nuclear energy and nuclear waste the good, the bad, and the ugly…
TRANSCRIPT
Nuclear Energy and Nuclear WasteThe Good, The Bad, and the Ugly…
What is Nuclear Energy?• Nuclear energy is the energy that exists within the
nucleus of an atom.• There are 2 types of Nuclear Energy:
• Nuclear fission is the splitting of a large nucleus, releasing HUGE amounts of energy.
• Nuclear fusion is the combining of smaller nuclei to form heavier nuclei, releasing HUGE amounts of energy.
How is Nuclear Fission Energy produced?
If a Nuclear Reaction is not controlled…
Nuclear Energy must be harnessed if used to make energy.
• Nuclear reactions in a nuclear power plant occur at a controlled, manageable pace and release energy slowly.
• Heat is generated and used to boil water, creating steam. The steam turns turbines which rotate electric generators, creating electricity.
• Steam is released from the cooling towers.
How does a Nuclear Power Plant Work?
How much energy is produced?• Nuclear power is an extremely
rich energy source.
• A single uranium fuel pellet the size of a fingertip contains as much energy as – 17,000 cubic feet of natural gas, – 1,780 pounds of coal or – 149 gallons of oil.
• One in every 5 houses in the U.S. is supplied with nuclear energy.
Where are Nuclear Power Plants located?
Pros for Nuclear Power• Rich energy source.
• Reactors run for years without refueling or being shut down and need little maintenance.
• No air pollution!
Cons about Nuclear Power• Produces Radioactive Waste
• There is no permanent long-term disposal site for commercial nuclear waste.
• There is a relatively short supply of 235U (only enough left for 100~200 years)
• Nuclear Power Plants are expensive to build.
• Minor maintenance problems can be very expensive to fix.
• Safety concerns!!! If some goes wrong… CATASTROPHIC consequences
Potential for Disaster!• Chernobyl meltdown in the
former Soviet Union in 1986– Thousands died from radiation
exposure.– Thousands contracted cancers
from high levels of radiation exposure.
– Death toll may exceed 90,000– Undetermined number
suffered genetic damage, birth defects
– 350,000 people had to abandon their homes
A major Spike in Norwegian reindeer radioactivity linked to Chernobyl October 8, 2014They may not have red noses, but Norway’s reindeer may be glowing in another sense this fall.Nearly 30 years ago the explosion sent radioactive caesium-137 particles into the atmosphere, eventually drifting into Norway where they landed and absorbed into the soil.Mushroom acts as a sponge for leaching caesium-137 out of the soil. There is bumper crop of one of the reindeers’ favorite food, & scientists are certain it’s the cause of the spike this year.The caesium-137 particles are set to reach their “half-life” expectancy in 2016 – a milestone that renders them half as radioactive as when they first landed in 1986 – but “it will take a very long time before the last part of it goes,” says Eikelmann. “It will never be zero.”
A Close Call at Home!!!
• The most serious nuclear accident in the U.S. occurred in 1979 at Three Mile Island nuclear power plant in Pennsylvania.
• A small amount of radioactive gas escaped the containment structure.
Fukushima, Japan• Resulted from natural disaster: earthquake
and resulting tsunami in 2011• Partial meltdown• Large amounts of radioactive steam
released.• Led Germany to cancel nuclear program• Full impact uncertain for some time• Cs-134, Cs-137, I-131
Fukushima, Japan• Since the accident, Japan has closed
down all 48 of its nuclear reactors for safety checks.
• government planning to re-open as many as possible, although 60 % of Japanese population is opposed to nuclear power.
• area closest to the nuclear station - radiation levels are so high -120 years before it will be safe to live 25,000 will not be able to return.
• Extremely low levels of radioactive cesium from Japan's 2011 Fukushima nuclear meltdown are present in ocean water offshore N. California 11/10/14
Nuclear Danger
• After the potential for cataclysmic accident,• Next biggest issue is the nuclear waste that
is produced
Nuclear Waste• Uranium, Plutonium, cesium,
strontium, iodine and other elements used or created in a nuclear reactor emit dangerous radiation that can literally knock electrons off the atoms of our cells, disrupting or destroying cell function or even causing cells to mutate into cancer cells.
What is a Half-Life?• Every radioactive element
has a half-life• Half-life is the time it takes
for half of its atoms to decay.• Half-lives range from a
fraction of a second to billions of years
• Iodine-131: 8 days• Cs-137: 30 yrs• Plutonium-239: 24,000 yrs• Uranium 238: 4.5 billion yr• After 10 half-lives, an
element is usually harmless
1/2
1/4
1/81/16
Types of Waste• High-Level Waste
• The most dangerous radioactive waste
• Spent fuel comes from nuclear reactors
• liquid and solid waste from plutonium production
Types of Waste• Low and Mixed Low-Level Waste
– Includes radioactive and hazardous wastes from hospitals, research institutions, and decommissioned power plants
Uranium Mill Tailings
• Residues left from the extraction of uranium ore (265 million tons).
Types of Waste
What have we done in the past with Nuclear waste?
• Gas escaped from unfiltered stacks!• Water used to cool reactors was
returned to rivers!• Waste was stored in underground tanks
that leaked into the soil, eventually contaminating groundwater!
• Drums were dumped overboard at sea into deep water!
• Radioactive waste was incinerated!
Currently, nuclear waste is stored.• Radioactive waste is
temporarily stored on-site, awaiting approval of a national long-term nuclear waste storage facility.
• WE’RE RUNNING OUT OF SPACE!!!
Where to store waste???
• 1982 Nuclear Waste Policy Act (NWPA)
• Federal Government's responsibility to provide permanent disposal in a deep geologic repository for spent fuel and high-level radioactive waste
• In 2002, Congress approved Yucca Mountain to serve as the long-term storage facility for all nuclear waste in the U.S.
Ready…
Or NOT!!!
Scientists have studied Yucca Mountain
• DOE has spent over $15 billion building and testing Yucca mountain over 20 years.
• 200 pits, 450 boreholes, 6.8 miles of tunnels, 75,000 feet of core samples, 18,000 other geological samples,
What is Yucca Mountain?• Site that has been declared
“scientifically sound” and technically suitable” to geologically isolate nuclear waste for at least 10,000 years.
• Located 100 miles from Las Vegas
• Accept over 77,000 metric tons of nuclear waste before another site is built.
• Transporting currently stored nuclear waste to Yucca Mountain would take 25 years to complete.
Inside Yucca Mountain
Scientists Created a Model• Scientists use a computer model to simulate what
may happen at Yucca Mountain over thousands of years.
• The model shows that Yucca Mountain will succeed as it slowly FAILS.
• Models show that containers used to store the radioactive waste will fail after 10,000 years
• BUT the plutonium won’t be safe for 400,000years
Failure of Yucca Mountain
Pros about Long Term Storage at Yucca Mountain
• Storage in the middle of the desert is far safer for radioactive waste than scattered around the country in temporary holding facilities.
• Yucca Mountain is remote and is made of hard-rock formations.
In a desert location Isolated away from population centers (Las Vegas is 90 mi away) Secured 1,000 feet under the surface In a closed hydrologic basin Surrounded by federal land Protected by natural geologic barriers Protected by robust engineered barriers and a flexible design
Cons -Yucca Mountain• The EPA has ruled that the DOE must demonstrate that Yucca
Mountain can meet EPA standards 10,000 years…..BUT The peak radiation dose to the environment will occur after 400,000 years!
• Yucca mountain is only about 100 miles north of Las Vegas, a major metropolis.
• Scientists cannot agree if Yucca Mountain is watertight. Water could corrode containers and contaminate the surrounding landscape, seeping into groundwater.
• It’s only a matter of TIME before Yucca Mountain FAILS…
Cons -Transportation of Nuclear Waste• “Mobile Chernobyls” to carry radioactive waste through 45 states, 3,000
tons a year for 25 years.
• 10.4 and 16.4 million people will live within one-half mile of a transportation route
• If an accident occurred en route, the nuclear fallout could kill thousands.
• Traveling convoys may become terrorists target.
• Current accident rates for trains and trucks, statistics suggest there would be nearly 100 truck accidents and 10 rail accidents
• Some politicians are in favor of Yucca Mountain only because it will get their nuclear waste out of their back yard.
Yucca Mountain
• After years of delay and protest:
• Defunded in 2010• Unfortunately, now
have no long term solution to storing nuclear waste
Alternative Solutions?• Today’s inefficient reactors burn only 3% of Uranium. The
other 97% is declared “spent,” – Develop technology to reuse the Uranium
• Accelerated decay– Continue the radioactive decay within the nuclear plant
until spent fuel is rendered harmless• Develop fusion technology
– No radioactive waste!!• Breeder & Burner Reactors
– A breeder reactor produces more nuclear fuel than it consumes
– A burner reactors main purpose is to destroy actinides, the waste that has the longer half-lives
– Issues with cost and development