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Why nuclear energy is sustainable and has to be part of the energy mix

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Humanity must face the reality that it cannot depend indefinitely on combustion of coal, gas and oil for most of its energy needs. In the unavoidable process of gradually replacing fossil fuels, many energy technologies may be considered and most will be deployed in specific applications. However, in the long term, we argue that nuclear fission technology is the only developed energy source that is capable of delivering the enormous quantities of energy that will be needed to run modern industrial societies safely, economically, reliably and in a sustainable way, both environmentally and as regards the available resource base. Consequently, nuclear fission has to play a major role in this necessary transformation of the 21st century energy-supply system.
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Why nuclear energy is sustainable and has to be part of the energy mix
Barry W. Brook
a,
, Agustin Alonso
b
,DanielA.Meneley
c
, Jozef Misak
d
, Tom Blees
e
, Jan B. van Erp
f
a
Faculty of Science, Engineering & Technology, University of Tasmania, 7109, Australia
b
Politecnica de Madrid, Spain
c
Univ. OIT, Ontario, Canada
d
UJV-Rež, Prague, Czech Republic
e
Science Council for G lobal Initi atives, USA
f
Consultant, energy technologies, USA
abstractarticle info
Article history:
Received 7 October 2014
Accepted 12 November 2014
Available online 20 November 2014
Keywords:
Nuclear ssion
Renewables
Fossil fuels
Carbon dioxide
Methane
Humanitymust face the realitythat it cannot depend indenitely oncombustion of coal,gas and oil for most of its
energy needs. In the unavoidable process of gradually replacing fossil fuels, many energy technologies may be
considered and most will be deployed in specic applications. However, in the long term, we argue that nuclear
ssion technology is the only developed energy source that is capable of delivering the enormous quantities of
energy that will be needed to run modern industrial societies safely, economically, reliably and in a sustainable
way, both environmentally and as regards the available resource base. Consequently, nuclear ssion has to
play a major role in this necessary transformation of the 21st century energy-supply system.
In a rst phase of this necessary global energy transformation, the emphasis should be on converting the major
part of the world'selectrical energygeneration capacity from fossil fuelsto nuclear ssion. This can realisticallybe
achieved within a few decades, as has already been done in France during the 1970s and 1980s. Such an energy
transformation would reduce the global emissions of carbon dioxide profoundly, as well as cutting other signif-
icant greenhouse gases like methane. Industrial nations should take the lead in this transition.
Because methane is a potent greenhouse gas, replacing coal-red generating stations with gas-red stations will
not necessarily resultin a reduction of the rateof greenhouse-gasemission even for relatively lowleakage rates of
the natural gas into the atmosphere.
The energy sources popularly known as renewables(such as wind and solar), will be hard pressed to supply the
needed quantities of energy sustainably, economically and reliably. They are inherently intermittent,depending
on backup poweror on energy storage if they areto be used for delivery of base-load electricalenergy to the grid.
This backup power has to be exible and is derived in most cases from combustion of fossil fuels (mainly natural
gas). If used in this way, intermittent energy sources do not meet the requirements of sustainability, nor are they
economically viable because they require redundant, under-utilized investment in capacity both for generation
and for transmission.
Intermittent energy installations, in conjunction with gas-red backup power installations, will in many cases
be found to have a combined rate of greenhouse-gas emission that is higher than that of stand-alone coal-red
generating stations of equal generating capacity. A grid connection fee, to be imposed on countries with a large
intermittent generating capacity, should be considered for the purpose of compensating adjacent countries
for the use of their interconnected electric grids as back-up power. Also, intermittent energy sources tend to
negatively affect grid stability, especially as their market penetration rises.
The alternative dedicated energy storage for grid-connected intermittent energy sources (instead of backup
power) is in many cases not yet economically viable. However, intermittent sources plus storage may be
economically competitive for local electricity supply in geographically isolated regions without access to a
large electric grid. Yet nuclear ssion energy will, even then, be required for the majority displacement of fossil
fuels this century.
© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/3.0/).
1. Introduction
In the long history of human economic activity prior to the nine-
teenth century, the only available energy capable of replacing human
Sustainable Materials and Technologies 12(2014)816
The article "The case for a near-term commercial demonstration of the Integral Fast
Reactor will be published with the next issue of SUSMAT"
Corresponding author.
E-mail address: barry.brook@utas.edu.au (B.W. Brook).
http://dx.doi.org/10.1016/j.susmat.2014.11.001
2214-9937/© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).
Contents lists available at ScienceDirect
Sustainable Materials and Technologies
labor was derived from falling water, wind and domesticated
animals consuming local vegetation. As a source of heat, humanity
relied on burning biomass, i.e., wood, peat and cow dung. The
large-scale use of fossil fuels with compact chemically stored energy
started in the early eighteenth century, with combustion of coal
being the driving force behind the steam engine and consequently
the industrial revolution. This use of fossil fuels (initially mainly
lignite and coal; later oil and natural gas) has served humanity well
during the historically short time period of about two centuries, hav-
ing allowed the world population, with its supporting agricultural
and industrial productivity, to grow to previously unimaginable
numbers while providing an average standard of living that is higher
than ever before.
But will it be possible to always use fossil-fuels at a rate that is equal
to or higher than current consumption? From a historic perspective, the
past two hundred years of large-scale use of fossil fuels is a very short
time period. Independent of the importance placed on anthropogenic
climate change, one inevitably comes to the conclusion that a change
in energy supply is necessary. Thus, the real question is not whether
change must occur, but on what time scale does this change have to
take place. There exist numerous pressing reasons why change has to
come soon, including (a) continued large-scale combustion has many
deleterious human-health and environmental consequences,
(b) extraction of fossil fuels will become increasingly difcult, costly
and energy-consuming so that the energy gain will become smaller
(i.e., energy obtained vs. energy invested) and (c) fossil fuels consti-
tute a nite and valuable resource for non-energy-related industrial
and manufacturing processes, and so should be used sparingly and
preserved for future generations. Even the strongest opponents of
change and those that dismiss the risk of anthropogenic global
warming will understand that it is simply not possible to continue
indenitely in the coming centuries as before when considering
that a large part of the easily recoverable fossil fuel resources have
already been extracted during the past two hundred years.
Clearly, global society must start to taper off its dependence on the
large-scale combustion of fossil fuels, initiating a new modus operandi
aimed at restricting the use of fossil resources mainly to residential
use and to feedstock for industrial (chemical) purposes. Industrial na-
tions should take the lead in this change because they are more capable
of doing so, having already developed the necessary technological and
mature economic base. Yet such a major transformation of the energy
supply system cannot be accomplished within a few years without
severe deleterious economic consequences that could well have devas-
tating consequences for humanity as a whole. Instead it has to be intro-
duced in a gradual and systematically planned way that causes the least
disruptions.
The energy consumption in industrial nations may be divided in
three roughly equal parts, namely for (a) electric energy generation,
(b) industrial process heat and space heating and (c) transportation.
Nuclear energy is already widely deployed for electrical-energy genera-
tion. Therefore, the least disturbing and most logical way to start reduc-
ing fossil-fuel consumption would be increasing the use of nuclear
power plants for electricity supply. It would be well within realistic
limits to aim for replacement over a time period of several decades
of the major part of the world's fossil-fuel-based electrical-energy
generating capacity. In parallel to this major change in electrical energy
generation, the use of fossil fuels for transportation should be reduced
by greater reliance on both nuclear-derived electrical energy and liquid
fuels produced synthetically bymeans of nuclear power plants. Also the
use of nuclear-derived process heat for industrial application should be
encouraged.
2. History, development and sustainability of nuclear energy
The practical generation of nuclear energy was demonstrated on
the second day of December 1942 when the rst human-controlled
self-sustaining nuclear ssion reaction was achieved at the University
of Chicago under the guidance of Italian-born physicist Enrico Fermi.
This experimental reactor (in those days called an atomic pile) made
use of slow(usually called thermal) neutrons, capable of sustaining
a chain reaction in the rare ssileuranium isotope U-235 that consti-
tutes only 0.7% of natural (mined) uranium; the rest (99.3%) being the
fertileisotope U-238. From this small experimental reactor, an entire
industry emerged that has led to 435 operating nuclear power reactors
(as of late 2014), 72 under construction, and 174 more on order or
planned,as well as numerous research reactors around the world, deliv-
ering clean energy and a large number of products and services for use
in many human activities, including medical diagnosis/therapy, indus-
try and agriculture. While all of these applications and products have
become of utmost and growing importance in supporting our standard
of living and health, this article will deal solely with the application of
nuclear ssion reactors for the production of energy.
Nuclear energy derived from ssion of uranium and plutonium
(transmuted from U-238) is capable of replacing most, if not all, of
the stationary tasks now performed by the combustion of fossil fuels
(thorium might also have a future application). However, many envi-
ronmental organizations and governments have opposed, and continue
to oppose, the application of abundant nuclear energy. Among the
reasons usually given against nuclear ssion energy are that it is:
(a) unsustainable; (b) uneconomic; (c) unsafe and (d) has links to
proliferation of nuclear weapons. Below each of these key concerns is
addressed.
Two important questions that need to be asked are: Is nuclear ener-
gy sustainable, and would it be possible to replace fossil-fuel derived
energy with renewables(e.g., wind- and solar energy), as is advocated
by many governments and environmental organizations? To answer
these questions, it is necessary to ask what is understood by the term
sustainable. The term sustainableis generally understood to mean
meeting the needs of the present without compromising the ability of
future generations to meet their own needs[1]. In the context of energy
options, sustainableimplies the ability to provide energy for indenite-
ly long timeperiods (i.e., on a very large civilization-spanning time
scale) without depriving future generations and in a way that is envi-
ronmentally friendly, economically viable, safe and able to be delivered
reliably. It should thus be concluded that the term sustainablein this
context is more restrictive than the term renewablethat is often
applied to energy derived from wind, sunlight, biomass, waves, tides
and geothermal resources, which for certain applications do not
meet all the criteria of sustainability (as discussed later).
Nuclear energy from ssion of uranium and plutonium is sustainable
because it meets all of the above-mentioned criteria: Today's commer-
cial uranium-fueled nuclear power plants can provide the world with
clean, economical and reliable energy well into the next century on
the basis of the already-identied uranium deposits (Table 1). Further-
more, as was pointed out by Enrico Fermi already in the 1940s, nuclear
reactorsoperating with fastneutrons are capable to ssion not only the
rare isotope U-235 but also the ssionable isotopes generated from the
transmutation of the abundant fertileisotope U-238 (or Th-232). Thus
the use of fast-neutron ssion reactors (usually called fast reactors)
transforms uranium into a truly inexhaustible energy source,becauseof
their ability to harvest about one hundred times more energy from
the same amount of mined uranium than the commercially available
thermalreactors operating with thermal neutrons [2,3]. This fast-
neutron ssion technology has already been proven all that is needed
is to develop it to a commercial level and deploy it widely [4] (for an
extended discussion on the critical need for a near-term fast-reactor
deployment, refer to a companion paper in this journal). The amount
of depleted uranium (i.e., uranium from which most of the ssileiso-
tope U-235 has been removed) that is available and stored at enrich-
ment plants in a number of countries, together with the uranium
recoverable from used-fuel elements, contains enough energy to
power the world for several hundred years without additional mining.
9B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
Afterwards, mining of small quantities of uranium in future centuries,
including extracting uranium from lower-grade ores and if necessary
from seawater, could satisfy global energy needs economically for as
long as human civilization will endure [3].
In conclusion, the fuel supply side of nuclear power reactors does
not give reason for any doubt concerning its sustainability. As to the
materials used in the construction of nuclear power plants, none are
in short supply (and most are readily recyclable), so that they too do
not constitute a sustainability impediment.
3. Economic viability
Nuclear energy is capable of economic viability, as has been shown
(for instance) in the national energy program in France, where the
unit price of electricity in a market supplied about 75% by nuclear ssion
is among the lowest worldwide. After the oil boycott of 1973, France
decided that it needed to strive for greater energy independence. Over
a time period of about two decades, France converted the major part
of its electrical energy generating capacity from fossil-fuel-based to
uranium-based. The cost of the nuclear power plants was kept low by
producing them in a series of identical units and by minimizing the
needed changes that were implemented in a coordinated way in all
plants of a given series. In addition, delays during construction (that
could have been very costly) were prevented by careful preparations
by both the government and the utility (including good public informa-
tion and an efcient licensing process, focused sharply on the signicant
safety issues). An important additional benetofthisrelianceonnucle-
ar energy is that per-capita emission of greenhouse gases in France is
among the lowest for industrial nations worldwide and many times
lower than in otherwise similar countries that have no nuclear power
plants and that rely on a mix of fossil fuels and some contribution
from renewables (e.g. Australia, Denmark).
Important conditions for economic viability of nuclear energy are:
(1) presence of a level playing eld,i.e.anopenmarketthatisnot
skewed in favor of some technologies by means of subsidies and/or by
a legally imposed priority access for delivery to the electrical grid at a
xed high price that are unavailable to nuclear; (2) standardization of
the plants, built in large series and supported by a standardized supply
chain; (3) a long-term governmental energy policy (stable over a time pe-
riod of several decades) including, among other features, good (unbiased,
accurate, evidence-based) public information; (4) a stable and stream-
lined licensing process that is technology-neutral, risk-informed and
capable of resolving promptly any safety issues that may arise during
construction and operation, (5) careful siting considerations to avoid
areas most prone to severe natural hazards, and (6) introduction of
the concept of payment for external costs(e.g. air pollution, solid
wastes, decommissioning) that is applied to all energy technologies
based on common standards.
Many countries promote wind and solar energy with the aim of
reducing greenhouse-gas emissions. This is done in part by giving
them priority access for delivery to the grid. This means that other gen-
erating plants are forced to ramp output up and down to cope with the
intermittency of these inherently varying sources. This mode of forced
accommodativeoperation penalizes nuclear power plants more than
it does fossil-red plants because the capitalcost component of the
generating cost for the former is relatively high and the fuel cost compo-
nent is low, whereas for the latter the reverse is true, especially for
open-cycle natural-gas plants (Table 2). This practice of distorting the
energy market has serious and undesirable consequences, resulting in
closure of base-load generating capacity (including nuclear power
plants), loss of grid reliability and higher net greenhouse gas emissions.
Nuclear power plants are able to adapt to this load following mode
(even though this is not recommended for economic reasons) as long
as the percentage of intermittent sources is low, as has been proven in
France [5]. To compensate for the negative economic effect on base-
load plants, a grid servicetariff is applied in France to quantify the
cost of the supply-intermittency caused by wind and solar.
An important aspect of long-term commercial viability of power
plants is the future development of their respective fuel costs. Nuclear
power plants rank best in this respect because their sensitivity to fuel-
cost increases is small (Table 3). A temporary abundance of low-cost
natural gas may seem to make gas-red stations appear to be econom-
ically attractive. However, this will change because it can be expected
that gas prices will rise substantially during the 60+ lifetime of new-
build nuclear power plants.
Nuclear energy is not limited to the generation of electricity, but may
equally well be used for such important tasks as desalination, production
of hydrogen, space heating and process-heat applications in industry as
well as for extraction of carbon from CO
2
to combine with hydrogen to
create synthetic liquid fuels. Many of these alternative applications of
nuclear energy will combine very well with the generation of electrical
energy in that the reactors could be operated continuously at full
power, allocating the required amount of heat to satisfy the electrical
load demand and the rest for producing fresh water, hydrogen or
steam for industrial processes [6]. Many areas around the world are
already facing severe shortages of fresh water and it can be expected
that the need for fresh water will be ever increasing. Nuclear-energy-
driven desalination in coastal regions will be able to satisfy part of this
need. Alternatively, nuclear power plants will be able to provide the
Table 1
Uranium reserves in countries with more than 1% of proven world reserves.
Source: OECD. Uranium 2009: Resources, Productionand Demand. OECD NEA Publication
6891. 2010.
Country Reserves as
of 2009
World
share
Historical
production
up to 2008
World
share
Australia 1,673,000 31.0% 156,428 6.5%
Brazil 278,700 5.2% 2839 0.1%
Canada 485,300 9.0% 426,670 17.7%
China 171,400 3.2% 31,399 1.3%
India 80,200 1.5% 9153 0.4%
Jordan 111,800 2.1% 0 0.0%
Kazakhstan 651,800 12.1% 126,900 5.3%
Namibia 284,200 5.3% 95,288 4.0%
Niger 272,900 5.0% 110,312 4.6%
Pakistan 80,900 1.6% 1159 0.0%
Russia 480,300 8.9% 139,735 5.8%
South Africa 295,600 5.5% 156,312 6.5%
Ukraine 105,000 1.9% 124,397 5.2%
United States 207,400 3.8% 363,640 15.1%
Uzbekistan 114,600 2.1% 34,939 1.4%
Vietnam 140,800 2.2% 0 0.0%
Table 2
Generation cost breakdown.
Source: OECD International Energy Agency: World Energy Outlook 2005.
Nuclear (%) Coal (%) Gas (%)
Capital 59 42 17
Fuel 15 41 76
Operation & maintenance 26 17 7
10 B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
energy to pump fresh water from areas with a surplus to regions facing a
shortage.
4. Environmental considerations
As numerous scientic comparisons have shown, nuclear ssion is
among the energy sources that are least polluting and have the lowest
overall environmental impact [7]. Operating nuclear power plants
do not produce air pollution nor do they emit CO
2
. Annually, the 435
operating nuclear power plants prevent the emission of more than 2
billion tons of CO
2
. By contrast, coal-red stations emit worldwide
about 30 billion tons of CO
2
per year and cause health effects and pre-
mature death through air pollution and dispersion of pollutants, includ-
ing mercury (harmful to the nervous system, particularly for infants)
and other poisonous materials [8]. It is important to note that nuclear
power plants emit less radioactive material than do coal-red stations
(uranium and other radioactive isotopes are found naturally in coal
ash and soot) [9]. The most severe environmental impact associated
with nuclear energy is due to the mining of uranium. However, the
need for uranium mining will be drastically reduced after fast reactors
have become commercially available, as may be expected within the
coming decades.
New methods for efciently recycling the used fuel (already proven
and currently in an advanced stage of development for commercial ap-
plication) will drastically reduce the radioactive hazards as well as the
volume of the waste that must be kept isolated from the environment.
As an example, the level of radioactivity of a repository containing this
type of waste will, after about 300 years, be comparable to that of the
natural uranium deposits that are widely distributed around the
world. Furthermore, modern waste isolation technology will equal or
exceed the level of isolation originally provided by nature for radioac-
tive ores. In this way, the much-publicized radioactivity issue of the
waste will be reduced to a historical time scale of a few hundred
years, rather than a geological time scale of hundreds of thousands of
years. It is important to note that this waste will be disposed of in an en-
vironmentally inert form, i.e., ceramic or vitried solids that will not
start leaching any material into the environment for thousands of
years, long after their radioactivity will have dissipated. On the other
hand, large amounts of solid and gaseous waste from coal-red stations
(including mercury and heavy metals) will remain poisonous in perpe-
tuity and are not kept well separated from the environment.
The cooling water requirements of current commercial nuclear
power plants (light-water reactors LWRs) are slightly higher than
those of fossil-fueled power plants because of the lower operating tem-
perature of the former. However, the new generation nuclear power
plants (liquid-metal-cooled fast reactors LMFRs) will have operating
temperatures equal to those of fossil-fuel-red power plants and thus
will have about the same cooling water requirements as those of
fossil-fuel-red plants. It should be pointed out that power plants
(both nuclear and fossil-fuel-red) usually do not consumecooling
water; they only heat up the water and return it as chemically and ra-
dioactively cleanas before to its origin, be it river, lake or sea. Only in
the case that cooling towers are used, is water evaporated and returned
to nature as clean water vapor (Table 4). Some power plants with
cooling towers make use of city waste water which is rst cleaned and
then returned to nature in the form of clean water vapor. In this latter
way of cooling, no demand is made on water that could be used for
any other useful purposes. In locations where no water is available
heat rejection to the air could be implemented. This would, however,
entail a penalty on thermal efciency, depending on the temperature
of the air.
It is expected that the current temporary abundance of inexpensive
natural gas due to the new frackingtechnology, will be of short dura-
tion (perhaps about 50 years). The current supply rate of natural gas
cannot be sustained in the long term if it continues to be burned in
large and increasing quantities [10]. Natural gas is an irreplaceable
resource that should be used sparingly and preserved for future gener-
ations. Its use for the generation of electrical energy is particularly
wasteful in that up to 60% of the heat is being discarded by heating
the cooling water or by evaporation in the cooling towers. A better
application of natural gas is residential heating in which nearly full use
is made of the combustion heat. While combustion of natural gas
emits less CO
2
than coal, it nevertheless emits substantial amounts of
CO
2
and is often accompanied by leakage of gas (sometimes quite sub-
stantial) resulting in release of methane (a potent greenhouse gas)
into the atmosphere. If the aim is to lower the rate of greenhouse gas
emission, natural gas use and leakage must be reduced.
Another consideration is that the world supply of helium is inextri-
cably connected to the availability of natural gas. The reason is that
helium accumulates subterraneously in conjunction with natural gas
over hundreds of millions of years as a consequence of decay of uranium
and thorium. Once the easily recoverable global resources of natural gas
have been exhausted, humanity will also have eliminated its supply of
relatively inexpensive helium. Helium is an important industrial gas
that, among others, nds application as the coolant-of-choice in high-
temperature gas-cooled nuclear reactors that probably will be deployed
in the future for industrial processes requiring very high temperatures.
5. Safety
In spite of media-inspired misconceptions, nuclear ssion is among
the safest energy technologies in terms of health effects and fatalities
(Tables 5 and 6). This is true notwithstanding the three major nuclear
accidents that have occurred, namely at Three Mile Island (TMI) in the
U.S.A., at Chernobyl in Ukraine, and at Fukushima in Japan. Of these
three, only the Chernobyl accidentcaused a number of fatalities, namely
among those persons that were directly exposed tohigh radiation doses
during the urgent initial part of the cleanup operation. However, the
number of these fatalities is relatively small (less than one hundred) if
compared to the number of annual fatalities in the coal and oil/gas
industry [7]. As an example, global average values of the mortality rate
per billion kWh, due to all causes as reported by the World Health
Organization (WHO), are 100 for coal, 36 for oil, 24 for biofuel/biomass,
4 for natural gas, 1.4 for hydro, 0.44 for solar, 0.15 for wind and 0.04 for
nuclear (Table 6).
Both the accident at Chernobyl and that at Fukushima caused con-
siderable land contamination and required evacuation of the popula-
tion. However, in both cases the major part of the evacuated areas
has/had radiation levels that are lower than the normal background
level in many regions around the world, raising the question of how
much evacuation and for how long was/is really necessary. In the
case of Three Mile Island, there was no land contamination, but a
Table 3
Fuel price increase sensitivity.
Source: WEO '06/OECD IEA World Energy Outlook 2006.
Impact of a 50% increase in fuel price on generating cost
Nuclear IGCC
a
Coal steam CCGT
b
3% 20% 22% 38%
a
IGCC = integrated gasication combined cycle coal.
b
CCGT = combined cycle gas turbine.
Table 4
Cooling water requirements of 1000 MWe plants (million liters/day).
Type of cooling LWR (or typical
coal plant) with 32%
thermal efciency
LMFR (or fossil-fuel-
red plant) with 42%
thermal efciency
Once-through
cooling (temp. rise = 12 °C)
3690 2330
Cooling towers 81.2 52.8
11B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
short-term evacuation was imposed as a precautionary measure. It
should be noted that land contamination is not limited to severe nuclear
accidents; it is a repeated event in the chemical industry, in which the
contaminants often are extremely deadly and long lasting (Bopal,
India; Seveso, Italy).
The radioactive isotopes of iodine (I-131, half-life about 8 days) and
cesium (Cs-137, half-life about 30 years) have dominating importance
in accidents in which the containment is breached and radioactivity is
released into the environment. I-131 will decay relatively quickly to
zero and simple precautions can prevent its health effects. However,
Cs-137 will stay in the environment for a longer time period that is
determined by its biological half-life, i.e. the combination of its radioac-
tive half-life and the rate of removalfrom body tissues or the soil surface
by natural processes. This latter process can be accelerated by removal
of a thin layer of the top soil in areas where the radiation level exceeds
the allowable radiation level, as was successfully done in Goiania, Brazil,
where a medical radioactive cesium source had been abandoned and
subsequently breached with the content being spread into the
surrounding area. Any contamination with radioactive materials
can be remediated in the same way as done for spills of chemical
materials.
Natural background radiation varies greatly over the world
(depending on soil composition and the location's elevation)but higher
background has not been found to be correlated with higher rates of
cancer in the population. The average background radiation at sea
level in much ofthe world is about 3 millisievert (mSv) per year where-
as that in many regions around the world is considerably higher. As an
example, at Ramsar in Iran the background radiation level is about
138 mSv per year, i.e. about 46 times higher than the average back-
ground. Yet the incidence rate of cancer in the local population of
these regions with high background radiation has not been observed
to be higher than normal.
When addressing nuclear safety, it is important to make a clear
distinction between public safety and economic damage. There is no
doubt that the economic damage associated with nuclear accidents
can be substantial, as was demonstrated in the above-mentioned
three major accidents. This potential for severe economic damage
should be (and is) a strong incentive on the part of the owner/operator
of the nuclear power plant to observe extreme caution, observing strict-
ly all safety-related rules and regulationsand maintaining a strictsafety
culture (even without being continuously monitored by the relevant
regulatory organization).
As is normal in the evolution of any technology, also the new designs
of nuclear power plants incorporated many safety-related improve-
ments (even though the safety level in older plants is already very
high in comparison with other large-scale electricity generating tech-
nologies). For example, the calculated probability of the occurrence of
damage to the nuclear core for a new-generation nuclear power plant
is typically about one hundred times less than that of early plant de-
signs. An indicator of the high level of safety of new-generation plants
is that, even in the case of the most serious design-basis accidents, the
general public will not have to be subjected to any emergency actions
(no off-site countermeasures are required). Even for postulated very se-
vere accidents in which the reactor core is assumed to be completely
destroyed, dedicated safety systems will limit both the consequences
and the duration of the emergency. Moreover, advanced technology is
focused on inherently passivesafety, rather than on actively operated
engineered safety systems requiring externally supplied energy.
Public opposition to nuclear energy is in part due to fear of radiation
caused by memories of the effects of nuclear weapons used during
Table 5
Comparison of energy-related damage (fatalities per gigawatt year), based on historical experience of severe accidents that occurred in OECD
countries , non-OECD countries and EU-15 (fteen European countries).
Source: Paul Scherrer Institut, Technology Assessment, Risk Assessment, http://gabe.web.psi.ch/research/ra.
Table 6
Mortality rates for each energy source in deaths per billion kWh produced.
Source: Updated (corrected) data from: World Health Organization; CDC; Seth Godin;
John Konrad.
Energy source Mortality rate (deaths per billion kWh)
Coal global average 100 (50% of global electricity)
Coal China 160 (75% of China's electricity)
Coal U.S. 15 (44% of U.S. electricity)
Oil 36 (36% of global energy, 8% of global
electricity, none in U.S.)
Natural gas 4 (20% of global electricity)
Biofuel/biomass 24 (21% of global energy)
Solar (rooftop) 0.44 (b1% of global electricity)
Wind 0.15 (~ 1% of global electricity)
Hydro global average 1.4 (15% of global electricity, 171,000 Banqiao dead)
Nuclear global average 0.04 (17% of global electricity, with Chernobyl &
Fukushima none in US)
12 B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
World War IIand by sensationalized coverage by news media of nuclear
incidents. However, it should be stressed that nuclear power plants are
physically absolutely incapable of exploding in the same way as nuclear
weapons because the composition of the nuclear core (consisting main-
ly of U-238, zirconium and water) does not permit this. The explosions
that were observed during the accident at Fukushima were chemical
in nature, caused by the formation and accumulation of hydrogen
(and its subsequent chemical explosion) due to overheating of the
nuclear reactor core triggering the oxidation of the zirconium in the
cladding of the fuel rods by hot steam.
One cause of the public fear of radiation is the use of the scientically
unsubstantiated Linear-No-Threshold (LNT) hypothesis in which it is
erroneously assumed that the biological effects of nuclear radiation
are linear with dose over a range of some ve orders of magnitude,
i.e., even at very low levels [1113].
6. Potential diversion of weapons-grade materials
Production of nuclear weapons requires access to weapons-grade
materials, i.e., either the isotope Pu-239 or the isotope U-235. Both
these isotopes have to be of high purity. The isotope Pu-239 is obtained
by irradiation of U-238 (neutron capture), whereas the isotope U-235 is
produced from naturaluranium by enrichment, i.e., separation of U-235
from the mined naturaluranium.
Most countries have signed the Non-Proliferation Treaty, commit-
ting them to refrain from producing weapons-grade materials and
nuclear weapons. The main task of the International Atomic Energy
Agency (IAEA) is to verify adherence by the member states to the
Non-Proliferation Treaty. IAEA has fullled this task well and continues
to do so.
No currently operating commercial nuclear power reactor has ever
been used for the production of weapons-grade materials, with the ex-
ception of the dual-purpose RBMK-type reactors that were constructed
in the Soviet Union. One of the reasons that commercial nuclear power
reactors have not been used for the production of Pu-239 is that one
strives for economic reasons in nuclear power plant operation to
achieve a high burnupof the fuel, i.e., a high percentage of the U-235
and Pu-239 atoms have undergone ssion. Because of this high burnup,
a large fraction of the U-238 is transmuted into higher isotopes of pluto-
nium; the consequenceof this is that the material that can be chemically
extracted from the used fuel is either not useable at all for weaponsor is
of very low quality. The best weapons-grade material is produced from
low burnup fuel and is usually extracted from depleted uranium irradi-
ated in reactors that have been especially designed for this purpose.
Research continues to be performed to make the entire commercial
nuclear industry more resistant to diversion of materials that could po-
tentially be used for the production of nuclear weapons. This includes
also the development of advanced techniques for the early detection
of any violation of the Non-Proliferation Treaty.
Fast reactors with on-site recycling of the used fuel [4] (also referred
to as integral fast reactors,IFR)couldinthefuturemakeamajorcontri-
bution towards reducing the risk of diversion of weapons-grade material
for a number of reasons, including (a) no need for transportation of the
used fuel outside the reactor site, (b) the plutonium and other actinides
remain mixed in a form that cannot be used for nuclear weapons, and
(c) strong reduction (or elimination) of the need for uranium enrich-
ment facilities.
7. Wind and solar energy when applied to the electric grid
Wind energy has served humanity well during many centuries in
many applications, including grinding wheat, pumping water and
sawing wood. Large areas of low-lying wet land and lakes were made
habitable and ready for agricultural use in previous centuries by removing
the water by means of wind-driven pumps. Wind also served for a long
time as an important energy source for transportation, making possible
the exploration of the entire world by means of ships propelled by the
wind. The important common characteristic of these applications is that
they are not time-constrained: If there is no wind today, the tasks can
be nished tomorrow or the ships will arrive somewhat later. This is,
however, very different if one wishes to use wind and solar energy (that
rely on capture of natural ows of diffuse kinetic and radiant sources)
for base-load delivery of electrical energy to the grid because the grid
imposes strict demands that have to be fullled instantaneously and
completely.
Solar energy generated by means of photovoltaic (PV) panels have
found important uses in special applications such as in space explora-
tion and as small-power energy sources with built-in storage batteries
for numerous applications (small light sources, calculators,parking tick-
et dispensers, watches). However, as an industrial-scale energy source
for delivery of base-load quantities of energy to the electrical grid,
solar energy will always be dependent on subsidies and special legally
imposed regulations. On the other hand, wind energy is not likely to un-
dergo a near-term revival of its traditional applications of grinding
wheat, sawing wood and pumping water because modern technologies
aremoreeffectiveinthisrespect.
With the express purpose of reducing greenhouse gas emissions,
many countries are promoting intermittent renewables by means of
subsidies and by legislative directives requiring utilities to give priority
access for delivery to the grid. A few countries have even announced
that theirtarget is to replaceall (or most) of theirexisting generating ca-
pacity with renewables. Yet some of the energy sources that are termed
renewableare, in certain applications, not sustainablebecause not all
necessary criteria are being met.
For instance, as mentioned earlier, intermittent energy sources,
when used for delivery of base-load quantities of energy to the electric
grid, require the availability of exible backup power plants (capable
of rapid output adjustments) with capacity close to 100% of the name-
plate capacity of the installed intermittent sources. This is because
wind turbines and solar plants will vary their output between 0% and
100% of nameplate capacity and also because electrical energy from
the grid is produced and consumed simultaneously and there can be
no mismatch if grid stability and frequency is to be maintained within
strict tolerances. Wind turbines deliver (over the course of a year)
between about 20% and 40% of their nameplate production capacity
(depending on location). Therefore, the backup power plants will have
to deliver the remaining 60% to 80% of the energy (Fig. 1). This
means that wind turbines would be more reasonably characterized
as fuel-saving technologies for combustion power plants rather
than stand-alone generators of electrical energy. Similar consider-
ations are true for solar energy that has the added shortcoming of re-
quiring the near-exclusive use of large land areas with more serious
environmental consequences than wind installations (unless used at a
Fig. 1. Intermittency of wind energy in Germany. Annual share of daily wind power in
respective daily peak demand in the E.ON-grid in Germany.
Source:UCTE Position Paperon Integratingwind power in the European power systems
prerequisites for successful and organic growth, May 2004.
13B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
smaller scale on rooftop installations). Some recent commercial solar
thermal plants have included on-site heat storage for a few hours of
output based on molten salts (at additional costs and involving larger
mirror elds). However, this cannot compensate for large day-to-day
and seasonal uctuations in solar energy input (e.g. a string of cloudy
days).
Seasonalvariability is a major, yet rarely acknowledged,impediment
to all-renewables scenarios (Table 7). Advocates often dismiss theissue
of seasonal variability, pointing out that the wind blows more in the
winter when solar output is minimal, and asserting that wind and
solar balance out on a daily basis because wind blows more at night.
However, these generalizations do not hold up to scrutiny. While
some areas of the world do have more wind in the winter, others do
not. In fact, it can be just the opposite in, e.g., California.
Until recently, California had more installed wind capacity than any
other state in the U.S.A. Recent data (from 2013) reveal that the capacity
factor of wind throughout California is slightly less than 25% over the
year. But in the months of January, November and December of 2013,
the capacity factor was about half that much. Meanwhile, the winter
months in California saw solar photovoltaic output in the range of
1112%. So even if utility-scale storage could be developed, wind and
solar installations would have to be overbuilt by at least a factor of
eight to provide the necessary capacity to power California. Barring
that obviously impossible scenario, backup power generators will still
be required, since there are strings of days when neither wind nor
solar installations produce any meaningful output, especially in the
winter.
The backup power for wind and solar plants depends in most cases
on combustion of fossil fuels, primarily natural gas, because this is
much less expensive than energy storage. Storage may be of various
types: Thermal storage is practiced in heat-concentrating solar plants,
potential storage is done by pumping up water or compressing air,
whereas battery storage is a type of chemical storage. Most energy-
storage facilities are not cost-effective at a large scale. However, in
rare cases intermittent energy sources with stored-energy facilities
may be economically viable, particularly for isolated locations without
access to an electric grid [14].
The combination of grid-connected wind/solar installation plus gas-
red backup power plant will emit carbon dioxide and most likely also
methane. Furthermore, grid-connected wind and solar installations will
often be dependent on subsidies because redundant and under-utilized
investments are required (i.e., for the intermittent source, the backup
source and the additionally required transmission system). Because the
output of wind-energy installations (averaged over a year), may have
values from 20% to 40% of the name-plate capacity (depending on the lo-
cation), the required investment for backup power is under-utilized by
these same percentages. Many wind and solar installations are far
removed from the load centers, requiring long-distance transmission
lines, sized for their peak output, which are then under-utilized by 60%
to 80%. Furthermore, the backup power plant will have to operate in
stand-by mode, ready to adapt to the varying outputs (from 0% to
100%) of the intermittent energy source. This results in a penalty on
the overall thermal efciency of the backup plant. Taken in sum, this
means that a combination of an intermittent energy source and its
back-up power plant will seldom achieve economic viability (Table 8).
Much confusion exists concerning the generating cost per kWh
for wind and solar plants. In this respect it is important to distinguish
clearly between the barecost of a kWh generated by wind or solar
installations that is consumed or stored locally and the costof a kWh de-
livered to the electrical grid. In the latter case, it is necessary to account
for the investments in the backup power and transmission capacity. The
difference between these two prices can be substantial, the cost per
kWh delivered to the grid being in most cases several hundred percent
higher than the barecost. As an example, Table 8 shows that for the
combination of intermittent energy source plus gas-red backup
power, the cost for fuel per kWh varies between 5 and 12 times the
cost for operation and maintenance.
Another consideration of importance is that the intermittency
will cause grid disturbances that will deleteriously affect the grid's reli-
ability, particularly if the installed capacity of the intermittent sources
becomes a high percentage of the grid's total capacity. Delivery unreli-
ability of the electrical grid can have serious economic and social conse-
quences as was seen when long-lasting blackouts occurred in large
urban areas. To date, in most grids, renewableshave only reached a
low market penetration and so have been able to rely on existing
marginal capacity, or large importexport capacity of interconnected
other grids. Serious challenges will, however, emerge if there is a push
to expand non-hydro renewables substantially within more traditional
markets. In this connection, the question should be raised whether a
country with a large installed wind/solar electrical generating capacity
should pay for the use of the interconnected electric grids of neighbor-
ing countries for providing backup power capacity. This is of particular
relevance for countries relying (or planning to rely) to a large extent
on intermittent energy sources.
8. Methane as a greenhouse gas
As is well known, methane (CH
4
, the principal molecular component
of natural gas) is a potent greenhouse agent if released into the atmo-
sphere [15]. This greenhouse-gas potency (also called global warming
potentialor GWP) is dened as the ratio of the atmospheric heating ef-
fect of a discharge of methane over a certain time period (also referred to
as time horizon) as a ratio of that of an equal gram-mole of carbon-
dioxide (CO
2
) over the same time period (Fig. 2,[16]). The half-life of
methane in the atmosphere is about 11 years, meaning that the number
of molecules in an emission of methane decreases exponentially to half
Table 7
Seasonalvariabilityof wind-generatedelectrical energyin Texas, U.S.A.highest and lowest
monthly generation values (GWh).
Source: personal communication by Per Peterson.
Year Highest value (month) Lowest value (month) Ratio
Highest/lowest
2009 1993 (April) 1341 (July) 1.44
2010 2721 (April) 1589 (Sept) 1.75
2011 3311 (June) 1694 (Sept) 1.95
2012 3131 (March) 1821 (Aug.) 1.74
2013 3966 (May) 2023 (Sept) 1.96
Table 8
Average power plant operating expenses for U.S. electric utilities (mills/kWh).
Source: U.S. Energy Information Administration http://www.eia.gov/electricity.
Year Nuclear Fossil (coal) steam Hydro Intermittent plus gas turbine
Operation Maintenance Fuel Total Operation Maintenance Fuel Total Operation Maintenance Fuel Total Operation Maintenance Fuel Total
2008 9.9 6.2 5.3 21.5 3.7 3.6 28.4 35.7 5.8 3.9 0.0 9.7 3.8 2.7 64.2 70.7
2009 10.0 6.3 5.4 21.7 4.2 4.0 32.3 40.5 4.9 3.5 0.0 8.4 3.0 2.6 52.0 57.6
2010 10.5 6.8 6.7 24,0 4.0 4.0 27.7 35.7 5.3 3.8 0.0 9.1 2.8 2.7 43.2 48.7
2011 10.9 6.8 7.0 24.7 4.0 4.0 27.0 35.0 5.1 3.8 0.0 8.9 2.8 2.9 38.8 44.5
2012 11.6 6.8 7.1 25.5 3.7 4.0 24.0 31.7 6.7 4.6 0.0 11.3 2.5 2.7 30.5 35.7
14 B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
its initial value in 11 years. Because the half-life of atmospheric methane
is much shorter than that of CO
2
, the ratio of their atmospheric heating
effects depends on the time horizon considered: A short time horizon re-
sults in a higher value for the GWP than a long horizon. The Intergovern-
mental Panel on Climate Change (IPCC) determined that the values for
the GWP of methane are about 60, 28, and 5, respectively, for time hori-
zons of 20, 100 and 500 years [17]. The GWP value approaches 120 for
the moment at which methane is released into the atmosphere, i.e. for
a time horizon equal to zero.
The IPCC seems to recommend using a time horizon of 100 years. In
reality, however, the large global combustion of natural gas does not
occur in discrete discharges but takes place as a continuous ow. The
associated leakage of methane into the atmosphere will therefore also
occur incessantly and the amount of atmospheric methane will thus
be constantly replenished. In fact, because of the worldwide rapidly
increasing use of natural gas, the rate of replenishment exceeds the
rate of decay, resulting in an ever increasing concentration of methane
in the atmosphere. A time horizon of 100 years would therefore appear
to be too long, particularly in view of warnings by IPCC of near-term
impending dangerous climatic consequences due to global warming. A
time horizon, considerably shorter than 100 years, would therefore
seem to be more appropriate, e.g. 5 or 10 years.
Measurements and estimates of the leakage rates of natural gas into
the atmosphere (at the mining well-head, during processing and from
the long pipelines) varyconsiderably and have been reported toexceed
4% [18]. This may be expected if the gas is transported over large dis-
tances such as when coming from Siberia, North Africa and the Middle
East.
Given that gas-red stations produceabout one half of the amount of
CO
2
as that produced by coal-red stations of equal generating capacity,
it follows that:
Gas-red stations will have higher rates of greenhouse-gas emission
than coal-red stations of equal generatingcapacity if the atmospher-
ic gas leakage rates exceed about 1.0% and 1.7%, respectively, for a
GWP value of 100 (for a short time horizon) and for a GWP value of
60 (for a time horizon of 20 years).
Grid-connected intermittent energy installations with gas-red back-
up power, operating at 25% and 50% availability, will for GWP equal to
100 have a higher rate of greenhouse-gas emission than stand-alone
coal-red stations of equal generating capacity if the atmospheric
gas leakage rate exceeds, respectively, 1.5% and 2.0% (not taking into
account the reduction in thermal efciency of the backup power plant
due to varying demand which could be as high as 20%).
Grid-connected intermittent energy installations with gas-red
backup power, operating at 25% and 50% availability, will for GWP
equal to 60 have a higher rate of greenhouse-gas emission than
stand-alone coal-red stations of equal generating capacity if the as-
sociated atmospheric gas leakage rate exceeds, respectively, about
2.5% and about 3.35% (not taking into account the reduction in thermal
efciency of the backup power plant due to varying demand which could
be as high as 20%).
Countries that depend on imported natural gas should be aware
of the above and should take full responsibility for the associated atmo-
spheric leakage of methane, including the part that occurs outside their
borders.
It is important in this respect to consider that the current atmospheric
concentrations of methane and CO
2
are, respectively, 1.893 ppm and
395 ppm, having risen since the start of the industrial revolution from,
respectively, 0.722 ppm and 280 ppm (i.e., increases of, respectively
162% and 41%, indicating that the increase in methane concentration
has been nearly four times larger than that of CO
2
).
There does not exist a difference in the heating effect between meth-
ane molecules that were released recently into the atmosphere and
those that were released a long time ago. Therefore, the currently present
amounts of atmospheric methane and CO
2
contribute to atmospheric
heating over the next 20 years in the ratio of, respectively, 95 to 395.
For a time horizon of 5 years this ratio will be about 190 to 395, meaning
that close to half of the atmospheric heating effect over the next 5 years is
attributable to methane.
The atmospheric methane concentration of 0.722 ppm prior to
the industrial revolution represents the equilibrium value between
the rate of decay and the rate of replenishment by (mainly) non-
anthropogenic sources (e.g. decaying vegetation, ruminant digestion).
However, the current value of atmospheric methane concentration of
1.893 does not represent an equilibrium value because of the rapidly
growing global role of natural gas as an energy source in the last half-
century and the increasing release of methane from thawing perma-
frost. If the use of natural gas continues to rise rapidly (as is expected),
it may well be possible that the warmingeffect of atmospheric methane
will becomecomparable to that of CO
2
within a few decades. This would
make it counterproductive to continue the large-scale useof natural gas
as a fuel of primary importance and in particular to use it as the main
fuel to provide the backup power for intermittent energy sources.
Nuclear and hydro are the only backup power energy sources
that would result in an emission-free combination of intermittent plus
backup energy source. However, the amount of hydro power is limited
and is associated with serious environmental consequences. The use of
nuclear power plants as backup for intermittent energy sources isnot an
economically viable option [19] and is arguably pointless from a
climate-change mitigation perspective.
Using biomass for large-scale energy production is also a limited
sustainable option. The reasons for this are multiple and include:
(a) displacement of agricultural production, (b) land degradation after
many years of intensive use through topsoil erosion and runoff with lim-
ited replenishment of stubble, (c) increased generation of anthropogenic
methane, (d) dependence on shrinking freshwater resources, (e) land
areas that can be withdrawn from food production for biomass produc-
tion will decrease in time with the growth in the world population and
(f) further destruction of natural habitats not yet under agricultural pro-
duction. It should be noted that countries that import biofuels should
take full responsibility for their part of the environmental impact caused
in the country where the fuel is produced (including the associated
greenhouse gas emissions).
9. Conclusion
Humanity will have to systematically reduce its dependence on the
large-scale combustion of fossil fuels for energy production over the
coming decades, with the aim of completing this transformation before
Fig. 2. Value of methane and carbon dioxide absolute global warming potential as a
function of time horizon.
Taken from IPCC, Climate Change 2013, Chapter 8,p. 712).
15B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
the end of this century. In doing so, all energy sources may be considered
and some will be deployed in useful nicheapplications. However, only
nuclear power plants are capable of sustainably and reliably supplying
the large quantities of clean and economical energy needed to run indus-
trial societies with minimal emission of greenhouse gases. Nuclear
energy meets all the criteria of sustainability as dened by the U.N.
Brundtland Commission [1].
In a rst phase, the world's industrial nations should take the lead in
transforming the major part of their stationary electrical energy generat-
ing capacity from fossil-fuel based to nuclear-ssion based. With a long-
term energy policy and proper incentives, this could be achieved with in a
few decades (as was already done by France). Such a transformation
could drastically reduce the global rate of greenhouse-gas emission
with respect to both atmospheric carbon-dioxide and methane.
Renewable energy sources (primarily wind and solar) will not be able
to supply the needed large quantities of energy sustainably, economical-
ly and reliably. In addition, renewable energy sources with fossil-red
backup power will in many cases not contribute towards reduction of
greenhouse-gas emissions. Distorting the market with subsidies and by
legislation to attract intermittent energy technologies into applications
for which they are not well suited is economically wasteful. Also, replac-
ing stand-alone coal-red stations with stand-alone gas-red stations
will, in many cases, not result in a reduction in the rate of emission of
greenhouse gases due to (often poorly quantied)problemsofmethane
leakage. Countries that depend on imported natural gas should be aware
that they carry full responsibility for their part of the global conse-
quences due to atmospheric leakage of methane associated with their
part of the imported gas, including the leakage taking place outside
their borders.
One solution to avoid free ridingwould be a grid-connection fee, to
be imposed on countries with a large intermittent generating capacity,
for the purpose of compensating adjacent countries for the use of their
interconnected electric grids as back-up power, and for having to accept
surplus intermittent energy at times when it is not needed, thus forcing
their base-load power plants to operate in an uneconomic accommoda-
tivemode.
Intermittent energy sources with stored-energy facilities might, in
some cases be economically viable, particularly for isolated locations
without access to an electric grid. But the heavy liftingin terms of re-
placing the global use of coal, oil and gas must come from a large-scale
deployment of nuclear ssion energy, with a goal for full fuel recycling
for maximum long-term sustainability of this critical zero-carbon energy
source.
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16 B.W. Brook et al. / Sustainable Materials and Technologies 12(2014)816
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... The application of radioactive materials in agriculture research, medicine, and power generation plays a vital role in the economic and technological development of a country. Major applications of nuclear technology include diagnosis and treatment of a variety of diseases, generation of electricity, archaeology, pollution mitigation, etc. [1][2][3][4][5][6][7][8][9]. Nuclear technology uses different radioactive rays, such as gamma rays, X-rays, and neutrons, that have the potential to cause serious health and environmental problems [10][11][12][13]. ...
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Nuclear fission fuel is inexhaustible
  • D Lightfoot
D. Lightfoot, et al., Nuclear fission fuel is inexhaustible, CNS Climate Change Technology Conference, May 10-12, 2006, Ottawa, Ontario, Canada, 2006.