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Glossary
Glossary
Pages 53-64
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From page 53... ...
For He very low doses and dose rates that were associated with fallout Tom nuclear testing around the world, there are large uncertainties about risks of harm from radiation exposure, because these radiogen~c contributions are at most very small when compared to contributions from other sources, e.g., "spontaneous" normal processes of living. Activity - the number of nuclear transformations occulting in per unit of tune.
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From page 54... ...
absorb neutrons, then split, releasing energy and more neutrons, which in turn cause additional atom splitting and neutron releases so that the process continues. Nuclear weapons tests that were conducted around the world were based on uncontrolled chain reactions.
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From page 55... ...
Dose - general tenn for the quantity of energy absorbed from ionizing radiation in a volume of a material divided by its mass. See absorbed dose, equivalent dose, effective dose, and collective effective dose.
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From page 56... ...
Effective dose - a calculated dose quantity obtained by multiplying the equivalent doses to various tissues and organs by a tissue/organ weighting factor appropriate to each and summing the products. The unit is J/kg; its special name is sievert (Sv)
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From page 57... ...
Gamma rays are similar to x rays, but x rays have lower energy. Gray - special name of the unit of absorbed dose J/kg (joules per kilogram)
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From page 58... ...
ICRU - the International Commission on Radiation Units and Measurements, a nongovernmental agency headquartered in Bethesda, MD, USA, concerned with recommendations regarding harmonized measurement of radiation and responsible for recommending nomenclature for quantities, units and their special names, e.g., Bq, Gy, Sv.
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From page 59... ...
For low-LET radiations such as X rays, gamma rays, and beta particles, little energy is lost when traversing a sheet of paper. For high-LET alpha particles emitted by plutonium isotopes, essentially all ofthe particle's energy is lost in the sheet of paper.
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From page 60... ...
implies that doubling the dose will double the calculated excess risk. For low radiation doses and dose rates, there are large uncertainties about what are the true risks to humans and how they relate to dose.
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From page 61... ...
. ORERP - the acronym for the Offsite Radiation Exposure Review Project that sought to determine the exposures of individuals residing in a limited number of counties near the Nevada Test Site.
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From page 62... ...
- a factor used to compare the biological effectiveness of absorbed radiation doses due to different types of ionizing radiation for a defined biological endpoint, e.g., cell killing, this factor is experimentally determined using X- or gamma rays as the standard of comparison. Thus, if ~ Gy of fast neutrons produced the same amount of cell killing as 5 Gy of gamma rays, the RBE of neutrons for cell killing would be 5.
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From page 63... ...
RERF (Radiation Effects Research Foundation) - the nonprofit research foundation sponsored by the governments of Japan and the United States that currently supervises the studies of the atom~c-bomb survivors; the successor in 1975 of the Atomic Bomb Casualty Commission.
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From page 64... ...
are used to convert absorbed dose to equivalent dose. Other weighting factors are used to convert equivalent doses to effective dose, which is more often used in risk assessment.
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Key Terms
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