Proceedings of the NATIONAL NCADEMY OF SCIENCES Volume 57 * Number I * January 15, 1967 EVENING PUBLIC LECTURE BY INVITATION OF THE COMMITTEE ON ARRANGEMENTS FOR THE AUTUMN M\1EETING THE N[UCLEAR ENERGY REVOLUTION 1966* BY ALVIN MI. WEINBERG AND GALE YOUNG OAK RIDGE NATIONAL LABORATORYt Delivered before the Academy, October 17, 1966 Twenty-four years have passed since Fermi and his co-workers at Chicago achieved the first nuclear chain reaction. During most of these years nuclear power for civilian use has -been too expensive and experimental in nature to play much of a role in our economy, but during the past couple of years the situation has changed. Nuclear reactors now appear to be the cheapest of all sources of energy. We believe, and this belief is shared by many others working in nuclear energy, that we are only at the beginning, and that nuclear energy will become cheap enough to influence drastically the many industrial processes that use energy. If nuclear energy does not, as H. G. Wells put it in 1914, create "A World Set Free," it will nevertheless affect much of the economy of the coming generation. It is this Nuclear Energy Revolution, based upon the permanent and ubiquitous availability of cheap nuclear power, about which we shall speculate. Our outlook is admittedly optimistic; yet optimism in nuclear energy seems justi- fied. In 1955, at the first International Conference for the Peaceful Uses of Atomic Energy, in Geneva, some American authorities were chided for predicting nuclear power priced at 4-5 mills per kilowatt hour (kwh). Today TVA has announced that it expects to generate power from its 2200-megawatt (M\Iw) Browns Ferry boiling- water nuclear plant at 2.4 mills/kwh. Even if the Browns Ferry plant were operated by a private utility, the electricity at the bus bar would cost less than 3.5 mills/kwh. We are very hopeful that still lower costs will be achieved in the future with breeder reactors. Cheap Nuclear Energy Is Close at Hand. -The economic breakthrough in nuclear energy came in 1963 when the Jersey Central Power and Light Company con- tracted with the General Electric Company to construct the Oyster Creek boiling- water nuclear power plant. At its expected electrical output of 620-Mw the capital cost of this plant is $110/kw or the same as that for a coal-fired power plant of the same size at the same location.' The announcement of Oyster Creek was at first regarded by many as a sort of fluke. But Oyster Creek was followed by a succession of orders for large light-water-cooled power plants, so that now there are 29 com- 1 Downloaded by guest on October 15, 2020
Transcript
Proceedings of theNATIONAL NCADEMY OF SCIENCES
Volume 57 * Number I * January 15, 1967
EVENING PUBLIC LECTURE BY INVITATION OF THE COMMITTEE ON ARRANGEMENTSFOR THE AUTUMN M\1EETING
THE N[UCLEAR ENERGY REVOLUTION 1966*
BY ALVIN MI. WEINBERG AND GALE YOUNG
OAK RIDGE NATIONAL LABORATORYt
Delivered before the Academy, October 17, 1966
Twenty-four years have passed since Fermi and his co-workers at Chicagoachieved the first nuclear chain reaction. During most of these years nuclear powerfor civilian use has -been too expensive and experimental in nature to play much ofa role in our economy, but during the past couple of years the situation haschanged. Nuclear reactors now appear to be the cheapest of all sources of energy.We believe, and this belief is shared by many others working in nuclear energy,that we are only at the beginning, and that nuclear energy will become cheap enoughto influence drastically the many industrial processes that use energy. If nuclearenergy does not, as H. G. Wells put it in 1914, create "A World Set Free," it willnevertheless affect much of the economy of the coming generation. It is thisNuclear Energy Revolution, based upon the permanent and ubiquitous availabilityof cheap nuclear power, about which we shall speculate.Our outlook is admittedly optimistic; yet optimism in nuclear energy seems justi-
fied. In 1955, at the first International Conference for the Peaceful Uses of AtomicEnergy, in Geneva, some American authorities were chided for predicting nuclearpower priced at 4-5 mills per kilowatt hour (kwh). Today TVA has announced thatit expects to generate power from its 2200-megawatt (M\Iw) Browns Ferry boiling-water nuclear plant at 2.4 mills/kwh. Even if the Browns Ferry plant were operatedby a private utility, the electricity at the bus bar would cost less than 3.5 mills/kwh.We are very hopeful that still lower costs will be achieved in the future withbreeder reactors.Cheap Nuclear Energy Is Close at Hand.-The economic breakthrough in nuclear
energy came in 1963 when the Jersey Central Power and Light Company con-tracted with the General Electric Company to construct the Oyster Creek boiling-water nuclear power plant. At its expected electrical output of 620-Mw the capitalcost of this plant is $110/kw or the same as that for a coal-fired power plant of thesame size at the same location.' The announcement of Oyster Creek was at firstregarded by many as a sort of fluke. But Oyster Creek was followed by a successionof orders for large light-water-cooled power plants, so that now there are 29 com-
Millstone Point,BrookwoodIndian Point 2Turkey Point 3Turkey Point 4Dresden 3RobinsonPalisadesPoint BeachQuad Cities 1 and 2
MonticelloBrowns FerryVernonKeowee DamPeach Bottom 2Delaware Valley
SurryBoston
UtilityJersey CentralSouthern California EdisonNiagara MohawkConnecticut YankeeCommonwealth EdisonBoston EdisonNortheast, UtilitiesRochester Gas & ElectricConsolidated EdisonFlorida Power & LightFlorida Power & LightCommonwealth EdisonCarolina Power & LightConsumers Power CompanyWisconsin Michigan PowerCommonwealth Edison and Iowa-
Illinois G & ENorthern States Power Co.TVAVermont YankeeDuke Power CompanyPhiladelphia ElectricPublic Service Electric & Gas of New
JerseyVirginia Electric Power Co.Boston Edison
NominalMW
5154295004637556005494208736526528107608104802 X 810
5402 X 11005402 X 8202 X 11001000
ManufacturerGeneral ElectricWestinghouseGeneral ElectricWestinghouseGeneral ElectricGeneral ElectricGeneral ElectricWestinghouseWestinghouseWestinghouseWestinghouseGeneral ElectricWestinghouseCombustion Engr.WestinghouseGeneral Electric
General ElectricGeneral ElectricGeneral ElectricBabcock and WilcoxGeneral ElectricWestinghouse
2 X 800 Westinghouse600 General Electric
mitments for construction of large nuclear power reactors in the United States(Table 1). More than half of the large station generating capacity ordered inrecent months is scheduled to be nuclear.None of the plants listed in Table 1 are as yet operating. Oyster Creek will go
on the line early in 1968. The optimism expressed in the many purchases of light-water-moderated and cooled reactors is based partly upon our generally good ex-perience with such reactors in the nuclear navy, and partly upon the operatingexperience with such power plants as the Yankee pressurized-water reactor (175MIw) and the Dresden 1 boiling-water reactor (200 Mw). Yankee, for example,has been generating electricity for five years, and during the past year has beenavailable for generation 76 per cent of the time. Dresden 1 has operated for sixyears, and during the past year has been available 83 per cent of the time.In some ways it is surprising that the world's cheapest nuclear reactors should
derive from the original pressurized-water line used to power the Nautilus. Pres-surized water was chosen for the Nautilus not because it seemed to be a path tocheap nuclear energy, but rather because such reactors, being moderated by hydro-gen and fueled with enriched uranium, are relatively compact. If anything, the earlyreactor designers viewed these systems as being rather expensive. And in countriesother than the United States and the Soviet Union, the main-line reactors utilizenatural uranium and either graphite or heavy water as moderator.But the early designers failed to appreciate the extent to which the extraordinary
success of the gaseous diffusion plants would reduce the price of U235. In 1948,when the Nautilus was designed, U235 cost about $35/gm. Today it costs $12/gm,which is only four times its price as unseparated isotope in ore costing $8/lb of U308!This remarkable reduction in the cost of separating U235, more than any other singlefactor, underlies the economic success of the American water-moderated reactors.
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The fuel cycle in a reactor like Browns Ferry that burns enriched uranium costs only1.25 mills/kwh, which is appreciably lower than coal even in cheap coal country(Table 2).The American reactors, being compact, were expected to be cheaper to build than
the large graphite or heavy-water reactors that use natural uranium. But priorto Oyster Creek it was not clear how cheap a reactor could be, especially if its outputwere large enough. It was R. P. Hammond who first stressed the principle that anuclear reactor ought to scale rather favorably. Thus, although the total cost of alarge nuclear reactor will be greater than that of a smaller one, the cost per kilowattof the large reactor should be less than that of the smaller one. Hammond's con-tention has been amply confirmed by the price estimates published, for example, bythe General Electric Company. Figure 1 shows that the cost per kilowatt of a200-'Mw boiling-water reactor (BWR) is around $180/kw, whereas the cost perkilowatt of a 1000-Mw BWR is only $110/kw. All the new, competitive nuclearpower plants are large, and they capitalize on the advantage of size.
The Necessity for Breeders. -Nuclear power at 2.4 mills/kwh at Browns Ferry isa remarkable achievement, but it is not remarkable enough to serve as the basis fora Nuclear Energy Revolution. In the first place, we are hopeful that breederreactors can shave another mill off the cost and thus perhaps provide the basis fornew heavy chemical and other industries. In the second place, the light-waterreactors burn only a small fraction of all the natural uranium mined to fuel them;thus such reactors will rapidly use all the U. S. low-priced reserves of uranium ore,and the price of nuclear energy will rise as we are obliged to burn more expensiveores. This is illustrated in Figure 2, based by Dietrich3 on estimates made a fewyears ago by the Atomic Energy Commission of U. S. ore reserves and reactors tobe built.4 Since then, ore prospecting has been resumed, but water reactor sales areoutrunning the estimates.We therefore find ourselves in a serious dilemma. The current great success of
nuclear energy is making our economy increasingly dependent upon nuclear power.But as we turn to nuclear energy we shall exhaust our low-grade ore reserves.By the time (say in 1990) we have become very heavily committed to nuclearenergy, its price will probably begin to rise significantly.Of course we shall find more low-cost ore. But eventually even this will be in-
sufficient, especially if our power requirements continue to grow. If we are toforestall a major economic power crisis, say 20 years from now, we shall have tolearn how to utilize not 1 per cent or so of the raw materials (uranium and thorium)for fuel, but much more -hopefully close to 100 per cent. Should we learn how toburn a large fraction of the uranium and thorium, we would gain in three respects:we would forestall a serious rise in the cost of power; we would reduce the fuel cyclecost of a reactor, since in effect we would be burning the abundant and very cheapU238 or Th232, not the costly U235; and we would make available, at relatively smalleconomic penalty, the vast residual amounts of uranium and thorium in the earth'scrust. To anticipate our conclusion, we could hope to achieve power costs of only1.5 mills/kwh in publicly owned stations, and we could foresee maintaining this lowcost essentially forever. It is this prospect, and what it implies for energy-consum-ing industrial processes, that warrants our using the extravagant phrase "TheNuclear Energy Revolution."
FIG. 1.-Cost of nuclear electric plants. The length of each short-line segment represents theuncertainty in the ultimate output of each reactor. The values shown are mostly manufacturers'"turn-key" prices, and do not in many cases include all the customers' costs. Complete data areusually not available.
Fuel cycle (mills/kwh)Total power cost (mills/kwh)
116*Expected stretch,
620 Mw301088
First 101.5
0.481.673.65
TVAnuclear
116tGuaranteed
1100 Mw355.7
85First 12
0.89
0.231.252.37
TVA coal
117
355.7
85First 12
0.90
0.241.692.83
* Includes $4/kw transmission and $2/kwvworking capital other than fuel.t Reduces by $9/kw if anticipated stretch is realized.
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The key technical problem" is to develop a breeder reactor-one that will produceat least as much fissile material-as it burns. Most of the world's attention isfocused on the fast-neutron breeder based on the U2 -Pu239 cycle. This is natural
since the primary question about a breeder-will it create more fissile material thanit consumes -is not in doubt in this system. The number of neutrons produced per
fast neutron absorbed in Pu239 is around 2.9. Since only one neutron is requiredto maintain the chain, 1.9 neutrons are available for breeding. Even with inevi-table losses, engineered fast breeders show breeding ratios (that is, the number ofnew atoms of Pu239 produced per atom of Pu239 consumed) of around 1.3 to 1.5.
Several sodium-cooled fast reactors have been built-EBR-1, EBR-2, and Fermiin the U. S.; Dounreay in the U. K.; Obninsk in the U.S.S.R.-and plans are wellunder way to build several more prototypes, notably a 200-Mw sodium-cooledfast breeder in England.
3.0O
FIG. 2.-Ore costs for H20 reactors with pluto-nium recycle.
1970 1990 2010 2030YEAR
Yet, in spite of the great emphasis on fast breeders that the world now displays,there are some difficulties that must be overcome before fast breeders become com-
mercially successful. The fast reactor suffers from being such a compact device.The high fission density leads to a strong flux of high-energy neutrons, and theresulting intense fast-neutron bombardment of the cladding and other structuralmembers in the core of the reactor reduces their strength. For example, heliumproduced by (na) reactions in structural metals like stainless steel or nickel-basedalloys tends to coalesce at grain boundaries (Fig. 3). As a result the metal can loseits high-temperature ductility. Though this "helium disease" can be controlledto some extent, say by providing additional sites on which the helium can precipitate(lower half of Fig. 3), this embrittlement imposes an undetermined limit on thelifetime of a fast reactor core. This is not to say that the reactor will not work; itis rather that the internal parts of the reactor may have to be replaced more oftenthan one would like.An additional difficulty is economic. Another facet of the compactness of the
fast reactor is that it is relatively "undiluted." In a fast breeder, the number ofother atoms with which each fuel atom is intimately mixed is of the order of 15,
2.5
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Standard Type 304 Stoahness Steel
ORNL Type '01 Stcii nr ss Steel Modifiedi w;sit' Tin iurn
$ (......oij°.~~ ~ ~ Vx-1 4.d
FIG. 3.-Comparison of grain boundaries in irradiated stainless steel.
while in a thermal breeder it is of the order of 1,000. As a result, several times asmuch heat per unit of fuel can be extracted in a thermal machine and still leave itseveral times as comfortable as regards temperature rise under coolant flow block-age, afterheat, etc. In other words, the thermal breeder has a higher "specificpower" or a lower "specific inventory." The basic problem of the fast breeder is,so to speak, not to make it breed but to get the heat out.,The high specific inventory (amount of fuel required per unit output) of most fast
breeders is a weakness of this reactor type and constitutes an economic disadvan-tage. The total amount (q) of fissile material that must be obtained from an outsidesource to stock a system of breeders depends upon the specific inventory (m) andthe doubling time (T) of the breeder, and upon the power growth curve of thesystem. For a linear power rise of the breeder system, q is proportional6 to mT;more generally it is proportional to mf(T), where f is an increasing function of Tand depends upon the shape of the power rise curve.
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Since T is proportional to m and inversely proportional to the breeding gain (b),and since fast breeders typically have values of both b and m several times largerthan do thermal breeders, the values of T are generally comparable in the two types.For example, in a group of fast-breeder designs7 the estimated doubling timesranged from 7 to 30 years depending somewhat upon the conservatism of the design,whereas in some recent thermal-breeder design studies8 the doubling time rangedfrom 6 to 21 years, being 13 for the reference design. For equal values of T, thefuel from outside required to fuel the system is proportional to the specific inventorym, so that stocking a fast-breeder system puts several times as much demand on theore supply as would stocking a thermal-breeder system. This difference can bequite costly, especially if the introduction of the breeders is delayed until the low-cost ore is exhausted. However, once the fast system is stocked and established,it will yield a larger surplus fuel output in the future for possible uses outside thesystem.
The Status of Thermal Breeders-The Molten-Salt Reactor Experiment.-We shouldlike now to describe the outlook for nuclear breeding in the thermal U233-Th212cycle. The outstanding contender for achieving low doubling time in an econom-ically attractive embodiment appears to us to be the molten-salt breeder. In thisreactor the fuel and the fertile Th232 are carried in separate streams as fluoridesdissolved in a carrier salt of BeF2-Li7F. These mixtures melt at around 500'C;but once molten, they can be handled with remarkable ease. The salts hardlyattack nickel-based alloys, since the negative free energy of formation of the con-stituent halides in the salts is comfortably higher than the negative free energy offormation of the fluorides of nickel, chromium, molybdenum, and iron. Moltensalts have been circulated in systems made of INOR-8, a specially developed alloycontaining Ni-Fe-Cr-AMo, for tens of thousands of hours without causing anyappreciable attack on the metals.A breeder based on molten fluorides might consist of a central core of graphite
through which the uranium-bearing fluoride would circulate (Fig. 4). When thefuel is in the graphite core, it undergoes chain reaction; the fuel carries its heat to aheat exchanger where it is cooled by a secondary salt that in turn raises steam in asteam generator. Breeding takes place in a separate stream of molten salt con-taining thorium fluoride. This stream flows around the outside of the core, catch-ing neutrons that leak from the core.The molten-salt breeder has certain advantages that intrigue those of us who
have worked on it. The reactor operates at high temperature and low pressure.The liquids are noninflammable and do not significantly react chemically withwater. Since the fuel is molten, costly refabrication is unnecessary. The chemicalreprocessing, for recovering newly bred U233 and eliminating fission products, canbe performed handily by fluorinating the mixture to remove UF6, and by vacuum-distilling to separate the nonvolatile rare-earth fission products from the more vola-tile carrier salts. We estimate, on the basis of preliminary designs, that the fuelcycle should cost between 0.2 and 0.3 mills/kwh (Table 3).A 1000-Mw molten-salt breeder has been designed in a preliminary way at
ORNL.8 Though it is premature to place much credence on such designs, thereactor is expected to combine a breeding ratio of 1.07 with a doubling time of 13years and a specific inventory of 0.7 kg/kw. We are gratified that our estimates of
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the capital cost per kilowatt of the reactor (including the cost of the salts and fertilematerial, i.e., of all the necessary working fluids except the cost of the fissionablefuel proper) are the same as those for the TVA reactor in Table 2. Recent pre-liminary design studies of several reactor types carried out by the manufacturersor other especially qualified organizations indicate that the capital costs drop below$100/kw for plants a few times larger than the TVA unit. Since we wish to look alittle into the future, we shall assume that the cost of the molten-salt breeder hasalso been brought to this value by size scaling, or by the use of cheaper materialsthan INOR-8, or simply by design improvement and evolution. Then, correspond-ing to the two nuclear columns of Table 2, we obtain the hypothetical results shown
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in Table 3. As shown in Table 3, the projected over-all cost of power from a breedercomes to about 1.2 mills/kwh, assuming TVA financing (5.7% fixed charges), and1.9 mills/kwh, assuming Oyster Creek financing (10% fixed charges). Mostpublicly owned plants would fall between these two extremes, and some privatelyowned plants might show fixed charges a little higher than Oyster Creek.The road to a successful molten-salt breeder is not an easy one. The main
objection to such a system is that it handles intensely radioactive fuel in a highly
* Reckoned at 1.5%/yr of the plant capital cost, as in the TVA plant of Table 2.t No income from the sale of surplus bred fuel has been assumed in these estimates.
labile form. Perhaps the most serious question is: Can such a reactor be serviced,once it has become radioactive?To answer such intangible, though real, questions of feasibility, we have con-
structed and operated at ORNL a small molten-salt reactor experiment (Fig. 5)that embodies some of the principles of a full-scale molten-salt breeder. The reac-tor uses graphite as moderator; but instead of circulating two fluids, a streamcontaining fertile Th232 and a stream containing fissile U283, it circulates only astream containing fissile U231. The reactor is therefore not a breeder, but simplyburns U235 at very high temperature.As of this writing, the reactor has completed 1000 hours of operation at a power
of about 7.5 Mw. It has operated to date with surprisingly little trouble,especially considering its novelty. The reactor is now undergoing its second en-durance run at high power. If the molten-salt reactor experiment continues to goas well as it has thus far, we hope that by the early 1970's we shall be able toconstruct a true molten-salt breeder.
The Uses of Cheap Energy-Desalting the Sea.-We have tried to make plausiblethe proposition that within about 20 years or so we may be able to generate elec-tricity on a big scale at costs of perhaps 1.2 mills/kwh (TVA financing) or 1.9mills/kwh (private financing). We should like now to examine the question:What can one do with blocks of electricity that are this cheap, and that have thegreat advantage of not requiring a nearby coal field?
If the cost of electricity is so low, thus implying a low cost for prime steam, thecost of steam which has been partially expanded through a turbine will be lower still.The prime steam needed to produce electricity at 1.2 mills/kwh is worth around100/106 Btu, assuming a high-temperature reactor. If steam is extracted from aback-pressure turbine at 250'F, its value, as measured by its capability to generate1.2-mill power, is down to about 30/106 Btu.We doubt that the chemical industry has ever seriously been confronted with the
availability of energy as steam at 30/106 Btu or as electricity at 1.2 mills/kwh.Obviously, with energy at this price, it pays to devise a chemical process to trade
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off energy for simplicity of capital equipment, i.e., to use energy more lavishly, ifin so doing one can simplify the process and its equipment.
It was this basic notion that underlay R. P. Hammond's approach to the de-salting of the sea. Sea water contains 35,000 ppm dissolved solids. To remove thesalt from 1000 gallons of sea water, about 3 kwh of mechanical work (requiring, at41% efficiency of converting heat to work, 2.5 X 104 Btu of heat for its production)is necessary, provided the desalting is done reversibly. At 1.2 mills/kwh thisenergy would cost less than 0.40/1000 gallons.
Simple distillation requires over 300 times as much heat as the ideal process.However, this statement exaggerates the difference since the heat required for powerproduction must be at high temperature, whereas heat needed for distilling can beat relatively low temperature and is therefore inexpensive.
Multiple-effect evaporators reuse the heat many times by putting it, so to speak,through many simple distillation steps in series. Raising the performance ratio-the number of times the heat is used-reduces the amount of heat needed.9 How-ever, higher performance ratio means more expensive equipment -the evaporator,for example, must have at least one additional effect for each unit of performanceratio. Roughly, the capital cost increases linearly with performance ratio. Thus,for each cost of energy and for each incremental capital cost per unit performanceratio, there is a performance ratio that minimizes the cost of water. Reducing thecost of energy lowers the optimum performance ratio.
Until Hammond's views prevailed, no one took very seriously the possibility ofusing energy as cheap as a few cents per 106 Btu in a distillation plant. Most of thedevelopment in evaporator design was directed at increasing the performance ratioto 30 or more and raising the maximum water temperature. Hammond's emphasison the possibility of cheap energy has focused attention on evaporators, especiallyin large size, with lower performance ratios. The recently described MetropolitanWater District of Los Angeles plant-which is now going forward to construction-is to produce 150,000,000 gallons per day of water at a performance ratio of 10.4.It uses two large light-water reactors and also produces 1500 Mw of power. Theestimated water cost at the plant site is 210/1000 gallons, and the power is valuedat 2.7 mills/kwh. These costs reflect the usual very low fixed charges assessedagainst municipal water projects. A more recent study at ORNL using an organic-cooled heavy-water reactor as the energy source and a slightly more advancedevaporator with a performance ratio of 10 has come out, under the same generalrules, with 250,000,000 gallons per day at 160/103 gallons plus some 600 Mw at 2mills/kwh. 10
It appears fair to say that responsible opinion now views 150/103 gallons as areasonable target visible along the lines of currently accessible technology. But thenext factor of two in cost reduction below that is going to be much more difficult toaccomplish. Is there any chance of reaching agricultural water prices, say, lessthan 100/1000 gallons? Most writers say absolutely no, that completely unforeseentechnical breakthroughs are needed to achieve such costs. We think the situationis not anywhere near that hopeless. For if the above 1.2 mills/kwh figure is ac-cepted, with its exhaust steam cost of 30/106 Btu, then at a performance ratio of 12,the heat energy costs 20/103 gallons (note that this is only a few times the energycost of the ideal reversible process).
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TABLE 4HyPorn!TIcA Fulrupx WATER COSTS
Component Cents/103 gallonsHeat 2Capital 4.1Operation and maintenance 1.2Pumping power and chemicals 1
Total 8.3
Vertical-tube evaporators can be made self-pumping to a considerable degree, toreduce pumping power costs; and it may be possible to eliminate the need for theacid treatment employed at present. Improved heat transfer with fluted tubes orspecial surfaces to promote boiling and dropwise condensation may substantiallyreduce the tube surface required, and therefore the plant capital cost. These arepossibilities that to us seem to lead to water in the agricultural range of interest.At the very least, we believe the goal of agricultural water is a plausible and im-portant one and that the kind of engineering research that led to very cheap reactorssurely should lead to very cheap evaporators.We are assuredly not able to evaluate these possibilities numerically at this time.
Much hard work in engineering and research and development must precede anyeconomic assessment, but to sketch one possibility let us suppose the following.Imagine that a large evaporator costs 250/daily gallon. Although this is lower thanany published figures, it is not impossibly lower. Take the capital charge to be 5.4per cent annually, and suppose operation and maintenance and interim replace-ment11 to add another 1.6 per cent for a total of 7 per cent. At 90 per cent loadfactor this amounts to 5.3¢/103 gallons. We suppose further that it has been pos-sible to reduce pumping power and chemical costs to 14/103 gallons. We wouldthen have a cost for water at the plant as shown in Table 4. Such a cost wouldprobably be said to be in the useful agricultural range.The preceding supposes that the turbine power generated in expanding the prime
steam down to a temperature suitable for evaporator use can be sold at cost aselectricity. If this is not the case, mechanical power would be employed to drive aheat pump "topping cycle" to produce additional fresh water in another evaporator.Vapor compressors for this purpose are being studied. The results are not yet in,but it appears probable that the cost of water from such "water-only" stationsmay be a cent or two higher than from "dual-purpose" stations such as representedin Table 4.
The Uses of Cheap Power -Hydrogen and Other Chemicals.-Can very cheap andvery nearly inexhaustible nuclear electricity be converted into other staple require-ments of our human existence, in particular the important raw material hydrogen?We choose hydrogen because in some ways hydrogen is the key heavy chemical:It is needed for manufacturing nitrogenous fertilizer and therefore for providing theworld's growing billions with food; it is an all but universal reducing agent and,in the very long run, it may displace carbon as the reductant for winning metalsfrom their oxide ores; it is the key element in converting coal (which is hydrogen-deficient) into liquid or gaseous fuels.We at ORNL have thus far done rather little on these intriguing questions; yet
we have encountered enough of interest to warrant a much more thorough exami-nation of these matters.
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The cost of gasoline at the refinery is about $1/106 Btu (12.86 per gallon). Ifrectified power were available at 1.5 mills/kwh to an ideal electrolysis cell, theenergy cost alone for hydrogen would be 440/106 Btu. This must be increasedbecause of the overvoltage, and to it must be added the capital cost; on the otherhand, the by-product oxygen if it can be sold at $4/ton reduces the cost of the H2 by260/106 Btu.The capital costs depend strongly on the design and performance of electrolysis
cells. Here the prime question is how much current can be pushed through the cellper unit area of electrode surface. Recent work on applications of fuel cells forauxiliary power in space suggests that current densities as high as 1600 amp/ft2may be achievable eventually, and that the power required for such high-currentdensities does not go up exorbitantly. In our estimates of capital cost the optimumcurrent densities are around 800-1200 amp/ft2. As the cost of power rises, it paysto use more efficient cells operating at lower current density.We have a study now under way aimed at recasting this advanced technology
into the design of large stationary plants. In the meantime our cost estimates arerather preliminary, but for what they are worth, they are as follows. With 1.5-millpower and no oxygen credit, the cost of hydrogen is $1.10/106 Btu. With theabove-mentioned oxygen credit, the hydrogen cost reduces to 850/106 Btu, so thatif hydrogen is regarded as a potential fuel, its production cost appears competitivewith gasoline.As a fuel, hydrogen is more convenient (though perhaps less clean) if it is carried
in combination with carbon, either as liquid hydrocarbon (CH2) or methane (CH4).12We have made estimates that oil from coal via electrolytic hydrogen might, as aminimum, cost $2.40/bbl or about 400/106 Btu, of which the hydrogen wouldrepresent half the cost. This does not appear to have advantage over the moreconventional steam reforming methods (which use more coal), unless the price ofcoal were to increase noticeably.Another way to carry hydrogen as a fuel would be in the form of ammonia.
Ammonia made from electrolytic hydrogen is considerably more expensive as a fuelthan is hydrogen itself, coming to about $2.00/106 Btu without oxygen credit.But ammonia is of much greater importance for use as fertilizer in food productionthan as vehicle fuel, and here the picture is more interesting. The standard methodof producing hydrogen for ammonia is by steam-methane reforming of natural gas.Table 5 gives cost estimates for the production of ammonia from electrolytic hydro-gen in 3000-ton-per-day plants.'3 The last column shows the cost of natural gas atwhich the standard reforming method can produce ammonia at the same cost asthe electrolytic method. In these estimates, nuclear electricity was assumed to beavailable at 1.6 mills/kwh.A great many standard ammonia plants are now being built throughout the
world in an effort to stave off what Senator Carlson"4 calls "the impending worldcrisis of mass starvation .., a global famine of incomprehensible magnitude anddevastation," and their performance will surely be improved during this largeamount of engineering activity. On the other hand, the electrolytic plant studymentioned above may lead to some improvement also. In particular, it may showthat more cost scaling with plant size is justified, a possibility for which only partialcredit has been taken in the estimates shown in Table 5.
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TABLE 5COST ESTIMATES FOR PRODUCTION OF AMMONIA
ElectrolyticNuclear electric Return on plant oxygen Competitive
power cost investment credit Production cost natural gas cost(mills/kwh) (%/yr) ($/ton 02) ($/ton NHs) (t/1O' Btu)*
* The average cost of natural gas, delivered, in the U.S. is -350/106 B3tu.t After income tax.I Off-peak power, available 50% of the time.
Though the production of hydrogen by electrolysis does not appear at presentto be competitive with methane reforming at locations where natural gas is cheapand abundant, it does appear to hold the promise of a limitless supply for the futureat essentially any location at a reasonable cost.Summary-The Nuclear Energy Revolution.-We have tried to show that energy
at about 1.5 mills/kwh anywhere on earth could make a qualitative change inthe world's industrial economy. At this price for prime energy it seems plausiblethat we can desalt sea water economically, and it seems to us to be at least a plausiblespeculation that we can produce hydrogen, and thence ammonia, and possibly even
fluid fuel from coal at prices that are not much higher than we now pay for thesecommodities. The great advantage of basing these processes upon nuclear energyis that when breeder reactors are developed, the energy will be available quiteindependently of the availability of raw materials. Once a breeder reactor is in-ventoried with its initial load of fuel and fertile material, it can run without requir-ing any new fuel or fertile material for many decades. Thus the energy economyof a country, and therefore the many parts of its industry that can be based ulti-mately on energy, becomes decoupled from the accident of local distribution of fuels.One cannot help but be impressed with the vast change in relations between nationsthat would ensue from this ubiquity of cheap energy. It is one of the most excitingprospects the world can expect from the Nuclear Energy Revolution.
* Public lecture delivered during the Autumn Meeting of the National Academy of Sciences,held at Duke University, 1)urham, N. C., October 17-19, 1966.
t Operated for the U.S. Atomic Energy Commission by Union Carbide Corporation.l Jersey Central Power and Light Company, "Report on economic analysis for Oyster Creek
nuclear electric generating station," Nuclear News, 7, no. 4, Special Supplement (April 1964).The station being built is a little less expensive than the one analyzed in the report.
2 Tennessee Valley Authority, Comparison of Coal-Fired and Nuclear Power Plants for theTVA System (Chattanooga, Tenn.: Office of Power, June 1966).
3 Dietrich, J. R., "Efficient utilization of nuclear fuels," Power Reactor Technology, 6, no. 4,34 (Fall 1963), U.S. Atomic Energy Commission Division of Technical Information, Oak Ridge,Tennessee.
4 U. S. Atomic Energy Commission, Civilian Nuclear Power: A Report to the President-1 962,and Appendices (Oak Ridge, Tenn.: U.S. Atomic Energy Commission 1)ivision of TechnicalInformation Extension, 1962).
5 Weinberg, A. M., and E. P. Wigner, The Physical Theory of Neutron Chain Reactors (Chicago,Ill.: Univ. of Chicago Press, 1958), pp. 127-130.
6 Young, G., "The fueling of nuclear power complexes," Nuclear News, 7, no. 11, 23-30 (Novem-ber 1964).
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7AEC Chicago Operations Office, An Evaluation of Four Design Studies of a 1000 MweCeramic Fueled Fast Breeder Reactor, COO-279, Table 3.6 (December 1964). Only the fuel in-ventory in the reactor proper was taken into account here, the external holdup in cooling timeand fabrication and reprocessing plants not being included.
8 Kasten, P. R., E. S. Bettis, and R. C. Robertson, Design Studies of 1000 Mwe Molten-SaltBreeder Reactors (ORNL-3996, Oak Ridge National Laboratory, August 1966), p. 138. The ex-ternal fuel processing holdup was included here.
9 At a performance ratio of 8, 1000 gallons of water requires 106 Btu of heat. This is convenientto remember since heat costs are usually given in 0/106 Btu. Thus, at a performance ratio of 8,the energy cost in ¢/101 Btu is the same as the energy cost in ¢/1000 gallons.
10 Hammond, R. P., J. A. Parsons, and I. Spiewak, Conceptual Design Study of a 250 MillionGallons Per Day Multistage Distillation Plant (Office of Saline Water R and D Progress Reportno. 214, U.S. Department of the Interior, Washington, D. C., February 1966).
11 The tubes are considered to last the write-off life of the plant without replacement, with afew per cent blocked off as they fail.
12 Electricity itself may well be the most convenient and cleanest fuel for vehicle use, with theelectric automobile now showing signs of a comeback. A complete switch-over to electric autoswould about double our use of electricity and thus substantially increase the fraction of our totalenergy which can be supplied by nuclear power. See Hoffman, G. A., "The electric automobile,"Sci. American, 215, no, 4, 34-40 (October 1966).
13 Blanco, R. E., et al., An Economic Study of the Production of Ammonia Using Electricity froma Nuclear Desalination Reactor Complex (ORNL-3882, Oak Ridge National Laboratory, June1966).
14 Carlson, Frank, U. S. Senator (Kansas), "The Importance of Reclamation to Agriculture,"talk presented at a meeting of the National Reclamation Association, Kansas City, November 11,1965.
