Presentation Notes
1. Nuclear Power and Waste- a local and global engineering problem
a. Q- Why is nuclear power attractive?
i. Take a few answers from class
ii. A- Nuclear fuel has a lot of energy
1. Pass around mock fuel pellet
b. Q-What’s wrong with nuclear energy?
i. A- radioactive waste
c. Reality
i. Society has decided to build nuclear power
ii. There is nuclear waste, in the US people want it to go to or move through Utah
iii. Your mission as an engineer (should you choose to accept it)
1. Build a box that will keep waste from killing anyone for a very long time
2. Radiation
a. Q- What is radiation?
i. Flip light switch (you’ve been irradiated)
ii. Definition- radiation is energy in the form of rapidly moving waves or particles
b. Nuclear radiation = Ionizing radiation
i. “Ionizing” radiation has enough energy to knock electrons off an atom
1. Makes free radicals, chain reactions, mutations, apoptosis (cell death)
ii. Three common types of ionizing radiation in nuclear waste
1. Alpha- α Helium nucleus
2. Beta- β electrons or positrons
a. Neutron → proton, makes electron (β-)
b. Proton → neutron, makes positron (β+)
3. Gamma rays- γ-ray, photon with very short λ
iii. What will keep you safe from radiation?
1. Be far away from source
a. The sun is a fusion explosion
b. The sun is 93 million miles away from Earth
2. Have lots of stuff between you and source
3. Back to the box
a. We can test both of these ideas
b. Lots of stuff between you and source
i. Shielding demonstration
ii. Fish overhead image
1. Which is more damaging?
a. Good news, the biggest and easiest to catch stuff is also the
most dangerous
b. Fish diagram
c. Be far away
i. Radiation intensity demonstration
ii. What’s going on?
1. Fit the data to gain insight (how engineers use math)
d. How long does my box have to last?
i. Q- what is a half-life?
1. Exponential decay
2. Mass → Energy
ii. The good news about half-lives
1. More energy = more dangerous
2. More energy = more mass disappearing
3. Result: really dangerous stuff disappears really fast
4. Half-Life diagram
iii. The bad news about half-lives
1. not really dangerous stuff disappears not really fast
iv. Q- What is the best box built by people so far?
1. Pyramids? I don’t know
2. We can make a box today that is at least that good
3. Eventually, the box will break, but by then
a. Most of the bad stuff is gone
b. … and if you’re still alive remember to be far away
4. Questions?