Duration
The dose rate from a single uptake decays over time due to both radioactive decay and biological decay. (i.e. excretion from the body.) The combined radioactive and biological half-life, called the effective half-life of the material, may range from hours for medical radioisotopes to decades for transuranic waste. Committed dose is the integral of this decaying dose rate over the presumed remaining lifespan of the organism. Most regulations require this integral to be taken over 50 years for uptakes during adulthood or over 70 years for uptakes during childhood. In dosimetry accounting, the entire committed dose is conservatively assigned to the year of uptake, even though it may take many years for the tissues to actually accumulate this dose.
Read more about this topic: Committed Effective Dose Equivalent (CEDE)
Famous quotes containing the word duration:
“What matters it that man should have a little more knowledge of the universe? If he has it, he gets little higher. Is he not always infinitely removed from the end, and is not the duration of our life equally removed from eternity, even if it lasts ten years longer?”
—Blaise Pascal (1623–1662)
“This pond never breaks up so soon as the others in this neighborhood, on account both of its greater depth and its having no stream passing through it to melt or wear away the ice.... It indicates better than any water hereabouts the absolute progress of the season, being least affected by transient changes of temperature. A severe cold of a few days’ duration in March may very much retard the opening of the former ponds, while the temperature of Walden increases almost uninterruptedly.”
—Henry David Thoreau (1817–1862)
“Higher than the question of our duration is the question of our deserving. Immortality will come to such as are fit for it, and he would be a great soul in future must be a great soul now.”
—Ralph Waldo Emerson (1803–1882)