Power Plant Engineering

NUCLEAR POWER PLANT 327

10.11 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.

Reactor

Feed

Water

Steam

Reactor

Hot Coolant

Pump Feed

Water

Steam

Generator

Steam

()a ()b

Reactor

Pump Pump

Primary

Coolant

Secondary

Coolant

1 HX

Steam

Steam

Generator

Feed

Water

Fig. 10.7

10.12 Neutron Flux

It is a measure of the intensity of neutron radiation and it is the number of neutrons passing
through 1 cm^2 of a given target in one second. It is expressed as uv, where u is number of neutrons per
cubic centimeter and u is velocity of neutrons in cm/sec.

10.13 CLASSIFICATION OF REACTORS

The nuclear reactors can be classified as follows :

1. Neutron Energy. Depending upon the energy of the neutrons at the time they are captured by
   the fuel to induce fissions, the reactors can be named as follows :
   (a) Fast Reactors. In such reactors fission is brought about by fast (non moderated) neutrons.
   (b) Thermal Reactors or Slow Reactors. In these reactors the fast moving neutrons are slowed
   down by passing them through the moderator. These slow moving neutrons are then captured by the fuel
   material to bring about the fission of fundamental research.

10.14 Cost of Nuclear Power Plant

Nuclear power plant is economical if used as base load power plant and run at higher load fac-

tors. The cost of nuclear power plant is more at low load factors. The overall running cost of a nuclear

power plant of large capacity may be about 5 paisa per kWh but it may be as high 15 paisa per kWh if the

plant is of smaller capacity. The capital cost of a nuclear power plant of larger capacity (say 250 mW) is

nearly Rs. 2500 per kW installed. A typical sub-division of cost is as follows :