Chapter 7 - The Fires of Nuclear Fission

Question 1

How much electricity is generated from nuclear power plants?

Answer 1

15%

Question 2

Who invented nuclear power?

Answer 2

Hahn, Meitner, Strassman
-bombarded uranium with neutrons –> made barium (you can’t usually change and element into a new element)
Ur + n –> Ba + Kr

Question 3

What is fission?

Answer 3

taking a large atom and splitting it into 2 or more smaller atoms
-extra neutrons –> unstable isotope –> splits atom’s nucleus –> makes more neutrons (chain reaction)

Question 4

A
X
Z

Answer 4

A: mass #
Z: atomic #
X: element symbol

Question 5

Chemical vs. Nuclear Reactions

Answer 5

Chemical:

• atoms don’t change
• no neutrons
• mass conserved
• any isotopes

Nuclear:

• atoms change
• neutrons (don’t cancel)
• mass (mostly) conserved
• specific isotopes (notation)
• many products (random, complicated)

Question 6

Different types of uranium

Answer 6

Uranium-235 (.71%), Uranium-234 (.0054%), Uranium 238 (99.28%)

• all are radioactive
• Uranium-235 is only one good for energy, others stop the chain reaction

Question 7

Nuclear power plant

Answer 7

similar to coal burning: steam

differences: nuclear uses heat from chain reaction (nuclear energy), water stays in cycle
problems: thermal pollution (increase in temp of lake where water is taken from –> affects ecosystems)

Question 8

What controls the chain reactions?

Answer 8

Control rods

• boron/cadmium
• absorb excess neutrons
• move up/down to control heat produced

Question 9

Chernobyl

Answer 9

reactor blew up, cheap graphite rods caught fire

results:
- 50 different reactive isotopes were released with half-lives spanning from 2 hours to 24,000 years, shot 1.5 miles in sky
- 1000 injuries and 31 deaths
- health threatening levels of radioactive material found in at least 20 nations afterwards, 25 million people exposed
- an estimated 7,500 to 1 mil future cancers
- distrust of government (the kept cheap material a secret)

Question 10

Tsunami and Fukushima Power Plant

Answer 10

reactors 1, 2, 3 melted down (luckily 4/5 were shut down at time)
-ocean contamination –> constantly moving so most radioactive material was diluted

Question 11

What is enrichment?

Answer 11

making nuclear fuels

-achieving critical mass (mass in order to create chain reaction)