A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

G
general emergency:
See emergency class.

geological disposal:
See disposal.

geological repository:
See repository.

geosphere:
Those parts of the lithosphere not considered to be part of the biosphere.
In waste safety, usually used to distinguish the subsoil and rock (below the depth affected by normal human activities, particularly agriculture) from the soil that is part of the biosphere.

gray (Gy):
Name for the SI unit of kerma and absorbed dose, equal to 1 J/kg.

H

half-life, T₁:
1.   For a radionuclide, the time required for the activity to decrease, by a radioactive decay process, by half.
Where it is necessary to distinguish this from other half-lives (see (2)), the term radioactive half-life should be used.
The half-life is related to the decay constant, l, by the expression:

2.   The time taken for the quantity of a specified material (e.g. a radionuclide) in a specified place to decrease by half as a result of any specified process or processes that follow similar exponential patterns to radioactive decay.

• biological half-life: The time taken for the quantity of a material in a specified tissue, organ or region of the body (or any other specified biota) to halve as a result of biological processes.
• effective half-life, T_eff: The time taken for the activity of a radionuclide in a specified place to halve as a result of all relevant processes.
   (or
  )
  where T_i is the half-life for process i.
• radioactive half-life: For a radionuclide, the time required for the activity to decrease, by a radioactive decay process, by half.
  The term ‘physical half-life’ is also used for this concept.

health effects (of radiation):

• deterministic effect: A radiation effect for which generally a threshold level of dose exists above which the severity of the effect is greater for a higher dose. [40]
  The level of the threshold dose is characteristic of the particular health effect but may also depend, to a limited extent, on the exposed individual.  Examples of deterministic effects include erythema and acute radiation syndrome (radiation sickness).
  The term non-stochastic effect is used in some older publications, but is now superseded.
  Contrasting term: stochastic effect.
• early effect: A radiation-induced health effect that occurs within months of the exposure that caused it.
  All early effects are deterministic effects; most, but not all, deterministic effects are early effects.
• hereditary effect: A radiation-induced health effect that occurs in a descendant of the exposed person.
  The less precise term ‘genetic effect’ is also used, but hereditary effect is preferred.
  Hereditary effects are normally stochastic effects.
  Contrasting term: somatic effect.
• late effect: A radiation-induced health effect that occurs years after the exposure that caused it.
  The most common late effects are stochastic effects, such as leukaemia and cancer, but some deterministic effects (e.g. cataract formation) can also be late effects.
• non-stochastic effect: See deterministic effect.
• somatic effect: A radiation-induced health effect that occurs in the exposed person.
  This includes effects occurring after birth that are attributable to exposure in utero.
  Deterministic effects are normally also somatic effects; stochastic effects may be somatic effects or hereditary effects.
  Contrasting term: hereditary effect.
• stochastic effect: A radiation-induced health effect, the probability of occurrence of which is greater for a higher radiation dose and the severity of which (if it occurs) is independent of dose.
  Stochastic effects may be somatic effects or hereditary effects, and generally occur without a threshold level of dose.  Examples include cancer and leukaemia.
  Contrasting term: deterministic effect.

health professional:
An individual who has been accredited through appropriate national procedures to practise a profession related to health (e.g. medicine, dentistry, chiropractic, podiatry, nursing, medical physics, radiation and nuclear medical technology, radiopharmacy, occupational health). [40]
Used in the BSS to distinguish from a medical practitioner, who satisfies additional criteria.

hydrological dispersion:
See dispersion.