Nuclear Energy

Front 1

Energy from Fission

Back 1

1. Fission involves the breaking down of the nucleus of radioactive materials, Radioactive decay.

2. Products of Decay
o Electrons
o Helium nucleus
o Radiation
o Heat

3. Nuclear power involves controlling the rate of fission, and thus the rate of the heat production.

4. Uranium-235 is the only naturally occurring fissionable material useful for energy production.

5. Uranium-238 is not naturally fissionable, it will convert to plutonium-239 which is fissionable, and useful in making nuclear and “dirty weapons.”

Front 2

Geology & Distribution of Uranium

Back 2

1. Uranium is found in igneous rocks as a primary element in a variety of minerals. The igneous rock granite, particularly.

2. Uranium Deposits
o Sandstone impregnated with uranium materials including carnotite.
o Veins of uranium bearing minerals in rock fractures
o In 2.2 billion year old placer deposits.

Front 3

Reactor Design & Operation

Back 3

11. With the exception of handling of the fuel source, nuclear energy is quite a bit like the other ways that energy is produced using heat.

Front 4

Reactor Design-Burner Reactors

Back 4

1. Consume more fissionable material than they produce.

2. Can’t blow up like an atomic bomb.

Front 5

Types of Reactor Designs

Back 5

1. Light-water moderated reactor

2. Graphite Moderated Reactor

3. Pebble-Bed Reactor

4. Breeder Reactors

Front 6

Light-water moderated reactor

Back 6

1. The core is immersed in light water inside of a containment vessel.

2. Control rods, made up of neutron absorbing materials, when lowered reduce the rate of fission.

3. Radiation is contained within the core facility, with the steam used to turn the turbine never coming into contact with the radioactive materials.

4. Problems can occur when the pressure inside of the containment structure requires a release of radioactive steam into the environment (Three Mile Island, April 11, 1979).

Front 7

Graphite Moderated Reactor

Back 7

1. This type of reactor uses a block of graphite into which the fuel rods are raised and lowered.

2. When they are completely immersed, the reaction will not occur.

3. The only type of reactor that has had catastrophic failure (Windscale, England (1957) and Chernobyl, Russia (1986)).

Front 8

Pebble-Bed Reactor

Back 8

1. Not yet available

2. Only enough fuel is released into the reactor to produce electricity as needed, as a safety feature.

Front 9

Breeder Reactors

Back 9

1. These reactors produce more fuel than they use.

2. They bombard spent nuclear materials (U-235) to “recharge” them, making them reusable.

3. They can blow up like atomic bombs, they use plutonium.

Front 10

Sustainability & nuclear Energy

Back 10

1. Two Aspects
o Can be used to fuel the production of hydrogen from water or methane to produce electricity/power.
o Can be used directly as a fuel for powering systems.

2. U-235 is not sustainable, unless breeder reactors can be used economically. U-235 is a fixed, mineral resource.

3. Nuclear power plants are becoming more economical and safer.

4. Widespread use in France, but smaller reactors and an “accepted” set of plans, not a new plan for every reactor. Also, France is shutting down some of their reactors.

Front 11

Risks Associated with Fission Reactors

Back 11

1. Disposal of Wastes

2. Release of Radiation into the Environment

3. Transportation of nuclear Material

4. Terrorism

5. Accidents
o Three Mile Island – Human & Mechanical
o Chernobyl- Wacky Engineers

Front 12

The Future of Energy from Fission

Back 12

1. As the US is looking at increasing the amount of energy produced by nuclear power, the rest of the world is heading in the other direction (except for north Korea and Iran).

2. Many of the US power plants will have to be decommissioned within the next 20 years because of their age.

3. It is a much cleaner source of energy, if we can work out the problems with enrichment and disposal of fuel materials.

Front 13

Radioactive Waste Management

Back 13

1. The safe disposal of radioactive wastes is imperative if these resources are to be used.

2. Radioactive wastes are by-products that are produced in electricity production, medicine, the manufacturing industry, or materials produced in the weapons industry.

3. Low-level radioactive wastes

4. Transuranic Wastes

5. High-level wastes

Front 14

Low-level radioactive wastes

Back 14

1. Contain only a small amount of radioactive substance.

2. Includes solutions from chemical processing, solid or liquid plant wastes (sludges and acids), and slightly contaminated equipment.

3. This material is usually solidified or packaged with material that will absorb the liquid.

4. Must be stored for about 500 years, the main problems in radiation, not heat.

5. The primary solution, at present in the US, has been to dilute and disperse.

6. The particular nature of the geology of the disposal site is essential for safe disposal. The leakage from these sites can have adverse environmental effects.

Front 15

Transuranic Wastes

Back 15

1. Radioactive waste composed of human-made radioactive elements heavier than uranium.

2. Most is industrial trash

3. This material has low-level radiation, but an extremely long half-life. Storage may be for as much as 250,000 years.

4. Most transuranic waste is produced in the process of making nuclear weapons.

5. Disposed of at the WIPP facility near Carlsbad, new mexico.

Front 16

High-level wastes

Back 16

1. Produced as fuel assemblages in nuclear reactors.

2. The spent fuel must be removed, reprocessed, or disposed of.

3. Materials produced from nuclear reactors include kryton-85, strontium-90, and cesium-137. Each has a different half-life.

4. Again, this material must be stored for as much as 250,000 years.

Front 17

Yucca Mountain

Back 17

1. Isolated in welded tuff

2. Below is an impermeable layer of zeolitic rock

3. Deep water table.

Front 18

Nuclear Paladins

Back 18

1. Who will be around in 250,000 years to protect this material from terrorists and to monitor the effect on the environment?

Front 19

Nuclear Fusion

Back 19

1. Combines hydrogen to produce helium.

2. Like the sun, but how do we contain the sun?

3. Not in our lifetime, unless something “magical” happens in our understanding of science.

Front 20

Geothermal Energy

Back 20

1. Natural heat from the earth’s interior

2. Geothermal energy is used today in different regions around the world.

3. In the US, the Sierra Nevada, Basin and Range, and Battle Mountain area (northern Nevada and Oregon).

4. If only 1% of the geothermal energy in the upper 10 km of the world could be harnessed, it would amount to 500 times the total global oil and gas resources.

Front 21

Geology of Geothermal Energy

Back 21

1. Must have a higher than average amount of heat to be useful as an energy source.

2. Divergent and convergent plate boundaries, and areas of upwelling work best.

Front 22

Geothermal Energy -Hydrothermal Convection systems

Back 22

1. Characterized by geothermal basins in which a variable amount of hot water circulates. There are vapor-dominated systems, and hot-water systems.

2. Vapor-dominated systems have both water and steam present. These are not very common and recharge does not allow for replacement of the steam at a rate that is useful for power generation.

3. Hot-water systems are more common. In these systems, as steam is produced, water droplets must be removed before striking the turbine blades. For this system, recharge can work.

Front 23

Geothermal Energy -Groundwater Systems

Back 23

1. Some groundwater systems can produce warm water (such as found at hot springs), useful for heating air in a building.

2. This is used in Iceland for heating buildings.

Front 24

Environmental impact of Geothermal Energy Development

Back 24

1. Less severe than other sources.

2. On-site noise problems

3. Relatively low emissions of gases.

4. Scars on the land from the collection wells.

4. Thermal Pollution

5. Injection can cause movement along faults.

Front 25

Future of Geothermal Energy

Back 25

1. Increasing where it can be used, but localized potential

2. Usually more expensive than oil or gas, at the moment.

Front 26

Renewable Energy Sources

Back 26

1. Low quality, high quantity (not concentrated)

2. The use of solar and wind are increasing in use.

3. Alternative energy sources usually do not result in the production of pollutants and/or climate altering products.

4. They include wind, solar, hydropower, and biomass.

Front 27

Solar Energy

Back 27

1. Used directly through passive or active systems.

2. Passive systems enhance the absorption of heat without requiring mechanical power.

3. Examples of passive systems include windows that block summer sun while allowing in winter sunlight and heat, walls that absorb heat and reradiate it into rooms in a house.

4. Active systems require mechanical power, usually pumps, to circulate air, water, or other fluids from collectors to a heat sink.

5. Solar Collectors

6. Photovoltaics

7. Luz Solar electric Generating system

Front 28

Energy Policy for the Future

Back 28

1. Hard Path
o Continuing business as usual
o It requires no new thinking or realignment of political, social, or economic conditions.
o Party till its over, then look for alternatives.

Front 29

Soft Path

Back 29

1. Using energy alternatives that are renewable, flexible, decentralized, and environmentally more benign than those of hard path

2. The development of fuel cells, solar and wind power, new hydro sources, etc.

3. Today we use 90 EJ of energy, by 2030, we might be using either 60 E or 120 EJ, depending on which path we take.

Front 30

Sustainable Energy Policy

Back 30

1. Burning fossil fuels is degrading our environment, on a global scale.

2. With an ever increasing global population, we need to figure out how to do things better, or we will have to start to do without.

3. Coal will probably be the near-term solution.

4. Nuclear can grow, but only to a limit.

5. Renewable sources will have to be used on a greater scale.

6. Only increasing efficiency and by conservation can we get a handle on the beast.