Sources of Radiation Nuclear Power Reactors IAEA Day

Sources of Radiation Nuclear Power Reactors IAEA Day 4 – Lecture 3 1

Objective To discuss about Nuclear Power Reactors including their Types and Basic Elements IAEA 2

Contents § Types of Nuclear Reactors • PWRs • BWRs • CANDU • Advanced Nuclear Reactors § Components of a Nuclear Power Plant IAEA 3

The Beginning IAEA 4

Fossil vs Nuclear IAEA 5

Nuclear Reactors Ø Types of Nuclear Reactors: Ø Ø Ø IAEA Light Water Reactors (LWR) Heavy Water Reactors (HWR) High-Temperature Gas-Cooled Reactors Fast Neutron Fast Breeder 6

Primordial Nuclides Nuclide 235 U 238 U 232 Th IAEA Half-life Natural Activity 7. 04 x 108 yr 0. 711% of all natural uranium 4. 47 x 109 yr 99. 275% of all natural U; 0. 5 to 4. 7 ppm total U in common rocks 1. 41 x 1010 yr 1. 6 to 20 ppm in common rocks

Slow Neutron Interactions Fission 1 n + 235 U fission products available for more fission the mean number of neutrons released per fission for U 235 is 2. 5). This leads to a self-sustaining chain reaction or “critical mass. ” IAEA 8

Boiling Water (BWR) Nuclear Reactors IAEA 9

Pressurized Water (PWR) Nuclear Reactors IAEA 10

Components of a Nuclear Plant Ø The next five slides display the main components of a Nuclear Power Plant: Ø Ø Ø Control Building Containment Building Turbine Building Fuel Building Diesel Generator Building Auxiliary Building IAEA 11

Control Building IAEA 12

Containment Building IAEA 13

Turbine Building IAEA 14

Fuel Building IAEA 15

Diesel Generator and Auxiliary Buildings IAEA 16

Protective Barriers IAEA 17

Steam Generator IAEA 18

Nuclear Reactors IAEA 19

Advanced Reactors Ø The first advanced reactors now operating in Japan Ø Nine new nuclear reactor designs either approved or at advanced stages of planning Ø Incorporate safety improvements and are simpler to operate, inspect, maintain and repair IAEA 20

Advanced Reactors Ø The new generation of reactors have: Ø a standardised design to expedite licensing, reduce capital cost and reduce construction time Ø higher availability and longer operating life, will be economically competitive in a range of sizes, further reduce the possibility of core melt accidents Ø higher burn‑up to reduce fuel use and the amount of waste IAEA 21

Advanced Reactors Ø More 'passive' safety features which rely on gravity, natural convection to avoid accidents Ø Two broad categories: Ø Evolutionary - basically new models of existing, proven designs Ø Developmental - depart more significantly from today¹s plants and require more testing and verification before large‑scale deployment IAEA 22

CANDU Reactors Ø CANDU stands for "Canada Deuterium Uranium“ Ø It is a pressurized‑heavy‑water, natural‑uranium power reactor designed first in the late 1950 s by a consortium of Canadian government and private industry Ø All power reactors in Canada are CANDU type Ø The CANDU designer is AECL (Atomic Energy of Canada Limited), a federal crown corporation IAEA 23

CANDU Reactors IAEA 24

CANDU Reactors IAEA 25

High Temperature Gas Cooled Reactors IAEA 26

High Temperature Gas Cooled Reactors IAEA 27

Pebble Bed Reactor In the 1950 s, Dr Rudolf Schulten ( 'father' of the pebble bed reactor) had an idea. The idea was to compact silicon carbide coated uranium granules into hard billiard-ball-like graphite spheres to be used as fuel for a new hightemperature, helium-cooled type of reactor. The idea took root, and in due course, the AVR, a 15 MW (megawatt) demonstration pebble bed reactor, was built in Germany. It operated successfully for 21 years. IAEA 28

Pebble Bed Reactor IAEA 29

Pebble Bed Reactor Potential Problems (according to some groups) Ø It has no containment building Ø It uses flammable graphite as a moderator Ø It produces more high level nuclear wastes than current nuclear reactor designs IAEA 30

Pebble Bed Reactor Potential Problems (according to some groups) Ø It relies heavily on nearly perfect fuel pebbles Ø It relies heavily upon fuel handling as the pebbles are cycled through the reactor Ø There's already been an accident at a pebble bed reactor in Germany due to fuel handling problems IAEA 31

Where to Get More Information Ø Cember, H. , Johnson, T. E, Introduction to Health Physics, 4 th Edition, Mc. Graw-Hill, New York (2009) Ø More information at: http: //www. pbmr. co. za/index. htm IAEA 32