Spent Fuel Decay Heat
When a nuclear reactor has been shut down and the nuclear fission chain reaction has ceased, a significant amount of heat will still be produced in the fuel due to the beta decay of fission products. For this reason, at the moment of reactor shutdown, decay heat will be about 7% of the previous core power if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power. After a day, the decay heat falls to 0.4%, and after a week it will be 0.2%. The decay heat production rate will continue to slowly decrease over time.
Spent fuel that has been removed from a reactor is ordinarily stored in a water-filled spent fuel pool for a year or more (in some sites 10 to 20 years) in order to cool it and provide shielding from its radioactivity. Practical spent fuel pool designs generally do not rely on passive cooling but rather require that the water be actively pumped through heat exchangers.
Read more about this topic: Spent Nuclear Fuel
Famous quotes containing the words spent, fuel, decay and/or heat:
“The Athenians and strangers which were there spent their time in nothing else, but either to tell or to hear some new thing.”
—Bible: New Testament Acts 17:21.
“I had an old axe which nobody claimed, with which by spells in winter days, on the sunny side of the house, I played about the stumps which I had got out of my bean-field. As my driver prophesied when I was plowing, they warmed me twice,—once while I was splitting them, and again when they were on the fire, so that no fuel could give out more heat. As for the axe,... if it was dull, it was at least hung true.”
—Henry David Thoreau (1817–1862)
“Now, a corpse, poor thing, is an untouchable and the process of decay is, of all pieces of bad manners, the vulgarest imaginable. For a corpse is, by definition, a person absolutely devoid of savoir vivre.”
—Aldous Huxley (1894–1963)
“Friendship is evanescent in every man’s experience, and remembered like heat lightning in past summers.”
—Henry David Thoreau (1817–1862)