NUCLEAR POWER PLANTConservation Ratio,

Neutron Flux,Economics of nuclear power plant,

Nuclear power station in India

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Conservation Ratio• It is defined as the ratio of number of secondary fuel

atoms to the number of consumed primary fuel atoms. • A reactor with a conversion ratio above unity is known

as a breeder reactor. • Breeder reactor produces more fissionable material

than it consumes. • If the fissionable material produced is equal to or less

than the consumed, the reactor is called converter reactor.

React0r

React0r

React0r

Feed Water

Steam

Steam

Steam

Pump

Steam Generat

or

Primary Coolant

Pump

Pump

Steam Generat

or

Secondary Coolant

Feed Water

Feed Water

Hot Coolant

(a)

(b)

Neutron Flux• The neutron flux is a quantity used in nuclear

reactor physics corresponding to the total length travelled by all neutrons per unit time and volume.

or • Nearly equivalently number of neutrons travelling through a

unit area in unit time.• The neutron beam flux (φ) have units of neutrons/cm2⋅sec

• Mathematically, this is the equation below

Φ=n v

• Where• φ = neutron flux (neutrons/cm -sec)2

• n = neutron density (neutrons/cm )3

• v = neutron velocity (cm/sec)

Difference between Neutron Intensity (I) and Flux (φ)• When the neutrons are mono directional, we speak of

the neutron intensity (I), but • when the neutrons become multi-directional, we

change the nomenclature to flux (φ)I = n v & φ = n v

• where n is number of neutrons/cm3 and v is the neutron speed.

Neutron Flux• Two type of Neutron Flux:• Natural neutron flux• Artificial neutron flux

Natural Neutron flux • Neutron flux in asymptotic giant branch stars and

in supernova is responsible for most of the natural nucleosynthesis producing elements heavier than iron. • In stars there is a relatively low neutron flux on the order of

105 to 1011 neutrons per cm2 per second, resulting in nucleosynthesis by the s-process (slow-neutron-capture-process).• In core-collapse supernova, there is an extremely high neutron

flux, on the order of 1022 neutrons per cm2 per second, resulting in nucleosynthesis by the r-process(rapid-neutron-capture-process).

Artificial Neutron Flux• Artificial neutron flux refers to neutron flux which is man-made,

either as byproducts from weapons or nuclear energy production or for specific application such as from a research reactor .

• A flow of neutrons is often used to initiate the fission of unstable large nuclei. The additional neutron(s) may cause the nucleus to become unstable, causing it to decay (split) to form more stable products.

• This effect is essential in fission reactors and nuclear weapons.

The radial distribution of the thermal neutron flux density

• Within a nuclear fission reactor the neutron flux is primarily the form of measurement used to control the reaction inside.• The flux shape is the term applied to the density or relative

strength of the flux as it moves around the reactor.• Typically the strongest neutron flux occurs in the middle of the

reactor core, becoming lower toward the edges.• The higher the neutron flux the greater the chance of a nuclear

reaction occurring as there are more neutrons going through an area.• A reactor vessel of a typical nuclear power plant endures in 40

years (32 full reactor years) of operation approximately 3.5×1019 n/cm²•  Neutron flux causes reactor vessels to suffer

from embrittlement and the steel gets activated.

Economics of nuclear power plant• Typically all costs of nuclear power plants are boken into the

following categories:

1) Capital costs (total)2) Fuel costs (Per year)3) Other operating and maintenance costs (Per year)

Capital costs:• Capital costs are those costs which occur only once and are

usually limited to the costs of procurement and construction of the facilities prior to the time of commercial operation.•  Which include the cost of Site preparation Construction Manufacture Commissioning and financing a nuclear power plant Building a large-scale nuclear reactor takes thousands of workers Huge amounts of steel and concrete Several systems to provide electricity, cooling, ventilation, information control and communication

Capital costs:• Capital costs may be calculated with the financing

costs included or excluded.•  If financing costs are included then the capital costs

change in the ‘investment cost’.• If the financing costs are excluded from the calculation

the capital costs is called the ‘overnight cost’.

Fuel costs:• An understanding of nuclear-fuel costs requires an

understanding of the nuclear fuel cycle.• Fuel costs a affected by the number of functional

services which must be performed on the uranium fuel to prepare.

Nuclear Fuel cycle:Mining

Ore extraction

Conservation to

enrichment chemical

formEnrichment

Conversion to fuel chemical form

Fabrication Fabrication

Reconversion

Atomic power plant

1

2

3

4X

9 5 10

10Y Z 9

8

6 7

1. Uranium ore2. Uranium concentrate3. Refined uranium as UF44. Slightly enriched uranium as UF45. Slightly enriched uranium dioxide in power or pellet form6. Fabricated fuel assemblies 7. Spent fuel8. Recovered uranium and plutonium fuel material 9. Recycled uranium as uf410. Recycled plutonium and possibly uranium in fuel chemical formX- deleted uranium “tail” to storageY- radioactive waste concentrates to storageZ- useful radio isotopes other than fuels

Fuel costs:• Fuel costs have from the outset given nuclear energy an

advantage compared with coal, oil and gas-fired plants.• Uranium, however, has to be processed, enriched and

fabricated into fuel elements, and about half of the cost is due to enrichment and fabrication.•  The total fuel costs of a nuclear power plant are typically

about a third of those for a coal-fired plant and between a quarter and a fifth of those for a gas combined-cycle plant.•  The US Nuclear Energy Institute suggests that for a coal-

fired plant 78% of the cost is the fuel, for a gas-fired plant the figure is 89%, and for nuclear the uranium is about 14%

Fuel costs:•  The approx. US $ cost to get 1 kg of uranium as UO2 reactor fuel,

Uranium 8.9 kg U3O8 x $97 US$ 862 46%

Conversion 7.5 kg U x $16 US$ 120 6%

Enrichment: 7.3 SWU x $82 US$ 599 32%

Fuel fabrication: per kg (approx.) US$ 300 16%

Total, approx.: US$ 1880

Operations and Management costs:• It fall in the following groups:

1) Labor 2) Material, supplies and services3) Insurance 4) Fuel management 5) Working capital

Nuclear Power Station in

India

Nuclear power station in IndiaPower station State Type Operator Units

Total capacity

(MW)Kaiga Karnataka PHWR NPCIL 220 x 3 660

Kalpakkam Tamil Nadu PHWR NPCIL 220 x 2 440Kakrapar Gujarat PHWR NPCIL 220 x 2 440

Rawatbhata Rajasthan PHWR NPCIL100 x 1200 x 1220 x 4 

1180

Tarapur Maharashtra BWR (PHWR) NPCIL 160 x 2540 x 2 1400

Narora Uttar Pradesh PHWR NPCIL 220 x 2 440Total 19 4560

NPCIL: Nuclear Power Corporation of India Ltd.

PHWR: Pressurized heavy-water reactor BWR: Boiling water Reactor

Some of the nuclear power plant projects which are under construction can be listed below:

Power station State Type Operator Units

Total capacity

(MW)Kudankula

m Tamil Nadu VVER-1000 NPCIL 1000 x 2 2000

Kaiga Karnataka PHWR NPCIL 220 x 1 220

Kalpakkam Tamil Nadu PFBR NPCIL 500 x 1 500

Total 4 2720

Some of the nuclear power projects which are planned up for the future are as follows

Power station Operator State Type Units

Total capacity

(MW)Rawatbhata NPCIL Rajasthan PHWR 640 x 2 1280

Kakrapar NPCIL Gujarat PHWR 640 x 2 1280Jaitapur NPCIL Maharashtra EPR 1600 x 4 6400

Kudankulam NPCIL Tamil Nadu VVER 1200 x 2 2400

Kaiga

NPCIL

Karnataka

PWR 1000 x 1, 1500 x 1 2500

NPCIL AHWR 300 300NPCIL PHWR 640 x 4 2560NTPC PWR 1000 x 2 2000

Total 10 20600

Thank You…