Chapter 15, Problem 9CR

To determine

The key concepts for this section. The concept of nuclear fission and nuclear fusion. The working of a nuclear fission reactor. The major safety features of a nuclear fission reactor. The description of a nuclear fuel cycle. The three countries are the three leading users of nuclear power. The percentage of the electricity generated in the United States comes from nuclear power. The relationship between nuclear power plants and the spread of nuclear weapons. The risks related to storage of highly radioactive spent fuel rods. The problem of high-level radioactive waste from spent fuel rods dealt by the United States. The fate of worn-out nuclear power plants. The arguments over the widespread use of nuclear power would slow down the projected climate change during this century. The arguments of experts who disagree over the future of nuclear power. The relationship between nuclear power plants and the spread of nuclear weapons. The Fukushima Daiichi nuclear power plant accident and list its five major effects. The potential of nuclear fusion as an energy resource.

Answer to Problem 9CR

The nuclei of certain isotopes having large mass numbers split into two or more lighter and smaller nuclei by a neutron during nuclear fission. The nuclei of two isotopes of a light element fuse at a high temperature to produce a heavier nucleus with the release of energy. This process is called nuclear fusion. The fuel in a nuclear reactor is enriched uranium ore that is processed into uranium dioxide pellets. The pellets are packaged into fuel rods and bundled together in the core of reactor. The control rods move in and out of the core and absorb neutrons in the nuclear fission chain reaction. The United States, France, and Russia are the leading users of producers of nuclear power. The United States generates 19% of electricity using nuclear power plants. Nuclear fusion can be a potential energy source as no risk of a breakdown or of a release of radioactive materials, and risk of nuclear weapons. No air pollution will be there, as the fossil fuels will not be required to generate electricity, and climate-changing CO₂ emissions. It is also used to provide desalination process, eliminate toxic wastes, and produce clean-burning hydrogen fuel.

Explanation of Solution

Nuclear fission: It occurs when the nuclei of certain isotopes with large mass numbers are split into two or more lighter nuclei by a neutron.

Nuclear fusion: During the process of nuclear fusion, the nuclei of two isotopes of a light element such as hydrogen are forced to fuse at high temperatures to form a heavier nucleus with the release of energy.

The working of a nuclear fission reactor: The heat produced by the chain reaction of fission is used to convert water to steam. The steam is utilized to spin a turbine that generates electricity. The fuel for a nuclear reactor is produced from enriched uranium ore. The enriched uranium is processed into uranium dioxide pellets. The pellets are packaged into closed pipes called fuel rods. The rods are bundled together and placed in the core of reactor. The control rods are moved in and out of the core to absorb neutrons in the nuclear fission chain reaction. A coolant circulates the core of the reactor to remove heat.

The major safety features of a nuclear fission reactor:

1. i. A containment shell surrounds the reactor core that prevents the escape of radioactive materials into the environment during an internal explosion or a core meltdown.
2. ii. A coolant prevents the melting of fuel rods and other reactant components. It releases massive amounts of radioactivity into the environment.
3. iii. An emergency core cooling system prevents a meltdown of the reactor’s radioactive core.

The description of a nuclear fuel cycle:

The nuclear power cycle includes the following processes:

1. i. Uranium mining.
2. ii. Processing and enriching of uranium.
3. iii. Utilizing uranium in a reactor.
4. iv. Storage of highly radioactive spent fuel rods for thousands of years until their radioactivity achieves safety levels.
5. v. Retiring of worn-out plant and safe storage of radioactive parts for thousands of years.

The three countries that are the leading users of nuclear power: The United States, France, and Russia are the leading producers of nuclear powers also the leading users.

The percentage of the electricity generated by the United States from nuclear power: The United States generates 19% of electricity using nuclear power plants.

The relationship between nuclear power plants and the spread of nuclear weapons:

The United States and 14 other countries have been selling commercial and experimental nuclear reactors, uranium fuel-enrichment, and waste reprocessing technology to other countries for decades. Much of these data and tools can be used to create bomb-grade plutonium and uranium for use in nuclear weapons. Sixty countries own nuclear weapons or have gained knowledge to develop most of such data by applying civilian nuclear power technology. This is a serious threat to national and global security as the single most significant reason for not constructing more nuclear power plants that use plutonium or uranium-235 as a fuel or that produce plutonium-239.

The storage of highly radioactive used fuel rods:

The highly radioactive spent fuel rods are safely stored for thousands of years until their radioactivity reaches safety levels. After removal from the reactor, they are stored in water-filled pools. The rods are transferred to dry casks and filled with inert helium gas after many years of cooling and decay their radioactivity. The rods may also be processed to remove their radioactive plutonium for making nuclear fuel.

The risks of highly radioactive spent fuel rods:

A single spent-fuel rod assembly can emit enough radiation to kill a person standing one meter away in less than three minutes.

The problem of high-level radioactive waste from spent fuel rods dealt by the United States:

The United States government abandoned a nuclear fuel recycling approach after spending billions of dollars. The underground burial was considered as the safest method to store high-level radioactive wastes by most scientists. This method was abandoned for scientific, economic, and political reasons. However, the United States has not yet come up with a solution for storing high-level radioactive wastes for thousands of years.

The fate of worn-out nuclear power plants:

The three ways to decommission worn-out nuclear power plants are as follows:

1. i. Removal and storage of the highly radioactive parts in a permanent, secure repository.
2. ii. Installation of a physical barrier around the plant and storage of radioactive parts in a repository.
3. iii. The enclosure of the entire plant in a concrete and steel-reinforced tomb.

The arguments over the widespread use of nuclear power would slower down the projected climate change during this century:

Some supporters of nuclear power claim that the increased use of nuclear energy would reduce the emission of carbon dioxide. They consider that nuclear power is a carbon-free energy resource. However, the carbon dioxide emissions during the nuclear fuel cycle are lower than that of coal-burning power plants. They still contribute to atmospheric warming and climate change.

The arguments of experts who disagree over the future of nuclear power:

It was observed that the global production of electricity from nuclear power is the world’s slowest-growing form of commercial energy. This is because electricity can be produced quickly and at a lower cost from natural gas, wind, and solar energy. The high cost and low net energy of the nuclear power fuel cycle are the factors that make the future of nuclear power controversial. It also contributes to the spread of technology that may be utilized to make nuclear weapons.

The relationship between nuclear power plants and the spread of nuclear weapons:

Several countries have been selling commercial and experimental nuclear reactors and uranium fuel-enrichment and waste reprocessing technology to other countries for decades. The countries that have nuclear weapons or the knowledge to develop them have acquired information using nuclear power technology. The nuclear power plants that use the fissionable isotopes of uranium and plutonium as a fuel or produce plutonium isotopes can be used to make nuclear weapons.

The potential of nuclear fusion as an energy resource:

The advantages of using nuclear fusion as an energy resource:

1. i. There would be no risk of a meltdown or release of a large amount of radioactive materials.
2. ii. Only a small risk of spread of nuclear weapons.
3. iii. There would be no requirement of fossil fuels to produce electricity.
4. iv. There will be the elimination of most of the earth’s air pollution.
5. v. Fusion power may be utilized to destroy toxic wastes.
6. vi. Fusion power might be used to supply electricity for desalinating water and for decomposing water to produce hydrogen fuel.

The Fukushima Daiichi Nuclear Power Plant accident and list its five major effects:

Fukushima Daiichi Nuclear Power Plant is located on the northeast coast of Japan. On March 11 2011, there was a nuclear accident that took place. A powerful offshore earthquake that caused a dangerous tsunami destroyed coastal areas and triggered the nuclear accident. An enormous wave of ocean water washed away the protective walls of the nuclear plant and attacked the circuits and backup diesel generators of the emergency core cooling systems for the three operating reactors of the nuclear power plants. Then, the roofs of the reactor building blew due to the explosions caused by the buildup of hydrogen gas by the exposed nuclear fuel rods. This released radioactive materials to the adjacent coastal water and into the atmosphere. The cores of these three reactors experienced complete breakdown and contaminated a large area with low-to-moderate levels of radioactivity. In 2013, the coastal waters near the plant experienced a leak from the low-level radioactivity from contaminated groundwater and from one of the plant’s 1,000 wastewater storage tanks.

About 130,000 people were evacuated from the area near the nuclear plant, 15,891 people died in the tsunami; however, no one died directly from exposure to radioactivity from the nuclear accident. Eventually, 100 or more people died of thyroid and other cancers associated with their exposure to radioactivity.

The five major effects resulted from the nuclear plant accident:

• Increased public fear regarding the use of nuclear power to generate electricity.
• It exposed that a single accident can add an estimated $500 billion to the already high cost of nuclear power.
• Germany, Switzerland, and Belgium phased out of nuclear power and switched to solar and wind energy to generate electricity.
• Japanese citizens experienced air pollution from the use of coal.
• It encouraged Japan to decrease its energy use by reducing energy waste and improving energy efficiency.

The potential of nuclear fusion as an energy resource:

Nuclear fusion is the process that involves forcing the nuclei of two isotopes of a light element such as hydrogen at exceedingly high temperatures until they join to form a heavier nucleus, thereby releasing energy.

The sun uses the process of nuclear fusion to warm the Earth and sustain its life. Some researchers expect that controlled nuclear fusion on the Earth will provide an almost inexhaustible source of energy.

There will not be any risk of a breakdown or of a release of huge quantities of radioactive materials and little risk of the spread of nuclear weapons. Fossil fuels will not be required to generate electricity, thus eradicating most of the atmospheric pollution of the Earth and climate-changing CO₂ emissions. It can also be used to provide electricity for desalinating water, to eliminate toxic wastes, and for decomposing water to produce clean-burning hydrogen fuel.