Nuclear Energy Lecture Notes

Modeling and Design of Energy Systems

  • ENVE 162 – CRN 111515 Spring 2025
  • MW 1:30-2:45pm; Granite Pass Room 135
  • Abbas Ghassemi, Ph.D. Emeritus Professor
  • Teaching Professor; Civil and Environmental Engineering
  • SE2 372; aghassemi2@ucmerced.edu
  • Lecture Notes- April 7, 2024

Energy Generation and Losses (2015)

  • Estimated U.S. Energy Consumption in 2015: 97.5 Quads
  • Source: LLNL (Lawrence Livermore National Laboratory) and EIA (Energy Information Administration)

Energy Sources and Consumption (Quads)

  • Solar: 0.532 (rejected energy), 8.34 (energy services)
  • Nuclear: 0.16 (rejected energy), 8.34 (energy services), 2.38 (electricity generation)
  • Hydro: 2.39 (rejected energy), 1.81 (energy services)
  • Wind: 0.04 (rejected energy), 1.82 (energy services)
  • Geothermal: 0.224 (rejected energy)
  • Natural Gas: 28.3 (rejected energy), 15.7 (residential), 14.3 (commercial), 4.72 (industrial)
  • Coal: 9.99 (rejected energy), 0.52 (residential), 0.28 (commercial), 24.5 (industrial)
  • Biomass: 0.25 (rejected energy)
  • Petroleum: 35.4 (rejected energy), 11.3 (transportation)

Net Electricity Generation and Consumption (Quads)

  • Net Electricity Imports: 0.08
  • Electricity Generation: 38.0

Sector Consumption (Quads)

  • Residential: 3.3 (electricity), 4.75, 0.02 (imports), 9.36 (rejected energy), 0.01
  • Commercial: 0.92 (electricity), 1.41, 0.45 (imports), 0.98 (rejected energy), 0.06
  • Industrial: 0.13 (electricity), 0.56, 1.35 (imports), 2.28 (rejected energy), 8.2
  • Transportation: 25.4 (rejected energy), 3.95 (electricity), 4.78 (imports)

Renewable Energy Sources Overview

  • What are the renewable energy sources?
  • What are the environmental impacts of these energy sources?

Types of Renewable Energy

  • Solar energy: Solar heating (passive and active), solar power plants, photovoltaic cells
  • Biomass energy: Direct (combustion of biomass), Indirect (chemical conversion to biofuel)
  • Wind energy: Vertical and horizontal axis
  • Hydro energy: High head, large dams, low head, high flows
  • Geothermal energy: Power plants, direct use, heat pumps
  • Ocean energy: Tidal; salinity-driven
  • Nuclear: Potentially considered (controversial)

World Energy Consumption

  • A significant portion continues to be from Fossil resources.

Global Power Generation Projection

  • Renewable Energy Projected to Account for Three Quarters of Global Power Generation by 2050

Energy Source Projections (Thousands of Terawatt Hours - TWh)

  • The data shows projections from 1995 to 2050 for various energy sources:
    • Coal: Decreasing from 40 TWh (1995) to 24 TWh (2050).
    • Gas: Increasing from 24 TWh (1995) to 27 TWh around 2030, then fluctuating to 27 TWh (2050).
    • Oil: Decreasing slightly from 13 TWh (1995) to 15 TWh (2050).
    • Nuclear: Increasing from 21 TWh (1995) to 30 TWh (2050).
    • Hydro: Increasing from 36 TWh (1995) to 45 TWh (2050).
    • Wind: Increasing significantly from minimal TWh (1995) to 49 TWh (2050).
    • Solar: Increasing drastically from minimal TWh (1995) to a substantial amount in 2050.
    • Other: Includes biomass, geothermal, and marine; Increase from 18 TWh (1995) to 33 TWh (2050).

Share of Renewables

  • Share of Renewables: 18% (1995) -> 73% (2050)

Renewable Energy in the United States

  • Renewable generates ~ 20% of all U.S. Electricity. % renewable electricity production in 2021

Nuclear Energy

Potential Energy Sources

  • Fusion: Magnetic Plasma, Confinement, Inertial Fusion
  • Fission: Waste & Nuclear Proliferation

Nuclear Reactor Needs for 10 TW

  • To get 10 TW, 10,000 new 1 GW reactors needed; i.e., a new reactor every other day for the next 50 years.

Fission and Fusion

  • All of the energy we produce comes from basic chemical and physical processes.
  • Fission and fusion are two physical processes that produce massive amounts of energy from atoms.
  • They yield millions of times more energy than other sources through nuclear reactions.

Fission

  • Fission occurs when a neutron slams into a larger atom, forcing it to excite and split into two smaller atoms—also known as fission products.
  • Additional neutrons are also released that can initiate a chain reaction.
  • When each atom splits, a tremendous amount of energy is released.
  • Uranium and plutonium are most commonly used for fission reactions in nuclear power reactors because they are easy to initiate and control.

Fusion

  • Fusion occurs when two atoms slam together to form a heavier atom, like when two hydrogen atoms fuse to form one helium atom.
  • This is the same process that powers the sun and creates huge amounts of energy—several times greater than fission.
  • Fusion produces little or no radioactive fission products.
  • Fusion reactions are difficult to sustain for long periods of time because of the tremendous amount of pressure and temperature needed to join the nuclei together.

Comparison of Chemical Reaction, Fission, and Fusion

Fuel

  • Chemical Reaction: Coal
  • Fission: UO2UO_2 (3% U-235 + 97% U-238)
  • Fusion: Deuterium + Tritium

Temperature

  • Chemical Reaction: 700°K
  • Fission: 1,000°K
  • Fusion: 100,000,000 K

Energy (J/kg)

  • Chemical Reaction: 3.3×1073.3 \times 10^7
  • Fission: 2.1×10122.1 \times 10^{12}
  • Fusion: 3.4×10143.4 \times 10^{14}

Nuclear Fission Details

  • Reaction where the nucleus of an atom splits into two or more smaller nuclei, releasing energy in the form of heat and radiation.
  • When hit by a neutron, the nucleus of an atom of uranium-235 splits into two smaller nuclei (i.e. a barium nucleus and a krypton nucleus) and two or three neutrons.
  • Extra neutrons will hit other surrounding uranium-235 atoms, which will also split and generate additional neutrons in a multiplying effect, thus generating a chain reaction in a fraction of a second.
  • The heat can be converted into electricity in a nuclear power plant, similarly to how heat from fossil fuels.

Nuclear Power Plant

  • PWR – Pressurized Water Reactor
  • PWR constitute the large majority of the world's nuclear power plants is a type of light-water nuclear reactor.

Nuclear Fuel Cycle

  • The nuclear fuel cycle is an industrial process involving various steps to produce electricity from uranium in nuclear power reactors.
  • The cycle starts with the mining of uranium and ends with the disposal of nuclear waste.

Nuclear Power in the U.S.

  • Nuclear power plants have generated about 20% of U.S. electricity since 1990.
  • As of August 1, 2023, 93 nuclear reactors were operating at 54 nuclear power plants in 28 states.
  • Of the 54 operating nuclear power plants, 19 have one reactor, 31 have two reactors, and 4 have three reactors.

California's Electricity Sources

  • Natural gas is still by far the leading source of California's electric power.

Sources

  • Non-renewable: Natural Gas, Coal, Oil, Waste Heat / Petroleum Coke
  • Renewable: Solar, Large Hydro, Wind, Geothermal, Biomass, Small Hydro
  • Unspecified: Unspecified

Diablo Canyon Power Plant

  • PG&E's Diablo Canyon Power Plant, 2,240-megawatt nuclear reactors in Avila Beach, California supplies enough power for 3 million people
  • Gov. Newsom says he is considering applying for federal funding that would keep it open past its scheduled 2025 closure to avoid rolling blackouts.

Capacity Factor

  • Nuclear Has The Highest Capacity Factor of any other energy source.
  • This basically means nuclear power plants are producing maximum power more than 92% of the time during the year.

Yellowcake Uranium Ore

  • Yellowcake is the basis for nuclear fuel.

Uranium Oxide Pellets

  • Uranium oxide pellets are not hazardous until activated.
  • Uranium is the fuel most widely used to produce nuclear energy because uranium atoms split apart relatively easily.
  • It's also a very common element, found in rocks all over the world.
  • However, the specific type of uranium used to produce nuclear energy, called U-235, is rare (< 1% of the uranium in the world)
  • Typical composition of UO2UO_2 fuel before and after approximately three years in the once-through nuclear fuel cycle of a Light-water reactor

Uranium Isotopes

  • Proportions of the isotopes uranium-238 (blue) and uranium-235 (red) found in natural uranium and in enriched uranium for different applications.
  • Light water reactors use 3–5% enriched uranium, while Canadian pressurized heavy-water reactor design reactors work with natural uranium.

Control Rods

  • Rods of material called "nuclear poison" can adjust how much electricity is produced.
  • The more rods of nuclear poison that are present during the chain reaction, the slower and more controlled the reaction will be.
  • Removing the rods will allow a stronger chain reaction to create more electricity.

Cesium Pool

  • Reinforced stainless-steel containers of radioactive cesium-137 sit in a four-meter deep pool at the Hanford Site, a nuclear facility in Richland, Washington.
  • This is one of the final steps in the process of generating nuclear energy.
  • Cesium must sit underwater for 10 years until it is cool enough to be removed to a nuclear-waste storage site.

Nuclear Waste Repository

  • Concrete nuclear waste disposal containers with a maximum of 25 curies of radiation per drum in an abandoned salt mine near Asse, Germany, about one kilometer beneath the earth. (A curie is the radioactivity of one gram of uranium)
  • Nuclear waste flasks generated by the US during the Cold War are stored underground at the Waste Isolation Pilot Plant (WIPP) in New Mexico.
  • Dry cask storage is a method of storing high-level radioactive waste, such as spent nuclear fuel that has already been cooled in the spent fuel pool for at least one year and often as much as ten years. Casks are typically steel cylinders that are either welded or bolted closed. The fuel rods inside are surrounded by inert gas.

Radioactive Waste Management

  • The operation of nuclear power plants produces waste with varying levels of radioactivity and managed differently depending on their level of radioactivity and purpose.
  • Radioactive waste is a small portion of all waste. It is the by-product of medical procedures each year, industrial and agricultural applications that use radiation and nuclear reactors that generate around 11 % of global electricity.

Nuclear Accidents

Three Mile Island

  • The Three Mile Island nuclear power plant, near Harrisburg, Pennsylvania, is capable of generating 892 MW of electricity, enough to power more than 800,000 homes and businesses. In 1979, part of the Three Mile Island facility suffered a meltdown and was never reopened.

Chernobyl

  • A Geiger counter measures radiation outside the Chernobyl (Ukraine) Nuclear Power Plant, which exploded in 1986. The explosion created a cloud of radioactive particles that fell to the ground, called fallout. The fallout drifted with the wind and entered the water cycle as rain. Radioactivity traced to Chernobyl fell as far away as Scotland and Ireland, although most fallout was detected in Belarus.

Fukushima

  • Accident occurred at the Fukushima Daiichi nuclear power plant in Ōkuma, Fukushima, Japan on March 2011.
  • It was due to earthquake and tsunami which caused electrical grid failure and damaged nearly all of the power plant's backup energy sources.
  • The subsequent inability to sufficiently cool reactors after shutdown compromised containment and resulted in the release of radioactive contaminants into the surrounding environment.