Assignment no. 01
Amrit Pal Singh
Nuclear fuel is any material that can be consumed to derive nuclear energy.
The most common type of nuclear fuel is fissile elements that can be made
to undergo nuclear fission chain reactions in a nuclear reactor
The most common nuclear fuels are 235U and 239Pu. Not all nuclear fuels
are used in fission chain reactions
When a neutron strikes an atom of uranium, the uranium splits in to two
lighter atoms and releases heat simultaneously.
Fission of heavy elements is an exothermic reaction which can release large
amounts of energy both as electromagnetic radiation and as kinetic energy
of the fragments
Operating Principles of Nuclear Power Plants
A nuclear power plant is a facility at which energy released by the
fissioning of atoms is converted to electrical energy under strictly
regulated operating conditions.
The major processes are the same as those in nonnuclear
(conventional) power plants except that the coal or oil fired boiler is
replaced by a nuclear reactor.
A nuclear reactor is a device in which nuclear chain reactions are
initiated, controlled, and sustained at a steady rate, as opposed to a
nuclear bomb, in which the chain reaction occurs in a fraction of a
second and is uncontrolled causing an explosion.
Control rods made of a material that absorbs neutrtons are inserted
into the bundle using a mechanism that can rise or lower the
The control rods essentially contain neutron absorbers
like, boron, cadmium or indium.
Steam generators are heat exchangers used to convert water into
steam from heat produced in a nuclear reactor core.
Either ordinary water or heavy water is used as the coolant.
The coolant pump pressurizes the coolant to pressures of the order
The pressure of the coolant loop is maintained almost constant with
the help of the pump and a pressurize unit.
Steam coming out of the turbine, flows through the condenser for
condensation and recirculated for the next cycle of operation.
The feed pump circulates the condensed water in the working fluid
Condenser is a device or unit which is used to condense vapor into
The objective of the condenser are to reduce the turbine exhaust
pressure to increase the efficiency and to recover high quality feed
water in the form of condensate & feed back it to the steam
generator without any further treatment.
Cooling towers are heat removal devices used to transfer process
waste heat to the atmosphere.
Water circulating through the condenser is taken to the cooling
tower for cooling and reuse .
Thermal reactors need a “moderator” a component
where neutrons are slowed down thus avoiding (or
minimizing) loosed due to capture in 238U.
The ideal moderator has to be:
light (atomic mass comparable to neutron mass, for
efficient slowing down)
Not neutron thirsty (i.e. does not capture neutrons)
Most common used materials are
light water (H20)
heavy water (D2O)
The reactor core
consists of fuel rods
and control rods
◦ Fuel rods contain
◦ Control rods are
inserted between the
fuel rods to absorb
neutrons and slow the
Control rods are made
of cadmium or
boron, which absorb
A nuclear reactor is a device
which initiates and controls a
sustained nuclear chain
reaction. Nuclear reactors are
used at nuclear power plants
for generating electricity. A
nuclear power plant can have
A steam generator is
a machine where
chemical energy is
from steam boilers
in the fact that they
are much larger and
A steam turbine is a
mechanical device that
extracts thermal energy from
pressurized steam, and
converts it into useful
alloys and super alloys have
been used for steam
99.99% of water molecules contain normal
hydrogen (i.e. with a single proton in the
Water can be specially prepared so that the
molecules contain deuterium (i.e. hydrogen
with a proton and a neutron in the nucleus)
Normal water is called light water while water
containing deuterium is called heavy water
Heavy water is a much better moderator but
is very expensive to make
NUCLEAR CHAIN REACTIONS
A chain reaction refers to a
process in which neutrons
released in fission produce an
additional fission in at least one
further nucleus. This nucleus in
turn produces neutrons, and the
process repeats. If the process is
controlled it is used for nuclear
power or if uncontrolled it is
used for nuclear weapons.
During a nuclear reaction the change in mass of particle represents
the release or an absorption of energy, consequently, in the mass of
the resultant particle, will cause the absorption of energy.
A nuclear reaction can be written as follows:
1. The bombarded nuclei is written first from left hand side.
2. In the middle with in brackets, first is the incident particle and
second one is ejected .
3. On the right side the resultant nucleus is placed .
11 na23 +1H1 ____
U235 + n → fission + 2 or 3 n + 200 MeV
If each neutron releases two more neutrons, then the number of
fissions doubles each generation. In that case, in 10 generations there
are 1,024 fissions and in 80 generations about 6 x 10 23 (a mole)
The radioactive half-life for a given
radioisotope is the time for half the
radioactive nuclei in any sample to undergo
radioactive decay. After two half-lives, there
will be one fourth the original sample, after
three half-lives one eight the original
sample, and so forth.
The government wants to build new nuclear power stations. If their plan succeeds, it
will be at the cost of blocking the real solutions to climate change and a reliable future
energy supply. It will also result in the continued production of dangerous nuclear waste
and an increased risk from terrorism, radioactive accident and nuclear proliferation.
New nuclear power stations would not stop climate change. Even at the most optimistic
build rate - 10 new reactors by 2024 – our carbon emissions would only be cut by four
per cent: far too little, far too late. Given the nuclear industry’s poor track record it's
highly unlikely that ten reactors could be built within two decades. The most
contemporary example of building a new reactor is in Finland; just one year into
construction, the completion date has been delayed by 18 months and its costs have
spiralled by up to 2 billion Euros over budget.
Worse still, new investment in nuclear power and its infrastructure will block
development of renewable energy and energy efficiency – the real solutions to climate
Nor would new nuclear power stations address the anticipated gap in our future energy
supply. This is because nuclear power only produces electricity and so only marginally
deals with our need for services like hot water and central heating which are mainly met
by gas. Its overall contribution to total energy demand is too small to make a difference
to the UK's energy security.
Aside from the risk of a terrorist strike directly onto a nuclear power station, the nuclear
industry transports thousands of tonnes of radioactive waste around the UK by road, rail
and sea. Every week, communities up and down the country are put at risk from
potential radioactive contamination as these trains trundle through our cities, towns and
villages. There are no police or security personnel on board and there are no local plans
in place to deal with an emergency. If a nuclear waste train was involved in a terrorist
attack, tens of thousands of people could be exposed to cancer causing radiation and
whole regions might have to be evacuated.
Over twenty years since the world’s worst nuclear disaster, Chernobyl, the human and
environmental consequences are still being suffered internationally. Nuclear power is
inherently dangerous and, despite claims of improvements in safety, scientists agree
that another catastrophe on the scale of Chernobyl could still happen any
Reprocessing and nuclear proliferation
Nuclear waste is taken from wherever it is produced, across the country, to Sellafield in
Cumbria for reprocessing. During reprocessing, plutonium is separated from other
wastes for supposed re-use in nuclear reactors. In reality none of this plutonium is
reused for electricity generation. The UK now has a stockpile of over a hundred tonnes
of deadly plutonium - and no plans for what to do with it.
The nuclear industry is hugely expensive.