1. releases large amounts of energy from small amounts of mass

2. very efficient

3. convert nuclear energy into thermal energy

4. the fuel lasts a long time

Control the reaction rate by absorbing neutrons that are generated but not needed. They are typically made of cadmium or boron, elements that have very large neutron capture crosssections (a measurement of the statistical probability of a given nuclear interaction).

This sounds like a nuclear core meltdown, reactor meltdown, or just a meltdown.

In a pressurized water reactor the primary cooling water is under pressure of around 150 atm and its inlet temperature around 320 degree centigrade.

Its not used in any reactor designs. Most use ordinary water. A few designs use molten metals like sodium, NaK (sodium-potassium alloy), mercury, etc. because they do not slow the neutrons as water would and they want fast neutrons in these designs. These metals also transfer heat more efficiently than water does.

The condition known as going solid means that the reactor is shut down and cooled down, and the pressurizer is completely filled with water. The pressurizer is a component of the nuclear power plant that maintains high pressure on the coolant to keep it from flashing into steam. There is a steam bubble (a large volume) in the top of the pressurizer when the plant is online. Once cooled down and depressurized, we can pump more coolant into the plant to completely fill the pressurizer. The plant is then said to go solid when this happens.

Well, as nuclear reactors are nuclear reactors, nuclear reactors are not used inside nuclear reactors.

Graphite can be used as a moderator, that is to slow down the fast neutrons produced in fission. Early reactors including Hanford and Windscale used graphite, and in the UK this type of reactor was built extensively for power production. However water reactors such as PWR and BWR have proved cheaper to build and have a longer life, so graphite is now little used, there are a few still running but none being planned or built as far as I know.

Never ever

As of end of August 2013, there are 434 working nuclear power reactors (with total rated power 370.543 Gigawatt plus 69 nuclear power reactors under construction (with total rated power 67.196 Giagawatt).

All power reactors are thermal reactors except few ones that are fast nuclear reactors.

no

A nuclear reactor emits radiation. In a PWR reactor, if the reactor temprature is around 650 Degrees, The emission near the reactor core is 2.57 Roentgen. That is the amount of radiation a human is exposed to in around 20 Years.

There is also the dust, This dust if inhaled will cause cancer. If a Nuclear Powerplant explodes the story is different.

Lets take chernobyl NPP for instance.

The vincinity of the reacter core after explosion was 30,000 Roentgens per hour. That is 300 Sieverts per hour. That is enough to kill a man in 20 seconds. The fuel fragments that were realeased outward from the explosion the reactor had 15,000-20,000 Roentgens Pewr hour, And these fragments were laying on the ground after the explosion. Enough to kill a man in 30 seconds.

Nuclear, coal-fired, and hydroelectric power plants provide electricity.

For shielding against radiation and to provide more safety barrier against any unexpected emergency conditions.

By the control rods and by the moderator.

Unless they explode, The only negative effects is waste which is taken and buried at secure locations. And the waste generates is 79% Lower than the waste generated by coal powerplants.

Radioisotopes for many uses (e.g. medical, industrial, scientific) are produced in nuclear reactors.