Disasters & Failures - Nuclear Power

Energy

ability to do work; potential (stored), kinetic (energy causing damage)

Work

transfer of energy from one system to another by applying force

4 Primary Forces

strong nuclear bonds, weak nuclear bonds, electromagnetic forces, gravitational forces

Nuclear Energy

inside atom, get by modifying atom make-up

Chemical Energy

Mechanical Energy

Thermal Energy

Electromagnetic Energy

1st Law: Conservation of Energy

energy cannot be crated or destroyed but it can be converted to another form or energy; work done by changing energy state (p to k) or converting it from one form to another

2nd Law: Entropy

process of loss, if area of energy contains more energy than you can convert to work, 1.) will be lost to heat/electromagnetic waves 2.) heat losses move energy between matter 3.) EM waves move energy between points in space; entropy is order to disorder, ex. low entropy (ice cubes) —> high entropy (melted ice/water)

Man-Made Energy Cycle

1.) energy generated by fuel burning 2.) useful work: chemical energy to heat energy, heat to mechanical (steam turbine), mechanical to electrical (generator) 3.) heat loss: hot gasses leave by stack, coolant used to condense steam is heated, friction in turbine creates heat 4.) em wave leakage: from generator and the wires

Energy Resources: Fossil Fuels

stored by plant-animal energy cycle, use outweighs replacement, coal, oil, natural gas

Energy Resources: Renewable

tapping into Earth’s natural energy cycles, expensive, hydroelectric, geothermal, biomass, solar, wind

Energy Resources: Nuclear Power

naturally occurring radioactive minerals, hard to use safely but long lasting, fission (doable), fusion (can’t fully do yet)

Nuclear Energy: Fission

the process of breaking a heavy nucleus apart to release bonding energy using slow neutrons, used in power plants and bombs, simple/cheap, creates waste, radiation can escape, spent fuel highly radioactive

Nuclear Energy: Fusion (not yet figured out)

the process of combining two small nuclei

1 Calorie

energy needed to increase the temperature of 1 gram of water by 1 degree C

1940-50s

nuclear power part of war effort (WWII/Cold War), operation of an location of power plants classified, accidents either not reported or only in sketchy detail

1960-70s

nuclear power industry grows, seen as “energy of the future,” many plants designed and built

1970-80s

age of disasters: eats Germany, three mile island PA, Chernobyl Ukraine

1980-2000

industry slows, 97 U.S. nuclear reactors cancelled during design/construction, peak number of power plants around 1990

Ionizing Radiation

it can kill but also save lives, nuclear weapons, bombs, energy, medicine

Radiation

energy that travels through space from its source, emitted as electromagnetic waves or as ionized subatomic particles

Electromagnetic Spectrum

as sun burns its fuel by nuclear fusion it releases immense amounts of energy in form of EM spectrum, travels at speed of light, EM waves vary in length/frequency, higher energy/shorter wavelength=more dangerous, non-ionizing & ionizing

Non-Ionizing Radiation

lower energy EM waves, not enough energy to break molecular bonds, can excite electrons in their orbits, microwaves, infared/invisible light

Ionizing Radiation

higher energy EM waves, has enough energy to pull electrons from orbites, ionizes atoms bu breaking bonds bewteen atoms and meolecules, can affect attoms in living things, UV, x-rays, radioactive decay

Atomic Number

number of protons in the nucleus

Atomic Mass

protons + neutrons

Stable

do not decay into other elements and are non-radioactive

Radioactive Decay

radionuclide transforms into a different atom as it decays, called “daughter product," continues until a stable end product is reached

Half-Life

time required for half of the radioactive atoms present to decay into the daughter product

Alpha Particles

positively charged, 2 neutrons & 2 protons ejected from nucleus during decay, formed from decay of heavy elements, very energetic

Beta Particles

negatively charged, decay of tritium, carbon14, and strontium90, electron from outside of nucleus of atom

Photons (gamma rays)

energy emitted from the nucleus during decay, no mass, easily penetrates, radiation hazard for entire body

Photons (x-rays)

emitted from electron orbits during decay, lower energy than gamma rays, natural or man-made

Fission Reactor: Fuel Rods (Core)

naturally occurring/enriched radioactive material housed in either fuel rods or a core block, Uranium

Fission Reactor: Control Rods

used to slow/stop nuclear chain reaction in reactor

Fission Reactor: Moderator

used to slow down neutrons so they can create new fission reactions

Fission Reactor: Coolant

used to remove heat from the reactor, heat normally used to generate steam for running a turbine

Light Water Reactors

normal water used as coolant and moderator, uses fuel rods of enriched uranium; Boiling Water Reactors-water passing through reactor allowed to boil to create steam for turbine; Pressurized Water Reactors-most common, water passing through reactor kept from boiling and heats a second loop of water that creates the steam for running the turbine

Heavy Water Reactors

deuterium oxide used as coolant and moderator, allows these to use non-enriched fuel, not used because expensive and wasteful

Three Mile Island, PA

2 PWPs, stuck-open relief valve, large amounts of coolant water escaped, heat buildup in reactor, control rods fell into core halting further chain reactions (safety measure), residual heat still built up and damaged fuel pellets releasing radioactive isotopes into containment area, system shut down 8 hrs after accident started; radioactive gas had to be released, cleanup started ‘79 and ended ‘93, restarted first reactor in ‘85, never rebuilt second

NRC Changes from Three Mile Island

design changes, training programs, approval process difficult

Chernobyl, Ukraine, 1986

design problems, everything about this reactor was bad, built because cheap, issues: cheap materials, graphite moderator, little/no safety systems, water neutron absorber; accident during test, restarted reactor using prohibited control rod configuration, power surge at base of reactor that ruptured reactor and lost coolant, steam caused massive explosions & destroyed containment building, reactor core fire for 8 days, radioactive contaminants spread through Russia/Europe/entire world; estimate 9k ppl died, 19 mile exclusion zone, sealed site with concrete sarcophagus, cleanup scheduled to be done by 2065

Fukushima Daiichi, 2011

one of largest in world, 9.0 mag earthquake, 45-ft tsunami wave slammed into plant, disabled cooling water pumps & flooded station, power failures/failed cooling systems so explosions and release of radioactive material; radioactive water contained and allowed to decontaminate, discharging water back into ocean (just started releasing water in past few years), last until 2050

Nuclear Waste

form of used rods, each reactor has a storage pool (temporary holding place), ~150 days then transported but 30 yrs and counting, huge variety of radioactive products with a whole range of half-lives, Yucca Mountain

Nuclear Waste: Burial Issues

1.) radioactive emissions themselves are not radioactive 2.) absorb emissions in concrete/earth and no effect on biology 3.) problem is the patience of time

Status of Nuclear Power

world is running out of fossil fuels, renewable energy still too expensive on a large-scale, clean fusion power is still far in the future, 24 new plants currently under construction, many of U.S. reactors reaching end of life