Institute for Solid-State Nuclear Physics
Institut für Festkörper-Kernphysik
The Dual Fluid Reactor can be used for electricity, automotive fuel production, and heating. The only primary resources needed are naturally occuring fissionable materials, i.e. Uranium and Thorium.
Fission of the uranium nucleus results in an energy release 100 million times more than chemical burning of the atom, for example carbon. Thus, 1 kg of uranium has an energy content of 2,700 tons of hard coal. Present light water reactors use barely 1% of the energy content of natural uranium, thorium is not used at all. Already with today's nuclear power plants the fuel costs make up only a fraction of the operating costs.
For the DFR the exploitation is about 100 times as much, so that even higher fuel costs by a factor of 100 are acceptable, which would allow to continue the exploitation down to regions of average concentration within the Earth's crust. The concentration within granite rock, which is available in abundance, is about 10 to 20 ppm, which in addition correlates with the average concentration of thorium. Uranium deposits with higher concentration were also discovered at the bottom of the oceans. The Japanese method for the recovery of dissolved uranium from seawater is to cost several hundred US$ per kilogram.
In this manner with the DFR system every country can establish an economic autarkic complete energy supply for millions of years.
In the following, all estimations relate to the costs of a batch production. The construction of a test facility and a prototype plant which includes licensing procedures will have expenses several times those of a batch produced plant.
The challenge in the construction of a power reactor is to guarantee a negative temperature coefficient under all circumstances to avoid criticality accidents (Chernobyl) and to ensure the removal of the residual decay heat (Harrisburg, Fukushima). This includes limiting the consequences of an accident to the inside of the reactor building by an appropriately sturdy containment.
With the DFR operating under normal pressure special safeguards such as an excess pressure containment can be pared down without compromising safety. Similar to all other modern types of reactors the DFR has a negative temperature coefficient. Continious removal of fission products avoids a build-up of them as is common in solid fuel elements, thus significantly reducing the production of residual decay heat. The cooling system operates so effectively, that the passive removal of residual decay heat is guaranteed and redundant cooling circuits and emergency cooling systems are unnecessary. All in all, this leads to substantial simplifications and reductions in the building's construction, which significantly reduce the building costs per amount of power compared to other types of reactors.
The impact of the simplifications of the DFR system will be estimated quantitatively in the following. This will lead to a conservative assessment for a serially produced reactor based on experience from plant engineering and construction:
|Item||500 MWe DFR||1500 MWe DFR|
|Concrete containment for reactor, earthquake-proof||100||130|
|Reactor with primary circuit, features including a facility for pyrochemistry||250||300|
|Secondary loop, heat exchanger*||60||150|
|Supercritical water turbine 500 MWe (3x), generator, transformer*||200||580|
|Tertiary cooling system with cooling tower||140||250|
|Planning and building authority, contingency||130||200|
|Costs per installed power||2 US$ / W||1.2 US$ / W|
*For the future gas cooling option, the heat exchangers cost less (about 30/70 millions) and the turbines a bit more (250/650 million) compared to the given values in the table. Therefore the sum remains unchanged.
A closed working gas loop with a tertiary cooling system was assumed. Chosing an open air operated loop, the tertiary cooling system can be omitted, which reduces the costs by 10%.
The capital costs of the DFR are comparable to those of a coal-fired power station. They are far below the capital costs for a modern nuclear power plant, which are of the order of for example 3.3 US$ / We for the EPR. Scaling for the number of simultaniously built blocks as well as for the size of the reactor a further reduction in costs is achievable. Because no pressure tanks are necessary, it is technically easy to increase the power while the building costs would rise logarithmically. The technology of the reactor also allows to substitute expensive turbines in the conventional section by modern techniques for electricity generation, thus additionally reducing the costs in the further development.
Hence, the operating company does not have to balance high capital vs. low fuel costs for a nuclear power plant compared with a coal-fired power station, where the situation is the opposite, with the nuclear power plant starting to profit from the gains not before 20 to 30 years.
Assuming a service life of 50 years the annual operating costs are composed as follows:
|Item||500 MWe DFR||1500 MWe DFR|
|Operating personnel: 30 man-years (3 shifts 10/12 man-years each 130,000 US$)||4||5|
|Nuclear fuel: 400 (1200) kg (300 US$ mining, 300 US$ transport, 600 US$ per kg waste management)||0.5||1.5|
|Maintenance, conventional section (2.5% building costs per annum)||9.5||25|
|Maintenance, nuclear and pyrochemical section (2% building costs per annum)||5||7|
|Reserve for decommissioning (25% of the building cost of 1000/1900 million US$)||5||9|
Based on an annual average of 8,000 full-load hours, which corresponds to an operational availability of 90%, the electricity production results in 4,000 million kWh at a production cost of 0.56 ¢ / kWh. Here, the fuel costs have a share of 0.0165 ¢ / kWh, even when assuming an uranium price of 330 US$ / kg. Depending on the configuration, the capital costs sum up to 0.43 to 0.50 ¢ / kWh. Thus, the production costs add up to a total of 1.00 to 1.05 ¢ / kWh with the fuel costs contributing ~1.6%.
|Item||500 MWe DFR||1500 MWe DFR|
Already with the small 500 MWe plant the electricity production costs are only 30% of the costs of a light water reactor or a coal-fired power station. They further decrease to 20% for the 1500 MWe DFR. The DFR output power can be scaled up much more easily contrary to pressurized water reactors due to their size-limited pressure vessels.
The high temperature of the DFR makes a very efficient production of propellants possible. This can be a direct production of synthetic fuels but also support for heat-intensive oil extraction, e.g. from oil sands. In the following, cost savings for hydrazine, ammonia, and DFR-aided oil extraction are compared.
Hydrogen is the base input material needed. Conventional facilities burn natural gas to produce hydrogen while the DFR can produce it directly from water. From hydrogen, hydrazine is produced in two steps. These steps and their corresponding facility costs per kilogram hydrazine are
The sum is 11-13 US¢ / kg. However, the synergistic and scaling effects reduce it to 8 US¢ / kg. That synergistic and scaling effects are so large can be seen from typical (10 million tons annual output) petroleum refineries which are far more complex than the hydrazine production facility.
Apart from facility costs, additional costs for energy is needed. The energy input for the production of 1kg hydrazine combines as follows:
Those needs can be matched by a 3,000 MWth DFR with turbines producing 800 MWel. The overall costs of such a DFR system would be 10% cheaper than the 1,500 MWel DFR mentioned in the preceeding section because it needs less turbine power but has the same total thermal power, leading to energy costs of 0.5 US¢ / kWhel and 0.22 US¢ / kWhth. The hydrazine output of such a DFR would be about 3,000 tons per day at 90% load. The resulting energy costs for hydrazine production are 7 US¢ / kg.
Both, the energy costs and facility costs add up to 15 US¢ / kg, and, not considering synergistic effects, up to 21 US¢ / kg. For smaller plants the price could rise as high as nearly 20 US¢ / kg. A similar calculation for the new SSAS process leads to total costs of 11 US¢ / kg and 17 US¢ / kg without synergetics, respectively.
The hydrazine production costs can now be compared with conventional fuel extraction and production costs. The following table shows crude oil costs using different extraction methods as well as production costs for gas and coal liquefaction evaluated 2008.
|Method||Costs US$ / barrel||Costs US¢ / kg[a]|
|Natural/Artificial lift||10 - 40||8 - 35|
|Deep / ultra-deep-water oil fields||30 - 65||25 - 55|
|Heavy oil/bitumen||20 - 70||15 - 60|
|Steam/Gas injection (oil sands)||30 - 80||25 - 65|
|Oil/tar shale extraction||50 - 110||40 - 90|
|Gas to liquids||40 - 110||35 - 90|
|Coal to liquids||60 - 120||50 - 100|
For refinery, additional cost of 6 ¢ / kg (8 $ / barrel) must be added.
The energy costs contribution is not negligible and depends on the method by which the oil is extracted. For refined oil from the Middle East it is only 2 ¢ / kg  but for the energy intense oil sand extraction in Canada (in-situ SAGD process with suceeding hydro cracking) it contributes with remarkable 7-8 ¢ / kg. Here the DFR can reduce the costs significantly by providing heat and electricity at extremely low costs.
The energy cost savings become extreme when producing synthetic fuels. With conventional methods the ammonia and hydrazine production is dominated by 70-80% energy costs and therefore can not compete even with gasoline. This changes dramatically when using the DFR. Hydrazine and ammonia can now even compete with Middle East oil. The following table shows overnight costs for some fuel production processes, both for with conventional energy supply and DFR energy supply. A fuel-producing DFR facility unites all processing steps in one unit causing lower labor and capital costs, compared to the conventional production lines.
|Method||Total costs US¢ / kg[a]||Total costs US¢ / MJ[b]|
|Refined oil from Middle East||11 - 13||10 - 12||0.27 - 0.31||0.25 - 0.29|
|Refined oil from oil sands, Canada[c][d]||31 - 42||27 - 37||0.75 - 1||0.6 - 0.9|
|Hydrazine production||~44||15 - 21||2.4||0.8 - 1.1|
|Hydrazine production, SSAS||~37||11 - 17||2.0||0.6 - 0.95|
|Ammonia production, SSAS||15||4 - 5||0.8||0.25|
[a] 1 barrel (~159 l) of light oil/gasoline and hydrazine has a mass of about 120 kg and 160 kg, respectively.
[b] The lower heating value of oil-based fuels, hydrazine and ammonia are ~42 MJ/kg, 19 MJ/kg and 18 MJ/kg, respectively.
It is stressed again that hydrazine can be used in vehicles with higher efficiency when mixed with water compared with gasoline which does not mix with water. Therefore, the hydrazine costs related to the mechanical energy (or to the distance driven by a vehicle) are a factor of 1.5-2 lower than the per-energy costs. On a per-energy basis, the hydrazine-producing DFR facility can compete with oil production costs equal to or higher than 40 US$ per barrel (including refining), so only conventional oil sources on land are cheaper. On a per-weight as well as on a per-distance basis, only oil fields suitable for primary oil recovery (e.g. Middle East) can compete with hydrazine from the DFR facility. These resources are expected to be exhausted first and soon.
An assessment of the need for nuclear power plants results from an overview on the present energy market.
The annual energy consumption in Germany is as follows: 1,300 million MWh mineral oil, 850 million MWh natural gas and coal, 600 million MWh electricity.
Per-capita consumption: 16 MWh mineral oil, 10 MWh natural gas and coal, 7.5 MWh electricity.
This can be converted into the number of DFR plants necessary to produce the same amount of electricity and nuclear energy for the production of fuel. Here, the assumed size of the plant is the some 3 GWth reference we used here before. The fuel market could be transfered quickly and profitably to nuclear synthesis by successive expansion. In the case of electricity plants, a lot of old sites are due for shut down, which results in a need for additional sites. For the complete fulfillment of demand 80 plants would be necessary for the generation of electricity and about 90 nuclear plants for the production of fuel, including the recovery of waste heat and variations.
The world wide consumption ranges at 22,000 million MWh of electricity and 84,000 million MWh of fuels and heating, respectively.
With respect to the increase in standard of living in emerging countries forecasts expect these numbers to double until 2050, corresponding to a need of 3,500 DFRs for electricity and at least 6,500 DFRs for the production of fuel and heating. This compares to the number of old sites, that need to be replaced (today 80% of all existing plants) and fossil fuels, that need to be subsituted for.
Today a power plant capacity of 750 GW for the production of electricity is available within Europe. Of this 475 GW will already need to be replaced by 2020 due to aging of facilities.
Forecasts on the price for fossil fuels on the world market expect only little increase for coal until 2050. However, the prices for mineral oil and natural gas are expected to rise significantly. This is less a result of a shortage in supply, but rather based on the fact, that the means of exploitation for available deposits become more costly. The nuclear synthesis of XtL-fuels will become a continually growing market.
The deployment of new power plants, such as the DFR system, can be seen in the context of the general economical and political situation. However, with rational contemplation the choice for a technology of energy generation is guided mainly by physical measures, which leads by itself to economical productivity.
At first, the term energy production should be specified. In consequence of the conservation of energy law, energy can neither be produced nor nor destroyed, but is merely transduced from one form into another. A power plant produces exergy, that fraction of energy, that is available for mechanical work. The electric energy produced by a power plant from the employed primary energy is pure exergy, since it can be completely utilized for mechanical work or converted into any other form of energy. The unusable fraction called anergy remains and is dissipated at low temperature as heat. Therefore, with respect to the primary energy, every exergy production has an efficiency of < 1.
The economical productivity of a power plant is rated by the ERoEI. The ERoEI or ERoI is the energy returned on the energy invested (or energy return on investment). It is the quotient of the sum of exergy produced by a power plant during its service life and that exergy, in this case actual work, that is needed for its construction, operation (including procurement of fuel) and waste management. A power plant has to have an ERoEI significantly bigger than 1, otherwise the invested effort does not pay off. In the economical process a power plant is the more productive the higher the ERoEI. For a low ERoEI the effort is wasted.
In the following, the ERoEIs for different types of power plant technologies are compared.
|Power plant technology||ERoEI|
|Pressurized water reactor[a]||80|
|Black-coal fired power||29|
|Solar thermal (desert)[b]||9|
|Wind power (german coast)[c]||4|
|DFR (500 MWe)||1200|
|DFR (1500 MWe)||2000|
[a] This value is calculated using the today's enrichment technology and mix. Earlier values are lower because of energy intense diffusion enrichment.
[b] The ERoEI for solar energy includes pumped-storage hydroelectricity, which is energetically most favourable, to balance day-night fluctuations (factor 2). This storage is unlikely to be applicable in the desert and has to be replaced by other storage means, further reducing the ERoEI. Damages by sandstorms are also not included in the ERoEI.
[c] The ERoEI includes over capacity needed to provide supply for seasonally weak periods (factor 2) and pumped-storage hydroelectricity to balance short-term fluctuations (factor 2). Without those facilities, the ERoEI for wind at the german coast would be 16.
The so-called renewable sources of energy (energy is not renewed, especially not exergy) have low ERoEIs and employ the spent exergy inefficiently, thus not sustainably. They are characterized by a very high exergy input for the construction of the plants and high maintenance with relatively short service lifes, except for hydroelectric dams. Since electricity cannot be stored, a power plant must produce the electricity on demand. The 'renewables' are incapable of that and need means to store the untimely produced exergy by conversion to other forms of storable energy. The exergy expenses for these storage facilities enter the denominator of the ERoEI thus reducing it considerably. Growing experience with environmental inclemencies, increasing maintenance expenses, and/or shortening service life are not yet considered and would further reduce the ERoEI significantly. So the values for the 'renewables' as given in the table pose upper limits.
The monetary return on investment factor is usually lower than the ERoEI because deviating market prices and different personnel expenses reduce the value albeit there is a proportionality. Empirically, the value of the ERoEI must be greater than 5 to gain profit.
So the ERoEI determines the energy generation costs. In an economic region the energy price is determined by the ERoEI of the prevailing power plant technology. If the power technology is changed the quotient of the energy prices before and after the change are equal to the inverse of the quotient of the correspondent ERoEI's. During the transition, energy generation costs of the 'new' power plants are still dominated by the 'old' power technology since the 'new' power plants are constructed with energy from the 'old' power technology. If a change from fossil power to solar power is be done the quotient of the ERoEI's is about 0.1. The energy price will be 10-fold after the change is accomplished. Meanwhile the solar energy price is considerably lower (although increasing) because of the subsidization by fossil power. Conversely, while changing to the DFR technology the DFR energy price is increased by fossil power though finally decreasing below one tenth.