From Wikipedia, the free encyclopedia
Civilian nuclear power supplied 2,488
terawatt hours (TWh) of electricity in 2017, equivalent to about 10% of global electricity generation.
As of April 2018, there are
449 civilian fission reactors in the world, with a combined electrical capacity of 394
gigawatt
(GW).
Additionally, there are 58 reactors under construction and 154 reactors
planned, with a combined capacity of 63 GW and 157 GW, respectively.
Over 300 more reactors are proposed.
Most of reactors under construction are of
generation III reactor design, with the majority in Asia.
Some
accidents have occurred in nuclear power plants.
These include the
Chernobyl disaster in the Soviet Union in 1986, the
Fukushima Daiichi nuclear disaster in Japan in 2011, and the more contained
Three Mile Island accident
in the United States in 1979.
There have also been some nuclear submarine accidents.
In terms of lives lost per unit of energy generated, nuclear reactors
have caused the lowest number of fatalities per unit of energy generated
when compared to the other major energy producing methods.
Coal, petroleum, natural gas and hydroelectricity each have caused a
greater number of fatalities per unit of energy, due to air pollution
and
accidents.
History
Origins
The Nuclear binding energy
of all natural elements in the periodic table. Higher values translate
into more tightly bound nuclei and greater nuclear stability. Iron (Fe) is the end product of nucleosynthesis within the core of hydrogen fusing stars. The elements surrounding iron are the fission products of the fissionable actinides
(e.g. uranium). Except for iron, all other elemental nuclei have in
theory the potential to be nuclear fuel, and the greater distance from
iron the greater nuclear potential energy that could be released.
In 1932 physicist
Ernest Rutherford
discovered that when lithium atoms were "split" by protons from a
proton accelerator, immense amounts of energy were released in
accordance with the principle of
mass–energy equivalence. However, he and other nuclear physics pioneers
Niels Bohr and
Albert Einstein
believed harnessing the power of the atom for practical purposes
anytime in the near future was unlikely, with Rutherford labeling such
expectations "moonshine."
The same year, his doctoral student
James Chadwick discovered the
neutron,
which was immediately recognized as a potential tool for nuclear
experimentation because of its lack of an electric charge.
Experimentation with bombardment of materials with neutrons led
Frédéric and
Irène Joliot-Curie to discover
induced radioactivity in 1934, which allowed the creation of radium-like elements at much less the price of natural radium. Further work by
Enrico Fermi in the 1930s focused on using
slow neutrons
to increase the effectiveness of induced radioactivity. Experiments
bombarding uranium with neutrons led Fermi to believe he had created a
new, transuranic element, which was dubbed
hesperium.
In 1938, German chemists
Otto Hahn and
Fritz Strassmann, along with Austrian physicist
Lise Meitner and Meitner's nephew,
Otto Robert Frisch,
conducted experiments with the products of neutron-bombarded uranium,
as a means of further investigating Fermi's claims.
They determined that the relatively tiny neutron split the nucleus of
the massive uranium atoms into two roughly equal pieces, contradicting
Fermi.
This was an extremely surprising result: all other forms of
nuclear decay involved only small changes to the mass of the nucleus, whereas this process—dubbed "fission" as a
reference to biology—involved a complete rupture of the nucleus.
Numerous scientists, including
Leó Szilárd, who was one of the first, recognized that if fission reactions released additional neutrons, a self-sustaining
nuclear chain reaction could result.
Once this was experimentally confirmed and announced by Frédéric
Joliot-Curie in 1939, scientists in many countries (including the United
States, the United Kingdom, France, Germany, and the Soviet Union)
petitioned their governments for support of nuclear fission research,
just on the cusp of World War II, for the development of a
nuclear weapon.
First nuclear reactor
In the United States, where Fermi and Szilárd had both emigrated, the
discovery of the nuclear chain reaction led to the creation of the
first man-made reactor, known as
Chicago Pile-1, which achieved
criticality on December 2, 1942.
This work became part of the
Manhattan Project, a massive secret U.S. government military project to make
enriched uranium and by building large production reactors to produce (
breed)
plutonium for use in the first nuclear weapons.
The United States would test an atom bomb in July 1945 with the
Trinity test, and eventually two such weapons were used in the
atomic bombings of Hiroshima and Nagasaki.
In the same month, with the end of the war, Seaborg and others would file hundreds of initially classifed
patents, most notably
Eugene Wigner and
Alvin Weinberg's Patent #2,736,696, on a conceptual
light water reactor (LWR) that would later become the United States' primary reactor for
naval propulsion and later take up the greatest share of the commercial fission-electric landscape.
The United Kingdom, Canada, and the USSR proceeded to research and develop nuclear energy over the course of the late 1940s and early 1950s.
Electricity was generated for the first time by a nuclear reactor on December 20, 1951, at the
EBR-I experimental station near
Arco, Idaho, which initially produced about 100
kW.
Early years
The launching ceremony of the USS Nautilus January 1954
The first organization to develop nuclear power was the
U.S. Navy, with the
S1W reactor for the purpose of propelling
submarines and
aircraft carriers. The first nuclear-powered submarine,
USS Nautilus, was put to sea in January 1954. The trajectory of civil reactor design was heavily influenced by Admiral
Hyman G. Rickover, who with Weinberg as a close advisor, selected the PWR/
Pressurized Water Reactor design, in the form of a
10 MW reactor
for the Nautilus, a decision that would result in the PWR receiving a
government commitment to develop, an engineering lead that would result
in a lasting impact on the civilian electricity market in the years to
come. The
United States Navy Nuclear Propulsion design and
operation community,
under Rickover's style of attentive management retains a continuing
record of zero reactor accidents (defined as the uncontrolled release of
fission products to the environment resulting from damage to a reactor
core). with the U.S. Navy fleet of nuclear-powered ships, standing at some 80 vessels as of 2018.
On June 27, 1954, the
USSR's
Obninsk Nuclear Power Plant, based on what would become the prototype of the
RBMK reactor design, became the world's first nuclear power plant to generate electricity for a
power grid, producing around 5 megawatts of electric power.
On July 17, 1955 the
BORAX III reactor, the prototype to later
Boiling Water Reactors, became the first to generate electricity for an entire community, the town of
Arco, Idaho. A motion picture record of the demonstration, of supplying some 2 megawatts(2 MW) of electricity, was presented to the
United Nations,
Where at the "First Geneva Conference", the world's largest gathering
of scientists and engineers, met to explore the technology in that year.
In 1957
EURATOM was launched alongside the
European Economic Community (the latter is now the European Union). The same year also saw the launch of the
International Atomic Energy Agency (IAEA).
The world's first "commercial nuclear power station",
Calder Hall at Windscale, England, was opened in 1956 with an initial capacity of 50 MW (later 200 MW), it was the first of a fleet of dual-purpose
MAGNOX reactors, though officially code-named PIPPA(Pressurized Pile Producing Power and Plutonium) by the
UKAEA to denote the plant's dual commercial and military role.
Development and early opposition to nuclear power
Number of generating and under construction civilian fission-electric reactors, over the period 1960 to 2015.
The total global installed nuclear capacity initially rose relatively quickly, rising from less than 1
gigawatt
(GW) in 1960 to 100 GW in the late 1970s, and 300 GW in the late 1980s.
Since the late 1980s worldwide capacity has risen much more slowly,
reaching 366 GW in 2005. Between around 1970 and 1990, more than 50 GW
of capacity was under construction (peaking at over 150 GW in the late
1970s and early 1980s) — in 2005, around 25 GW of new capacity was
planned. More than two-thirds of all nuclear plants ordered after
January 1970 were eventually cancelled. A total of
63 nuclear units were canceled in the United States between 1975 and 1980.
In 1972 Alvin Weinberg, co-inventor of the light water reactor
design (the most common nuclear reactors today) was fired from his job
at Oak Ridge National Laboratory by the
Nixon administration,
"at least in part" over his raising of concerns about the safety and
wisdom of ever larger scaling-up of his design, above the power rating
of ~ 500 MWe, in a
loss of coolant accident-scenario, the particular combination of compact solid-fuel cores and the
decay heat generated from ~ 500 MW is beyond the capabilities of passive/natural
convection cooling to prevent a rapid fuel rod melt-down and resulting in then far reaching
fission product
pluming. While considering the LWR, well suited at sea for the
submarine and naval fleet, Weinberg did not show complete support for
its use by utilities on land at the power output that they were
interested in for
supply scale reasons, and would request for the development and funding of his team's
molten salt reactor,
a design with greater inherent safety in this scenario and with that an
envisioned greater economic growth potential in the market of
large-scale civilian electricity generation.
In 1976
Idaho National Laboratory began a
test program focused on LWR reactors
under various accident scenarios, with the aim of understanding the
event progression and mitigating steps necessary to respond to a failure
of one or more of the disparate systems, with much of the back-up
safety equipment and nuclear regulations arising from these series of
investigations, heavily influencing the design of LWRs for the civilian
market.
During the 1970s and 1980s rising economic costs (related to
extended construction times largely due to regulatory changes and
pressure-group litigation)
and falling fossil fuel prices made nuclear power plants then under
construction less attractive. In the 1980s in the U.S. and 1990s in
Europe, the flat electric grid growth and
electricity liberalization also made the addition of large new
baseload energy generators economically unattractive.
Electricity
production in France has been dominated by fission-electric stations
since the early 1980s with a large portion of the electricity exported
to neighboring Germany etc. today.
thermofossil
hydroelectric
nuclear
Other renewables
The
1973 oil crisis
had a significant effect on countries, such as France and Japan, which
had relied more heavily on oil for electric generation (39% and 73% respectively) to invest in nuclear power.
The french plan, known as the
Messmer plan, was for the complete independence from oil, with an envisaged construction of 80 reactors by 1985 and 170 by 2000.
France would construct
25 fission-electric stations,
installing 56 mostly PWR design reactors over the next 15 years, though
foregoing the 100 reactors initially charted in 1973, for the 1990s. As of 2018 over 70% of french electricity, is generated from these 56 reactors, the highest percentage by any nation in the world.
Some local opposition to nuclear power emerged in the early 1960s, and in the late 1960s some members of the scientific community began to express their concerns. These
anti-nuclear concerns related to
nuclear accidents,
nuclear proliferation,
nuclear terrorism and
radioactive waste disposal. In the early 1970s, there were large protests about a proposed nuclear power plant in
Wyhl,
Germany. The project was cancelled in 1975 the anti-nuclear success at
Wyhl inspired opposition to nuclear power in other parts of Europe and
North America.
By the mid-1970s anti-nuclear activism gained a wider appeal and
influence, and nuclear power began to become an issue of major public
protest. In some countries, the
nuclear power conflict "reached an intensity unprecedented in the history of technology controversies". In May 1979, an estimated 70,000 people, including then governor of California
Jerry Brown, attended a march against nuclear power in Washington, D.C.
Anti-nuclear power groups emerged in every country that has had a nuclear power program.
Three Mile Island and Chernobyl
The abandoned town of Pripyat with the Chernobyl plant and the Chernobyl New Safe Confinement
arch in the distance, prior to it moving into place and retaining the
hazardous dust generated during the disassembly process, on site.
According to some commentators, the 1979
accident at Three Mile Island, and the 1986
Chernobyl disaster played a major part in the reduction in the number of new plant constructions in many countries, although the public policy organization, the
Brookings Institution
states that new nuclear units, at the time of publishing in 2006, had
not been built in the United States because of soft demand for
electricity,
cost overruns on nuclear plants due to regulatory issues and construction delays.
By the end of the 1970s it became clear that nuclear power would not
grow nearly as dramatically as once believed. Eventually, more than 120
reactor orders in the United States were ultimately cancelled and the construction of new reactors ground to a halt. A cover story in the February 11, 1985, issue of
Forbes
magazine commented on the overall failure of the U.S. nuclear power
program, saying it "ranks as the largest managerial disaster in business
history".
In 1982, occurring amongst a backdrop of ongoing protests directed at the construction of the first commercial scale
breeder reactor in France, a later member of the
Swiss Green Party fired five
RPG-7 rocket-propelled grenades at the still under construction
containment building of the
Superphenix
reactor. While 2 warheads hit and caused minor damage to the reinforced
concrete outer shell. It was the first time protests reached such
heights. After examination of the damage, the prototype fast breeder
reactor started and operated for over a decade.
A simplified diagram of the major differences between the most common nuclear reactor design, the Light water reactor and the Chernobyl RBMK design. 1. In "red", the use of a graphite moderator in a water cooled reactor. 2. A positive steam void coefficient that made the power excursion possible, which blew the reactor vessel. 3. The control rods were very slow, taking 18–20 seconds to be deployed. With the control rods having graphite tips that moderated and therefore increased the fission rate in the beginning of the rod insertion. 4. No reinforced containment building.
Unlike the Three Mile Island accident, the much more serious
Chernobyl accident did not increase regulations affecting Western
reactors since the Chernobyl reactors were of the problematic
RBMK design only used in the Soviet Union, for example lacking "robust"
containment buildings.
Over 10 RBMK reactors are still in use today. However, changes were
made in both the reactors themselves (use of a safer enrichment of
uranium) and in the control system (prevention of disabling safety
systems), amongst other things, to reduce the possibility of a duplicate
accident.
An international organization to promote safety awareness and professional development on operators in nuclear facilities, the
World Association of Nuclear Operators
(WANO), was created as a direct outcome of the 1986 Chernobyl accident.
The organization was created with the intent to share and grow the
adoption of nuclear safety technology, where before there was an
atmosphere of
cold war secrecy.
Numerous countries, including Austria (1978), Sweden (1980) and
Italy (1987) (influenced by Chernobyl) have voted in referendums to
oppose or phase out nuclear power.
Nuclear renaissance
Olkiluoto 3 under construction in 2009. It was the first EPR, a modernized PWR design with a core catcher,
to start construction but problems with workmanship and supervision
have created costly delays which led to an inquiry by the Finnish
nuclear regulator STUK.[77] Allowing the later started Taishan Nuclear EPR project
to reach first connection to a national grid, in 2018. In December
2012, Areva estimated that the full cost of Olkiluoto will be about €8.5
billion, or almost three times the original delivery price of €3
billion and it will not be connected to the grid until the 2020s.
Since about 2001 the term
nuclear renaissance has been used to refer to a possible nuclear power industry revival, driven by rising
fossil fuel prices and new concerns about meeting
greenhouse gas emission limits.
With the energy source, as of 2010, an established alternative, providing two thirds(2/3) of the twenty seven nation
European Union's
low-carbon electricity.
However since commercial nuclear energy began in the mid-1950s, 2008 was
the first year that no new nuclear power plant was connected to the
grid, although two were connected in 2009. In 2009, Petteri Tiippana, the director of STUK's nuclear power plant division, told the
BBC that it was difficult to deliver a
Generation III reactor
project on schedule because builders were not used to working to the
exacting standards required on nuclear construction sites, since so few
new reactors had been built in recent years.
In 2018 the
MIT
Energy Initiative study on the future of nuclear energy concluded that
together with the strong suggestion that government should financially
support development and demonstration of new Generation IV nuclear
technologies, for a world wide renaissance to commence, a global
standardization of regulations needs to take place, with a move towards
serial manufacturing of standardized units akin to the other complex
engineering field of aircraft and aviation. At present it is common for
each country to demand
bespoke
changes to the design to satisfy varying national regulatory bodies,
often to the benefit of domestic engineering supply firms. The report
goes on to note that the most cost-effective projects have been built
with multiple (up to six) reactors per site using a standardized design,
with the same component suppliers and construction crews working on
each unit, in a continuous work flow.
Fukushima Daiichi Nuclear Disaster
Following the
Tōhoku earthquake on 11 March 2011, one of the largest earthquakes ever recorded, and a subsequent tsunami off the coast of Japan, the
Fukushima Daiichi Nuclear Power Plant
suffered multiple core meltdowns due to failure of the emergency
cooling system for lack of electricity supply. This resulted in the most
serious nuclear accident since the Chernobyl disaster.
The Fukushima Daiichi nuclear accident prompted a re-examination of
nuclear safety and
nuclear energy policy in many countries and raised questions among some commentators over the future of the renaissance.
Germany approved plans to close all its reactors by 2022, Italian nuclear energy plans in 2009, ended when Italy banned the generation, but not consumption of, nuclear electricity in a June 2011 referendum.
China, Switzerland, Israel, Malaysia, Thailand, United Kingdom, and the Philippines reviewed their nuclear power programs.
In 2011 the
International Energy Agency halved its prior estimate of new generating capacity to be built by 2035.
Nuclear power generation had the biggest ever fall year-on-year in 2012,
with nuclear power plants globally producing 2,346 TWh of electricity, a
drop of 7% from 2011.
This was caused primarily by the majority of Japanese reactors remaining
offline that year and the permanent closure of eight reactors in
Germany.
Post-Fukushima
The Fukushima Daiichi nuclear accident sparked controversy about the
importance of the accident and its effect on nuclear's future.
The crisis prompted countries with nuclear power to review the safety of
their reactor fleet and reconsider the speed and scale of planned
nuclear expansions.
In 2011, The Economist opined that nuclear power "looks
dangerous, unpopular, expensive and risky", and that "it is replaceable
with relative ease and could be forgone with no huge structural shifts
in the way the world works".
Earth Institute Director Jeffrey Sachs disagreed, claiming combating climate change would require an expansion of nuclear power.
Investment banks were also critical of nuclear soon after the accident.
In September 2011, German engineering giant
Siemens announced it will withdraw entirely from the nuclear industry as a response to the Fukushima accident.
By contrast, the
Associated Press and
Reuters reported in 2011 the suggestion that the safety and survival of the younger
Onagawa Nuclear Power Plant, the closest reactor facility to the
epicenter
and on the coast, demonstrate that it is possible for nuclear
facilities to withstand the greatest natural disasters. The Onagawa
plant was also said to show that nuclear power can retain public trust,
with the surviving residents of the town of Onagawa taking refuge in the
gymnasium of the nuclear facility following the destruction of their
town.
Following an
IAEA
inspection in 2012, the agency stated that "The structural elements of
the [Onagawa] NPS (nuclear power station) were remarkably undamaged
given the magnitude of ground motion experienced and the duration and
size of this great earthquake,”.
In February 2012, the United States Nuclear Regulatory Commission approved the construction of two additional reactors at the
Vogtle Electric Generating Plant, the first reactors to be approved in over 30 years since the Three Mile Island accident.
In October 2016,
Watts Bar 2 became the first new United States reactor to enter commercial operation since 1996.
By 2015, the IAEA's outlook for nuclear energy had become more
promising.
"Nuclear power is a critical element in limiting greenhouse gas
emissions," the agency noted, and "the prospects for nuclear energy
remain positive in the medium to long term despite a negative impact in
some countries in the aftermath of the [Fukushima-Daiichi] accident...it
is still the second-largest source worldwide of low-carbon electricity.
And the 72 reactors under construction at the start of last year were
the most in 25 years."
According to the World Nuclear Association, as of 2015 the global trend
was for new nuclear power stations coming online to be balanced by the
number of old plants being retired. Eight new grid connections were completed by China in 2015.
Future of the industry
As of 2018, there are over 150 nuclear reactors planned including 50 under construction. However, while investment on upgrades of existing plant and life-time extensions continues, investment in new nuclear is declining, reaching a 5-year-low in 2017.
In 2015, the International Energy Agency reported that the
Fukushima accident had a strongly negative effect on nuclear power, yet
nuclear power prospects are positive in the medium to long term mainly
thanks to new construction in Asia.
In 2016, the U.S. Energy Information Administration projected for its
“base case” that world nuclear power generation would increase from
2,344
terawatt hours (TWh) in 2012 to 4,501 TWh in 2040.
Most of the predicted increase was expected to be in Asia.
The future of nuclear power varies greatly between countries, depending on government policies.
Some countries, many of them in Europe, such as Germany, Belgium, and Lithuania, have adopted policies of
nuclear power phase-out.
At the same time, some Asian countries, such as China and India, have committed to rapid expansion of nuclear power.
Many other countries, such as the United Kingdom
and the United States, have policies in between.
Japan generated about 30% of its electricity from nuclear power before
the Fukushima accident.
In 2015 the Japanese government committed to the aim of restarting its
fleet of 40 reactors by 2030 after safety upgrades, and to finish the
construction of the Generation III
Ōma Nuclear Power Plant.
This would mean that approximately 20% of electricity would come from nuclear power by 2030.
As of 2018, some reactors have restarted commercial operation following inspections and upgrades with new regulations.
While
South Korea has a large nuclear power industry, the new government in 2017, partly influenced by a large anti-nuclear movement,
committed to halting nuclear development and to gradually phase out
nuclear power as reactors that are now operating or under construction
close after 40 years of operations.
The Generation IV
roadmap. Nuclear Energy Systems Deployable no later than 2030 and
offering significant advances in sustainability, safety and reliability,
and economics.
The nuclear power industry in some western nations have a history of
construction delays, cost overruns, plant cancellations, and nuclear
safety issues, despite significant government subsidies and support.
These problems are related to very strict safety requirements, uncertain
regulatory environment, slow rate of construction, and large stretches
of time with no nuclear construction and consequent loss of know-how.
Commentators therefore argue that new nuclear is impractical in western
countries because of popular opposition, regulatory uncertainty, soft
demand for multiple reactor units and high costs.
Recent financial problems of western nuclear companies, most prominently the bankruptcy of
Westinghouse
in March 2017 because of US$9 billion of losses from nuclear
construction projects in the United States, suggest a shift to the East,
as the dominant exporter and designer of nuclear fuel and reactors.
The greatest new build activity is occurring in Asian countries like South Korea, India and China.
In March 2016, China had 30 reactors in operation, 24 under construction and plans to build more.
In 2016 the
BN-800 sodium cooled
fast reactor in Russia, began commercial electricity generation, while plans for a
BN-1200
were initially conceived the future of the fast reactor program in
Russia awaits the results from MBIR, an under construction multi-loop
Generation IV research facility for testing the chemically more inert lead, lead-
bismuth and
gas coolants, it will similarly run on recycled
MOX (mixed uranium and plutonium oxide) fuel. An on-site
pyrochemical processing,
closed fuel-cycle facility, is planned, to recycle the spent
fuel/"waste" and reduce the necessity for a growth in uranium mining and
exploration. In 2017 the manufacture program for the reactor commenced
with the facility open to collaboration under the "International Project
on Innovative Nuclear Reactors and Fuel Cycle", it has a construction
schedule, that includes an operational start in 2020. As planned, it
will be the world's most-powerful research reactor.
In the United States, licenses of almost half of the operating nuclear reactors have been extended to 60 years.
The U.S. NRC and the U.S. Department of Energy have initiated research into
Light water reactor sustainability
which is hoped will lead to allowing extensions of reactor licenses
beyond 60 years, provided that safety can be maintained, to increase
energy security and preserve low-carbon generation sources.
Research into nuclear reactors that can last 100 years, known as
Centurion Reactors, is being conducted.
According to the
World Nuclear Association,
globally during the 1980s one new nuclear reactor started up every
17 days on average, and in the year 2015 it was estimated that this rate
could in theory eventually increase to one every 5 days, although no
plans exist for that.
Nuclear power station
Just as many conventional
thermal power stations generate electricity by harnessing the
thermal energy released from burning
fossil fuels, nuclear power plants convert the energy released from the
nucleus of an atom via
nuclear fission that takes place in a nuclear reactor. When a
neutron hits the nucleus of a
uranium-235 or
plutonium
atom, it can split the nucleus into two smaller nuclei. The reaction is
called nuclear fission. The fission reaction releases energy and
neutrons. The released neutrons can hit other uranium or plutonium
nuclei, causing new fission reactions, which release more energy and
more neutrons. This is called a
chain reaction. The reaction rate is controlled by
control rods
that absorb excess neutrons. The controllability of nuclear reactors
depends on the fact that a small fraction of neutrons resulting from
fission are
delayed.
The time delay between the fission and the release of the neutrons
slows down changes in reaction rates and gives time for moving the
control rods to adjust the reaction rate.
A fission nuclear power plant is generally composed of a
nuclear reactor,
in which the nuclear reactions generating heat take place; a cooling
system, which removes the heat from inside the reactor; a
steam turbine, which transforms the heat in
mechanical energy; an
electric generator, which transform the mechanical energy into electrical energy.
Life cycle of nuclear fuel
The nuclear fuel cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, (1) which is delivered to a nuclear power plant.
After usage in the power plant, the spent fuel is delivered to a
reprocessing plant (2) or to a final repository (3) for geological
disposition. In reprocessing 95% of spent fuel can potentially be recycled to be returned to usage in a power plant (4).
A nuclear reactor is only part of the fuel life-cycle for nuclear power.
The process starts with mining.
Uranium mines are underground,
open-pit, or
in-situ leach mines.
In any case, the uranium ore is extracted, usually converted into a stable and compact form such as
yellowcake, and then transported to a processing facility.
Here, the yellowcake is converted to
uranium hexafluoride, which is then generally
enriched using various techniques.
Some reactor designs can also use natural uranium without enrichment.
The enriched uranium, containing more than the natural 0.7%
uranium-235, is generally used to make
rods
of the proper composition and geometry for the particular reactor that
the fuel is destined for.
In modern light-water reactors the fuel rods will spend about 3
operational cycles (typically 6 years total now) inside the reactor,
generally until about 3% of their uranium has been fissioned, then they
will be moved to a
spent fuel pool
where the short lived isotopes generated by fission can decay away.
After about 5 years in a spent fuel pool the spent fuel is radioactively
and thermally cool enough to handle, and it can be moved to dry storage
casks or reprocessed.
Conventional fuel resources
Proportions of the isotopes uranium-238 (blue) and uranium-235 (red) found in natural uranium and in enriched uranium for different applications. Light water reactors use 3-5% enriched uranium, while CANDU reactors work with natural uranium.
Uranium is a fairly common
element in the Earth's crust: it is approximately as common as
tin or
germanium, and is about 40 times more common than silver.
Uranium is present in trace concentrations in most rocks, dirt, and
ocean water, but is generally economically extracted only where it is
present in high concentrations.
As of 2011 the world's known resources of uranium, economically
recoverable at the arbitrary price ceiling of 130 USD/kg, were enough to
last for between 70 and 100 years.
The OECD's red book of 2011 said that conventional uranium
resources had grown by 12.5% since 2008 due to increased exploration,
with this increase translating into greater than a century of uranium
available if the rate of use were to continue at the 2011 level. In 2007, the OECD estimated 670 years of economically recoverable uranium in total conventional resources and
phosphate ores assuming the then-current use rate.
Light water reactors make relatively inefficient use of nuclear fuel, mostly fissioning only the very rare uranium-235 isotope.
Nuclear reprocessing can make this waste reusable. Newer
Generation III reactors also achieve a more efficient use of the available resources than the
generation II reactors which make up the vast majority of reactors worldwide.
With a pure
fast reactor fuel cycle with a burn up of all the Uranium and
actinides (which presently make up the most hazardous substances in
nuclear waste),
there is an estimated 160,000 years worth of Uranium in total
conventional resources and phosphate ore at the price of 60–100 US$/kg.
Unconventional fuel resources
Unconventional uranium resources also exist.
Uranium is naturally present in seawater at a concentration of about 3
micrograms per liter, with 4.5 billion tons of uranium considered present in seawater at any time.
In 2012 it was estimated that this fuel source could be extracted at 10 times the current price of uranium.
In 2014, with the advances made in the efficiency of seawater
uranium extraction, it was suggested that it would be economically
competitive to produce fuel for light water reactors from seawater if
the process was implemented at large scale.
Uranium extracted on an industrial scale from seawater would constantly
be replenished by both river erosion of rocks and the natural process of
uranium
dissolved from the surface area of the ocean floor, both of which maintain the
solubility equilibria of seawater concentration at a stable level.
Some commentators have argued that this strengthens the case for
Nuclear power to be considered a renewable energy.
Breeding
As opposed to light water reactors which use uranium-235 (0.7% of all
natural uranium), fast breeder reactors use uranium-238 (99.3% of all
natural uranium). In 2006 it was estimated that with seawater
extraction, there was likely some five billion years' worth of
uranium-238 for use in these power plants.
Breeder technology has been used in several reactors, but the
high cost of reprocessing fuel safely, at 2006 technological levels,
requires uranium prices of more than US$200/kg before becoming justified
economically.
Breeder reactors are however being pursued as they have the potential to
burn up all of the actinides in the present inventory of nuclear waste
while also producing power and creating additional quantities of fuel
for more reactors via the breeding process.
As of 2017, there are two breeders producing commercial power,
BN-600 reactor and the
BN-800 reactor, both in Russia.
The BN-600, with a capacity of 600 MW, was built in 1980 in Beloyarsk and is planned to produce power until 2025.
The BN-800 is an updated version of the BN-600, and started operation in 2014. The
Phénix breeder reactor in France was powered down in 2009 after 36 years of operation.
Another alternative to fast breeders is thermal breeder reactors that use uranium-233 bred from
thorium as fission fuel in the
thorium fuel cycle.
Thorium is about 3.5 times more common than uranium in the Earth's crust, and has different geographic characteristics.
This would extend the total practical fissionable resource base by 450%.
India's three-stage nuclear power program features the use of a thorium fuel cycle in the third stage, as it has abundant thorium reserves but little uranium.
Nuclear waste
The lifecycle of fuel in the present US system
The most important waste stream from nuclear power plants is
spent nuclear fuel.
It is primarily composed of unconverted uranium as well as significant quantities of transuranic actinides (plutonium and
curium,
mostly).
In addition, about 3% of it is fission products from nuclear reactions.
The actinides (uranium, plutonium, and curium) are responsible for the
bulk of the long-term radioactivity, whereas the fission products are
responsible for the bulk of the short-term radioactivity.
High-level radioactive waste
Typical composition of UOx LWR fuel, before and after approximately 3 years of fission service in the once-thru fuel cycle. Thermal reactors, which presently constitute the majority of the world fleet, cannot burn up the reactor grade plutonium
that is generated efficiently, limiting the effective useful fuel life
to a few years at most. Reactors in Europe and Asia are permitted to
burn later refined MOX fuel, though the burnup is similarly not complete.
In
the years outside a reactor, the activity of spent UOx fuel, in
reference to the activity of natural uranium ore. Together with the
varied plutonium isotopes that are generated, the minor actinides constitute the primary hazard following the relatively rapid decay of the fission products after approximately 300 years.
During power production, high-level radioactive waste is generated
that requires treatment, management and disposal. The technical issues
in accomplishing this are considerable, due to the extremely long
periods some particularly mobile, albeit mildly
radioactive wastes, remain potentially hazardous to living organisms, namely the
long-lived fission products,
Technetium-99 (half-life 220,000 years) and
Iodine-129 (half-life 15.7 million years), which dominate the true-waste stream in radioactivity after the more intensely radioactive
short-lived fission products have decayed into stable elements, after approximately 300 years. To successfully isolate this waste from the
biosphere, some variation of a
synroc treatment and permanent storage is commonly suggested.
The most concerning isotopes found in spent fuel that does not undergo reprocessing, are the medium-lived
transuranic elements, which are led by
reactor grade plutonium (half-life 24,000 years).
While in the US, spent fuel in its entirety is legally classified as a
nuclear waste and is treated similarly, in other countries it is
considered a fuel.
Some proposed reactor designs, such as the American
Integral Fast Reactor and the
Molten salt reactor can more completely use or
burnup the spent
reactor grade plutonium fuel and other minor actinides, generated from light water reactors, as under the designed
fast fission
spectrum, these elements are more likely to fission and produce the
aforementioned fission products in their place. This offers a
potentially more attractive alternative to deep geological disposal.
Another possibility is the use of thorium. While still containing
similar fission products, used thorium fuel, owing to its starting
point below uranium on the periodic table, builds up much less
transuranic elements and therefore spent thorium fuel, is less concerning from a radiotoxic and security standpoint.
Low-level radioactive waste
The nuclear industry also produces a large volume of low-level
radioactive waste in the form of contaminated items like clothing, hand
tools, water purifier resins, and (upon decommissioning) the materials
of which the reactor itself is built. Low-level waste can be stored
on-site until radiation levels are low enough to be disposed as ordinary
waste, or it can be sent to a low-level waste disposal site.
Waste relative to other types
In countries with nuclear power, radioactive wastes account for less
than 1% of total industrial toxic wastes, much of which remains
hazardous for long periods. Overall, nuclear power produces far less waste material by volume than fossil-fuel based power plants.
Coal-burning plants are particularly noted for producing large amounts
of toxic and mildly radioactive ash due to concentrating naturally
occurring metals and mildly radioactive material from the coal. A 2008 report from
Oak Ridge National Laboratory
concluded that coal power actually results in more radioactivity being
released into the environment than nuclear power operation, and that the
population
effective dose equivalent, or dose to the public from radiation from coal plants is 100 times as much as from the operation of nuclear plants.
Although coal ash is much less radioactive than spent nuclear fuel on a
weight per weight basis, coal ash is produced in much higher quantities
per unit of energy generated, and this is released directly into the
environment as
fly ash, whereas nuclear plants use shielding to protect the environment from radioactive materials, for example, in
dry cask storage vessels.
Waste disposal
The
placement of waste containers, generated during US cold war activities,
underground at the WIPP facility. The facility is seen as a potential
demonstration, for later civilian generated spent fuel, or constituents
of it.
Disposal of nuclear waste is often said to be the among the most problematic aspects of the industry.
Presently, waste is mainly stored at individual reactor sites and there
are over 430 locations around the world where radioactive material
continues to accumulate.
Some experts suggest that centralized underground repositories which are
well-managed, guarded, and monitored, would be a vast improvement.
There is an "international consensus on the advisability of storing nuclear waste in
deep geological repositories", with the lack of movement of nuclear waste in the 2 billion year old
natural nuclear fission reactors in
Oklo,
Gabon being cited as "a source of essential information today."
Most waste packaging, small-scale experimental fuel recycling chemistry and radiopharmaceutical refinement is conducted within remote-handled Hot cells.
There are no commercial scale purpose built underground high-level waste repositories in operation. However, in Finland the
Onkalo spent nuclear fuel repository is under construction as of 2015. The
Waste Isolation Pilot Plant (WIPP) in
New Mexico
has been taking nuclear waste since 1999 from production reactors, but
as the name suggests is a research and development facility.
In 2014 a radiation leak caused by violations in the use of chemically
reactive packaging
brought renewed attention to the need for quality control management,
along with some initial calls for more R&D into the alternative
methods of disposal for radioactive waste and spent fuel.
In 2017, the facility was formally reopened after three years of
investigation and cleanup, with the resumption of new storage taking
place later that year.
Reprocessing
Separation of uranium and plutonium from spent nuclear fuel by the 1940s-1950s PUREX method.[207] While variations of this wet-chemical process are employed to separate reactor grade plutonium(RGPu) for later re-use as MOX fuel. The process is controversial as it can be used to produce chemically pure WGPu.
Today's
thermal reactors primarily run on the
once-through fuel cycle though they can reuse once-thru reactor-grade plutonium to a limited degree in the form of mixed-oxide or
MOX fuel.
This is a routine commercial practice in most countries outside the
United States, as it increases the sustainability of nuclear fission and
lowers the volume of high level nuclear waste.
Reprocessing can potentially recover up to 95% of the remaining uranium
and plutonium in spent nuclear fuel, putting it into new
mixed oxide fuel.
This produces a reduction in long term radioactivity within the
remaining waste, since this is largely short-lived fission products, and
reduces its volume by over 90%. Reprocessing of civilian fuel from
power reactors is currently done in Europe, Russia, Japan, and India.
The full potential of reprocessing had not been achieved as of 2013
because it requires breeder reactors, which were not commercially
available at that time.
Nuclear reprocessing reduces the volume of high-level waste, but does not reduce the
fission products
that are the primary residual heat generating and radioactive
substances, thus still requiring geological waste repository management.
Reprocessing has been politically controversial because of the
potential to contribute to
nuclear proliferation, vulnerability to
nuclear terrorism and because of its high cost compared to the once-through fuel cycle.
In the United States, spent nuclear fuel is currently all treated as waste. A major recommendation of the
Blue Ribbon Commission on America's Nuclear Future
was that "the United States should undertake...one or more permanent
deep geological facilities for the safe disposal of spent fuel and
high-level nuclear waste".
In France, the
La Hague reprocessing facility has operated commercially since 1976.
The plant is responsible for half the world's reprocessing as of 2010
treating spent nuclear fuel from France, Japan, Germany, Belgium,
Switzerland, Italy, Spain and the Netherlands, it produces new fuel,
with the non-recyclable part of the radioactive waste eventually sent
back to the user nation.
Up to 2015, more than 32,000 tonnes of spent nuclear fuel had been
reprocessed, with 70% of that from France, 17% from Germany and 9% from
Japan.
When initially opened La Hague received criticism from Greenpeace,
though more recently they have ceased attempting to criticize the fuel
reprocessing facility on technical grounds, having succeeded at
performing the process without serious incidents that have been frequent
at other such facilities around the world.
In the past, the antinuclear movement argued that reprocessing would not
be technically or economically feasible.
Nuclear decommissioning
The financial costs of every nuclear power plant continues for some
time after the facility has finished generating its last useful
electricity. Once no longer economically viable, nuclear reactors and
uranium enrichment facilities are generally decommissioned, returning
the facility and its parts to a safe enough level to be entrusted for
other uses, such as
greenfield status.
After a cooling-off period that may last decades, reactor core materials
are dismantled and cut into small pieces to be packed in containers for
interim storage or
transmutation experiments.
In the United States a
Nuclear Waste Policy Act
and Nuclear Decommissioning Trust Fund is legally required, with
utilities banking 0.1 to 0.2 cents/kWh during operations to fund future
decommissioning. They must report regularly to the
Nuclear Regulatory Commission
(NRC) on the status of their decommissioning funds. About 70% of the
total estimated cost of decommissioning all U.S. nuclear power reactors
has already been collected (on the basis of the average cost of $320
million per reactor-steam turbine unit).
In the United States in 2011, there are 13 reactors that had permanently shut down and are in some phase of decommissioning. With
Connecticut Yankee Nuclear Power Plant and
Yankee Rowe Nuclear Power Station
having completed the process in 2006–2007, after ceasing commercial
electricity production circa 1992.
The majority of the 15 years, was used to allow the station to naturally
cool-down on its own, which makes the manual disassembly process both
safer and cheaper.
Decommissioning at nuclear sites which have experienced a serious
accident are the most expensive and time-consuming.
Installed capacity and electricity production
Share of electricity produced by nuclear power in the world
The status of nuclear power globally (click image for legend)
Net electrical generation
by source and growth from 1980 to 2010. (Brown) – fossil fuels. (Red) –
Fission. (Green) – "all renewables". In terms of energy generated
between 1980 and 2010, the contribution from fission grew the fastest.
The
rate of new construction builds for civilian fission-electric reactors
essentially halted in the late 1980s, with the effects of accidents
having a chilling effect. Increased capacity factor
realizations in existing reactors was primarily responsible for the
continuing increase in electrical energy produced during this period.
The halting of new builds c. 1985, resulted in greater fossil fuel
generation, see above graph.
Electricity generation trends in the top five fission-energy producing countries (US EIA data)
Nuclear fission power stations, excluding the contribution from
naval nuclear fission reactors, provided 11% of the world's electricity in 2012, somewhat less than that generated by
hydro-electric stations
at 16%.
Since electricity accounts for about 25% of humanity's energy usage with
the majority of the rest coming from fossil fuel reliant sectors such
as transport, manufacture and home heating, nuclear fission's
contribution to the
global final energy consumption was about 2.5%.
This is a little more than the combined global electricity production from wind, solar,
biomass and geothermal power, which together provided 2% of global final energy consumption in 2014.
In addition, there were approximately 140 naval vessels using
nuclear propulsion in operation, powered by about 180 reactors.
Nuclear power's share of global electricity production has fallen
from 16.5% in 1997 to about 10% in 2017, in large part because the
economics of nuclear power have become more difficult.
Regional differences in the use of nuclear power are large.
The United States produces the most nuclear energy in the world, with
nuclear power providing 19% of the electricity it consumes, while France produces the highest percentage of its electrical energy from nuclear reactors—80% as of 2006.
In the
European Union as a whole nuclear power provides 30% of the electricity.
Nuclear power is the single largest low-carbon electricity source in the United States, and accounts for two-thirds of the
European Union's low-carbon electricity.
Nuclear energy policy differs among European Union countries, and some, such as Austria,
Estonia, Ireland and
Italy,
have no active nuclear power stations.
In comparison, France has a large number of nuclear reactors in use and
nuclear power supplied over 70% of its electricity in 2017.
Economics
The economics of new nuclear power plants is a controversial subject,
since there are diverging views on this topic, and multibillion-dollar
investments depend on the choice of an energy source.
Nuclear power plants typically have high capital costs for building the
plant, but low fuel costs.
Comparison with other power generation methods is strongly dependent on
assumptions about construction timescales and capital financing for
nuclear plants as well as the future costs of fossil fuels and
renewables as well as for energy storage solutions for intermittent
power sources.
On the other hand, measures to
mitigate global warming, such as a
carbon tax or
carbon emissions trading, may favor the economics of nuclear power.
Analysis of the economics of nuclear power must also take into account who bears the risks of future uncertainties.
To date all operating nuclear power plants were developed by
state-owned or
regulated electric utility monopolies
Many countries have now liberalized the
electricity market
where these risks, and the risk of cheaper competitors emerging before
capital costs are recovered, are borne by plant suppliers and operators
rather than consumers, which leads to a significantly different
evaluation of the economics of new nuclear power plants.
Nuclear power plants, though capable of some grid-
load following,
are typically run as much as possible to keep the cost of the generated
electrical energy as low as possible, supplying mostly base-load
electricity.
Internationally the price of nuclear plants rose 15% annually in 1970–1990.
With
PWR
stations, having total costs in 2012 of about $96 per megawatt hour
(MWh), most of which involves capital construction costs, compared with
solar power at $130 per MWh, and natural gas at the low end at $64 per
MWh.
The Fukushima Daiichi nuclear disaster, is expected to increase the costs of operating and new
LWR power stations, due to increased requirements for on-site spent fuel management and elevated design basis threats.
Accidents, attacks and safety
Nuclear reactors have three unique characteristics that affect their safety, as compared to other power plants.
Firstly, intensely
radioactive materials are present in a nuclear reactor. Their release to the environment could be hazardous.
Secondly, the
fission products, which make up most of the intensely radioactive substances in the reactor, continue to generate a significant amount of
decay heat even after the fission
chain reaction
has stopped. If the heat cannot be removed from the reactor, the fuel
rods may overheat and release radioactive materials.
Thirdly, a rapid increase of the reactor power is possible if the chain
reaction cannot be controlled in certain reactor designs.
These three characteristics have to be taken into account when designing
nuclear reactors.
Accidents
The
Chernobyl accident in 1986 caused approximately 50 deaths from direct and indirect effects, and some
temporary serious injuries.
The future predicted mortality from cancer increases, is usually estimated at some 4000 in the decades to come. With a higher number of the routinely treatable
Thyroid cancer, set to be the only type of
causal cancer, likely to be seen in future large studies.
According to Benjamin K. Sovacool, fission
energy accidents
ranked first among energy sources in terms of their total economic
cost, accounting for 41 percent of all property damage attributed to
energy accidents.
Another analysis presented in the international journal
Human and Ecological Risk Assessment found that coal, oil,
Liquid petroleum gas and hydroelectric accidents (primarily due to the
Banqiao dam burst) have resulted in greater economic impacts than nuclear power accidents.
Nuclear power works under an
insurance framework that limits or structures accident liabilities in accordance with the
Paris convention on nuclear third-party liability, the Brussels supplementary convention, the
Vienna convention on civil liability for nuclear damage and the
Price-Anderson Act
in the United States.
It is often argued that this potential shortfall in liability represents
an external cost not included in the cost of nuclear electricity; but
the cost is small, amounting to about 0.1% of the levelized cost of
electricity, according to a CBO study.
These beyond-regular-insurance costs for worst-case scenarios are not unique to nuclear power, as
hydroelectric power plants are similarly not fully insured against a catastrophic event such as the
Banqiao Dam disaster, where 11 million people lost their homes and from 30,000 to 200,000 people died, or large
dam failures
in general. As private insurers base dam insurance premiums on limited
scenarios, major disaster insurance in this sector is likewise provided
by the state.
Safety
In terms of lives lost per unit of energy generated, nuclear power
has caused fewer accidental deaths per unit of energy generated than all
other major sources of energy generation.
Energy produced by coal, petroleum, natural gas and
hydropower has caused more deaths per unit of energy generated due to air pollution and
energy accidents.
This is found when comparing the immediate deaths from other energy
sources to both the immediate nuclear related deaths from accidents and also including the latent, or predicted, indirect cancer deaths from nuclear
energy accidents.
When the combined immediate and indirect fatalities from nuclear power
and all fossil fuels are compared, including fatalities resulting from
the mining of the necessary natural resources to power generation and to
air pollution,
the use of nuclear power has been calculated to have prevented about
1.8 million deaths between 1971 and 2009, by reducing the proportion of
energy that would otherwise have been generated by fossil fuels, and is
projected to continue to do so.
Following the 2011 Fukushima nuclear disaster, it has been estimated
that if Japan had never adopted nuclear power, accidents and pollution
from coal or gas plants would have caused more lost years of life.
Forced evacuation from a nuclear accident may lead to social
isolation, anxiety, depression, psychosomatic medical problems, reckless
behavior, even suicide.
Such was the outcome of the 1986
Chernobyl nuclear disaster
in Ukraine.
A comprehensive 2005 study concluded that "the mental health impact of
Chernobyl is the largest public health problem unleashed by the accident
to date".
Frank N. von Hippel, an American scientist, commented on the 2011 Fukushima nuclear disaster, saying that a disproportionate
radiophobia,
or "fear of ionizing radiation could have long-term psychological
effects on a large portion of the population in the contaminated areas".
A 2015 report in
Lancet
explained that serious impacts of nuclear accidents were often not
directly attributable to radiation exposure, but rather social and
psychological effects.
Evacuation and long-term displacement of affected populations created
problems for many people, especially the elderly and hospital patients.
In January 2015, the number of Fukushima evacuees was around 119,000, compared with a peak of around 164,000 in June 2012.
Attacks and sabotage
Terrorists could target
nuclear power plants in an attempt to release
radioactive contamination
into the community. The United States 9/11 Commission has said that
nuclear power plants were potential targets originally considered for
the
September 11, 2001 attacks. An attack on a reactor's
spent fuel pool
could also be serious, as these pools are less protected than the
reactor core. The release of radioactivity could lead to thousands of
near-term deaths and greater numbers of long-term fatalities.
In the United States, the NRC carries out "Force on Force" (FOF)
exercises at all Nuclear Power Plant (NPP) sites at least once every
three years.
In the United States, plants are surrounded by a double row of tall fences which are electronically monitored.
The plant grounds are patrolled by a sizeable force of armed guards.
Insider sabotage is also a threat because insiders can observe and work around security measures.
Successful insider crimes depended on the perpetrators' observation and knowledge of security vulnerabilities.
A fire caused 5–10 million dollars worth of damage to New York's
Indian Point Energy Center in 1971.
The arsonist turned out to be a plant maintenance worker. Some reactors overseas have also reported varying levels of sabotage by workers.
Nuclear proliferation
United States and USSR/Russian nuclear weapons stockpiles, 1945–2006. The Megatons to Megawatts Program was the main driving force behind the sharp reduction in the quantity of nuclear weapons worldwide since the cold war ended. However, without an increase in nuclear reactors and greater demand for fissile fuel, the cost of dismantling has dissuaded Russia from continuing their disarmament.
Many technologies and materials associated with the creation of a
nuclear power program have a dual-use capability, in that they can be
used to make
nuclear weapons
if a country chooses to do so. When this happens a nuclear power
program can become a route leading to a nuclear weapon or a public annex
to a "secret" weapons program. The concern over
Iran's nuclear activities is a case in point.
A fundamental goal for global security is to minimize the nuclear
proliferation risks associated with the expansion of nuclear power.
The
Global Nuclear Energy Partnership is an international effort to create a distribution network in which developing countries in need of energy would receive
nuclear fuel
at a discounted rate, in exchange for that nation agreeing to forgo
their own indigenous develop of a uranium enrichment program.
The France-based
Eurodif/
European Gaseous Diffusion Uranium Enrichment Consortium is a program that successfully implemented this concept, with
Spain
and other countries without enrichment facilities buying a share of the
fuel produced at the French controlled enrichment facility, but without
a transfer of technology.
Iran was an early participant from 1974, and remains a shareholder of Eurodif via
Sofidif.
A 2009 United Nations report said that:
...the revival of interest in nuclear power could result in
the worldwide dissemination of uranium enrichment and spent fuel
reprocessing technologies, which present obvious risks of proliferation
as these technologies can produce fissile materials that are directly
usable in nuclear weapons.
On the other hand, power reactors can also reduce nuclear weapons
arsenals when military grade nuclear materials are reprocessed to be
used as fuel in nuclear power plants.
The
Megatons to Megawatts Program, the brainchild of Thomas Neff of
MIT, is the single most successful
non-proliferation program to date.
Up to 2005, the Megatons to Megawatts Program had processed $8 billion of high enriched, weapons grade uranium into
low enriched uranium suitable as nuclear fuel for commercial fission reactors by diluting it with
natural uranium.
This corresponds to the elimination of 10,000 nuclear weapons.
For approximately two decades, this material generated nearly 10 percent
of all the electricity consumed in the United States (about half of all
U.S. nuclear electricity generated) with a total of around 7 trillion
kilowatt-hours of electricity produced. Enough energy to energize the entire United States electric grid for about two years.
In total it is estimated to have cost $17 billion, a "bargain for US
ratepayers", with Russia profiting $12 billion from the deal. Much needed profit for the
Russian nuclear oversight industry, which after the collapse of the
Soviet economy, had difficulties paying for the maintenance and security of the Russian Federations highly enriched uranium and warheads.
The Megatons to Megawatts Program was hailed as a major success
by anti-nuclear weapon advocates as it has largely been the driving
force behind the sharp reduction in the quantity of nuclear weapons
worldwide since the cold war ended.
However without an increase in nuclear reactors and greater demand for
fissile fuel, the cost of dismantling and down blending has dissuaded
Russia from continuing their disarmament.
As of 2013 Russia appears to not be interested in extending the program.
Environmental impact
Carbon emissions
A 2008 meta analysis of 103 studies, published by Benjamin K. Sovacool, estimated that the mean value of CO2 emissions for nuclear power over the lifecycle of a plant was 66.08 g/kW·h, this 2008 study by Sovacool garnered controversy by comparing statistical mean with median values, to suggest various renewable energy sources were "two to seven times more effective at combating climate change", by presenting median values of "9–32 g/kW·h" for the latter. A similar 2012 meta-analysis by Yale University arrived at a different conclusion, with the median value, depending on which reactor design was analyzed, ranging from 11 to 25 g/kW·h of total life cycle nuclear power CO2e emissions, a figure comparable, and in some instances lower, than a number of renewable energy generation methods.
Radiation
The variation in a person's absorbed natural
background radiation, averages 2.4
mSv/
a globally but frequently varies between 1 mSv/a and 13 mSv/a depending in most part on the geology a person resides upon. According to the United Nations (
UNSCEAR), regular NPP/nuclear power plant operations including the nuclear fuel cycle, increases this amount to 0.0002
millisieverts (mSv) per year of public exposure as a global average.
The average dose from operating NPPs to the local populations around them is
less than 0.0001 mSv/a.The average dose to those living within 50 miles of a
coal power plant is over three times this dose, 0.0003 mSv/a.
As of a 2008 report, Chernobyl resulted in the most affected
surrounding populations and male recovery personnel receiving an average
initial 50 to 100 mSv over a few hours to weeks, while the remaining
global legacy of the worst nuclear power plant accident in average
exposure is 0.002 mSv/a and is continually dropping at the decaying
rate, from the initial high of 0.04 mSv per person averaged over the
entire populace of the Northern Hemisphere in the year of the accident
in 1986.
Comparison with renewable energy
While the majority of installed renewable energy across the world is currently in the form of
hydro power
and an approximate doubling of present world hydro capacity is
considered possible in developing nations, in western nations by
contrast, the economically feasible geography for new hydropower is
lacking, with every geographically suitable area largely exploited.
With the growing apparent
negative externalities
from the use of fossil fuels, a need for alternatives that could be
implemented on a large scale has resulted in an ongoing debate on the
relative benefits of nuclear power compared to conventional "new
renewable" energy sources for the generation of low-carbon electricity.
These "new renewable" proponents, suggest that with government supports
the expanding of Wind and Solar energy is feasible and could eliminate
the need for nuclear power.
Nuclear powered aircraft carriers, presently require as depicted, jet-fuel Replenishment at sea operations, by expensive Replenishment oilers. The Naval Research Laboratory team led by Heather Willauer
has developed a process that is designed to use the ample electrical
power onboard carriers, for alternative in-situ snythesis of jet-fuel,
from its chemical building blocks. Extracting the carbon dioxide (CO2) in seawater, in tandem with hydrogen (H2) and recombining the two into long chain hydrocarbon liquids. Writing in the Journal of Renewable Sustainable Energy, in 2012, Willauer estimated that the carbon neutral jet fuel for Navy and Marine aviation,
could be synthesized from seawater in quantities up to 100,000 US gal
(380,000 L) per day, at a cost of three to six U.S. dollars per gallon. The U.S. Navy is expected to deploy the technology some time in the 2020s.
Nuclear power proponents argue that conventional renewable energy
sources, wind and solar do not offer the scalability necessary for a
large scale decarbonization of the electric grid, mainly due to their
intermittency and note that wherever implementations of these "new
renewables" are attempted in industrialized nations, such as the "
energy transition" in Germany and Denmark, an invariable increase in the extraction, reliance and use of fossil fuels, occurs.
With a number of commentators questioning if the promotion of "new
renewables", is simply a way for the fossil fuel industry to ensure its
position in the world energy market, by the backdoor. These commentators point, in support of the assessment, to the expansion of the coal burning
Lippendorf Power Station in Germany and in 2015 the opening of a large, 1730 MW
coal burning power station in Moorburg, the only such coal burning facility of its kind to commence operations, in Western Europe in the 2010s. With Germany now committed to coal mining and burning until well into 2050, widely missing its 2020 emission reduction target.
While in Denmark, before being pressured to step down in 2018, former
chair of the Danish Council on Climate Change, was directly requested
not to publish criticisms of the Danish governments "unambitious"
decarbonizing policy, after it became apparent that the 2020 emission
reduction target, would similarly, not be met.
Several studies suggest that it might be theoretically possible
to cover a majority of world energy generation with new renewable
sources.
The
Intergovernmental Panel on Climate Change
(IPCC) has said that if governments were supportive, renewable energy
supply could account for close to 80% of the world's energy use by 2050
by subsidizing renewables with 1% of
global GDP, equating to $1
trillion annually.
Nuclear power by contrast is proposed as a tested and practical
way to implement a 100% low-carbon energy infrastructure, as opposed to
renewable sources.
Analysis in 2015 by professor and chair of Environmental Sustainability
Barry W. Brook
and his colleagues on the topic of replacing fossil fuels entirely,
from the electric grid of the world, has determined that at the
historically modest and proven-rate at which nuclear energy was added to
and replaced fossil fuels in France and Sweden during each nation's
building programs in the 1980s, nuclear energy could displace or remove
fossil fuels from the electric grid completely within 10 years,
"allow[ing] the world to meet the most stringent greenhouse-gas
mitigation targets.".
In a similar analysis, Brook had earlier determined that 50% of all
global energy, that is not solely electricity, but transportation
synthetic fuels
etc. could be generated within approximately 30 years, if the global
nuclear fission build rate was identical to each of these nation's
already proven installation rates in units of installed
nameplate capacity,
GW per year, per unit of global
GDP (GW/year/$).
This is in contrast to the conceptual studies for a
100% renewable energy world, which would require an orders of magnitude more costly global investment per year, which has no historical precedent,
along with far greater land that would have to be devoted to the wind,
wave and solar projects, and the inherent assumption that humanity will
use less, and not more, energy in the future.
As Brook notes, the "principal limitations on nuclear fission are not
technical, economic or fuel-related, but are instead linked to complex
issues of societal acceptance, fiscal and political inertia, and
inadequate critical evaluation of the real-world constraints facing [the
other] low-carbon alternatives."
According to a transatlantic collaborative research paper on
Energy return on energy Invested
(EROEI), conducted by six analysts led by German academic D. Weißbach,
and described as "...the most extensive overview so far based on a
careful evaluation of available
Life Cycle Assessments". Published in the
peer reviewed journal
Energy in 2013. The uncorrected for their
intermittency("unbuffered") EROEI for each energy source analyzed is as depicted in the attached table at right.
While the buffered (corrected for their intermittency) EROEI stated in
the paper, for all low-carbon power sources, with the exception of the
only two baseload energy supplying systems of biomass and nuclear, were
lowered considerably due to weather variations, a reduction of EROEI
proportional to how reliant the other systems are on the manufacture of
back-up energy sources, a reliance necessary in order to approximate the
steady electrical supply characteristics of a biomass or nuclear facility.
Nuclear power stations require
orders of magnitude less materials per unit of energy generated. An analysis by researchers at
Uppsala University
in 2016 returned the conclusion that due to the much greater dependence
on materials for renewable energy construction, while a theoretical
expansion of "new renewables" to supply a future 50% of global final
energy demand is often conceptualized, the physical expansion of the
crucial mining and raw material extraction rates, would be
un-sustainable.
A number of other studies similarly report that solar and wind
energy are presently not cost-effective compared to nuclear power.
The
Brookings Institution published
The Net Benefits of Low and No-Carbon Electricity Technologies
in 2014 which states, after performing an energy and emissions cost
analysis, that "The net benefits of new nuclear, hydro, and natural gas
combined cycle plants far outweigh the net benefits of new wind or solar
plants", with the most cost effective low carbon power technology being
determined to be nuclear power.
Several studies suggest that wind and solar power have costs that
are comparable or lower than nuclear power, when considering price per
kWh.
The cost of constructing established nuclear power reactor designs has
followed an increasing trend due to frequently changing
regulations, public protests and delaying
court cases whereas the
levelized cost of electricity (LCOE) is declining for wind and solar power.
In 2010 a report from Solar researchers at Duke University suggested
that solar power may be already cheaper than new nuclear power plants.
However they state that if government aid/financial subsidies were
removed for solar power, the crossover point would be delayed by years.
Data from the U.S.
Energy Information Administration
(EIA) in 2011 estimated that in 2016, solar will have a levelized cost
of electricity almost twice as expensive as nuclear (21¢/kWh for solar,
11.39¢/kWh for nuclear), and wind somewhat less expensive than nuclear
(9.7¢/kWh).
However, the EIA has also cautioned that levelized costs of intermittent
sources such as wind and solar are not directly comparable to costs of
"dispatchable" sources (those that can be adjusted to meet demand), as
intermittent sources need costly large-scale back-up power supplies for
when the weather changes.
A 2010 study by the Global Subsidies Initiative compared global relative
energy subsidies,
or government financial aid for the deployment of different energy
sources.
Results show that fossil fuels receive about 1 U.S. cents per kWh of
energy they produce, nuclear energy receives 1.7 cents / kWh, renewable
energy (excluding hydroelectricity) receives 5.0 cents / kWh and
biofuels receive 5.1 cents / kWh in subsidies.
Nuclear power is comparable to, and in some cases lower, than
many renewable energy sources in terms of lives lost per unit of
electricity delivered.
However, as opposed to renewable energy, conventional designs for
nuclear reactors produce a smaller volume of manufacture and operations
related waste, most notably, the intensely radioactive spent fuel that
needs to be stored or reprocessed.
A nuclear plant also needs to be disassembled and removed and much of
the disassembled nuclear plant needs to be stored as low level nuclear
waste for a few decades.
In an EU wide 2018 assessment of progress in reducing
greenhouse gas emissions per capita,
France and Sweden were the only two large industrialized nations within
the EU to receive a positive rating, every other country received a
"poor" to "very poor" grade.
Debate on nuclear power
The nuclear power debate concerns the controversy
which has surrounded the deployment and use of nuclear fission reactors
to generate electricity from nuclear fuel for civilian purposes. The
debate about nuclear power peaked during the 1970s and 1980s, when it
"reached an intensity unprecedented in the history of technology
controversies", in some countries.
Proponents of nuclear energy contend that nuclear power is a
sustainable energy source that reduces
carbon emissions and increases
energy security by decreasing dependence on imported energy sources.
Proponents claim that nuclear power produces virtually no conventional
air pollution, such as greenhouse gases and smog, in contrast to the
main alternative of
fossil-fuel power stations. Nuclear power can produce
base-load power unlike many renewables which are
intermittent energy sources lacking large-scale and cheap ways of storing energy.
M. King Hubbert saw oil as a resource that would
run out, and proposed nuclear energy as a replacement energy source.
Proponents claim that the risks of storing waste are small and can be
further reduced by using the latest technology in newer reactors, and
the operational safety record in the Western world is excellent when
compared to the other major kinds of power plants.
Opponents believe that nuclear power poses many threats to people and the environment.
These threats include the problems of processing, transport and storage
of radioactive nuclear waste, the risk of nuclear weapons proliferation
and terrorism, as well as health risks and environmental damage from
uranium mining.
They also contend that reactors themselves are enormously complex
machines where many things can and do go wrong; and there have been
serious
nuclear accidents.
Critics do not believe that the risks of using nuclear fission as a
power source can be fully offset through the development of new
technology. In years past, they also argued that when all the
energy-intensive stages of the
nuclear fuel chain are considered, from uranium mining to
nuclear decommissioning, nuclear power is neither a low-carbon nor an economical electricity source.
Use in space
Both
fission and fusion appear promising for
space propulsion applications, generating higher mission velocities with less
reaction mass.
This is due to the much higher energy density of nuclear reactions:
some 7 orders of magnitude (10,000,000 times) more energetic than the
chemical reactions which power the current generation of rockets.
Research
Advanced fission reactor designs
Current fission reactors in operation around the world are
second or
third generation systems, with most of the first-generation systems having been already retired.
Research into advanced
generation IV reactor
types was officially started by the Generation IV International Forum
(GIF) based on eight technology goals, including to improve nuclear
safety, improve proliferation resistance, minimize waste, improve
natural resource utilization, the ability to consume existing nuclear
waste in the production of electricity, and decrease the cost to build
and run such plants.
Most of these reactors differ significantly from current operating light
water reactors, and are generally not expected to be available for
commercial construction before 2030.
One disadvantage of any new reactor technology is that safety
risks may be greater initially as reactor operators have little
experience with the new design.
Nuclear engineer
David Lochbaum
has explained that almost all serious nuclear accidents have occurred
with what was at the time the most recent technology.
He argues that "the problem with new reactors and accidents is twofold:
scenarios arise that are impossible to plan for in simulations; and
humans make mistakes".
As one director of a U.S. research laboratory put it, "fabrication,
construction, operation, and maintenance of new reactors will face a
steep learning curve: advanced technologies will have a heightened risk
of accidents and mistakes. The technology may be proven, but people are
not".
Hybrid nuclear fusion-fission
Hybrid nuclear power is a proposed means of generating power by use
of a combination of nuclear fusion and fission processes. The concept
dates to the 1950s, and was briefly advocated by
Hans Bethe
during the 1970s, but largely remained unexplored until a revival of
interest in 2009, due to delays in the realization of pure fusion. When a
sustained nuclear fusion power plant is built, it has the potential to
be capable of extracting all the fission energy that remains in spent
fission fuel, reducing the volume of nuclear waste by orders of
magnitude, and more importantly, eliminating all actinides present in
the spent fuel, substances which cause security concerns.
Nuclear fusion
Schematic of the ITER tokamak under construction in France.
Nuclear fusion reactions have the potential to be safer and generate less radioactive waste than fission.
These reactions appear potentially viable, though technically quite
difficult and have yet to be created on a scale that could be used in a
functional power plant.
Fusion power has been under theoretical and experimental investigation
since the 1950s.
Several experimental nuclear fusion reactors and facilities exist.
The largest and most ambitious international nuclear fusion project currently in progress is
ITER, a large
tokamak
under construction in France.
ITER is planned to pave the way for commercial fusion power by
demonstrating self-sustained nuclear fusion reactions with positive
energy gain.
Construction of the ITER facility began in 2007, but the project has run
into many delays and budget overruns.
The facility is now not expected to begin operations until the year 2027
– 11 years after initially anticipated. A follow on commercial nuclear fusion power station,
DEMO, has been proposed. There are also suggestions for a power plant based upon a different fusion approach, that of an
inertial fusion power plant.
Fusion powered electricity generation was initially believed to
be readily achievable, as fission-electric power had been. However, the
extreme requirements for continuous reactions and
plasma containment
led to projections being extended by several decades. In 2010, more
than 60 years after the first attempts, commercial power production was
still believed to be unlikely before 2050.
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