May 12, 2008
Nucular Reactors:
Classification and Technology
Oliver Gothe
Nucular Physics Laboratory
Professor Ralf Gothe
May 12, 2008
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Reaction Types
•Three main reaction types:
•Radioactive Decay
•Atomic Batteries
•Radioisotope thermoelectric generators
•passive
•Nuclear Fusion
•Not suitable for power production yet
•Nuclear Fission
•Used in most reactors including all commercial ones
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Reactors - Introduction
•Conventional thermal power plants
•All have a fuel source to provide heat
•Gas, coal, or oil
•Nuclear fission
•Uranium-235 or plutonium-239
•Produce steam
•Drive a turbine that generates electricity (86%)
•Enriched uranium is uranium in which the percent
composition of uranium-235 has been increased from that of
uranium found in nature
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Radioactive Decay (passive) - RTG
•Electric Generator
•Obtains power from passive radioactive decays
•Utilized in satellites and space probes
•Seebeck effect
• Junction of two dissimilar metals at different
temperatures create a current
•Fuel
•Long half life, low shielding...
•Plutonium 238 most common
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Advantages and Disadvantages
•Advantages:
•Relatively constant power
production
•Useful for long time
missions
•Solar Panels not applicable
•Disadvantages:
•Decays over time
•May require shielding
•Radioactive waste
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fusion
•Experimental Technology
•Not yet in use
•Generally utilizes Hydrogen as
fuel
•Contained with Magnetic fields
•Farnsworth-Hirsch Fusor
•Not viable for power creation
•Neutron Generator
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission Reactors - Overview
•First Reactor:
•Chicago Pile-1
•Enrico Fermi in 1942
•Inspired by the discovery that Uranium fissions after being
bombarded with neutrons
•Fission process creates new neutrons
•Creates chain reaction that needs to be moderated
•Unmoderated reaction used for bombs
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission - Process
• Fission is initialized in the
reaction chamber
• Creates Chain reaction
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission - Process
• Fission is initialized in the
reaction chamber
• Creates Chain reaction
• Moderators are used to
control the amount of
neutrons in the reactor
chamber
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission - Process
• Fission is initialized in the
reaction chamber
• Creates Chain reaction
• Moderators are used to
control the amount of
neutrons in the reactor
chamber
• Heat released from fission
is processed via heat
exchangers or directly via
steam turbines
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission - Process
• Turbines create electricity
and the coolant is recycled
through the reactor
• The environmental
problems with nuclear
reactors is the heat that is
released into the
environment from the
condensors.
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission – Reactor Classification
•Two Types
•Thermal vs. Fast Neutron speeds
•Thermal Reactors (most common)
•Classified by Moderator Material
•Absorption cross-section much smaller than fission
cross-section
•Natural Uranium
•Fast Reactors
•No moderator
•Requires Enriched Uranium
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Fast Neutron Reactor
•Fuel must be enriched
•Produces fast neutrons
•Can be used for transmutation
•Fuel Production
•Breeder Reactors
•Fast Breeder Reactors
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission - Moderators
•Graphite moderate reactors
•Graphite has high neutron absorption cross section
•Water moderated reactors
•Heavy water moderated reactors
•can be fueled with unenriched uranium
•Light Water moderated reactors
•Negative feedback stabilizes reaction (neutron
absorption)
•Light element moderated reactors
•are moderated by a light elements such as Li or Be
•Organically moderated reactors
•Use biphenyl and terphenyl as moderator and coolant
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission Reactors - Coolant
•Pressurized Water Cooling
•specialized pressure vessel
•A pressurizer is partially
filled with water
•steam bubble is maintained
above it by heating the
water with submerged
heaters
•Avoid film boiling
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission Reactors - Coolant
•Pressurized Water Cooling
•specialized pressure vessel
•A pressurizer is partially
filled with water
•steam bubble is maintained
above it by heating the
water with submerged
heaters
•Avoid film boiling
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Nuclear Fission Reactors - Coolant
•Boiling water reactor
•Simplification of designs for civilian purposes
•Heat is generated directly in the reaction chamber
•Chamber is still pressurized and boils at about 285 degrees
Celsius
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Pool Type Reactors
•In pool type reactors the reactor core and
control roads are immersed into a pool
•Water is simultaneously:
•Cooling agent
•Moderator
•Shielding
•Used for:
•Neutron generation
•Training
•Not for generating electricity
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Liquid Metal Cooled Reactors
•Liquid metal cooled nuclear reactor
•primary coolant is a liquid metal
•Used in nuclear submarine use
•extensively studied for power
generation applications
•Fast Breeder Reactors
•Lead
•Sodium
•Bismuth
•Mercury
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Gas Cooled Reactors
•
Gas cooled reactors
• Use inert gases such as Helium
or Carbon dioxide to cool
• Some heat the gas enough to
run turbines
• Older models run through heat
exchangers to generate steam
• Can be refuelled while online
• Higher thermal efficiency than
BWRs
• Uses fuel less efficiently though
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
1. Charge tubes
2. Control rods
3. Graphite moderator
4. Fuel assemblies
5. Concrete pressure vessel and radiation
shielding
6. Gas circulator
7. Water
8. Water circulator
9. Heat exchanger
10. Steam
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Molten Salt Reactors
•Molten salt reactors
•cooled by circulating a molten
salt
•mixture of fluoride salts, such
as LiF and BeF2
•Uranium is often dissolved in
the matrix
•Maintenance issues
•Corrosion
•Can use spent fuel
•Immature Technology
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Generations of Nuclear Reactors
• Generation I reactors
• Developed in 1950-60s
• used natural uranium fuel
• graphite as moderator
• Generation II reactors
• use enriched uranium fuel
• mostly cooled and moderated by water
• Generation III
• advanced reactors
• developments of the second generation with enhanced safety.
• Generation IV
•
•
drawing board
burn the long-lived actinides now forming part of spent fuel
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Examples – Pressurized Water Reactor
•Pressurized Water Reactors
•high pressure liquid
•majority of current reactors
•considered the safest and
most reliable
Diablo Canyon
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Examples – Boiling Water Reactor
•Boiling Water Reactors (BWR)
•Cooled and moderated by
water
•Lower pressure
•Water boils in reactor
•Simpler
•Potentially more stable
•Substantial percentage of
modern reactors
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
Laguna Verde nuclear power plant
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Examples – Pressurized Heavy Water Reactor
•Pressurized Heavy Water
Reactor (PHWR)
•Heavy water cooled and
moderated
•Hundreds of pressure tubes
•Fueled with natural uranium
•Thermal neutron reactor
design
•Can be refueled without
shutdown
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
CANDU at Qinshan
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Examples – High Power Channel Reactor
•High Power Channel Reactor
(RBMK)
•Produces plutonium as well
as power
•Graphite moderator
•Too large to have
containment buildings
•Chernobyl accident
•RBMK reactors are
considered the most
dangerous reactor designs in
use
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
The Ignalina Nuclear Power Plant
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Examples – Advanced Gas Cooled Reactor
•Advanced Gas Cooled Reactor
(AGCR)
•Graphite moderated
•CO2 cooled
•High thermal efficiency
compared with PWRs
•Thermal neutron reactor
design
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
Torness nuclear power station
USC -- Department
Princeton
Department of
of Physics
Chemistry
May 12, 2008
Questions?
Nuclear
Physics
Lab – Oliver
R. Gothe
Princeton
- Department
of Chemistry
USC -- Department
Princeton
Department of
of Physics
Chemistry