Common Physical Forms of Nuclear Fuel
Uranium dioxide (UO2) powder is compacted to cylindrical pellets and sintered at high temperatures to produce ceramic nuclear fuel pellets with a high density and well defined physical properties and chemical composition. A grinding process is used to achieve a uniform cylindrical geometry with narrow tolerances. Such fuel pellets are then stacked and filled into the metallic tubes. The metal used for the tubes depends on the design of the reactor. Stainless steel was used in the past, but most reactors now use a zirconium alloy which, in addition to being highly corrosion-resistant, has low neutron absorption. The tubes containing the fuel pellets are sealed: these tubes are called fuel rods. The finished fuel rods are grouped into fuel assemblies that are used to build up the core of a power reactor.
Cladding is the outer layer of the fuel rods, standing between the coolant and the nuclear fuel. It is made of a corrosion-resistant material with low absorption cross section for thermal neutrons, usually Zircaloy or steel in modern constructions, or magnesium with small amount of aluminium and other metals for the now-obsolete Magnox reactors. Cladding prevents radioactive fission fragments from escaping the fuel into the coolant and contaminating it.
-
Nuclear Regulatory Commission (NRC) Image of unirradiated (fresh) fuel pellets.
-
NRC Image of fresh fuel pellets ready for assembly.
-
NRC picture of fresh fuel being inspected.
Read more about this topic: Nuclear Fuel
Famous quotes containing the words common, physical, forms, nuclear and/or fuel:
“Though there are wreck-masters appointed to look after valuable property which must be advertised, yet undoubtedly a great deal of value is secretly carried off. But are we not all wreckers contriving that some treasure may be washed up on our beach, that we may secure it, and do we not infer the habits of these Nauset and Barnegat wreckers, from the common modes of getting a living?”
—Henry David Thoreau (1817–1862)
“A man’s thinking goes on within his consciousness in a seclusion in comparison with which any physical seclusion is an exhibition to public view.”
—Ludwig Wittgenstein (1889–1951)
“All forms of government symbolize an immortal government, common to all dynasties and independent of numbers, perfect where two men exist, perfect where there is only one man.”
—Ralph Waldo Emerson (1803–1882)
“Could it not be that just at the moment masculinity has brought us to the brink of nuclear destruction or ecological suicide, women are beginning to rise in response to the Mother’s call to save her planet and create instead the next stage of evolution? Can our revolution mean anything else than the reversion of social and economic control to Her representatives among Womankind, and the resumption of Her worship on the face of the Earth? Do we dare demand less?”
—Jane Alpert (b. 1947)
“Beware the/easy griefs, that fool and fuel nothing./It is too easy to cry “AFRIKA!”/and shock thy street,/and purse thy mouth,/and go home to thy “Gunsmoke,” to/thy “Gilligan’s Island” and the NFL.”
—Gwendolyn Brooks (b. 1917)