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Environmental Impacts of
Nuclear Technologies - 2
Bill Menke, October 25, 2005
Part 1: Health Consequence of
Nuclear Hazards
Isotopes that
contribute to
the activity
of nuclear
waste
• Ten years after removal from a reactor, the
surface dose rate for a typical spent fuel
assembly exceeds 100 Sv/hour
• Fatal dose is about 10 Sv, so exposure for
a few minutes would be fatal
• Fuel rod activity would decay to roughly
0.1 Sv/hour after 10,000 years, so a few
days of exposure would be fatal.
Biologically-active nuclides
Especially dangerous because they can be
incorporated into body tissues and
therefore expose the body to radiation
over many years
Iodine
• I129 (half life of 15.7 million years)
• I131 (half life of 8 days)
– Iodine is soluable in water
– Iodine used by thyroid gland
– can cause Thyroid cancer
– Iodine pills taken to dilute radioactive uptake
Strontium
• Sr90 (half life of 28 years)
– Strontium is concentrated in bones, because
it is chemically similar to calcium
– Concentrated in food chain (e.g. cows eat
grass contaminated with Sr90, and then
people drink the cow’s milk
Cesium
• Cs134 (half life of 2.1 years)
• Cs137 (half life of 30 years)
– Rapidly absorbed and distributed throughout body
– Rapidly excreted from body
– Some tendency to be concentrated in muscles
Chernobyl Accident, April 25, 1986
Power reactor fire/meltdown caused by
scandalously improper testing, although
the design wasn’t the greatest, either.
Graphic moderator caught fire, and
reactor core melted down.
No containment vessel, so atmospheric
release occurred
Concrete
containment
heroically
built around
reactor after
accident
Chernobyl release
• The main radionuclides in the cloud were:
•
•
•
131I
(half-life = 8.1 days)
134Cs (half-life = 2.1 years)
137Cs (half-life = 30.2 years).
Deaths through 2005:
50 acute radiation poisoning deaths
9 thyroid cancer deaths, out of a total of
about 4000 cases (high cure rate).
4000 possible cancer deaths in long term
among the 600,000 emergency workers and
local residents exposed to high radiation. This amounts
to a 3% increase in cancer death rate.
Military Usage
Hiroshima and Nagasaki Bombs
• Hiroshima
– U235 bomb, 15 kT yield
– 64,000 deaths in population of 250,000
• Nagasaki, 21 kT yield
– Pu239 bomb
– 39,000 deaths in population of 174,000
• Deaths
–
–
–
–
Most initial deaths due to blast, heat radiation
Radiation deaths mostly within 1 km of blast
Subsequently 400 cancer deaths over next 30 years
Some detectable Ce137 contamination of soil
Typical yield 250 kT
Is “fallout” (radioactive particulates) an
unintended consequence of nuclear
explosions?
Radionuclides in Fallout
•
•
•
•
•
Pu239 (24,000 yrs)
I131 (8 days)
Ce137 (30 years)
C14 (5,730 years)
Sr90 (29 years)
Part 2: Nuclear Waste Disposal
Disposal
What
are these ?
Disposal
Segments
Of
Submarines
Containing
Reactors
At
Hanford
Yucca Mountain
Controversial
And
Unopened
Waste
Storage
Facility in
Nevada
Design goal
To continually isolate nuclear waste and
protect people and the environment for at
least 10,000 years
Note: invert = platform
Design of tunnel
Natural Hazards
Water table rise, especially if
climate becomes wetter
Volcanic eruptions
Earthquakes
Anthropogenic Hazards
Terrorism
Warfare, intentionally bombing the site
Incidental human intrusion, e.g. drilling for
ground water, mining
Purposeful human intrusion, to recover
nuclear materials
Some of these hazards
are more amenable to
probabilistic analysis than others
Earthquakes
TSPA-SR Model
with 1 Chance in
10,000 of being
Exceeded
Each Year
Used as a basis
For designing
Shaking-resistant
containment
Climate Change
• Wetter climate increase the chance of transport
of radionuclides by ground water.
• Current rainfall now 190 mm/yr, but was as high
as 430 mm/yr during the glacial period.
• What is chance of major climate change in next
10,000 years? Can appeal to Pleistocene
history, but what is the certainty.
Human Intervention
• What will humans be doing 500 years from
now?
• Can compute the probability that someone
unaware of the repository and drilling for
water might accidentally breach a
cannister, but the chances of humans
drilling is less certain.
• What about mining of radionuclides for
heat or weapons? Consider the following
…
Lia, Georgia, Accident, 2001
• Three shepherds found a several canisters in
the mountains that appeared to have melted
nearby snow. They carried them back to their
camp, to use them for warmth. They all
developed severe radiation poisoning, e.g.
lesion on their backs.
• The canisters contained Sr90 from an old Soviet
thermoelectric generator dating from the cold
war. The men received does of about 4 Sv.
They survived, being treated 3 months in the
hospital.