Advantages of nuclear power plants over thermal or hydroelectric power plants

Geographical limitations - nuclear power plants don't require a lot of space; they do not need a large plot like a wind farm. But they have to be built  near a large body of water for cooling purposes - using the water as a heat sink. They are usually  found on the coast so there is no risk to drinking water sources.               

Nuclear power stations do not  contribute to carbon emissions - no CO2 is given out - it therefore does not contribute to global warming.              
              

Nuclear power stations do not produce smoke particles to pollute the atmosphere or emit gases that contribute to acid rain. 
              

Nuclear energy is by far the most concentrated form of energy - a lot of energy is produced from a small mass of fuel. This reduces transport costs - (although the fuel is radioactive and therefore each transport that  does occur is expensive because of security implications). 
              

Nuclear power is reliable. It does not depend on the weather. 
              

We can control the output from a nuclear power station to fit our needs. 
It is relatively easy to  control the output - although the time factor for altering power output  is not as small as for fossil fuel stations. It is said to have a long 'start up' time.  It cannot respond immediately to demand. That is why electricity  companies try to 'even out' demand by using tariffs that encourage use  at off peak time prides.
              
Nuclear power produces a small volume of waste (although that waste is radioactive)

Low Fuel Cost -  The main reason behind the low fuel cost is that it requires little  amount of uranium to produce energy. When a nuclear reaction happens, it  releases million times more energy as compared to traditional sources  of energy. Only about 28 gram of uranium releases as much energy  as produced from 100 metric tons of coal.

All the three (nuclear ,thermal, hydroelectric) power plants have their own advantages and disadvantages
Nuclear
Advantages: 

• It produces large amount of energy using      sophisticated processes like nuclear fission , nuclear decay and nuclear      fusion , so when compared to power plants which use fossil fuels it produces      less amount of co2 emissions but greater generation of power when compared      to others
• It is more efficient since the cost of the fuel      is roughly around 20% of what it produces.
• The process is not dependent on any      environmental aspects so it’s a more reliable source of energy
• They don’t require much space to set up

Disadvantages

• The amount of toxic substance (bio-hazard      substances) is high and it is difficult to dump since it can have serious      impact on the living beings living nearby.
• Even after having advanced systems, there is      still a high risk of leakage which can destroy the quality of living in      the nearby areas and can have serious medical and health issues.
• Depletion of uranium
• Initial cost of set up is high

Thermal
Advantages:

• Fuel is cheaper and power plants require less      space when compared to others.
• Economical in initial cost compared to hydro      plants and running costs are less compared to gas plants or diesel plants.
• Thermal plants can be placed near load centers      unlike hydro and nuclear plants. Hence transmission of power losses can be      minimized
• Thermal plants are able to respond to the load      demand more effectively and supports the performance of the electrical      grid

Disadvantages

• Higher maintenance and operational cost
• Amount of co2 emissions are very high and so is      the rate of pollution
• Huge requirement of water and handling of coal      and disposal of ash is quite difficult and requires large area
• Efficiency of thermal plant is quite less      (30-35%)

Hydroelectric :
Advantages

• Once a dam is constructed, electricity can be      produced at a constant rate.
• If electricity is not needed, the sluice gates      can be shut, stopping electricity generation. The water can be saved for      use another time when electricity demand is high.
• Dams are designed to last many decades and so      can contribute to the generation of electricity for many years / decades.
• The lake that forms behind the dam can be used      for water sports and leisure / pleasure activities. Often large dams      become tourist attractions in their own right.
• The lake's water can be used for irrigation      purposes.
• When in use, electricity produced by dam      systems do not produce green house gases. They do not pollute the      atmosphere.

Disadvantages

• Dams are extremely expensive to build and must      be built to a very high standard.
• The high cost of dam construction so its very      expensive to set up and needs longer period of time to get the ROI.
• The flooding of large areas of land means that      the natural environment is destroyed.
• People living in villages and towns that are in      the valley to be flooded, must move out. This means that they lose their      farms and businesses. In some countries, people are forcibly removed so      that hydro-power schemes can go ahead.
• The building of large dams can cause serious      geological damage.
• Building a large dam alters the natural water      table level.

In recent times some Indian companies like Gati Infra are building sources for alternative energy that move beyond these three.