The non-fixed contamination on the accessible surface averaged over 300 cm2 (or the area of the surface if less than 300 cm2) does not exceed 400 Bq/cm2 (10 -2 microcurie/cm2) for beta and gamma and low toxicity alpha emitters, or 40 Bq/cm2 (10 -3 microcurie/cm2) for all other alpha emitters.
The fixed contamination on the accessible surface averaged over 300 cm2 (or the area of the surface if less than 300 cm2) does not exceed 8x105 Bq/cm2 (20 microcurie/cm2) for beta and gamma and low toxicity alpha emitters, or 8x104 Bq/cm2 (2 microcurie/cm2) for all other alpha emitters.
The non-fixed contamination plus the fixed contamination on the inaccessible surface averaged over 300 cm2 (or the area of the surface if less than 300 cm2) does not exceed 8x105 Bq/cm2 (20 microcurie/cm2) for beta and gamma and low toxicity alpha emitters, or 8x104 Bq/cm2 (2 microcurie/cm2) for all other alpha emitters.
"Sealed source" means any radioactive material that is encased in a capsule designed to prevent leakage or escape of the radioactive material.
"Sealed Source and Device Registry" or "SSDR" means the national registry that contains all the registration certificates, maintained by the NRC that summarize the radiation safety information for the sealed sources and devices and describe the licensing and use conditions approved for the product.
"Secondary dose monitoring system" means a system that will terminate irradiation in the event of failure of the primary dose monitoring system.
"Secondary protective barrier" means the material that attenuates stray radiation.
"Self-contained breathing apparatus" or "SCBA" means an atmosphere-supplying respirator for which the breathing air source is designed to be carried by the user.
"Shadow tray" means a device attached to the radiation head to support auxiliary beam blocking material.
"Shallow dose equivalent" or "Hs" means the dose equivalent at a tissue depth of 0.007 centimeter (7 mg/cm2). "Shallow dose equivalent" applies to the external exposure of the skin of the whole body or the skin of an extremity.
"SI" means the abbreviation for the International System of Units.
"Shielded position" means the location within the radiographic exposure device, source changer or storage container that, by manufacturer's design, is the proper location for storage of the sealed source.
"Shutter" means a device attached to the tube housing assembly which may totally intercept the useful beam and which has a lead equivalency not less than that of the tube housing assembly.
"Sievert" or "Sv" means the SI unit of dose equivalent. The unit of dose equivalent is the joule per kilogram. The special unit of dose equivalent (rem) is being replaced by the sievert. 1 Sv=100 rem.
"Single tomogram system" means a CT x-ray system which obtains x-ray transmission data during a scan to produce a single tomogram.
"Site area emergency" means an event may occur, is in progress, or has occurred that could lead to a significant release of radioactive material and require a response by offsite response organizations to protect people offsite.
"Site boundary" means that line beyond which the land or property is not owned, leased or otherwise controlled by the licensee or registrant.
"Source" means the region and material from which the radiation emanates.
"Source applicator" means a device used to place a radioactive source in a precise anatomical location within the body.
"Source assembly" means an assembly that consists of the sealed source and a connector that attaches the source to the control cable. The source assembly may include a ballstop to secure the source in the shielded position.
"Source changer" means a device designed and used for replacement of sealed sources in radiographic exposure devices and which may also be used for transporting and storing sealed sources.
"Source holder" means a housing or assembly into which a radioactive source is placed to facilitate the handling and use of the source in well logging operations.
"Source-image receptor distance" or "SID" means the distance from the source of radiation to the center of the input surface of the image receptor.
Uranium or thorium, or any combination thereof, in any physical or chemical form.
Ores that contain by weight one-twentieth of one percent or more of uranium, thorium or any combination of uranium and thorium. Source material does not include special nuclear material.
"Special form radioactive material" means radioactive material that satisfies all the following conditions:
It is either a single solid piece or is contained in a sealed capsule that may be opened only by destroying the capsule.
The piece or capsule has at least one dimension not less than 5 millimeters (0.2 in.).
"Special nuclear material" means plutonium, uranium 233, uranium enriched in the isotope 233 or in the isotope 235, and any other material which the nuclear regulatory commission determines to be special nuclear material; or any material artificially enriched by any of the foregoing. Special nuclear material does not include source material.
"Special nuclear material in quantities not sufficient to form a critical mass" means uranium enriched in the isotope U-235 in quantities not exceeding 350 grams of contained U-235; uranium-233 in quantities not exceeding 200 grams; plutonium in quantities not exceeding 200 grams; or any combination of them under the following formula: For each kind of special nuclear material, determine the ratio between the quantity of that special nuclear material and the quantity specified above for the same kind of special nuclear material. The sum of such ratios for all of the kinds of special nuclear material in combination may not exceed one.
DHS 157.03 Note
Note: For example, the following quantities in combination would not exceed the limitation and are within the formula:
DHS 157.03 Note
175 (grams contained U-235) + 50 (grams U-233) + 50 (grams Pu) = 1
DHS 157.03 Note
350 200 200
"Special unit" means the alternative system of units for quantifying absorbed dose in rad, dose equivalent in rem and radioactivity in curie.
"Specific activity" of a radionuclide means the radioactivity of the radionuclide per unit mass of that nuclide. The specific activity of a material in which the radionuclide is essentially uniformly distributed is the radioactivity per unit mass of the material.
"Specific license" means a license, under requirements prescribed by the department by rule, to possess, use, manufacture, produce, transfer or acquire radioactive material or devices or equipment utilizing radioactive material.
"Spot film" means a radiograph, which is made during a fluoroscopic examination to permanently record conditions that exist during that fluoroscopic procedure.
"Spot-film device" means a device intended to transport and position a radiographic image receptor between an x-ray source and fluoroscopic image receptor. It includes a device intended to hold a cassette over the input end of an image intensifier for the purpose of making a radiograph.
"Stationary beam radiation therapy" means radiation therapy without displacement of one or more mechanical axes relative to the patient during irradiation.
"Stationary x-ray equipment" means x-ray equipment that is installed in a fixed location.
"Stereotactic radiosurgery" means the use of external radiation in conjunction with a stereotactic guidance device to deliver a dose to a tissue volume from multiple sources of radiation simultaneously.
"Stochastic effect" means a health effect that occurs randomly and for which the probability of the effect occurring, rather than its severity, is assumed to be a linear function of dose without threshold. Hereditary effects and cancer incidence are examples of stochastic effects.
"Storage area" means any secure location, facility or vehicle that is used to store and secure a radiographic exposure device, a radiation machine, a storage container or a sealed source, when it is not in use.
"Storage container" means a device in which sealed sources or radiation machines are secured and stored.
"Stray radiation" means the sum of leakage and scattered radiation.
"Structured educational program" means an educational program designed to impart particular knowledge and practical education through interrelated studies and supervised training.
"S-tube" means a tube through which the radioactive source travels when inside a radiographic exposure device.
"Subsurface tracer study" means the release of a substance tagged with radioactive material to trace the movement or position of the tagged substance in the well-bore or adjacent formation.
"Supplied-air respirator" or "SAR" means an atmosphere-supplying respirator for which the source of breathing air is not designed to be carried by the user.
"Surface casing for protecting fresh water aquifers" means a pipe or tube used as a lining in a well to isolate fresh water aquifers from the well.
"Surface contaminated object" or "SCO" means a solid object that is not itself classed as radioactive material, but which has radioactive material distributed on any of its surfaces.
"Survey" means an evaluation of the radiological conditions and potential hazards incident to the production, use, transfer, release, disposal or presence of sources of radiation. When appropriate, an evaluation includes tests, physical examinations and measurements of levels of radiation or concentrations of radioactive material present.
"Tailing" means the residual material resulting from the extraction of minerals from the earth.
"Target" means that part of an x-ray tube or accelerator onto which a beam of accelerated particles is directed to produce ionizing radiation or other particles.
"Target-skin distance" or "TSD" means the distance measured along the beam axis from the center of the front surface of the x-ray target or electron virtual source to the surface of the irradiated object or patient.
"Technique factors" means the following conditions of operation:
For capacitor energy storage equipment, peak tube potential in kV and quantity of charge in mAs.
For field emission equipment rated for pulsed operation, peak tube potential in kV and number of x-ray pulses.
For CT equipment designed for pulsed operation, peak tube potential in kV, scan time in seconds, and either tube current in millamperes (mA), x-ray pulse width in milliseconds, and the number of x-ray pulses per scan; or the product of tube current, x-ray pulse width, and the number of x-ray pulses per scan expressed as mAs.
For CT x-ray equipment not designed for pulsed operation, peak tube potential in kV, and either tube current in mA and scan time in seconds, or the product of tube current and exposure time in mAs and the scan time when the scan time and exposure time are equivalent.
For all other equipment, peak tube potential in kV and either tube current in mA and exposure time in seconds or the product of tube current and exposure time in mAs.
"Teletherapy" means a method of radiation therapy in which collimated gamma rays are delivered from a source at a distance from the patient or human research subject.
"Temporary job site" means a location where any of the following occur:
Radiographic operations are performed and sources of radiation may be stored other than at the location or locations of use authorized on the license or registration.
Radioactive materials are present for the purpose of performing well logging or subsurface tracer studies.
"Tenth-value layer" or "TVL" means the thickness of a specified material that attenuates x-radiation or gamma radiation to an extent that the air kerma rate; exposure rate or absorbed dose rate is reduced to one-tenth of the value measured without the material at the same point.
"Termination of irradiation" means the stopping of irradiation in a fashion that will not permit continuance of irradiation without the resetting of operating conditions at the control panel.
"Test" means the process of verifying compliance with an applicable regulation.
"Therapeutic dosage" means a dosage of an unsealed radioactive material that is intended to deliver a radiation dose to a patient or human research subject for palliative or curative treatment.
"Therapeutic dose" means a radiation dose delivered from a sealed source containing radioactive material to a patient or human research subject for palliative or curative treatment.
"Therapeutic radiation machine" means x-ray, gamma ray or electron-producing equipment designed and used for external beam or internal radiation therapy.
"Thermoluminescent dosimeter" or "TLD" means a dosimeter containing a crystalline solid for measuring radiation dose, plus filters to help characterize the types of radiation encountered. When heated, TLD crystals that have been exposed to ionizing radiation give off light proportional to the energy they received from the radiation.
"Tight-fitting facepiece" means a respiratory inlet covering that forms a complete seal with the face.
"Tomogram" means the depiction of the x-ray attenuation properties of a section through the body.
"Tomographic plane" means that geometric plane which is identified as corresponding to the output tomogram.
"Tomographic section" means the volume of an object whose x-ray attenuation properties are imaged in a tomogram.
"Total effective dose equivalent" or "TEDE" means the sum of the effective dose equivalent for external exposures and the committed effective dose equivalent for internal exposures.
"Total organ dose equivalent" or "TODE" means the sum of the deep dose equivalent and the committed dose equivalent to the organ receiving the highest dose.
"Transport index" or "TI" means the dimensionless number, rounded up to the next tenth, placed on the label of a package to designate the degree of control to be exercised by the carrier during transportation. The transport index is the number is determined by multiplying the maximum radiation level in millisievert (mSv) per hour at one meter (3.3 feet) from the external surface of the package by 100, which is equivalent to the maximum radiation level in millirem per hour at one meter (3.3 ft).
"Transuranic waste" means waste containing elements having an atomic number greater than 92, a half-life greater than 5 years and in quantities greater than 3.7 kBq/gm (100 nCi/gm).
"Treatment site" means the anatomical description of the tissue intended to receive a radiation dose, as described in a written directive.
"Tritium neutron generator target source" means a tritium target source used within a neutron generator tube to produce neutrons for use in well logging applications.
"Tube housing assembly" means the tube housing with tube installed. It includes high-voltage, filament transformers and other appropriate elements which are contained within the tube housing.
"Tube" means an x-ray tube, unless otherwise specified.
"Type A package" means a packaging that, together with its radioactive contents limited to A1 or A2 as appropriate, meets the requirements of 49 CFR 173.410
and is designed to retain the integrity of containment and shielding required under normal conditions of transport as demonstrated by the tests set forth in 49 CFR 173.465
, as appropriate.
"Type A quantity" means a quantity of radioactive material, the aggregate radioactivity of which does not exceed A1 for special form radioactive material or A2 for normal form radioactive material, where A1 and A2 are given in Appendix O or may be determined by procedures described in Appendix O.