chapter 17 nuclear energy

Percent use in world energy use

EIA (energy information administration) predicts 28% increase in world energy use by 2040

how does percent use fit into the global energy mix?

coal down, NG nuclear petroleum renewables up

how does percent use fit into the US energy mix?

solar increase most, natural gas increase second, wind third

how much of the world’s electricity does nuclear power provide

17%

how much of the world’s total energy does nuclear power provide

4.8%

Are they rising in importance or falling? or neither? why might that be?

rising bc increase in capacity use

Which countries rely the most on nuclear power?

France, Belgium, Sweden in order

Fusion

fusing of atomic nuclei

Fission

splitting of atomic nuclei

nuclear reactor

devices that produce controlled nuclear fission

What uranium isotope is needed for reactors?  %?

uranium-235 .07% of all natural uranium

Problems associated with enriching that .07% of uranium-235?

increase concentration to 3% BUT releases chain reaction and meltdown occurrence

meltdown

nuclear accident in which coolant system fails = nuclear fuel becomes so hot it forms a molten mass. breaches to containment of reactor. contaminates outside environment with radioactivity

How does a "chain reaction" work with nuclear fuels

fission reactors split uranium-235 by neutron bombardment = release more neutrons than it took to create first splitting = they strike other uranium-235 atoms = releasing more neutrons, other kinds of radiation, fission products, heat

Cooling systems? How many and what is their arrangement?

primary coolant loops and pumps circulate coolant through reactor. heat leaves reactor vessel, coolant goes in

moderator

primary coolant

control rods

contain materials that capture neutrons, move out of core = chain reaction increases, move into core = reaction slows. full insertion = stops fission reaction

What happens to the radioactive fuel waste?  What if its military? Difference?

WIPP waste isolation pilot plant in carlsbad, NM for transuranic waste disposal

What is a breeder reactor?

type of nuclear reactor designed to produce more fissionable material (fuel) than it consumes = “breeding” new fuel from readily available fertile materials

Basic difference between its core and a conventional nuclear core? What is produced?

breeder reactors typically don’t have moderator = allows fast neutrons to travel through core. fissile material

alpha radiation

least penetrating (helium nuclei)

beta radiation

moderate penetration (high-energy electrons)

gamma radiation

most penetrating due to its wave-like nature (high-energy photons)

What are Alpha, Beta and Gamma radiation?

three types of ionizing radiation emitted from unstable atomic nuclei during radioactive decay

What changes to atomic structure result from the emission of the particles/waves?

alpha: atomic number decreases by 2, mass number decreases by 4

beta: increases atomic number by 1, decreases neutron count by 1

gamma: does not change as it only releases energy from excited nucleus

Can radioactive elements enter ecosystems? How/why?

nuclear fuel cycle

nuclear fuel cycle

mining/processing of uranium to controlled fission, reprocessing of spent fuel, decomissioning of power plants, disposal of radioactive waste

Transmission of electromagnetic energy into and out of the atmosphere (how different gases absorb energy)

CO2 and other absorb different wavelengths, where there isn’t overlap with CO2, absorbance is greater than there would otherwise be

Projections for future CO2 emissions from developed vs. undeveloped economies?

developed: decrease in CO2 emissions, undeveloped: increase

Uncertainty in modeling? Why?

limitations of climate models, incomplete?

How does the greenhouse effect work?

gases in atmosphere absorb (trap) infrared radiation (heat) similar to glass roof of greenhouse = warm planet’s surface

Carbon cycling: Tons of emissions? Plant storage? Soil storage? flux to oceans and atmosphere?

65,500 billion metric tons. largest storage reservoir = ocean. plants store carbon via photosynthesis. soil = major carbon sink via the organic matter within it. ocean absorbs carbon dioxide from air

biosphere (plants) gaining carbon?

photosynthesis: absorb C from atmosphere and use solar energy to convert it into sugars for growth. gaining 3.2 gigatons of carbon/year