Fakulta sociálních studií, 10. 05. 2012 1
Environmental aspects of nuclear
energy
PhDr. Tomáš Vlček, Ph.D.
(Ing. Jiří Martinec, Ph.D.)
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Nuclear energy in general
- production of fissile materials
- production of electricity in nuclear power plants
- release of nuclear energy from the atomic
nucleus
- chain fission in nuclear fuel
- accompanying phenomenon - ionizing
radiation
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Mining in the open pit mines:
- extraction in open pit mines very similar to coal
production
- generally the least impact on the environment with
respect to other methods of mining
- extraction of nuclear fuel is just as harmful as other
methods of mining
- intervention in the landscape depends on the amount of
ore and yield (percentage of) nuclear fuel
Production of fissile materials
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Rössing, Namibia
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Brown coal production – chateau Jezeří
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Uranium production – Rožná
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- In situ leaching (ISL), also known as solution mining, or in situ recovery (ISR) in
North America, involves leaving the ore where it is in the ground, and recovering
the minerals from it by dissolving them and pumping the pregnant solution to the
surface where the minerals can be recovered.
- Consequently there is little surface disturbance and no tailings or waste rock
generated.
- However, the orebody needs to be permeable to the liquids used, and located so
that they do not contaminate groundwater away from the orebody.
- In 2015, 48% of world uranium mined was from ISL operations. Most uranium
mining in the USA, Kazakhstan and Uzbekistan is now by in situ leach methods,
also known as in situ recovery (ISR).
- ISL mining of uranium is undertaken in Australia, China, and Russia as well.
- In USA ISL is seen as the most cost effective and environmentally acceptable
method of mining, and other experience supports this.
In Situ Leaching
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In Situ Leaching
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In Situ Leaching
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In Situ Leaching
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The advantages of this technology are:
- the reduced hazards for the employees from accidents, dust, and radiation,
- the low cost;
- no need for large uranium mill tailings deposits.
The disadvantages of the in-situ leaching technology are:
- the risk of spreading of leaching liquid outside of the uranium deposit, involving
subsequent groundwater contamination,
- the unpredictable impact of the leaching liquid on the rock of the deposit,
- the impossibility of restoring natural groundwater conditions after completion of the
leaching operations.
- Moreover, in-situ leaching releases considerable amounts of radon, and produces certain
amounts of waste slurries and waste water during recovery of the uranium from the liquid.
In Situ Leaching
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- In the case of Königstein (Germany), a total of 100,000 tonnes of sulfuric acid was injected with the
leaching liquid into the ore deposit. At present, 1.9 million m3 of leaching liquid are still locked in the
pores of the rock leached so far.
- Groundwater impact is much larger at the Czech Republic‘s in-situ leaching site of Stráž pod Ralskem:
28.7 million m3 of contaminated liquid is contained in the leaching zone, covering an area of 5.74 km2.
This zone contains a total of 1.5 million tonnes of sulphate, 37,500 tonnes of ammonium, and others. In
addition to the chemicals needed for the leaching operation (including 3.7 million tonnes of sulfuric acid,
among others), 100,000 tonnes of ammonium were injected; they were a waste product resulting from
the recovery of uranium from the leaching liquid.
Moreover, the contaminated liquid has spread out beyond the leaching zone horizontally and vertically,
thus contaminating another area of 28 km2 and a further 235 million m3 of groundwater.
- In Bulgaria, a total of 2.5 million tonnes of sulfuric acid was injected into the ore deposits exploited by
in-situ leaching. It is estimated that about 10% of the surface area used for ISL could be contaminated
from solution spills.
- The Devladovo site in Ukraine was leached with sulfuric and nitric acid. The surface of the site was
heavily contaminated from spills of leaching solutions. Groundwater contamination is spreading
downstream from the site at a speed of 53 m/year. It has traveled a distance of 1.7 km already and will
reach the village of Devladovo after 24.5 years.
In Situ Leaching
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Production of fissile materials
Chemical processing of mined ore (Mydlovary MAPE, 20 km
from ETE):
- leaching with sodium bicarbonate (higher content of
carbonates) or sulfuric acid (reduced content of carbonates)
- ratio of sulfuric acid up to 560 g of 94% acid per one liter of
the leached material
- processed 16.7 mil. tonnes of ore, formation of tailing ponds
with a total area of 300 ha - 36 mil. tonnes of sludge
- heavy metals and radioactive substances
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Production of fissile materials
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Získávání jaderného palivaUran, alfa zářiče, radon apod.
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Underground mine in Straz pod Ralskem
- 1966-1970 first attempts introducing methods of
chemical leaching
- until the early 90s leaching fields with a total area of
7 km2
- during the entire period of the chemical extraction
of underground injected more than 4 mil. tons of
sulfuric acid
Production of fissile materials
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Production of fissile materials
Underground mine in Straz pod Ralskem
- contamination has spread to an area covering about
27 km2
- affected 370 mil. m3 of groundwater
- currently the contamination in an amount of 4.9 mil.
t of solutes
- beginning of restoration
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- restate geological environment to the state that will
ensure exploitation of drinking water in the region
- dispose of wells and surface facilities
- incorporate the surface of extracted fields in
ecosystems with regard to regional systems of
ecological stability
- several stages of redevelopment, estimated cost of
40 billion CZK
Restoration – Stráž pod Ralskem (DIAMO)
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Radioactivity
- radioactivity (or radioactive decay) is the
spontaneous transformation of nuclei unstable
nuclides other cores
- at the same time it generates ionizing radiation
- natural or artificial radioactivity
- transmutation
- decay of nuclei by decay series and the established
principles
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Radioactivity
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Radioactivity
- cosmogenic radionuclides: tritium 3H (half-life 12,5
years), carbon 14C (half-life 5730 years)
- Primary radionuclides : potassium 40K (half-life 1,26x109
years), thorium 232Th (half-life 1,4x1010 years), uranium
238U (half-life 4,5x109 years), 235U (7x108 years)
- Secondary radionuclides: radionuclides of decay series
– thorium, uranium, aktinouranium, neptunim
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Sources of radiation
Kosmícké zářežní - 14 %
Záření z půdy a hornin - 17 %
Přírodní radionuklidy v lidském
těle - 9 %
Lékařství - 11 %
Spad z testů jad. zbraní - 0,3 %
Jiné - 0,13 %
Radon v domech - 49 %
Cosmic 14%
Ground 17%
Natural
radionuclides
in human
body 9%
Medicine
11%
Nuclear
fallout 0,3%
Other 0,13 %
Radon in
houses 49%
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Radon
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Nuclear energy safety and environmental
aspects
- the use of nuclear energy is regulated by law
- Nuclear safety is not a mere formality, it is an
enforceable requirement
- All effects are monitored and evaluated
- responsibility is transferred to the operator's license
holder
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Nuclear safety – deep protection
Deep protection = means to achieve the basic
objective of safety
First barrier: molecular matrix fuel (almost all the
fission products resulting from fission are
captured in the matrix of the uranium tablets)
Second barrier: hermetic fuel cladding (an alloy of
zirconium-niobium)
Third barrier: the primary circuit pressure limit
(resistant to high pressure, temperature,
radiation and radiation dynamic conditions of
operation)
Fourth barrier: hermetic borders of rooms containment
(building design protection, resists
airplane crash, blast wave, explosion, storm,
extreme temperatures, extreme precipitation,
etc.)
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Operation of nuclear power plant
- nuclear fission
- necessary operating conditions
- waste production
- disposal of spent nuclear fuel
All the above can be part of the process or source of
ionizing radiation.
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Protection against radiation
Distance - ionizing radiation intensity decreases with the square
of the distance, ie. after 10 m it is 100 times lower, after 100
m it is 10000 times lower, after 1 km it is a million times lower.
Time - the shorter the exposure, the smaller the cumulative dose
Shielding - depending on the type of radiation: alpha radiation
skin tones, clothing, paper; beta radiation, aluminum sheet;
gamma rays concrete, a layer of water, soil; neutron radiation,
water, polystyrene, paraffin.
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Protection against radiation
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Protection against radiation
Objective of the radiation protection
To ensure that during normal operation the radiation exposure inside the
device and/or the release of radioactive materials into the
environment is as low as reasonably achievable, taking into
consideration economic and social factors and prescribed limits and
ensure mitigate the extent of exposure to radiation accidents.
The principle of ALARA
Observe the rules and seek new and better ways of performing work
Already applied in the design
Fakulta sociálních studií, 10. 05. 2012
Czech Republic - cca 3 mSv/year
Iran (Ramsar) - up to 400 mSv/year
India (Kerala) - up to 17 mSv/year
Brazil (Guarapari) - up to 175 mSv/year
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Protection against radiation
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Porovnání radiačních dávek a účinků
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Porovnání radiačních dávek a účinků
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Long distance flights in 10 km altitude
= ca. 4 μSv/hod
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Chemical effects of radiation
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Effects on human organism
Stochastic (random) - few cells damaged, subliminal dose or
repeated small doses.
- we can only calculate the probability of injury, no injury may in fact
occur.
- can be detected only by observing a large number of people. Risk of
small doses? Scientists still do not match, they can not confirm nor
deny it for there is not a sample of people who are not exposed to
any radiation at all. No control sample.
- It is known that there is a "protective effect" radiation (hormesis) in
places with higher radioactivity there is less incidence of cancer
(cells repair any damage).
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Effects on human organism
Non-stochastic effects (deterministic) - after a large dose of radiation,
many cells, appear in a short time.
Examples:
local dermatitis
Lenticular opacities
birth defects
fertility
Acute radiation sickness
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Protection against outer sources
Protection against earthquake
Protection from flood and adverse meteorological phenomena
Protection against pressure waves from explosions
Protection against the effects caused by the fall of the aircraft
Protection against the influence of third parties
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Storage
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Storage
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Storage
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Storage
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Storage
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Storage