Skip to main content

REACTOR FUEL ASSEMBLIES


Both boiling water reactor and pressurized water reactor fuel assemblies consist of the same major
components.  These major components are the fuel rods, the spacer grids, and the upper and lower end
fittings.  The fuel assembly drawing on page 1-11 shows these major components (pressurized water
reactor fuel assembly).
The fuel rods contain the ceramic fuel pellets.  The fuel rods are approximately 12 feet long and contain
a space at the top for the collection of any gases that are produced by the fission process.  These rods are
arranged in a square matrix ranging from 17 x 17 for pressurized water reactors to 8 x 8 for boiling water
reactors.
The spacer grids separate the individual rods with pieces of sprung metal.  This provides the rigidity of
the assemblies and allows the coolant to flow freely up through the assemblies and around the fuel rods.
Some spacer grids may have flow mixing vanes that are used to promote mixing of the coolant as it
flows around and though the fuel assembly.
The upper and lower end fittings serve as the upper and lower structural elements of the assemblies.  The
lower fitting (or bottom nozzle) will direct the coolant flow to the assembly through several small holes
machined into the fitting.  There are also holes drilled in the upper fitting to allow the coolant flow to
exit the fuel assembly.  The upper end fitting will also have a connecting point for the refueling
equipment to attach for the moving of the fuel with a crane.
For pressurized water reactor fuel, there will also be guide tubes in which the control rods travel.  The
guide tubes will be welded to the spacer grids and attached to the upper and lower end fittings.  The
guide tubes provide a channel for the movement of the control rods and provide for support of the rods.
The upper end of the control rod will be attached to a drive shaft, which will be used to position the rod
during operations.


Comments

Post a Comment

Popular posts from this blog

The World and Nuclear Fission

Purely as a physical phenomenon nuclear fission offers ample scope for intellectual problem-solving. If it implied nothing further it could be left to those specialists who might find satisfaction in its intellectual challenge; the rest of us could busy ourselves with other more pressing concerns. Unfortunately, nuclear fission  - as everyone knows  - implies much more than abstruse mathematical argument and donnish hairsplitting. Almost from the time it was first recognized, in 1938, nuclear fission has implied not merely articles in learned journals but major decisions of public policy. The social, economic and political context of nuclear fission has been from the beginning an essential factor in its development; in turn, it has exerted an extraordinary range of social, economic and political influence. To foresee with any clarity the shape of the nuclear future, a historical perspective is imperative. It is necessary to know not only how nuclear fission occurs,...
Post a Comment
Read more

HYDROELECTRIC PLANT

In a hydroelectric power plant, water, flowing from a higher level to a lower level, travels through the metal blades of a water turbine, causing the rotor of the electrical generator to spin and produce electricity. In a fossil-fueled power plant, heat, from the burning of coal, oil, or natural gas, converts (boils) water into steam (A), which is piped to the turbine (B).  In the turbine, the steam passes through the blades, which spins the electrical generator (C), resulting in a flow of electricity.  After leaving the turbine, the steam is converted (condensed) back into water in the condenser (D).  The water is then pumped (E) back to the boiler (F) to be reheated and converted back into steam.
Post a Comment
Read more