Standard Nuclear Standard Nuclear PowerPower

Unit 7Unit 7

Know and describe the Know and describe the following terms:following terms:

Element – Element – a a substance substance that cannot that cannot be divided be divided into into simpler simpler substancessubstances

Uranium – 92 protons

Uranium 235 = atomic mass (protons and neutrons)

Know and describe the following Know and describe the following terms:terms:

Periodic table – a chart that organizes Periodic table – a chart that organizes elements based upon electron arrangements elements based upon electron arrangements and their propertiesand their properties

Nucleus – small, positively charged core of Nucleus – small, positively charged core of an atom. Contains protons (positive an atom. Contains protons (positive particles) and neutrons (neutral particles).particles) and neutrons (neutral particles).

Electrons – are tiny in comparison with Electrons – are tiny in comparison with protons and neutrons, have a negative protons and neutrons, have a negative charge. charge.

Atomic number – the number of protons in an Atomic number – the number of protons in an atom’s nucleus (the number found above the atom’s nucleus (the number found above the element symbol in the periodic table).element symbol in the periodic table).

Mass number – the number Mass number – the number of nucleons (protons and of nucleons (protons and neutrons) in the nucleus of neutrons) in the nucleus of the atom the atom

Isotopes – atoms of the same Isotopes – atoms of the same element that differ in the element that differ in the number of neutrons they number of neutrons they contain – they are named by contain – they are named by their mass numbers.their mass numbers. U-235 – Mass number = U-235 – Mass number =

__________________________________________ U-238 – Mass number = U-238 – Mass number =

__________________________________________

Memorize the elements for Memorize the elements for these symbols:these symbols:

H = ___________________H = ___________________ He = __________________He = __________________ C = ___________________C = ___________________ N = ___________________N = ___________________ O = ___________________O = ___________________ Na = __________________Na = __________________ S = ___________________S = ___________________

Cl= Cl= ________________________________

K = _______________K = _______________ Ca = Ca =

______________________________ Ni =_______________Ni =_______________ I = ________________I = ________________ Pb = Pb =

______________________________ U = U =

________________________________

What is radioactivity?What is radioactivity?

When nuclei are unstable, they will When nuclei are unstable, they will emit radiation to try to get stable. emit radiation to try to get stable. Thus, they are radioactive. Thus, they are radioactive.

How do atoms try to fix How do atoms try to fix their instability?their instability?

Through decaying. Through decaying.

What are the three most What are the three most common ways nuclei decay?common ways nuclei decay? - (alpha particles) – are the nuclei of - (alpha particles) – are the nuclei of

fast-moving helium atoms. They only fast-moving helium atoms. They only move a few inches in the air and cannot move a few inches in the air and cannot penetrate through paper or dead skin. penetrate through paper or dead skin.

- particle emissions (beta particles) – - particle emissions (beta particles) – are fast-moving electrons. They can are fast-moving electrons. They can move several feet within the air and move several feet within the air and cannot penetrate through plastic, glass or cannot penetrate through plastic, glass or aluminum.aluminum.

- ray emissions (gamma rays) – are - ray emissions (gamma rays) – are electromagnetic radiation of very electromagnetic radiation of very high frequencies. Have an unknown high frequencies. Have an unknown range and can penetrate long range and can penetrate long distances through air or several distances through air or several centimeters through lead. Cannot centimeters through lead. Cannot penetrate through concrete, water penetrate through concrete, water or thick lead. or thick lead.

What is a half-life and what What is a half-life and what does it mean?does it mean?

A half-life refers to the time it takes half the A half-life refers to the time it takes half the atoms of a particular radioactive substance to atoms of a particular radioactive substance to disintegrate to another form that is more stable. disintegrate to another form that is more stable. After 1 year, 50% of a sample is not longer radioactive, After 1 year, 50% of a sample is not longer radioactive,

therefore, the half-life of the material is 1 year. therefore, the half-life of the material is 1 year. After 2 years, one half of the remaining radioactive half After 2 years, one half of the remaining radioactive half

will no longer be radioactive thus in total, you will have will no longer be radioactive thus in total, you will have 75% of the original material that is no longer 75% of the original material that is no longer radioactive. radioactive.

After 3 years 87.5% of the material is no longer After 3 years 87.5% of the material is no longer radioactive. radioactive.

The half-life serves as a “fingerprint” for The half-life serves as a “fingerprint” for identifying materials. (Scientists use this identifying materials. (Scientists use this concept when determining the age of rocks on concept when determining the age of rocks on earth – this is called radiometric dating).earth – this is called radiometric dating).

Is the nuclear fuel cycle Is the nuclear fuel cycle really a cycle? Why?really a cycle? Why?

No, the nuclear fuel cycle is not No, the nuclear fuel cycle is not really a cycle because nothing is fed really a cycle because nothing is fed back to the beginning of the chain. back to the beginning of the chain.

What is nuclear fission vs. What is nuclear fission vs. nuclear fusion?nuclear fusion?

Nuclear fission is when the nucleus Nuclear fission is when the nucleus of an atom is separated to form two of an atom is separated to form two atoms. atoms.

Nuclear fusion is when two atoms Nuclear fusion is when two atoms are combined to form one. are combined to form one.

Describe each step of the Describe each step of the cycle:cycle:

1.1. Exploration and Mining – Uranium Exploration and Mining – Uranium must be obtained through open pit must be obtained through open pit or underground mining.or underground mining.

2.2. Milling – Uranium ore is removed Milling – Uranium ore is removed from the rock by being crushed, from the rock by being crushed, sampled and concentrated. This sampled and concentrated. This material is now called yellowcake. material is now called yellowcake.

Describe each step of the Describe each step of the cycle:cycle:

3. 3. Conversion and Enrichment – Typical Conversion and Enrichment – Typical nuclear reactors use enriched U-235 for nuclear reactors use enriched U-235 for fuel. Naturally, only 0.7% of uranium is U-fuel. Naturally, only 0.7% of uranium is U-235. For nuclear fuel rods, this must be 235. For nuclear fuel rods, this must be increased to 3-4% (for bomb-grade material increased to 3-4% (for bomb-grade material it must be at least 85%). it must be at least 85%).

Gaseous diffusion – is a common enrichment Gaseous diffusion – is a common enrichment technique. Yellowcake is converted to a gas technique. Yellowcake is converted to a gas and passed through hundreds of porous and passed through hundreds of porous barriers. The type of material allows U-235 to barriers. The type of material allows U-235 to diffuse faster than U-238. diffuse faster than U-238.

4. 4. Fuel Fabrication – The gas is converted to Fuel Fabrication – The gas is converted to a uranium powder and made into pellets a uranium powder and made into pellets that are then installed in fuel rods.that are then installed in fuel rods.

A typical pellet of uranium weighs about 7 grams (0.24 ounces). It can generate as much energy as 3.5 barrels of oil, 17,000 cubic feet of natural gas, or 1,780 pounds of coal.

Describe each step of the Describe each step of the cycle:cycle:

5.5. Fuel Burning – These fuel rods are inserted Fuel Burning – These fuel rods are inserted into the reactor core. These must be replaced into the reactor core. These must be replaced (once every 3 years) because they will build up (once every 3 years) because they will build up radioactive wastes. radioactive wastes.

6.6. Spent Fuel Reprocessing –Currently these fuel Spent Fuel Reprocessing –Currently these fuel rods are stored under water for several months rods are stored under water for several months to allow the decay of short-lived radioactive to allow the decay of short-lived radioactive wastes (but there are still long-lived wastes (but there are still long-lived radioactive wastes remaining!). So fuel rods radioactive wastes remaining!). So fuel rods are dissolved in acid and the radioactive are dissolved in acid and the radioactive wastes are separated out and prepared for wastes are separated out and prepared for long-term storage. long-term storage.

Describe each step of the Describe each step of the cycle:cycle:

7.7. Waste Storage – Wastes will remain Waste Storage – Wastes will remain radioactive for thousands of years radioactive for thousands of years thus they must be continuously thus they must be continuously monitored. There are 5 categories monitored. There are 5 categories of nuclear wastes. of nuclear wastes.

What is one main way in What is one main way in which to dispose of nuclear which to dispose of nuclear

wastes? Why?wastes? Why? Burial, because it must be kept away Burial, because it must be kept away

from people and the environment for from people and the environment for long periods of time. long periods of time.

What is WIPP? What is its What is WIPP? What is its significance?significance?

The Waste Isolation Pilot Plant found The Waste Isolation Pilot Plant found in New Mexico is the designated site in New Mexico is the designated site for permanent disposal of for permanent disposal of radioactive waste. radioactive waste.

What occurs at Yucca What occurs at Yucca Mountain in Nevada?Mountain in Nevada?

Yucca Mountain is the disposal site Yucca Mountain is the disposal site for spent fuel and high-level waste. for spent fuel and high-level waste. It is necessary for this location to It is necessary for this location to hold the wastes for the next 10,000 hold the wastes for the next 10,000 years. years.

What is the difference in What is the difference in how nuclear power plants how nuclear power plants operate versus how other operate versus how other plants operate to produce plants operate to produce

electricity?electricity? The only way power plants operate The only way power plants operate

differently is in how energy is created to differently is in how energy is created to turn the turbine that connects to the turn the turbine that connects to the generator. In nuclear power plants, a generator. In nuclear power plants, a nuclear reaction produces heat which nuclear reaction produces heat which produces steam to drive the turbines. produces steam to drive the turbines.

Teacher Tube VideoTeacher Tube Video: : How a Nuclear Power How a Nuclear Power

Plant Works Plant Works

How does a nuclear power How does a nuclear power plant actually work?plant actually work?

1.1. One neutron hits one nucleus; it causes that One neutron hits one nucleus; it causes that nucleus to fission (separate) into two parts. nucleus to fission (separate) into two parts.

2.2. Other neutrons are released, causing Other neutrons are released, causing additional nuclei to fission so that we now additional nuclei to fission so that we now have (at least) four parts. have (at least) four parts.

3.3. This process continues until we have more This process continues until we have more and more nuclei fissioning. and more nuclei fissioning.

In a bomb, this would continue uncontrolled. In a In a bomb, this would continue uncontrolled. In a nuclear power plant, they use nuclear power plant, they use control rodscontrol rods that that absorb neutrons and stop the reaction from absorb neutrons and stop the reaction from continuing uncontrolled. (They simply drop them continuing uncontrolled. (They simply drop them down into the reaction and it begins to cool down).down into the reaction and it begins to cool down).

4.4. The continuous splitting of nuclei produces The continuous splitting of nuclei produces heat. This heat is made into steam to turn a heat. This heat is made into steam to turn a turbine. turbine.

TeachertubTeachertube video on e video on how how nuclear nuclear power power plants plants operateoperate

What is currently What is currently happening to US nuclear happening to US nuclear

power?power? It is currently at a standstill.It is currently at a standstill.

Summarize figure 10.31 (the pros and Summarize figure 10.31 (the pros and cons of nuclear power) into your notes.cons of nuclear power) into your notes.

AdvantagesAdvantages DisadvantagesDisadvantages

Energy Energy SourceSource

Creates a lot of Creates a lot of energy energy

Consumes uranium and Consumes uranium and thorium nuclear fuels; thus, thorium nuclear fuels; thus, if used a lot, we could if used a lot, we could deplete our nuclear deplete our nuclear reserves. reserves.

OperatioOperationn

We know how to We know how to build and operate build and operate fission reactors fission reactors

Process creates long-lived Process creates long-lived nuclear wastes.nuclear wastes.Difficult to store wastes Difficult to store wastes safely safely

DependeDependencyncy

Using nuclear power Using nuclear power will decrease our will decrease our country’s dependence country’s dependence on petroleum on petroleum

We may have to rely on We may have to rely on foreign sources of uranium foreign sources of uranium and thorium if we use it too and thorium if we use it too much much

PollutionPollution No pollutants No pollutants created, no created, no greenhouse gases greenhouse gases created created

Thermal pollution requires Thermal pollution requires expensive cooling towers expensive cooling towers and ponds. and ponds. Safely dispose of Safely dispose of radioactive waste radioactive waste

What is radiation?What is radiation?

Radiation is any “thing” that is sent Radiation is any “thing” that is sent out from an object (sun, light bulb, out from an object (sun, light bulb, heater) that is in the form of heater) that is in the form of particles or waves. Radiation particles or waves. Radiation interacts with whatever it travels interacts with whatever it travels through. through.

Radiation can be either an Radiation can be either an external or internal hazard. external or internal hazard.

Describe these.Describe these. External hazard – when the radiation External hazard – when the radiation

is able to penetrate deeply into is able to penetrate deeply into wood, water or our bodies.wood, water or our bodies.

Internal hazard – when radiation Internal hazard – when radiation enters into a substance (through enters into a substance (through ingestion or inhalation) and causes ingestion or inhalation) and causes damage. damage.

Describe how cancer Describe how cancer works.works.

Cancer results when a mutation Cancer results when a mutation occurs which causes cells to lose the occurs which causes cells to lose the ability to properly regulate their ability to properly regulate their growth, thus, they typically grow out growth, thus, they typically grow out of control. Thus, increased exposure of control. Thus, increased exposure to radiation could potentially to radiation could potentially increase rates of cancer because increase rates of cancer because they will cause mutations that affect they will cause mutations that affect our cells. our cells.