Uranium Ore - must be “enriched” most abundant = 238 U fissionable = 235 U (“fuel”) Reminder: Isotopes different # of neutrons Naturally occurring radioactive isotopes (alpha decay, beta decay, spontaneous fission) In uranium ore some 238 U is removed and 235 U is increased from 0.7% that occurs naturally to almost 3%. Wikimedia Commons." Nuclear Fission = neutrons split the nuclei of atoms such as uranium-235 & plutonium-239 and release energy mostly as high temperature heat which is used to produce high pressure steam to spin turbines to generate electricity.

The dome-shaped containment building at the Shearon Harris Nuclear Power Plant near Raleigh, NC

Light Water Reactors - Pressurized vs. Boiling Water Reactor Control Rods - made of neutron absorbing material (cadmium/boron) moved in and out of the spaces between the fuel. REGULATES rate of fission. Moderator - slows down the neutrons to keep chain reaction going. Material can be water (75%) graphite, or heavy water (deuterium oxide) Coolant - usually water circulates through the reactors to keep materials from melting and to produce steam for the turbines to produce electricity Core – contains 35,000-70,000 fuel rods packed with “pellets” that equal the energy out put of 1ton of coal

ADVANTAGES  Large Supply  Low Environmental Impact  Emits only 1/6 of CO2 as coal  Moderate land and water disruption (without accidents) DISADVANTAGES  High Cost – even with Govt. subsidies  Low net energy yield (facilities $$)  Major Accidents are HIGH environmental cost  Waste Solutions??  Encourages Technology for Weapons Use

CHERNOBYL  1986 – Ukraine  125,000 died from exposure  3.5 million have become ill  Cost = $358 million  Flaws in designs & operator errors THREE MILE ISLAND  1979  Pennsylvania  Operator Error