Power Plant Engineering

 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 :

---

328
POWER PLANT ENGINEERING
Item
Approximate Cost %
(a) Capital cost of land, building and
62%
equipment etc.
(b) Fuel cost
22%
(c) Maintenance cost
6%
(d) Interest on capital cost
10%
The capital investment items include the following :
(i) Reactor Plant : (a) Reactor vessel, (b) Fuel and fuel handling system, (c) Shielding. (ii) Cool-
ant system. (iii) Steam turbines, generators and the associated equipment. (iv) Cost of land and construc-
tion costs.
The initial investment and capital cost of a nuclear power plant is higher as compared to a ther-
mal power plant. But the cost of transport and handling of coal for a thermal power plant is much higher
than the cost of nuclear fuel. Keeping into view the depletion of fuel (coal, oil, gas) reserves and trans-
portation of such fuels over long distances, nuclear power plants can take an important place in the
development of power potentials.