Is there enough Uranium to run a nuclear industry big enough to take over from fossil fuels ?|
by Dave Kimble at www.peakoil.org.au
As supplies of easily recovered oil start to decline, (see Peak Oil )
world oil production will fail to meet world energy demand.
This raises the question of which alternative energy supplies can be expanded to cover the increasing shortfall.
One candidate is nuclear energy,
which in turn raises the question of whether there is enough Uranium resource to fully take over from Oil.
Will we run into Peak Uranium before we have coped with Peak Oil ?
Current world production of Uranium is around 36,000 tonnes of metal per year,
but production is limited by market forces which have a complicated history
resulting in large stockpiles, depressed prices and limited interest in mining.
Total world consumption of Uranium is 66,000 tonnes of metal per year,
with 30,000 tonnes coming from stockpiles, recycling of spent fuel and weapons decommisioning, see below.
Spot market prices (currently around US$20/pound) are a poor indicator of the true supply/demand situation,
as anyone wanting to build a commercial nuclear reactor with a life-span of 30 - 60 years
will want to have a long-term supply contract locked in before construction begins.
The spot market only handles about 12% of the overall market, and is subject to wild fluctuations.
Long-term contracts with power companies are expected to run at US$26 this year.
Correspondingly, suppliers know they will have to provide for long-term supply contracts
and this means it can make economic sense to stockpile Uranium while production is up and running,
rather than close down a mine because of short-term market considerations.
Over-enthusiastic expectations for increases in the nuclear energy industry have led to large stockpiles
and many small and low-grade ore mines have closed.
It is possible that if a large-scale swing to nuclear energy was to occur,
there might be shortfall in supply, but this would not be what we call Peak Uranium.
That only comes when a fully developed mining industry still cannot meet demand.
The mining and milling of Uranium ore to the yellow-cake stage is an expensive business
so the grade of the ore is particularly important, while there is a choice.
Recycling Uranium versus "Once Through"
When a conventional nuclear power reactor has used up about 4% of its uranium-235,
the resulting contamination of the fuel with by-products slows down the nuclear fission reaction
and it is time to change the fuel rods.
Usually about a third of the rods are changed every year.
What went in as 100% Uranium dioxide (~3.5% U-235), comes out as oxides of 96% Uranium,
1% Plutonium and 3% fission products and Actinides (heavier elements than Plutonium).
For most nuclear power reactors built in the US before the mid-1970s,
the intention was for them to reprocess the spent fuel to recycle the uranium
which still contains a lot of valuable U-235.
A number of reprocessing facilities were built to handle this work.
Unlike the reactors which were designed to 'cook' the fuel at relatively low temperatures
and produce a relatively pure Plutonium-239 fraction for weapons purposes,
the higher temperature cooking in a power reactor produces a significant proportion of Pu-240 and higher isotopes in the Plutonium mix.
These isotopes are very difficult to separate, given the highly radioactive and toxic nature of Plutonium.
Pu-240 has a shorter half-life than Pu-239 (6,564 years v. 24,110 years)
thus it has an increased tendency to fission spontaneously.
So it was thought that this made the Plutonium mixture recovered from power reactors unsuitable for bomb making.
However during the 1970s it became clear that although it would be difficult to make a bomb with a reliable yield,
a bomb could nevertheless be made from recovered power reactor Plutonium.
India's nuclear explosion in 1974 compounded these fears.
Worried about the potential for weapons proliferation,
and the overthrow of the Shah of Iran (who had a US-supported civil nuclear program)
in 1979 President Carter introduced the Nuclear Waste Policy Act
which banned commercial fuel recycling in the US,
including on behalf of foreign customers of US reactors.
This limited the fuel 'cycle' to a 'once through' process.
In the once through process, the spent fuel rods are still broken up and dissolved in nitric acid,
and the Plutonium is separated from the Uranium using the organic solvent "Purex" process.
But from there on the Uranium component is put directly into storage without being recycled.
President Reagan reversed the ban in 1981, but US policy was still to favour 'once through',
and the Nuclear Non-proliferation Act of 1978 forbids supporting reprocessing by non-nuclear weapon states.
The US nuclear industry has never taken up the recycling option again,
partly because the old reprocessing plants were no longer able to meet new safety requirements,
and partly because an over-estimation of future nuclear capacity has led to over-investment in mining and processing,
resulting in low prices for mined uranium
and hence a commercial preference for freshly-mined, rather than recycled, uranium.
The term "reprocessing" is now often used for both the "recycling" and "once through" processes.
Meanwhile France, UK and Russia have always allowed recycling,
and Japan also recycled up until 1997, when it sub-contracted the task to the UK's BNFL.
A 1997 study by the Nuclear Energy Agency of OECD put the additional cost of electricity from recycled fuel at 10%
over that derived from high-quality Uranium ores.
Nevertheless these countries have valued the increased security they get from a reduced dependence on imported Uranium.
The resulting Uranium also has a higher proportion of isotopes other than U-238 and U-235
which has the potential to shorten the reprocessed fuel rods' life.
However there may be technological solutions to this problem in the future.
Uranium from decommissioning ex-Soviet weapons
Another complicating factor in Uranium supply is the Highly Enriched Uranium Purchase Agreement
signed with Russia by the Clinton administration in 1993.
This agreement provides for the US purchase of 500 metric tons of Russian highly enriched Uranium (>90% U-235)
resulting from the dismantling of 20,000 nuclear warheads.
This uranium will be blended down to low-enriched Uranium (~3.5% U-235) in Russia over a 20-year period that began in 1995.
The cost for this agreement is $12 billion over the 20-year period.
The payments to Russia will compensate for the Uranium content and the enrichment services
as well as provide funds for the increased security of fissile material in Russia.
Overall, the net effect should be to provide for a budget neutral agreement, that is no profit, no subsidies.
The value of the low-enriched Uranium on the commercial market should equal the payment to Russia.
To date, the Agreement has succeeded in converting in excess of 111 metric tons of highly enriched Uranium,
enough for 5,000 nuclear weapons.
According to US nuclear safety regulators, this has resulted in the Russian low-enriched uranium supply representing approximately 50% of the Uranium supply for the nuclear power industry in the United States.
South Africa has never admitted to building nuclear weapons,
but they have given evasive answers to IEAE inquiries.
In October 1992, Nucleonics Week reported that IAEA inspectors had found machinery that had been used
"to shape spherical fissile cores for a nuclear explosive device" at their Pelindaba site.
That year they began talks with the US over de-commissioning stockpiles of highly enriched Uranium
and selling the low enriched uranium to the US on similar terms to the Russian program.
The current state of this program is unknown.
Re-enrichment of depleted Uranium
The element Uranium can exist as 22 different isotopes, ( http://chemlab.pc.maricopa.edu/periodic/U.html )
with half lives ranging from 1 microsecond (U-222) to 4.4 billion years (U-238).
Naturally occurring Uranium consists of three isotopes:
U-238 = 99.2745% ; U-235 = 0.7200% ; U-234 = 0.0055%
Despite its tiny proportion of the total by weight, U-234 produces ~49% of the radioactive emissions.
The standard enrichment process for pressurised water reactor (PWR) fuel converts this mix to:
fuel stream : U-238 = 96.4% ; U-235 = 3.6%
tailings stream : U-238 = 99.7% ; U-235 = 0.3%
However the concentration of U-235 left in the tailings stream is a commercial decision,
based on the type of enrichment technology used and the cost of process energy.
Since 1996 tailings from the British-Dutch-German consortium Eurenco
have been sent to the Russian company Minatom's plant at Novouralsk,
where it is re-enriched back to U-235 = 0.7% and returned to Eurenco for standard enrichment.
6,000 tonnes of tailings were processed in this way in 1996.
It has been suggested that Minatom cannot be charging the full cost of processing in this scenario,
but it has a large excess enrichment capacity and perhaps can afford to neglect capital costs on the deal.
Another suggestion (by a consultant to Uranium Exchange Co. in Nuclear Fuel, 19 October 1998)
is that Minatom is stripping the tailings further than contracted, and keeping the extra U-235 for itself.
Given the Russian excess stocks of highly enriched Uranium from redundant weapons stockpiles,
this latter scenario seems improbable.
All of these factors have an important bearing on when Peak Uranium occurs.
Total known Uranium ores of good quality are only sufficient to supply 3 years worth of total world energy needs,
although it needs to be remembered that there is probably a lot of ore left to be discovered,
and that electrical energy is only ever going to be a part of the overall energy mix.
Complicating matters still further, so much energy is spent in processing poorer ores,
that on current technology, ores of less than 0.01% purity are uneconomic and have EPRs of less than 1.
This doesn't stop nuclear spin-doctors from gloating about the zillions of tonnes of Uranium
to be found in rocks (at concentrations of 0.0004%) and in seawater (at concentrations of 0.0000002%).
If that is not complicated enough, it is possible to run most power reactors on a fuel containing up to 30% MOX,
which is a mixture of Uranium and Plutonium oxides.
The Plutonium comes from the recycling process, and the Uranium can come from either recycling or fresh mining.
This reduces the amount of Plutonium that has to be either permanently stored
(and potentially diverted to weapons production),
and so indirectly reduces costs for the nuclear industry.
However conventional reactor designs cannot utilise all the Plutonium produced,
so this does not solve all the problems.
As at the end of 1995, about 970 tonnes of Plutonium had been created in the 180,000 tones of spent fuel
Of this, about 185 tonnes had been separated, and 50 tonnes recycled as MOX fuel.
Other methods of using all this Plutonium for thermal energy purposes are thought by the industry to be at least 30 years away.
There are a number of other factors affecting the economic viability of nuclear energy.
The long-term storage of high-level nuclear wastes may have a technical solution,
but it has not yet begun in a practical way, and almost all spent fuel rods are sitting in cooling ponds
located at the power stations that created them.
The complete decommissioning of old reactors has scarcely begun,
and improving safety standards make the economic burden of compliance almost impossible to calculate.
Perhaps the best indication of the state of the reprocessing industry is this story from Asahi Shimbun, 7th January 2005:
The proliferation of uranium enrichment facilities around the world has recently led the head of the IAEA,
Mohamed ElBaradei, to call for a global five-year moratorium on new enrichment and reprocessing facilities.
This proposal will be discussed at the conference on the Nuclear Nonproliferation Treaty in New York in May 2005.
In conclusion I think that the number of variables in the possible strategies for fuelling nuclear reactors
means that discounting the future of nuclear power on the basis of Peak Uranium is not yet proven.
The nuclear industry uses lots of fossil energy in the mining, milling, enrichment and fabrication of nuclear fuel rods,
so it may well be that Peak Oil makes the mining of sufficient Uranium to keep the nuclear industry going impossible.
The real solution to energy resource depletion is demand side management - using less.
But given the ever-lasting growth paradigm we are almost universally engaged in,
I cannot see an outcome other than a miltary struggle for control of the world's diminishing oil resources,
such as we are currently seeing in Iraq.
As supplies get tighter still, this will lead to World War 3.