The uranium rods are kept cool by submerging them in water. When they're removed from the water a nuclear reaction occurs causing heat.The level of heat needed is controlled by raising and lowering the rods. If more heat is needed the rods are raised further out of the water and if less is required they lower farther into it.

Advantages :

1) The quantity of electricity produced in a nuclear power station is identical to that produced by a fossil fuelled power station.
2) Nuclear power stations don't burn normal fuels to supply electricity and accordingly they don't produce damaging, polluting gases.
3) Many followers of nuclear power production say that this sort of power is environmentally friendly and clean. In a world that faces global temperature increases they suggest that skyrocketing the employment of nuclear power is the sole way of protecting the environment and forestalling disastrous global warming.
4) Many developed states like the USA and the United Kingdom no longer need to depend on gas and oil imported from the Middle East, a politically unstable part of the planet.
5) Nations like France produce roughly ninety % of their electricity from nuclear power and lead the world in nuclear energy generating technology - establishing that nuclear power is an industrial alternative choice to ordinary fuel power stations.
5) Nuclear reactors can be made sufficiently little to power ships and submarines.

If this was stretched beyond army vessels, the quantity of oil burning vessels would be reduced and hence pollution.