Nuclear Energy - Lecture

Nuclear Power and Fission

• Nuclear power: uses nuclear reactions that release nuclear energy to generate heat, which is used in steam turbines to produce electricity

  • free of air pollution: emissions are water vapor

  • many misconceptions due to mercury, water disposal

• Fission vs fusion

  • fission: splitting of atoms aka nuclear energy

  • fusion: fuses atoms (sun)

Source of Nuclear Energy

• Uranium 235 and uranium 278

• Uranium 235 is radioactive

  • Radioactive and decays lead to uranium 207

• Uranium 236 is the most common but not enough neutron emissions for chain reactions

• After several years, in the reactor, it is depleted

• Spent fuel can be reprocessed, but it’s expensive

Nuclear Reactors

• Fission takes place in reactor core

• Containment building: prevents leaks of radioactivity due to accidents or catastrophes, not all reactors require this

• Control rods: metallic alloys that absorb neutrons

Nuclear Waste

• Spent fuel rods and other waste remain radioactive for thousands of years

  • waste is temporarily stored at plants

    • spent rods stored in water: wet storage

  • waste is stored in thick — of steel, lead, and concrete. US is running out of room

  • safer to store waste in one central location

  • Yucca Mt. is the designated location to store spent fuel

Nuclear Risks and Impacts

• Meltdown: occurs when temperatures rise inside the reactor core, melting surrounding fuel rods and releasing radiation

• Key disasters

  • 1974: Three Mice Island (Pennsylvania)

  • 1986: Chernobyl (human error)

  • 2011: Fukushima

Future of Nuclear

• Growth has slowed due to concerns about waste disposal, safety, and cost

• Plants are aging faster than predicted

• 3rd or 4th generation reactors: more fuel efficient, cheaper, and safer

  • reuse spent fuel?

Radioactive Waste

• Low level waste can be safer buried newer surface at burial sites

  • must be monitored

• High level waste from nuclear power plants and weapon production facilities remain hazardous for thousands of years

  • storage and monitored in stable bedrock permanent disposal needed

  • Yucca Mountain Nevada

Radioactivity

• Radioisotopes undergo radioactive decay, in which they’re transformed into a different element and produce radiation

  • alpha, beta, gamma: each have a different effect and and toxicity

  • isotopic with low-energy emissions and short half-lives are less dangerous than high energy emissions

    • exception: radon gas when in high concealed concentrations

      • radon gas in home