CH.19CONVENTIONAL ENERGY 1 9 . 5 N U C L E A R P O W E R Z AC H AN D E R S O N AD AM C O R E
NUCLEAR POWER• Beginning in the early 1950’s, President Eisenhower wanted to move towards a more nuclear-powered society. He presented “Atoms for Peace” speech before the United Nations in 1953, pushing for nuclear-powered generators to provide clean, abundant energy.• He pushed for nuclear energy as an alternative resource because it would fill the deficit that came from shortages of oil and natural gas.• This was also a very cheap form of energy.• Between 1970-1974 American utilities ordered 140 new reactors for power plants.• However in recent decades, increasing construction costs, declining demand for electric power and safety issues have made nuclear energy far less favorable.
NUCLEAR REACTORS• The most commonly used fuel in nuclear power plants is U₂₃₅, which is a naturally occurring radioactive isotope of uranium.• Usually U₂₃₅ makes up less than 1% of uranium ore.• Many people who are exposed to uranium mines suffer from lung cancer due to high levels of radon and dust.
NUCLEAR REACTORS (CONTINUED)• U₂₃₅ concentrations must reach 3%, so it can be formed into cylindrical pellets.• 100 rods together make up a fuel assembly. These fuel assemblies are packed together in a heavy steel vessel.• The radioactive uranium particles produced are unstable and undergo nuclear fission, releasing energy and neutrons.
REACTOR DESIGNS• 70% of the nuclear plants in the world are pressurized water reactors, (PWR) where water circulates through the core and absorb heat as it cools the fuel rods.• There is a simpler, but dirtier and more dangerous reactor is the boiling water reactor (BWR). In this model, water from the reactor core boils to make steam, which directly drives the turbine-generators.
REACTOR USES• Britain, France, and the former Soviet Union all use a common reactor design that uses graphite, both as a moderator and as the structural material for the reactor core. Britain uses MAGNOX, while in the Soviet the RBMK was used.• These were all originally thought to be safe due to graphite’s high capacity for both capturing neutrons and dissipating heat.• One of the most well known disasters was at Chernobyl, caused from burning graphite.
ALTERNATIVE DESIGNS• HTGCR- High Temperature Gas-Cooled Reactor• PIUS- Process-Inherent Ultimate Safety reactor
HTGCR• Fuel pellets are encased in ceramic.• Helium is used as the coolant.• All Coolant can be lost and no meltdown will occur.• Examples: Brown’s Ferry Reactor in AL (failed)• General Atomic in Europe (successful) • Suffered complete coolant loss—survived.
BREEDER REACTORS • Special reactors that create fuel from U238.
BREEDER REACTORS• Advantages • Disadvantages• Create enough fuel • Has to be run at to power nuclear high temperature so plants for 100+ years water can’t be• Use an abundant used as coolant. form of uranium Liquid Na is used. • Produce weapons grade plutonium.