Nuclear Reactor Arrangement

1. The main reactor components are the reactor core, reflector, pressure vessel, biological shielding.

2. The core contains nuclear fuel in the form of rods or plates, arranged in assemblies; the coolant, the moderator, the control rods.

3. The function of nuclear fuel is to release heat.

4. Nuclear fuel may be Uranium or Plutonium.

5. A gas, water or liquid metals used for coolant serve to absorb heat and to remove it to the heat exchanger.

6. Moderator is a neutron absorbing material used to slow down fast neutrons.

7. The moderator may be water, graphite or beryllium.

8. Pressure vessel, which is a heavy tank made of steel, contains all the reactor parts.

9. Reflector is a layer of moderating materials like water, graphite, beryllium used to reduce neutron leakage from the core.

10. Biological shielding is a layer of neutron absorbing materials like water, concrete, lead or iron used to protect personnel against radiation.

11. To control fission process in the core control rods made of boron or cadmium are used.

First Nuclear Power Station

1. The first electric power station working on nuclear fuel was built in the USSR in Obninsk by а team of scientists and engineers under the guidance of Igor Kurchatov in 1954.

2. The main purpose of the first NPS was to make sure of technical feasibility of converting nuclear energy into electrical one.

3. The reactor of the station was а uranium-graphite reactor of the channel type, water cooled.

4. The reactor core had the shape of а cylinder 150 cm high and 70 cm in diameter. It housed 128 fuel rods and 22 control rods, four of them were used for emergency cases.

5. The moderator was graphite in the form of а triangular lattice.

6. The double-circuit system produced superheated steam at the temperature of 280°С and the pressure of 12 atm. for а conventional turbine.

7. Heat capacity of the reactor was 30 MWt.

8. Four circulating pumps of centrifugal type circulated coolant through the primary circuit to four steam generators.

9. The biological shielding of the reactor was а layer of water one meter thick and а concrete wall 3 meters thick.

Types of Nuclear Power Plants

1. Nuclear power plants may be classified by the number of circuits.

2. There are single-circuit, double-circuit and three-circuit nuclear power plants.

3. If the circuits of the coolant and the working substance coincide, this will be а single-circuit nuclear plant.

4. If the circuits of the coolant and the working substance are separated, such а nuclear power station is called а double-circuit plant.

5. The circuit of the coolant is known as the primary and that of the working substance as the secondary.

6. А double-circuit plant always requires а steam generating plant, which separates the two circuits.

7. A steam generator belongs equally to the primary and the secondary circuit.

8. A three-circuit nuclear power plant consists of the primary circuit, the intermediate circuit and secondary circuit.

9. Three-circuit nuclear power plant has two heat exchangers – the primary HX and the secondary HX.

10. NPP may be classified according to the type of reactor, the type of steam turbines, the construction of the reactor and the type of moderator.