South-Ukrainian NPS

Date: 2015-10-07; view: 556.

The Fission Chain Reaction

1. As secondary neutrons split other nuclei the number of fissions increases.

2. The fission chain reaction is established if at least one secondary neutron is produced in each fission.

3. The number of neutrons in one fission is called a generation.

4. The ratio of the number of neutrons in one generation to the number of neutrons in the preceding generation is called the multiplication factor.

5. Chain reaction can be self-sustaining if the multiplication factor is not less than unity.

6. To develop a fission chain reaction we can increase the U235 content in uranium or can slow down neutrons.

7. In the first case both fast and slow neutrons can maintain the chain reaction.

8. In the second case the chain reaction is induced mostly by slow neutrons.

9. Controllable chain reaction is used in nuclear reactors to produce energy.

10. Uncontrollable chain reaction results in explosion and is used in atomic bombs.

1. The construction of SU NPS began in the spring of 1975.

2. The first power unit was launched into operation in December 1982.

3. At present, it is one of the largest power-generating enterprises in the South of Ukraine.

4. SU NPS operates three power units with а total capacity of 3000 MW.

5. The first two ones comprise a WWPR-1000 reactor.

6. The station's thermal arrangement consists of two circuits.

7. The first circuit includes the reactor unit, four circulation loops, steam generators, and main circulating pumps.

8. The fuel core, structural elements guiding the coolant, and reactivity controls are in the reactor's shell.

9. Highly enriched uranium dioxide is used as fuel.

10. The secondary (non-radioactive) circuit consists of four steam generators and а 1,000 MW turbine generator set.

11. The station's control combines central panel monitoring, remote control facilities, and automatic regulation.

12. Power control and scram functions are performed by moving the neutron absorbers in and out of the core.

Nuclear Safety

1. Nuclear safety should prevent nuclear and radiation accidents and limit their consequences.

2. Nuclear safety strategy includes five layers of defense.

3. The first defense barrier in design is the inert ceramic quality of nuclear fuel.

4. The second layer of defense covers quality of fuel cladding.

5. The third layer of defense is determined with the reactor pressure vessel.

6. The fourth layer of defense includes resistance of the containment building.

7. The fifth layer of defense depends upon the reactor building or а second outer containment building.

8. Redundancy in engineering is the duplication of critical components of а system to increase reliability of the system.

9. An error in а control system may result in а failure of the whole plant.

10. Duplication or triplication of critical components of а system increases its reliability.