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The
electrical utility industry is a major provider of energy in the
United States. The total amount of electricity sold in the United
States in 1998 was 3,240 billion GWh at a cost to the consumers
of $218 billion. Electricity generation plants can be divided into
seven generic types: fossil fuel, nuclear, hydroelectric, cogeneration,
geothermal, solar, and wind. The majority of electric power in the
United States is generated by fossil-fuel and nuclear supply systems.
The total annual direct cost of corrosion in the electrical utility
industry in 1998 was estimated to be $6.9 billion, with the largest
amounts for nuclear power at $4.2 billion and fossil fuel at $1.9
billion, and smaller amounts for hydraulic and other power at $0.15
billion, and transmission and distribution at $0.6 billion.
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Two different types of nuclear reactors are
currently in use in the United States, namely the boiling water
reactor (BWR) and the pressurized water reactor (PWR). The fuel
for these types of reactors is similar, consisting of long bundles
of two to four percent enriched uranium dioxide fuel pellets stacked
in zirconium-alloy cladding tubes. The BWR design consists of a
single loop in which the entering water is turned directly to steam
for the production of energy. The PWR is a two-loop system that
uses high pressure to maintain an all-liquid-water primary loop.
Energy is transferred to the secondary steam loop through two to
four steam generators. The PWR also uses a wet steam turbine. The
electric power industry uses three different types of fossil-fuel
power plants. The most common and widely used is the pulverized
coal-fired steam power plant. Fuel oil can be used instead of coal.
Gas turbines are usually smaller units that are used for peak loads
and operate only for a few hours per day. Combined cycle plants
using both steam and gas turbines are generally used for baseload
service, but also must be capable of addressing peak loads. Hydraulic
power systems include both hydroelectric and pumped storage hydroelectric
plants. In both processes, water is directed from a dam through
a series of tapering pipes to rotate turbines that create electricity.
In principle, the potential energy held in the dam converts into
kinetic energy when it flows through the pipes. The concept behind
the development of pumped storage plants is the conversion of relatively
low cost, off-peak energy generated in the thermal plant into high
value, on-peak power. Water is pumped from a lower to a higher reservoir
when low cost pumping is available from large, efficient thermal
plant generation. It is released during periods of high power demand
and displaces the use of inefficient, costly alternative sources
of generation.
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