collect the electrons, thus establishing a flow of electrical current, known as the beam, through the tube A high voltage power source, for example 30 to 150 kilovolts (kV), is connected across cathode and anode to accelerate the electrons. Electrons from the cathode collide with the anode material, usually tungsten, molybdenum, or copper, and accelerate other electrons, ions and nuclei within the anode material. About 1% of the energy generated is emitted, usually perpendicular to the path of the electron beam, as x-rays. The rest of the energy is released as heat. The x-ray spectrum depends on the anode material and the accelerating voltage.