NUCLEAR POWER PLANT

Assignment no. 01

Submitted to: Mr. Amrit

Pal Singh Submitted by:

Mr. Parmjeet Singh

10UME043

NUCLEAR FUEL

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

NUCLEAR FISSION

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

INTRODUCTION

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.

PRINCIPLES OF NUCLEAR ENERGY

COMPONENTS OF POWER PLANT

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

Control rods made of a material that absorbs neutrtons are inserted

into the bundle using a mechanism that can rise or lower the

control rods.

The control rods essentially contain neutron absorbers like, boron,

cadmium or indium. STEAM GENERATORS

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.

COOLANT PUMP

The coolant pump pressurizes the coolant to pressures of the

order of 155bar.

The pressure of the coolant loop is maintained almost constant

with the help of the pump and a pressurize unit. FEED PUMP

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

loop.

CONDENSER

Condenser is a device or unit which is used to condense vapor

into liquid.

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 TOWER

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 .

MODERATOR 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) cheap Not inflammable Most common used materials are light water (H20) heavy water (D2O) graphite

The reactor core consists of fuel rods and control rods◦ Fuel rods contain

enriched uranium◦ Control rods are

inserted between the fuel rods to absorb neutrons and slow the chain reaction

Control rods are made of cadmium or boron, which absorb neutrons

effectively

THE REACTOR CORE

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 several reactors

NUCLEAR REACTOR

A steam generator is a machine where chemical energy is transformed into heat energy. Generators differ from steam boilers in the fact that they are much larger and more complicated.

STEAM GENERATOR

STEAM TURBINE

A steam turbine is a

mechanical device that

extracts thermal energy

from pressurized steam,

and converts it into useful

mechanical

Various high-performance

alloys and super alloys have

been used for steam

generator tubing.

STEAM TURBINE

99.99% of water molecules contain normal hydrogen (i.e. with a single proton in the nucleus)

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

LIGHT VS. HEAVY WATER

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.

BASIC NUCLEAR REACTIONS

Nuclear reactions 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 .Examples:

11 na23 +1H1 ____ 12Mg23 0n1

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)

fissions.

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.

RADIOACTIVE HALF-LIFE

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.

Climate change 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 change.

Energy security 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.

TROUBLE SHOOTING AND REMEDIES.

Terrorism 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.

Safety 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 time, anywhere.

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.

Cost The nuclear industry is hugely expensive.