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Transcript of Radioactive Waste
design by Dóri Sirály for Prezi
1. What is radioactivity?
2. How long-lived are radioactive substances?
3. What are the hazards posed by radioactivity?
4. How is radioactivity measured?
5. Where do radioactive wastes come from?
6. What ways are there for disposing of radioactive waste?
7. How can radioactive waste be moved safely to a storage facility, and what are the risks associated with the different transport options?
What are the subatomic particles in the
1. What is radioactivity?
What are the types of radiation?
How long-lived are radioactive substances?
a learning opportunity adapted from "Resources for Enviornmental Literacy" a book by the Environmental Literacy Council and the National Science Teachers Association
Introduction to the waste products of nuclear energy:
Since WWII, hundreds of thousands of tons of radioactive waste materials have been produced in the U.S.
1 ton = how many lbs?
2,000 lbs = 1 ton
Initially, most was for military but over time, an increasing amount has been produced for civilian applications.
Major Issue: Disposal of Radioactive Waste
radioactivity can be harmful to living things
technical challenge to finding the best method
different types of radioactive material present different hazards
political and social ramifications
Goal of this learning experience: Help students learn how to discuss complex environmental concerns using arguments based on the science behind the issues.
What is the charge of a proton?
protons are positively charged so they repel each other with a force that increases the closer they are to each other.
However, they are bound together by a strong nuclear force many times greater than its repulsive force at short distances.
(As the distance increases, the nuclear force is easily overcome by the electrical repulsion)
As an atom gets bigger,
its nuclear distance (distance across nucleus gets bigger)
as nucleus distance gets bigger, nuclear force has almost no effect and the repulsive force (protons repelling protons) can easily overcome the nuclear force.
What is radioactive Decay?
nucleus changes energy states in a way that the total energy of the nucleus is decreased
energy lost by the nucleus through this rearrangement is carried off by gamma, alpha, or beta particles
when electrons in an atom change their energy state by moving closer to the nucleus, the atom emits photons
packets of light energy proportional to the frequency of an electromagnetic wave of visible light
energy lost by atoms is millions of times less than the energy lost by the nucleus when protons and neutrons rearrange themselves
because electric force holding the electrons in place is millions of times weaker than the strong force binding the nucleus together
very high energy electromagnetic radiation
gamma decays release photons but don't change the number of protons and neutrons in the nucleus
can travel many centimeters through matter but do relatively little damage = hard to protect against
lead sheets = used to stop gamma rays
when a proton changes into a neutron, it emits a positively charged electron (positron)
when a neutron changes into a proton, it emits an ordinary electron (- charged)
How can protons turn into neutrons and vice versa?
weak nuclear force (100,000 times weaker than the strong force on the nuclear distance scale) even though, the nuclear force is still much more powerful than the electric force.
Every beta emission is accompanied by a nearly massless particle (neutrino) that carries away the rest of the energy of the decay.
Why don't positrons and electrons emitted carry energy equal the differences in energy levels (of protons and neutrons)?
Neutrino has no charge (not influenced by electric force) and has little mass (not affected by gravity) so it can pass through things without causing any damage
positrons and electrons both carry an electric charge and damage matter as they pass through it
their harmful effects are halfway between the damage caused by alphas and gammas
sheets of thin aluminum are used to protect from beta radiation
beta decay changes the number of protons in the nucleus
Does it change the element's identity?
Yes (identity = # protons (atomic #)
an electron is emitted when a neutron turns into a proton
moves up in atomic #
a positron is emitted when a proton turns into a neutron
1 less proton
moves down in atomic #
The alpha particle released is the nucleus of a helium atom.
How many protons?
How many neutrons?
In very big atoms (heavy nuclei = those with high atomic #s) the nuclear force is strong enough to hold in alpha particles
rarely, alpha particles can escape (outside the nucleus, alpha particles are repelled because the nucleus is positive (alpha particles are also positively charged)
alpha particles move slow
because they're heavy
can only travel short distances inside matter before reacting with something, doing lots of damage as they travel
alpha decay reduces the charge of the nucleus by 2 units (remaining nucleus becomes a different element) with a lower mass than the original element
easy to block with paper
very very bad if swallowed
plutonium = deadly poison if its fine dust is inhaled
Making SENSE (Safe Environmental Nuclear-Waste Sites for Eons) is a project to suggest long-term solutions of how the United States should deal with accumulating nuclear wastes
What is SENSE?
The forum will be a meeting of 4 different task forces
The paramount vision of the task forces is guided by this compelling question:
What nuclear waste legacy will future generations face?
Yucca Mtn. Site
Yucca Mountain Nuclear Waste Dump in Nevada
Nuclear Waste Transportation
Looking at how the rest of the world uses, stores and transports nuclear waste. (Who should police it?)
Today's first task is to choose which of the 3 task forces you will be a member of.
1. Yucca Mountain Nuclear Waste Disposal Site Task Force
2. Hanford waste leak
3. The Nuclear Waste Transportation Task Force
4. The Global Concerns Task Force
Members will form groups/contribute to their task force as:
scientists, politicians, economists, environmentalists, and public interest groups (no public interest 2016)
Forum Ground Rules
exploring policy decisions
considering possible trade-offs
examining risks accompanying long-term disposal of high-level nuclear waste
Each Task Force will be:
What will each task force produce?
a position paper describing its main arguments and conclusions
What will your task force do with this position paper?
present the findings in a class forum
1. Respectful dialogue
2. Responsibility - responsible for adding to discussion
3. Ask Questions!
4. Think critically
5. Use facts of science
6. Only one person talks at once (listen to coach!)
How the forum works:
1. Blank piece of paper
As we're discussing, jot down thoughts (so you don't forget them when it's your turn)
2. Raise your turn to indicate you wish to speak
Coach will write down names (so we know order of speaking)
3. You must participate either by writing to your group and having them share or by speaking yourself
A significant portion of your grade will be based on your participation.
Starting the Forum:
Each task force will give a quick background summary (less than 5 min)
groups that are for or against
your group's position
5 minute forum pause. (during this time, task forces will decide if they agree or disagree with other task forces and prepare questions for other task forces)
Forum discussion will be open after the 5 minute pause.
Fission vs Fusion
What is binding energy and what is its significance to stability of an atom?
Who discovered radioactivity?
How can N/Z number help us to understand the stability of an isotope?
What is nuclear fission?
Why are nuclear fission reactions used in nuclear power plants and not nuclear fusion reactions?
When protons and neutrons that are far apart come together and form a nucleus, energy is released.
This makes the nucleus at a lower energy state than the protons on and neutrons were before they became the nucleus.
Lower state of energy = more stable
The energy released in this reaction is huge compared to the energy when chemical reactions occur.
The amount of energy required to remove nucleons from a nucleus.
a proton or a neutron
spontaneous breakdown of unstable nuclei to produce particles or energy
Stability of the nucleus depends on the ratio of neutrons to protons (N/Z number).
If an isotope has too many neutrons, the nucleus will emit a high-energy electron (beta particle) and change into a proton.
If a nucleus has too many protons, it can become more stable by absorbing one of its electrons into the nucleus. This changes a proton into a neutron (decreases the atomic number by 1). This releases an x-ray photon.
2. electron capture:
1. electron emission:
Many nuclear changes leave a nucleus in an excited state and when the nucleus stabilies, it releases this extra enegy (gamma ray).
3. positron emission:
Some nuclei with too many protons can become stable by emitting positrons, which are postiviley charged electrons.
There are 3 types of beta decay
A positron is the antimatter to an electron. (Basically antimatter means it's the opposite)
Positrons lose kinetic energy quickly so they can't travel far. Once they stop moving, they collide with electrons in a matter-antimatter annihalation reaction.
An unstable nucleus that has an N/Z number that is much larger than 1 can decay by emitting an alpha particle.
This means that it has more neutrons than protons.
None of the elements that have an atomic number greater than 83 and mass numbers greater than 209 have stable isotopes.
Many of these unstable isotopes decay by emitting alpha particles.
3 classes of nuclear change:
Occurs when very heavy nuclei split into smaller nuclei, each more stable than the original nucleus.
Some nuclei undergo fission without adding any energy (spontaneous fission).
A very small amount of naturally-occurring uranium nuclei is the isotope U-235 (this ungergoes spontaneous fission).
Born 11/7/1878 in Vienna, Austria.
She was Jewish.
She studied at the Universitry of Vienna and got her doctorate (phD) in 1906.
1907: Moved to Munich to study with Max Planck and Otto Hahn.
1923: She discovered radiationless transition (Auger effect) it's named for Pierre Victor Auger who discovered it two years later.
1938: Austria annexed by Germany so she had to flee as a refugee to Sweden.
She continued to work at Manne Siegbahn's Institute in Stockholm. Received little support because of Mr. Siegbahn's prejudice against women.
She and Hahn met in Coppenhagen in November to plan a new round of experiments.
January 1939: These experiments provided the evidence for nuclear fission.
February 1939: She published the physical explanation for the observations and with her nephew (physicist Otto Frisch) named the process nuclear fission.
This discovery lead other scientists to prompt Albert Einstein to write President Franklin D. Roosevelt to write a warning letter which triggered the Manhattan Project.
1878 - 1968
1944: Hahn awarded Nobel Prize for Chemistry for his reaseach into fission but Meitner was ignored because Hahn downplayed her role in the process of discovery after she fled Germany as a refugee.
1997: element 109 was named meitnerium (Mt) in her honor.
The discovery of radioactivity
Nov. 7, 1867: Born in Warsaw, Poland (it was controlled by Czarist Russia)
Her dad taught secondary school. She received a general education and her dad taught her science.
She was banned from her hometown uniersity because women weren't allowed to go to college. She went to a "floating university" which was an illegal night school that changed its location each meeting so that women could study at the college level and not get caught by czarist authorities.
1891: Studied at Sorbonne University in Paris.
1903: Jointly awarded the Novel Prize for physics with her husband Pierre Curie and Henri Becquerel for discovering radioactivity.
1906: Her husband dies. She takes over his professor of physics position. She becomes first female lecturer, professor and laboratory head.
1911: First human to win 2 Nobel Prizes. This one was in chemistry for her discovery of the radioactive elements polonium and radium.
She developed methods for the separation of radium from radioactive residues in sufficient quantities to allow for its characterization and the careful study of its properties, therapeutic properties in particular.
1934: Died of leukemia from exposure to radium.
Her notebooks and lab materials are still radioactive.
Fission 1 g of U-235 = 2700 kg coal
Fission produces a large amount of energy.
Nuclear power plants use nuclear fission reactions to produce electrical energy.
When small nuclei combine.
They combine to form a larger, more stable nucleus .
The new nucleus has a higher binding energy per nucleon than the smaller nuclei did. This means it's more stable because it would take more energy to remove a nucleon.
Fusion releases more energy than fission for the same mass of starting material.
Very high temperatures are required to bring nuclei together.
The temperature of the sun's core is about 1.5 x 10 degrees celsius. (Human cells begin to die around 41-45 degrees celsius. One of the hottest days' temperature in death valley = 55 degrees celsius but you can survive as long as you don't get dehydrated.)
Fusion is how the sun (and other stars) generate energy.
Fusion reactions are hard to maintain
1. Starting a fusion reaction requires so much energy.
It takes as much energy to start the reaction as is released by the reaction.
Not good for using as an energy generation source.
2. Finding a suitable place to perform a fusion reaction.
The reactants are in the form of plasma.
Plasma is a random mixture of positive nuclei and electrons.
No form of solid matter can withstand the tremendous temperatures required for fusion to occur.
This makes the plasma hard to contain.
Currently, scientists use strong magnetic fields to suspend the charged plasma particles.
This keeps the plasma from touching the walls of its container. (If it touched them, they would break)
Scientists have also experimented with high power lasers as the energy source to start the fusion reaction.
Fusion reactions have the possibility to be an endless source of energy but due to the fact they are difficult to start and contain, much more research needs to continue to be done before they can be used as a viable energy source.
What are the hazards posed by radioactivity?
Cells are made up of complex molecules. When particles emitted during radioactive decay hit an organism's cells, they can damage the molecules in the cell and it's DNA.
Living cells have the ability to repair damage done to their DNA and their other components.
The average person is struck by 15,000 radioactive particles every second.
Why aren't we all getting cancer all the time?
Any radioactive particle has the potential to cause cancer, however, the proability that any 1 particle will cause cancer is incredibly small (it's a 1 in 30 quadrillion chance).
Only 1% of fatal human cancers are caused by these radiation particles.
What is cancer?
Cancer is uncontrolled cell growth.
It's a collection of diseases (not just one disease)
It's when cells start dividing (mitosis) uncontrollably.
Normally, when cells are damaged or need to be replaced, existing cells divide to create the new ones needed.
What happens with cancer?
The normal process of growth and division breaks down. As more and more cells become abnormal, cells survive when they shouldn't (old and damaged cells that should die, instead divide).
These extra cells can form growths called tumors. Tumors are masses of tissue.
The only site that has been studied for geologic disposal.
The site is 90 miles from Vegas.
In 2002, President George W. Bush approved this site as a spot for nuclear waste disposal. Nevada's governor vetoed this decision. Congress overturned this veto. Currently, the site is abandoned and no nuclear waste is being stored there.
Spent nuclear fuel
(aka radioactive waste) is uranium-bearing fuel elements that have been used at commerical nuclear reactors that are no longer producing enough energy to sustain a nuclear reaction.
No nuclear reaction is happening but the spent fuel still produces radiation and heat. It has to be transported in containers that can contain both radiation and heat.
Radioactive Decay Flowchart
occurs naturally for elements whose atomic number
occurs in the nucleus
occurs when some elements become isotopes
which uses the amount of some elements to date the material
which decay into daughter elements
> 83 (atomic number = number of protons)
nucleus contains protons and neutrons
nucleon means its a particle from the nucleus
isotopes contain a different number of neutrons
isotopes are differentiated from atoms by adding their mass number to the end of their name
protons + neutrons = mass of the atom
neutrons affect the mass
Quick Review on Energy Sources:
The 5 most at risk cities for effects of climate change
Why is it important to reduce our reliance on fossil fuels?
Renewable Energy Sources Introduction:
A series of short videos to provide an introduction to the various types of renewable energy available.
Nov 7, 2015
What is plasma?
Lockheed is working to make fusion reactors smaller
How to spot a biased source:
Description of Responsibilities:
Describe the processes of nuclear energy and what occurs at the particle level.
Discuss/know of any laws regulating
Look at the costs
Know how it affects the environment
Public Interest Groups (not for 2016)
Know and explain the positions of groups representing the people (either for or against)
What is a photon?
technically has mass...but mass-less is a figure of speech used by physicists to describe something about a photon's particle-like properties using the language of particle physics
stream of photons each traveling in a wave-like pattern at the speed of light
Each photon contains a certain amount of energy
The different types of radiation are defined by the amount of energy found in the photons
This drawing is kind of large, so you might want to draw it on the right side.
All around you and on every surface of the Earth, there is radiation pummeling the atoms that make up matter.
Even as we sit here, we are being bombarded by radiation!
Everything on the electromagnetic spectrum transmits energy and therefore has radiation
The background radiation isn't harmful to you, it's the ionizing radiation that is but in small doses, it doesn't harm you
In small doses, ionizing radiation isn't harmful to you and the ionizing radiation that naturally occurs on Earth is called background radiation.
Some background radiation sources:
uranium and radon
radioactive materials in our body (certain kinds of)
We can't see these kinds of radiation directly but we can observe how they interact with particles we can see.
It's like how you can't see wind but you can see how it interacts with things like leaves, umbrellas, and plastic bags.
What's happening in the cloud chamber?
The solid CO is causing the isopropyl alcohol to become supersaturated.
When a high energy particle passes above the supersaturated layer, it ionizes the air.
The ionized air causes the alcohol vapor to condense and leave a visible trail
Optional Enrichment FOR 2016
Introduction to Energy Sources:
any resource than exists in limited supply and once it's gone, it's gone.
as resources that have the potential to be replaced over time by natural processes.
Emissions and Climate Change:
Emissions Effects on Oceans:
The 5 most at-risk cities for feeling the effects of climate change first
does not emit carbon dioxide into our atmosphere.
small amount of fuel produces lots of energy
Positive things about nuclear power:
It is a nonrenewable resource and it does require water.
slide 60 = beginning of sense forum
Hanford Nuclear Reservation Site
eastern Washington at the border of WA, OR, and ID on the Columbia River
The site was used to produce the plutonium for one of the bombs (fat man) that was dropped on Japan in WWII (the one dropped on Nagasaki).
56 million gallons of radioactive waste was produced and remains stored temporarily at this site.
At least 2 tanks holding the waste are currently leaking. Eleven workers became sick from the vapors leaking from the tanks.
The leak was first announced on February 13, 2013. It is projected the clean up and making a permanent solution for the waste will take 5 decades.