Nuclear Power plants
are similar to Coal powered plants and
hydroelectric powered plants in the way they
produce electricity. The difference in the systems is their fuel
sources. Essentially, the three
technologies produce the energy that drives the turbine and the
electromagnetic
rotor which creates
flow of electrons (or electricity). In coal powered plants, coal is burnt
and the heat is used to generate stem which is used to drive the turbine
and the electromagnetic rotor. In hydroelectric power plants, the power of
the moving water drives the turbine. Nuclear
power plants use the heat generated from the
atomic fission of Uranium or any other fissile (materials capable
of undergoing
fission) to produce the steam that is used to turn the turbine.
Uranium occurs naturally in several parts
of the World and it is mined from the ground just like other metals.Uranium is processed into small pellets.
A small
pallet emits very little radiation,
but has the potential to
produce
tremendous energy
when involved in atomic splitting (or fission).
Uranium
pellets are sealed into metal tubes and welded together
to form fuel bundles. The fuel bundles are
inserted into a large tank which is the core of the
nuclear reactor.
In a nuclear reactor, a uranium
atom splits into 2, in a process called fission,
when hit by a neutron and this
results in a tremendous amount of heat. Each
fission reaction releases at least two more free neutrons that proceed to
hit other nuclei to produce more reactions. This leads to a series of
chain reactions that continues for as long as the nuclei is still big
enough to split into two. The energy released in the process is used to
produce steam used to drive steam turbine that generates electricity.
Nuclear fusion (two nuclei binding together) is another reaction that
generates energy, but most existing nuclear power plants adopt the nuclear
fission approach.
Heavy water is used to facilitate
sustained fission in a reactor. Heavy water
is 10% heavier than ordinary water because it
containshigher than normal proportion of
deuterium, which is a form of hydrogen.The
heavy water surrounds the fuel bundles and slow
down the neutrons, so that they are more likely to hit and split the
uranium atom and ensure a chain reaction of atom
splitting and a constant source of heat, to heat
the heavy water. The heated heavy water is
pumped through the reactor to a set of boilers where it boils ordinary
water to high pressure steam. While the heavy
water is re-circulated
back to the reactor, the pressure steam
produced is transported through pipes to
a large turbine where it pushes the blades and turn the
shaft connected to a rotor in the generator
causing the rotor to spin.
The spinning rotor is a
large electromagnet that produces a rotating magnetic field. The field
moves through a coil of copper wire, producing electricity that can be
sent through transmission lines. Steam is condensed back into water using
cooling water from the surrounding body of water.
Modern
nuclear power stations use the same type of turbines and generators as the coal fired and
hydroelectric power stations.Nuclear
power plant costs about the same as coal powered plant but could be more
expensive to install when compared to other forms of energy source.
However, the cost of installing reactors have been consistently escalating
for the past 3 decades (see setbacks later on this page).
Some
of the advantages of Nuclear power plants
are:
They do
not produce smoke or carbon dioxide and so they do not
contribute to the greenhouse effect;
They produce
huge amounts of energy from small amounts of fuel
(uranium), compared to other power plants.
They also produce small
amounts of waste.
Nuclear
power is a very
reliable energy resource.
The drawbacks with
Nuclear Energy/Reactors are as follows:
Nuclear energy produced by using Uranium is non-renewable. Uranium has got the
potential to be depleted through continuous mining without immediate replacement.
Nuclear reactors are very expensive. The cost of installing nuclear
reactors have been increasing by 15% every year for the past 30 years.
Installing 1 reactor costs billions of dollars these days;
There are currently no good technology for safely managing nuclear wastes; most
proposed methods are very expensive and still require proofs of
reliability; and
Nuclear wastes or even
the nuclear production material (e.g. Uranium pellets) can fall into the
hands of those that would use them for destructive purposes. Nuclear
energy is sometimes discouraged to minimize or prevent the proliferation
of nuclear weapons.
