Nuclear power produces radioactive nuclear waste that remains dangerous for tens of thousands of years. Above-ground storage is unsuitable for such long-term storage. Deep underground storage is recommended for isolating nuclear waste and allowing its radiation levels to safely decline over time. The US has selected Yucca Mountain for a nuclear waste repository due to its dry climate, remote location, stable geology, and deep water table, though some oppose it.

1. Nuclear Waste Disposal
(based on text from a website by the Office of Civilian Radioactive Waste
Management, USA)
Radioactive isotopes are used in nuclear reactors to generate electricity cleanly and
efficiently. However, this produces nuclear waste (spent nuclear fuel), which is
dangerous because it is still highly radioactive and will continue to emit radiation for
tens of thousands of years, at least.
Waste storage facilities above ground will not withstand rain, wind, and other
environmental factors for such a long time.
A 1990 report from the National Academy of Sciences concludes that “deep
underground storage is the best option for disposing of highly radioactive waste.” As
long as nuclear waste remains in a solid form and is properly shielded, it will not harm
people or contaminate the environment — and over time it will produce less and less
radiation. The idea behind deep underground
disposal, therefore, is to keep the waste as dry and
isolated as possible, for as long as possible, so that its
radiation can drop to safe levels.
The USA government, with advice from scientists,
has chosen Yucca Mountain, Nevada, as a site for a
nuclear waste repository (permanent storage site)
owing to the area’s dry climate, remoteness, stable
geology, and deep water table. However, there is Yucca Mountain
strong opposition from many people.
Nuclear Waste Disposal
(based on text from a website by the Office of Civilian Radioactive Waste
Management, USA)
Radioactive isotopes are used in nuclear reactors to generate electricity cleanly and
efficiently. However, this produces nuclear waste (spent nuclear fuel), which is
dangerous because it is still highly radioactive and will continue to emit radiation for
tens of thousands of years, at least.
Waste storage facilities above ground will not withstand rain, wind, and other
environmental factors for such a long time.
A 1990 report from the National Academy of Sciences concludes that “deep
underground storage is the best option for disposing of highly radioactive waste.” As
long as nuclear waste remains in a solid form and is properly shielded, it will not harm
people or contaminate the environment — and over time it will produce less and less
radiation. The idea behind deep underground
disposal, therefore, is to keep the waste as dry and
isolated as possible, for as long as possible, so that its
radiation can drop to safe levels.
The USA government, with advice from scientists,
has chosen Yucca Mountain, Nevada, as a site for a
nuclear waste repository (permanent storage site)
owing to the area’s dry climate, remoteness, stable
geology, and deep water table. However, there is Yucca Mountain
strong opposition from many people.
Amanda George Page 1 24/02/2010

2. Nuclear Waste Disposal – Questions
1. Why does radioactive material emit less radiation as time goes on?
2. Why is it important that the storage site should have a deep (low) water table?
3. Imagine that a small amount of radioactive waste were to get into the drinking water supply.
Which do you think would be most dangerous to health: an emitter of alpha, beta or gamma rays?
Why?
4. Name the disease that radiation exposure increases our chances of getting.
5. A large proportion (often about 30%) of radioactive waste from nuclear power stations consists of
plutonium-239, atomic number 94 (which is virtually non-existent in nature). It is unstable and
breaks up (decays), emitting alpha particles. Write the symbol for the other product of this decay,
an isotope of uranium. (Answer: uranium-235, atomic number 92)
6. Current plans are to bury 70,000 tons of waste in Yucca Mountain, filling the available space by
about 2036. Let us assume that 20,000 tons of this waste consists of plutonium-239, which has a
half-life of 24,000 years. This means that if you take a handful of plutonium-239, you can predict
that half of its atoms will have decayed within 24,000 years (although you can’t predict which
ones). How much plutonium-239 will be left after 48,000 years?
7. Think of as many ways as you can for radioactive waste, after it has been buried, to find its way
up to the surface where it could harm people and other life. (Possible answers: volcanic eruption
(last one in the area was 10,000 years ago, and history shows the area is becoming less
volcanically active with time), earthquakes (waste containers will be designed to withstand ‘worst
case’ earthquakes, and earthquakes release most of their destructive force at the surface), raising
of water table, climate change leading to increased rainfall with water reaching the waste
containers below and corroding them (made of extremely corrosion-resistant alloy, and past
climate change suggests that rainfall is not likely to increase much in the next 10,000 years),
drilling/mining by future humans who are unaware of the repository’s presence (unlikely that
future inhabitants will lose knowledge of the repository while still retaining the technology to
drill/mine that deep, and anyway there are no resources worth mining).
8. Based on US Department of Energy calculations, an individual living at Yucca Mountain 10,000
years in the future will receive an annual radiation dose less than what he or she would receive
from eating a single banana a year. Have a guess as to why bananas might be slightly radioactive.
(Answer: bananas contain potassium which has a small naturally-occurring radioactive
component. Dose: 0.1 microsieverts.)
Amanda George Page 2 24/02/2010