Thorium
instead of Uranium?
It may well turn out that thorium
is a better nuclear fuel than uranium, since it offers the advantages that: (1)
it has around four times the abundance of uranium on Earth, overall; (2)
practically 100% of it can be bred into the fissile nuclear fuel 233U;
(3) smaller amounts of plutonium and other transuranic elements are produced
than is the case from uranium fuel; (4) the thorium fuel cycle might be used to
consume plutonium, thus reducing the nuclear stockpile, while converting it
into useful energy. There was a conference held in Chicago, in May 2013, on “5th Thorium Energy Alliance – Future of
Thorium, Energy and Rare Earths.” http://www.thoriumenergyalliance.com/
Thorium1 is a
naturally occurring radioactive element, with the chemical symbol Th
and an atomic number of 90. The mineral, now known as thorite, was
discovered in 1828 by the Norwegian priest and mineralogist, Morten Thrane
Esmark. In that same year, the element, thorium, was identified in the material
by the Swedish chemist, Jöns Jakob Berzelius, who named it after Thor, the
Norse god of thunder. Thorium is found in soils at an average concentration of
6 parts per million (p.p.m.), and in most rocks. In higher concentrations,
thorium occurs in several kinds of mineral, of which the most common is the
rare earth phosphate mineral, monazite, which contains up to about 12% thorium
phosphate, but 6-7% as an average. World monazite resources are estimated to be
of the order of 12 million tonnes, two-thirds of which are in heavy mineral
sands deposits on the south coast and east coast of India. The world total of
economically extractable thorium is estimated at around 2.61 million tonnes
(Table 1)2, and Australia and the United States top the list with
489,000 and 400,000 tonnes of it, respectively. Norway has 132,000 tonnes of
thorium, which adds to the large energy reserves of this country in terms of
gas, oil and coal, not to mention hydropower, from which 99% of its electricity
is generated. Other than negligible amounts of a few highly radioactive
isotopes, thorium occurs exclusively as 232Th. Although 232Th
is not fissile in itself, it can be converted to a fissile fuel in the form of 233U,
via the absorption of slow neutrons. Hence, as is the case for 238U,
232Th is "fertile" and may be bred into a nuclear fuel,
which in the former case is 239Pu. Kirk Sorensen, a major proponent
for the development of thorium power http://energyfromthorium.com/, in
particular in conjunction with the Liquid fluoride reactor, LFR (also called
the molten salt reactor, MSR) has offered the following3, in regard
to the essential differences between the two elements 232Th and 239Pu,
as pertaining to their use in nuclear weapons or “dirty bombs”:
“There are several reasons why
U-233 is unattractive for nuclear weapons. One is that it doesn't produce as
many neutrons in fast fission as Pu-239. Another is that its properties in very
fast fission (such as a nuclear detonation) are poorly understood.
But the biggest deterrent is that U-233 is inevitably contaminated with U-232
during its formation. It is highly impractical to separate them. And U-232 has
a short half-life (~80 years) and a decay chain that includes the strong gamma
emitter Tl-208. A few months after the U-233 is isolated from parent materials,
the decay chain of U-232 begins to set up and the strong 2.3 MeV gammas of
Tl-208 would irradiate the weapon, its electronics, as well as providing an
easily-detected alert to the world that U-233 was present in a location.
In contrast, the alpha decay of U-235 and Pu-239 are rather easily shielded,
making clandestine transport of these weapons much easier, and well as allowing
long-term storage with relatively little damage to the electronics of the
device. With all these drawbacks, it is not surprising that U-233 has not been
utilized in operational nuclear weapons. This inherent physical resistance to
proliferation is a powerful argument for the adoption of thorium as a basic
nuclear energy source.”
Table 1.
World sources of thorium (2007)2.
Country
|
Tons
|
% of total
|
Australia
|
489,000
|
19
|
USA
|
400,000
|
15
|
Turkey
|
344,000
|
13
|
India
|
319,000
|
12
|
Venezuela
|
300,000
|
12
|
Brazil
|
302,000
|
12
|
Norway
|
132,000
|
5
|
Egypt
|
100,000
|
4
|
Russia
|
75,000
|
3
|
Greenland
|
54,000
|
2
|
Canada
|
44,000
|
2
|
South Africa
|
18,000
|
1
|
Other countries
|
33,000
|
1
|
World total
|
2,610,000
|
|
Since 100% of naturally occurring
thorium can be converted into nuclear fuel (233U), compared with the
mere 0.7% of natural uranium that is fissile, i.e. 235U, which is
enriched by centrifugation or gaseous diffusion of uranium hexafluoride (UF6),
there is an obvious advantage4. Fuel for fuel, the advantage factor
is around 30, in favour of thorium - since that from uranium is enriched to
around 3% in 235U - but this is counterbalanced by a depletion of
this isotope in the remaining material, which is generally referred to as
“depleted uranium” and sometimes used in armaments and missiles. Roughly 1/3 of
the power from a U-fuelled fission reactor is due to the fissioning of 239Pu,
generated in situ from 238U,
and so we can ascribe an overall advantage factor of ca 100 for thorium over
uranium, though a value of 250 is claimed, when enrichment “losses” for 235U/238U
and higher efficiencies for thorium reactors are included http://energyfromthorium.com/.
It might be argued that the rest (234U has an abundance of only
about 0.0055%) of the 100% of the uranium (238U) can be converted to
plutonium in a similarly effective manner, but this requires fast neutrons in a
fast breeder reactor: a technology with certain disadvantages, including the
need to handle plutonium – a very toxic material, although there are as yet no
reported casualties from it - and fears over its proliferation. Often cited
too, is the potential fire hazard of pyrophoric liquid sodium, which is often
used as a coolant, although helium, lead or a lead-bismuth alloy have all been proposed
as alternatives. Thus, if the latter method is to be avoided, considerably more
energy might be extracted from thorium than from an equivalent quantity of
uranium. Even on the basis of the "known" 2.61 million tonne reserve
of thorium (Table 1), a simple sum indicates that it could provide nuclear
power for: [2.61 million (tonnes of thorium)/4.02 million (tonnes of uranium)]
x 100 (enhancement factor in favour of Th over U) x 62 years (i.e. the current
estimate based on uranium5) = ca
4,000 years. Even if we made all our electricity from thorium (currently, 13.5%
of world electricity is from nuclear power), there would still be around 500
years worth, and so if governments are intent on nuclear expansion to obviate
global warming, thorium may well prove advantageous.
Ralph W. Moir and Edward Teller (dubbed6
as the “father of the ‘H’ bomb” and the real “Dr Strangelove”), made a study of
thorium-based nuclear power from which they concluded that research should be
reinitiated after being abandoned for more than three decades7.
There is a comprehensive review published by the International Atomic Energy
Agency (IAEA) on the subject of thorium-based nuclear power8.
The
Thorium Age Waits in the Wings.
There are different ways in which energy might be extracted from
thorium, one of which is the accelerator-driven system (ADS)9. Such
accelerators need massive amounts of electricity to run them, as all particle
accelerators do. As noted below, an alternative means to use thorium as a fuel
is in a liquid fluoride reactor (LFR), also termed a molten salt reactor, which
avoids the use of solid oxide nuclear fuels. Indeed, China has made the
decision to develop an LFR-based thorium-power programme, to be active by 2020.
However, the matter of thorium reactors is not straightforward. Neutrons may be
produced from heavy elements by spallation, using high-current, high-energy
accelerators or cyclotrons. In this process, a beam of high-energy protons (> 500 MeV) is directed at a high-atomic number target (e.g.
tungsten, tantalum, depleted uranium, thorium, zirconium, lead, lead-bismuth,
mercury) by which means up to one neutron can be produced per 25 MeV of the
proton beam energy. A 1000 MeV beam will create 20-30 spallation neutrons per
proton, to be compared with 200-210 MeV released in the fission of one nucleus
of 235U or 239Pu. If the spallation target
is surrounded by a blanket assembly of nuclear fuel, containing e.g. 235U
or 239Pu (or 232Th which can breed to 233U), a
fission reaction may be sustained, which is an ADS. Here, the
spallation-neutrons cause fission in the fuel, and the process is assisted by
further fission-neutrons. Since an ADS burns fuel which lacks a sufficiently
large fission-to-capture ratio for neutrons to maintain a fission chain
reaction, the whole assembly may be instantly turned-off, merely by
shutting-off the proton beam, in contrast to inserting control rods to absorb
neutrons and make the fuel assembly subcritical, as is necessary in
conventional fission-reactors. The latter is often stressed as a key safety
feature of an ADS, and while it is true that fission could be stopped almost
instantly in an emergency, the substantially greater threat from decay heat
would remain, as at Fukushima.
Thorium
utilisation
To breed 232Th to 233U,
a driver fuel is needed – either plutonium or enriched uranium – otherwise
there are insufficient neutrons generated to keep the process going. As is the
case for uranium, in order to use all of the thorium as a fuel, fast neutron
reactors are required in the system. The concept9 of using an ADS,
based on the 232Th—233U fuel cycle, is due to Professor
Carlo Rubbia, in which the core would be mostly thorium, and located near the
bottom of a tank 25 metres high, and containing around 8,000 tonnes of molten
lead or lead-bismuth at a high temperature – this is the “primary
coolant”, which circulates by convection around the core. A beam of high-energy
protons from the accelerator, would be focussed along a beam-pipe to the
spallation target, inside the core, where the spallation-neutrons enter the
fuel and transmute the thorium into protactinium, the decay of which forms the
fissile 233U. The neutrons also induce fission in uranium, plutonium
and possibly any transuranic elements that are present, with an according
release of energy. Thus, a 10 MW proton beam might produce 1500 MW of heat.
This would accord with a generation of 600 MWe of electricity – allowing for
the usual Carnot Cycle energy losses - some 30 MWe of which would be needed to
drive the accelerator. However, existing accelerator technology can only
produce a proton beam with an energy of 1 MW. A reactor of this kind is
sometimes referred to as an energy amplifier. There is a U.K.-Swiss design for
an accelerator-driven thorium reactor (ADTR) which has advanced to the stage of
a feasibility study, and involves a 600 MWe lead-cooled fast reactor. The
proposal is for a ten-year self-sustained thorium fuel cycle, using plutonium
as a fission starter, with both the spallation target and the coolant being
provided by molten lead. For actual power production, the accelerators would
need to be increased in power by an order of magnitude, and massively in terms
of reliability (so, I am told). In 2008, a study was made in Norway which compared
the advantages and disadvantages of an ADS fuelled by thorium - relative to a
conventional nuclear power reactor - from which it was concluded that such a
system would be unlikely to be operating in the next 30 years9.
I note, however, that experiments are being undertaken in Norway to evaluate
the properties of a mixed thorium-uranium solid fuel http://www.world-nuclear-news.org/ENF_Thorium_test_begins_2106131.html.
An alternative technology to the
ADS, is the "Liquid Fluoride Reactor" (LFR), which is described and
discussed in considerable detail at http://energyfromthorium.com/, and reading
this site has convinced me that the LFR may provide the best means to achieve
our future nuclear energy programme. Thorium exists naturally as 232Th,
which is not of itself a viable nuclear fuel. However, by absorption of
relatively low energy "slow" neutrons, it is converted to protactinium10 (233Pa). The latter either decays further
to 233U or captures another neutron, which converts it to the
non-fissile 234U. 233Pa has a relatively long half-life
of 27 days and a high cross section for neutron capture (the so-called
"neutron poison"), hence, instead of undergoing a simple and fast
decay to 233U, a significant fraction of the 233Pa
consumes neutrons which convert it to non-fissile isotopes, so attenuating the
reactor efficiency. To avoid this, the 233Pa must be extracted from
the active zone of the thorium LFR, so that it may be allowed mainly to decay
to 233U. In one scenario, this may be achieved by using columns of molten
bismuth, with lithium dissolved in it, that are several metres high. The
function of the lithium is to selectively reduce protactinium salts to metallic
protactinium, which is then extracted from the molten-salt cycle, the bismuth
acting mainly as a carrier (solvent). Bismuth has a low melting point (271 °C),
a low vapour pressure, lithium and actinides are quite soluble in it, and it is
immiscible with molten halides10. The "breeding" cycle can
be initiated using plutonium, say, to provide the initial supply of neutrons,
and indeed the LFR could provide an efficient way of disposing of weapons-grade
plutonium and heavily-enriched uranium from the world's stockpiles, producing
useful energy in the process.
The LFR makes in-situ
reprocessing possible, and much more easily than is the case for solid-fuel
based reactors. To date, there have been two working LFR's built11,
and if implemented, the technology would avoid using uranium-plutonium fast
breeder reactors, which need high energy "fast" neutrons to convert 238U,
which is not fissile, to 239Pu which is. The design of the LFR is
inherently safer and does not require liquid sodium as a coolant, while it also
avoids the risk of plutonium getting into the hands of terrorists. I maintain
my reservations about how long other resources, e.g. oil and gas will last,
with which to mine and process either uranium or thorium, but if the latter
appears viable in the longer run, I suggest that molten salt (liquid fluoride)
reactors might provide a more viable approach than the far more complex (and as
yet untested) accelerator-driven systems.
More thorium would doubtless be
found if it were looked for hard enough, and so the basic raw material is not
at issue. Being more abundant in most deposits than uranium, its extraction
would place less pressure on other fossil fuel resources used for mining and
extracting it. Indeed, thorium-generated electricity could be piped-in for that
purpose. Despite these apparently impressive advantages, the new build of
infrastructure would be massive, to switch over entirely to thorium, as it
would be to convert to any other new technology, on the grand scale, including
hydrogen and biofuels, with attendant costs of materials, energy, labour and
other resources. Indeed, this provides the mass of resistance that is to be
expected over the implementation of all kinds of new technology. My belief is
that, once the “liquid fuels crisis” occurs, which will be the major, and most
immediate, consequence of a decline in world conventional crude oil production,
“peak oil”, we may be able to produce liquid fuels from coal, possibly using
electricity produced from thorium. The problem of nuclear waste is expected to
be lessened through the use of thorium, since fewer actinides result from its fuel
cycle compared with that from uranium. It is not clear how the development of
thorium energy in Europe will be funded, if at all, since much of the Euratom
budget is being spent on the ITER nuclear fusion project, and the remainder on
uranium-based fission programmes12.
Oak Ridge
National Laboratory (ORNL) molten salt breeder reactor.
232Th, 235U and 238U
are radionuclides that predate the formation of the Earth some 4.5 billion
years ago, and were created in the cores of dying stars through the r-process
being dispersed galactically by supernovas. Around half13 the
internal heat of the Earth is produced from the decay of these radioactive
elements, along with 40K, and it is this effect, unknown at the time
of Lord Kelvin, that led him to conclude this planet to be much younger than it
actually is, at between 20 million and 400 million years, rather than the
currently accepted value of 4.54 (±
0.05) billion years14. As a
result of both historical and technical factors, each of the above type of
nuclide tends to be associated with different kinds of reactor: across the
world, the principal nuclear fuel is 235U, as it has been since the
dawn of the nuclear age, and this is usually used in light water reactors; 238U/239Pu
has been used mainly in, liquid sodium cooled, fast breeder reactors and CANDU
Reactors; 232Th/233U is thought best suited to fuel
molten salt reactors (MSR)11.
The MSR
at Oak Ridge National Laboratory was pioneered by Alvin M. Weinberg, where two
prototype molten salt reactors were successfully designed, constructed and
operated. These were the Aircraft Reactor Experiment in 1954 and Molten-Salt
Reactor Experiment which ran between 1965 and 1969, and in both cases, liquid
fluoride fuel salts were used. Fuelling with 233U and 235U
was demonstrated during separate test runs. A proposed molten salt breeder
reactor (MSBR) was designed at ORNL, during the period 1970-1976, with LiF-BeF2-ThF4-UF4
(in the relative proportion: 72:16:12:0.4) as its fuel, and with a graphite
moderator, to be replaced every four years, with NaF-NaBF4 as the
secondary coolant, and a peak operating temperature of
705 °C. However, the MSR program was closed in the early 1970s, in favour of
the liquid metal fast-breeder reactor (LMFBR). Research into MSRs then lapsed
in the United States, and as of 2011, the ARE and the MSRE remained the only
molten-salt reactors ever operated. The MSBR project received funding until
1976, equivalent to $38.9 million from 1968 to 1976 (compensated for inflation
to the monetary $ value in 1991)11.
Rare Earth Elements and
Thorium Power.
Thorium is present in the
ores of rare earth elements, and indeed, there is more thorium available from
this source than the world demand for it15. As a consequence of its radioactive nature of thorium, a hazard is posed
from its content in waste produced by the processing of rare earth oxides.
However, as we have noted, thorium could be bred into a nuclear fuel and most
simply used in a liquid fluoride reactor (LFR), rather than burying it
underground in concrete. 97% of world market
supplies of rare earth elements (REEs) come from China and look to become
insecure in regard to meeting "green" energy targets, since supplies
of REEs are scheduled to be retained for Chinese home energy projects. REEs are
essential raw materials for the fabrication of high-performance magnets in
hybrid cars and wind-turbines. The REE distribution in monazite sands is around
45 - 48 % cerium, 24% lanthanum, 17% neodymium, 5% praseodymium, along with
minor quantities of samarium, gadolinium and yttrium. Europium concentrations
tend to be low, in the region of 0.05%, and very low concentrations of the
heaviest lanthanides in monazite accord with the term "rare" earth
for these elements, with correspondingly high prices. The thorium content16
of monazite is variable and can be as high as 20 - 30 %, although commercial
monazite sands typically contain 6 - 12% thorium oxide.
In January, 2013, a controversial REE
processing plant was commissioned by the Australian based mining company Lynas
in Malaysia17, where it is argued that environmental protection laws
are less rigorous than in Australia. The plant is predicted to produce one
third of global demand for REEs, hence breaking the Chinese monopoly.
Thorium-based
power: positive and negative features.
Positive
aspects4.
Although precise knowledge of the
true amount of reserves, globally, is limited, thorium is estimated to be about
3-4 times more abundant than uranium in the Earth's crust. Very likely, further
sources of the material would be found, if they were sought with sufficient
assiduousness, noting that the EROEI would fall with the decreasing grade
(thorium content) of particular ores. Current demand for thorium (mostly not
for power generation) has been satisfied as a by-product of rare-earth
extraction from monazite sands, but demand for the metal is relatively low in
comparison with that for REEs, so that the thorium ends-up as radioactive waste
from processing this mineral. Since thorium consists of a single isotope (232Th),
it can be employed in thermal reactors without requiring isotope separation,
unlike natural uranium, from which the fissile 235U must be
separated and enriched for use as a nuclear fuel in fission-reactors.
Relative
to uranium-based fuels, thorium offers a number of appealing features: the
thermal neutron absorption cross section (σa) is about three times,
and the resonance integral (average of neutron cross sections over intermediate
neutron energies) about one third for 232Th of the respective values
for 238U, meaning that the conversion of thorium is more efficient
in a thermal reactor. Although the thermal neutron fission cross section (σf)
of the resulting 233U is comparable to 235U and 239Pu,
it has a much lower capture cross section (σγ) than the latter two
fissile isotopes, providing fewer non-fissile neutron absorptions and a better
neutron economy. Finally, the ratio of neutrons released per neutron absorbed
(η) in 233U is > 2, and over a wide range of energies, which
covers the thermal spectrum, meaning that thorium-based fuels might be used in
a thermal breeder reactor.
Because
the 233U produced in thorium fuels is always contaminated with 232U,
thorium-based nuclear fuel has an inherent proliferation resistance. 232U
cannot be separated from 233U by chemical means, and it has several
decay products which emit high energy gamma radiation, alerting to the presence
of such materials, e.g. “a bomb in a suitcase”. 233U can be
denatured by mixing it with natural or depleted uranium, meaning that before it
could be used in nuclear weapons, isotopic separation would be necessary.
On a
timescale, roughly of 103 to 106 years, the
radiological hazard of conventional uranium-based used nuclear fuel is
dominated by plutonium and other minor actinides, but once these have decayed,
long-lived fission products once more make a significant contribution. A single
neutron capture in 238U is sufficient to produce transuranic
elements, whereas six such captures are generally necessary to so convert 232Th.
98–99% of the nuclei in the thorium-cycle fuel would fission either at the 233U
or 235U stage, thus resulting in fewer long-lived transuranics. As a
result, in mixed oxide (MOX) fuels, thorium offers an advantage over uranium,
in minimising the generation of transuranics while maximising the destruction
of plutonium.
The
advantages of thorium in nuclear waste management, while noting that it
produces far less in the way of transuranics, are mitigated by the production
of 231Pa. also an α-emitting actinide, with a half-life of 3.3 x 104
years, along with the full range of fission products. It is the presence of the
latter, more than their amounts, this is the problem. Indeed, the chemical
intractability of thorium oxide makes it a good waste form in its own right,
although it does almost preclude volume reduction by separating the few percent
of genuine waste from unused material. That said, direct disposal eliminates
the plant and secondary waste production incurred in such separation, which
naturally is equally available for uranium.
Negative aspects4.
The
application of thorium as a nuclear fuel poses a number of problems,
particularly for solid fuel reactors. Since natural thorium contains no fissile
isotopes, it is necessary to add fissile material 233U, 235U,
or plutonium, in order to attain criticality. Along with the high sintering
temperature necessary to make thorium-dioxide fuel, this is a complicating
factor in fuel fabrication. ORNL experimented11 with thorium
tetrafluoride as a fuel component, in their run of a molten salt reactor from
1964–1969, which was far easier both to process and to separate from
contaminants, which slow-down or actually halt the chain reaction.
In an
open fuel cycle (using 233U in
situ), a higher burn-up is necessary to achieve a favourable neutron
economy. Although thorium dioxide performed well at burn-ups of 170,000 MWd/t
and 150,000 MWd/t at Fort St. Vrain Generating Station
http://en.wikipedia.org/wiki/Fort_St._Vrain_Generating_Station and AVR
http://en.wikipedia.org/wiki/AVR_reactor respectively, achieving this in
light water reactors (LWR), which are the vast majority of existing power
reactors, worldwide, is a challenge. In a once-through thorium fuel cycle, the
residual 233U constitutes long-lived radioactive waste.
The main
objection on the part of the nuclear industry to thorium is its radiotoxicity,
greater by an order of magnitude than that of uranium, in consequence of the
presence of 232U and decay products, therefrom. Thus, a completely
new infrastructure would be required, involving more stringent dust control.
The
thorium fuel cycle requires a relatively long interval to breed 232Th
to 233U. The half-life of 233Pa is about 27 days, which
is an order of magnitude longer than the half-life of 239Np, as
occurs in breeding from 238U to 239Pu. As a result,
substantial quantities of 233Pa, which is an effective absorber of
neutrons, build up in thorium-based fuels. Thus, instead of undergoing a simple
and fast decay to 233U, a significant fraction of 233Pa
consumes neutrons which convert it to non-fissile isotopes, e.g. 234Pa,
and this attenuates the reactor efficiency. Therefore, the 233Pa
must be extracted from the active zone of the thorium LFR, so that it may be
allowed mainly to decay to 233U. Eventually, the 233Pa
would breed into fissile 235U, but this process requires overall two
more neutron absorptions, and hence occurs at the further expense of the
neutron economy. The likelihood of transuranic production is also increased.
Although
the presence of 232U would inhibit its use in a nuclear weapon, 233U
was once so employed, as part of a bomb core in the MET blast during “Operation
Teapot” in 1955, though the energy yield was appreciably less than had been anticipated.
Current
thorium projects18.
Research and development of
thorium-based nuclear reactors, primarily the Liquid fluoride thorium reactor
(LFTR), MSR design, has been or is currently ongoing18 in the U.S.,
U.K., Germany, Brazil, India, China, France, the Czech Republic, Japan, Russia,
Canada, Israel and the Netherlands.
- China. Using components produced
by the West and Russia, it was reported early in 2012 that China planned
to build two prototype thorium molten salt reactors by 2015. A budget for
the project was established at $400 million, which will require 400
workers. China has also finalized an agreement with a Canadian nuclear
technology company to develop improved CANDU reactors using thorium and
uranium as a fuel.
- India. This is the "only
country in the world with a detailed, funded, government-approved
plan" to focus on thorium-based nuclear power. In late June, 2012,
India announced that their "first commercial fast reactor" was
near completion and would rely on thorium for its fuel. The nation plans
to develop up to 62, mostly thorium-based reactors, intended to be fully
operational by 2025.
- Norway. In Norway, the
privately-owned company, Thor Energy, announced in late 2012, that in
collaboration with the government and Westinghouse, it will start a 4-year
long trial to employ thorium as a nuclear fuel in one of its existing
nuclear reactors.
- U.S. In its report to the
Secretary of Energy, in January 2012, the Blue Ribbon Commission on
America's Future notes that a "molten-salt reactor using thorium
[has] also been proposed”, while in the same month, it was stated the U.S.
Department of Energy is "quietly collaborating with China" on a
molten salt reactor using thorium fuel.
- Japan.
In
the aftermath of three meltdowns at nuclear power plants in 2011, Japan
utility Chubu Electric Power, wrote in June, 2012, that they are
considering thorium as “one of future possible energy resources.”
- Israel. Researchers from
Ben-Gurion University in Israel and Brookhaven National Laboratory in New
York began, in May 2010, a collaboration to develop self-sustaining
thorium reactors, "meaning one that will produce and consume about
the same amounts of fuel."
- U.K. In Britain, a member of the
House of Lords, Bryony Worthington, is actively promoting thorium, which
she refers to as “the forgotten fuel”. However, the UK’s National Nuclear
Laboratory (NNL) has published a paper on the thorium fuel cycle, finding
that, "the thorium fuel cycle does not currently have a role to
play," in that it is "technically immature," and “would
require a significant financial investment and risk without clear
benefits," and which are "overstated." The environmental
group, Friends of the Earth UK, are of the opinion that research into
thorium-based power might be "useful" as a fallback option.
References.
(1)
http://en.wikipedia.org/wiki/Thorium
(2) Data taken from Uranium 2007:
Resources, Production and Demand, Nuclear Energy Agency (June 2008), NEA#6345
(ISBN 9789264047662). The 2009 figures are largely unchanged. Australian data
from Thorium, in Australian Atlas of Minerals Resources, Mines & Processing
Centres, Geoscience Australia
(3) http://ergobalance.blogspot.co.uk/2006/06/thorium-instead-of-uranium.html.
(4) http://en.wikipedia.org/wiki/Thorium_fuel_cycle
(5)
http://en.wikipedia.org/wiki/Peak_uranium
(6)
http://nucleargreen.blogspot.co.uk/2008/03/edward-teller-listens-as-eugene-weigner.html
(7)
http://pbadupws.nrc.gov/docs/ML0930/ML093090346.pdf
(8)
http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pdf.
(9)
http://www.world-nuclear.org/info/Current-and-Future-Generation/Accelerator-driven-Nuclear-Energy/#.UVA32VevPRk.
(10)
http://en.wikipedia.org/wiki/Protactinium
(11)
http://en.wikipedia.org/wiki/Molten_salt_reactor#Oak_Ridge_National_Laboratory_molten_salt_breeder_reactor
(12)
http://blogs.telegraph.co.uk/finance/ambroseevans-pritchard/100022190/last-chance-to-protest-before-the-eu-snuffs-out-thorium-energy-in-europe/
(13)
http://news.sciencemag.org/sciencenow/2011/07/earth-still-retains-much-of-its-.html,
(14)
http://en.wikipedia.org/wiki/Age_of_the_Earth.
(15)
http://www.the-weinberg-foundation.org/2012/11/20/how-to-manage-the-dirty-side-of-thorium-and-assure-its-global-supply/
(16)
http://www.world-nuclear.org/info/Current-and-Future-Generation/Thorium/#.UVGnXlevPRk
(17)
http://www.miningaustralia.com.au/news/lynas-ramps-up-rare-earth-processing-in-malaysia
(18) http://en.wikipedia.org/wiki/Thorium-based_nuclear_power#World_sources_of_thorium
