fusion reactors: their commercial potential

Journal of Fusion Energy, Vol. 4, Nos. 2/3, 1985

Panel Discussion

Fusion Reactors: Their Commercial Potential

Philip Stone, ~ Michael Monsler, z B. Grant Logan, 3 Betty K. Jensen, 4 and Daniel R. Cohn s

REMARKS BY PHILIP STONE

I want to outline our plans for the Reactor Studies Program next year and beyond. First of all, we will complete the TFCX Preconceptual Design work. That is a central part of the reactor design activities that are going on now. About half of the work in the Reactor Studies Program this year is, in one way or another, directly tied into the TFCX design activity that's going on this year. We hope to start conceptual design late in the year or first thing next fiscal year.

We would like to initiate a STARFIRE II tokamak power reactor design. We haven't defined what this is; we haven't even yet settled on the name STAR F IR E II. STARFIRE is such a superbly suit- able name for these reactor design studies that we're reluctant to give it up, so maybe STARFIRE II will be what we call it.

More importantly, we are trying now to de- termine what the boundaries should be for this S TAR F IR E II study that we would start next year. Should it be a complete new power reactor design; should it be an upgrade of the original STARFIRE; or should it be some combination in between? This has not yet been determined. It is our intention to use the more recent physics that has gone on in the past five years, the better scaling laws that we have now, to put in perhaps a new blanket, better RF, whatever. There have been advances in five years, and we want

1Office of Fusion Energy, Office of Fusion Research, U.S. Dept. of Energy, ER-532, Germantown, Washington, D.C., 20545.

2KMS Fusion, Inc., P.O. Box 1567, Ann Arbor, Michigan 48106. 3 Lawrence Livermore National Laboratory, P.O. Box 5511 L-644, Livermore, California 94550.

4Betty K. Jensen, PSE & G Research Corp., P.O. Box 570, T16A, Newark, New Jersey 07101.

5Daniel R. Cohn, Massachusetts Institute of Technology, NW16- 140, Cambridge, Massachusetts 02139.

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to revisit those issues and do it in a systematic and fairly thorough fashion. That program would be started next year.

Parallel to that, we want to go back and continue work on the MARS Tandem Mirror power reactor design activity. MARS was completed in fiscal year '83. The design report is soon to be out. But there are improvements in the end-cell magnets; there are difference approaches to some of the costing sections, and there are a number of things that we would like to do to improve and continue delibera- tions on the MARS concept. The parallelism between having both the STARFIRE-type and a MARS-type reactor design going on together next fiscal year is something that 1 think is favorable. In particular, it brings them to the same time scale, the same level of understanding in the basic physics. It also allows them to be done in a way that approaches standard procedures for design elements. We want to try to identify and get a consensus in the reactor design community as to what those standards should be and how the design studies should be conducted so that comparisons can be made- -same costing techniques, same magnet design criteria, and that kind of thing. Clearly, we cannot always have that standardization. So there may indeed be exceptions where, for in- stance, a particular design feature of magnets in a MARS configuration may be different from a tokamak. But at least by attempting to define standards parallel to the work, possibly even a little bit in advance of it, we can understand clearly where the exceptions have to be taken. We want to put effort into that during this and the next fiscal year.

This year we are looking at an Engineering Test Reactor for a tandem mirror; something to be on the table somewhat analogous to the INTOR-type of ETR design we have for tokamaks. This work has

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162 Stone, Monsler, Logan, Jensen, and Cohn

been going on since last fiscal year; it's going on this fiscal year between the Design Center and Livermore. I call it a system level design. I 'm not sure Grant Logan would call it that, but it's not exactly a full conceptional design--i t is more a top-down, system- level look, tradeoff studies, and analysis. We want to complete that this fiscal year and then go back to the MARS activity next fiscal year.

We of course will continue the INTOR workshop, which is in "PHASE IIA," a Critical Issues Study. Finally, I would like very much to develop a study of "high-power density kinds" of concepts--a generic study, one that can begin to look at, from the engineering viewpoint, certain generic characteristics of high-power density systems, so that we can get a handle on the attractiveness of these concepts as a group. I don' t think the physics is in such a stage that we should undertake a detailed conceptual design of one particular concept, an RFP or a Field Reversed Configuration, or whatever; but, clearly, certain generic issues such as high-wall loading characteristics of these kinds of machines can be studied. Maybe some other characteristics such as these could be looked at from a reactor design viewpoint with the idea of really evaluating whether or not such high-wall loadings-- i f that's the issue we pick--are a problem for us. Maybe it will give incentive back to the physics experimental program. Maybe it will clarify our own thinking as to just where the high-power density activities can fit into the program in the long run. That program hasn't been designed yet. I 'm not sure just what that activity is; it's general in our minds at this point. How we carry that out and exactly who carries it out, is not yet determined. I envision the work as a group activity among several of the laboratories that are involved in our Reactor Design Studies Program, but that is still to be arranged. Starting next year I am anxious to pay serious attention to the high-power density concepts.

Beyond next year things are much less clear, as you can understand. Assuming that our TFCX program does get funded and we proceed with that, then the reactor studies program itself would probably go back to looking at, in a serious way, a comparison between mirrors and tokamaks of power reactor designs-- that is commercial-level designs--and to seriously evaluate the high-power density concepts for that purpose and to develop both a mirror and tokamak engineering test reactor design. That is, we still envision that there is an engineering reactor, a

test facility of some kind beyond the TFCX, beyond whatever nuclear testing facilities are put in place in the next decade, and that this engineering reactor then would be the next step. We would want to have a mirror and tokamak design on the table, done to more or less equal levels of sophistication. If TFCX were not to go, or if we got a clear-cut signal that ignition experiments in general were not to go, I imagine we would go back to the engineering reactor designs as a first priority. I think if TFCX does go, there will be a lot of attention given to where we go after that; that is, to where the fusion program is going. TFCX, if it gets accepted, will be looked at as very much an intermediate step. There will be a lot of attention and a lot of questions asked about what the engineering reactor design is mad what that attractive reactor concept out there is that we are eventually going to build.

REMARKS BY MICHAEL MONSLER

My objective is to communicate two major points, one specific to Inertial Confinement Fusion (ICF) and one applicable to fusion in general. First, inertial fusion has some very compelfing features which can lead to reactors that have promise for low cost, low radioactivity, low afterheat, and high maintainability and reliability. These features spring from very fundamental considerations, that I will describe, which are not generally appreciated outside the ICF community.

Second, in both ICF and magnetic fusion, I believe we are doing an inadequate job of communi- cating a vision of our final product. The fusion reactors that we have promised are not sufficiently attractive to pull a greater funding rate from the public and from Congress. We have wrongly deem- phasized, or taken for granted in some way, a market need for our product and instead emphasized the frustrating "technology push" approach. I will return to this second theme in a moment.

To demonstrate the unique features of ICF, which are likely to lead to attractive reactors, I am going to transform Harold Furth's idealized magnetic fusion reactor into an idealized ICF reactor. We begin with a burning plasma several meters across surrounded by a first wall and vacuum chamber, which is then surrounded by the blanket where the neutron energy is absorbed, which is then surrounded

Commercial Potential of Fusion Reactors 163

by the shield and cryogenic magnets, which is then surrounded by the plasma heating and refueling equipment, which is then surrounded by utility ex- ecutives praying that the whole thing will all hold together and nothing goes wrong.

Because in an MFE reactor 60 to 70% of the energy must be transmitted through the first wall (the steel wall) in the form of 14 MeV neutrons, to deposit their energy outside, the walt becomes embrittled and radioactive and must be changed out every five years, or so. The cryogenic magnets and plasma engineering equipment also become radioactive, and they must be maintained by clever robots. Now I do not for a minute doubt that this can be done. But let's instead make a gedanken transformation here. First, shrink the plasma down to a few millimeters in size, in such a way that its decoupled from the vacuum chamber. You see, an ICF pellet has plasma physic constraints that are separate from the reaction chamber constraints.

This allows us to take the neutron blanket, which was formerly outside the first wall, and bring it inside in the form of a meter thick layer of damage-proof liquid, which might be lithium, lithum-lead or molten salt or a number of variations.

Ninety percent of the neutron energy is now deposited in the liquid blanket before it reaches the structure, so the wall is going to last at least ten times longer. In addition, it has ten times less, or maybe closer to 50 times less, radioactivity and afterheat. So now we have a concept which, in principle, never needs a first wall changeout, has the size and power density comparable to a fission reactor vessel (not the core), and does not need an emergency core cooling system to protect against melt-down in the event of a loss of coolant. Now, unfortunately, even roses have thorns; the energy in an ICF reactor is released in a pulsed way, in fact, in a potentially damaging manner. Fortunately we now know how to design, at least conceptually again, the configuration of a liquid metal blanket to dissipate much of the kinetic energy that is created and to spread out the momentum generated over a very long time period compared to wall re- sponse time, in such a way, that we can get the transient stresses well within the fatigue limits.

Finally, of course, we throw out the magnets and cryogenics and put the lasers in a separate building where they do not have to be maintained by robotic means. The laser, if desired, can also be used to drive a number of modular reactors. So now, from a funda-

mental viewpoint, you can envision a reactor that has excellent promise for the things we are looking for: a high-power density reactor of rather remarkable simplicity. Now I don't for a moment underestimate the enormous engineering development that has to go into such a ICF reactor, but it's always best to begin with a concept, it seems to me, that has the requisite elegance and simplicity before you get into all the complications.

Now I want to return to my second, more general point. We are paying insufficient attention to the marketing of our eventual product, fusion reactors, and fusion research. We take for granted the desir- ability of the fruits of our labor. We are relying too much on " technology push" rather than on the pull of the market. Inadequate funding is a result. Both in ICF and MFE, we are in a frustrating box. We need another physics machine that is quite expensive. In each case, we must study the physics of burning plasmas, with a large enough product of size and density, before we can be sure of technical feasibility. But technical feasibility is only necessary and not a sufficient step toward success. The political landscape is littered with technologies of proven technical feasibility that the market was unwilling to accept. Exam- ples are synthetic fuels, breeder reactors, supersonic airliners, maybe even today's lightwater reactors, at least in the U.S. They did not meet a genuine market need or they missed some key factor that was important. We are not short of energy. We have three hundred years of coal and infinite fissionable resources, near infinite in a breeder economy. What we are short of is a cleaner and safer version of this energy, that's inexpensive to buy and operate. Now that is pure motherhood, but we are measured against those terms. We are viewed as too complex and expensive, with fair justification. STARFIRE, MARS, HYLIFE, and HIBALL are, frankly, not sufficiently attractive visions of the future to spring loose more tax money or to induce people to run higher deficits.

I cannot resist offering my own analogy to this development path here. We are saying we need a budget increase of a few hundred million dollars a year because we are on the threshold of demonstrat- ing the technical feasibility of a biplane with cloth wings and wire struts and so forth, which is our state of the art. And, by the way, we can foresee a huge airliner entirely made of spruce with 12 propellers on it that takes off from the water (it's too heavy for landing gear). It can't carry many passengers because


all it can carry is its own fuel, and so forth. A n d Congress is saying, "Well, your biplane progress is interesting, but we will ride the trains a few more years and you will continue a level of effort."

Ok, we must look beyond the Spruce Goose to the 747 of fusion reactors, beyond the close extrapo- lations from what we know how to do. Now there are big risks in that, but I feel we must take the political risks of potential failure, of overpromising, and pro- ject a vision of a future fusion reactor that's only limited by the laws of physics and not by our current engineering limitations and our natural conservatism. In fact, I believe we must take several million dollars from the currently underfunded physics programs and take some of the brightest people from the labs and industries and apply the people and money to innovating a truly attractive fusion reactor.

Once we have created a real demand, and a political constituency for our future product, we will obtain increased funding to do the fusion research. The U.S. is not short of funds. The superconducting supercollider, the Strategic Defense Initiative, the Manned Space Station, all will be funded at the level of 10 billion dollars or whatever, because somewhere there is a demand, there is a political constituency.

As managers of R & D, we are used to counsel- ing people to not cut the research when the funding is tight. Thou shall not eat thy seed corn if you want a future crop. But we overlook the equally short-sighted nature of cutting the marketing function. A field of corn is useless if you haven't created a demand for corn products.

We cannot base our program on the fallacious premise that a demonstration of technical or scien- tific feasibility will spring loose a torrent of public funds. It did not work for breeders or others and it will not work for us: it is just necessary but not sufficient. In fact, we have heard of Furth's first law: "Progress is when your critics stop saying you can't do it and say, instead, that they don' t want it." Now we laugh at this all the time because its both true and very frustrating. I 'd like to add Monsler's second law: success is when your critics say, " I still don't want it, but it's better than the alternatives and I'll take it." I think that is the way decisions get made. Nobody is ever happy with what they are offered, but if you do have a decent alternative, they will indeed adopt it.

So let's go back and put a top priority on creating the demand and creating a political constituency. A larger political constituency for fusion research will lead to increased funding. This requires

investing now in the innovation of truly attractive fusion reactor designs.

REMARKS BY B. GRANT LOGAN

A lot of the discussion for this Fusion Power Associates meeting is stimulated by people asking: What 's wrong with fusion? Why isn't it moving ahead as fast as we had hoped? It doesn't look like experimental results are really holding us back. Some people, like Larry Lidsky, have said, it's our product; nobody wants our product. If I were to try to draw a consensus of the sentiment of this meeting in a few words I would conclude: we want something smaller, something with a higher power density, and we want something that can be modularly built.

Another thing we shouldn't forget is safety. Let me bring that about in connection with cost. From studies of fission problems, we know that safety and cost are related. So far, in fusion reactor studies, we haven't been sophisticated enough to be able to trans- late safety advantages in terms of cost. But it's a very real issue for fission.

I would suggest that, while we're asking our- selves what's wrong with fusion, let's also listen to our colleagues in fission, some of whom have at least asked the question "What 's wrong with fission?" even before Clinch River.

Put another way, let's beware of some of the pitfalls that fission has gone through and beware that we set a standard for fusion to aspire to, which would be to compete on every level in size and in safety characteristics with a light water reactor. That may be the wrong standard; indeed to some people it's a tarnished standard. If there's a path for fusion that would differentiate it in characteristics from fission, let's try to exploit those characteristics. So let me make a few quick comments on directions for improvements in our future studies.

First of all, the most frequently heard thing is cost. The problem is that most people believe that if fusion is somewhere around twice the capital cost of an LW R that is a serious impediment for fusion, no matter what other characteristics you have. If fission is too expensive, something twice as expensive as that would surely be a real impediment.

There's also the fact that even to do that well, we generally had to design large systems, not so much because that's a preferred way to go, but because if our plasma physics concepts with confinement scaling would have allowed us to get away with a smaller


unit size without coming into severe penalties in the energy balance in the plasma, I think: we would have done that. I think we are trying to listen to the utilities asking for smaller units, but we just haven't been able to find a way so far. We need to keep trying to find a confinement system where the plasma confinement is still adequate for units of smaller size so you don' t pay an undue penalty. Even so, when you design smaller units, it's a fair statement that fusion, like fission, always has an economy of scale. Perhaps fusion's economy of scale is a stronger function of unit size than fission, but certainly it's been well recognized that fission does have the economy of scale and can have some problems in capital costs per kilowatt. But I think there's a new idea, presently, which says that that may be true about the direct costs, but the indirect costs that have to do with construction time, the ability to build factory compo- nents, can more than offset the disadvantage of economy of scale. That's something that I hope we can learn from some of the studies of small fission reactors.

Most people take superconducting magnet technology as a known entity; that it is a given that all fusion blankets will be a certain thickness and that the magnets are going to be so thick and cost so much and that that's an irreducible intrinsic limit. There is quite a bit of range of performance for superconducting magnets. We are just beginning to explore what possibilities there might be that could be developed within the next 50 years in reducing the weight, stored energy, and cost of the superconducting magnets, and also to allow them to take a higher neutron fluence so that you can get by with a thinner shield and ba-ing the radius of the magnet in. Some of this has come about simply because the people designing blankets and doing neutron shielding calcula- tions, who tend to have neutronics backgrounds, weren't the same people as the magnet designers who were designing magnets without considerations of neutron damage in mind. If you ask the magnet designers if they have ideas to make radiation- hardened magnets, they would say yes, we've got all kinds of ideas if we can get on with the development. We'll see quite a shrinkage for a given plasma and wall loading, quite a shrinkage in the size, weight, and cost of the structure around it. So we're attacking the dollars per kilowatt, if you will, by reducing the numerator. The other way is to raise the denominator by putting more power in through the first wall for a given cost of magnet and blanket. However, that may

well bring out a problem on safety, a point I'll return to in a minute.

We've heard a lot about what we need in the blanket area. Here is a short summary of my own feelings on what we should try to emphasize. Reliabil- ity is a serious issue. Dan Cohn brought that up. We've just got to find ways to reduce the plumbing and number of welds because of the failure rates which are common experience in fission. There are ideas to make these systems tolerant of swelling. Swelling is one of the leading causes that determines blanket lifetime. Corrosion can be another, but swelling is often the limit. There are ways to design around that and, in some cases, one can go much more than 10 or 20 megawatt years per square meter. The prospect of having blankets last a much longer period of time is something we ought to look hard at. We shouldn't ignore safety in this, even if our eye is on capital cost per kilowatt, because when you do the balance of plant, the safety systems, the emergency core cooling systems can cost you a lot of money, as people in fission well know. I think it's true that in some blanket designs it's possible to come up with designs in which you can withstand loss of coolant and loss of flow without having a meltdown. That's an advantage that may be true for lots of different designs of fusion blankets, and it's one we ought to try to retain if we can.

There's a large number of alloys, but certainly there are some steel alloys, practical materials, that would reduce the severity of the waste problem of the long-lived isotopes. If you look at the periodic table of isotopes, the bad actors (e.g., nickel) are not actu- ally in the majority. Most metals decay in five years or less, so that in a 100 years the activity problem for waste-disposal purposes can be ameliorated quite a bit.

I think the balance of plant is something we also should not treat as a given; namely, that it is a fixed cost for fission and fusion alike and there's nothing you can really do about it. In fact, when you try to make a fusion design fit a steam cycle, a standard steam cycle, you have to worry about tritium permea- tion into the steam. Maybe the marriage between a 21st century energy source and a 19th century energy conversion system is inappropriate. We can be equally inventive in finding energy conversion systems that, first of all, reduce the amount of piping and we can make compact systems that will fit within a reactor vault building where it is tritium compatible. A cou- ple of ideas include helium turbines that are direct


cycle, something that HTGR people looked at, and liquid metal MHD. Some blanket designs, with direct energy conversion, might be a real step forward.

We ought seriously to take into account in the design of these fusion reactors, ways in which we could subdivide the design, the modules, the first wall, blanket, shield, and magnets, in a way in which you could fashion the reactor out of a set. Either you could come up with a fusion concept, such as compact toruses, in which the whole reactor is one mod- ule, or in a design like the tandem mirror to find a way to go away from systems where the coils are too big to put on a railroad car, because they won't go through a 16-foot railroad tunnel. Instead, try to shrink the size enough to where the weight comes down to around 400 tons, where the diameter is about 12 feet, where you can slice it up. Make interface breaks, so that you factory-assemble these modules. Then reduce the on-site construction to a few hook-ups, so you speed up the construction time. You can also have improved quality assurance in a controlled manufacturing environment. I think that gets at the question of indirect costs. You could design this so it's built in place, or you could design it to be chopped up. However, when you look at the indirects, those are very important issues that we need to take a look at for fusion designs.

Just one last comment on the power density issue. MARS had a wall loading of about 4 megawatts per square meter and, in a loss of coolant, loss of flow, worst case accident, the first wall maximum temperature would rise to about a 1000~ in a few hours. If you did nothing to the design but just increased the wall loading to 10 and 20 megawatts per square meter, you would find that you would get either melting or certainly you would get sagging of the blanket materials. So, if you go to higher wall loading, you would be obliged to put in an emergency core-cooling system. Also, the MARS blanket concept is rather simple and rugged where cooling is easy to do with simple, large diameter tubes in the first wall. But if you go to high heat flux, high wall loading, you've got to get lots of small tubes dose together and reliability will become very important. So power density has to be traded off very carefully against safety and reliability.

REMARKS BY BETIN K. JENSEN

I head the Nuclear Research Group at Public Service Electric and Gas Company, which is the sixth

largest electric and gas company in the nation. We believe it is too early to evaluate the commercial potential of fusion, but it's not too early to address it. To discuss the market pull, the thrust of my comments is directed towards addressing the role of the electric utility in the development of fusion and the responsibilities others are envisioning for the utilities and private industry in the fusion development plan.

I will address, first, the role utilities could have in the development of fusion. A number of studies have been conducted to examine the characteristics of research programs which led to the eventual commercialization of a new technology. A common char- acteristic among those technologies which were suc- cessful was the early involvement of the ultimate user. Early involvement of engineering and manufacturing companies allows for a smooth learning curve and helps assure commercial readiness. Early participation of the utility will help insure that the end result of the research program will result in a usable product. Utifities can help assure that reliability requirements are built into the product early on, since it is difficult to change course at a later stage. The lessons learned from other commercialization programs can be meaningfully applied to fusion. The types of utility participation envisioned are threefold: sponsor, advisor, and direct participant. Sponsorship includes contributions of direct funds and/or labor. This form of participation has existed, at a small scale, since the 1950s and is continuing now, both directly by the utilities, and indirectly at a very small level I might add, by the Electric Power Research Institute.

The advisory role is filled frequently by corporate officials who are asked to help assess various stages of program development and may serve in management boards of development projects. The principal achievement expected from the advisory role is in the development of program goals. These program golas must be developed in conjunction with the ultimate user. One near-term goal, essential to the success of fusion, is the resolution of fusion's environmental and safety issues. For nuclear fission, it has been the public's perception of environmental and safety issues that have proven to be a major stumbling block. Strong efforts should be expended in this area and should be significantly increased during the engineering stage.

The utilities may also become direct participants in fusion research and development. Direct participation requires a corporate commitment of financial


and manpower resources to perform fusion studies. This type of participation begins to be particularly appropriate during the engineering development phase. The utilities' experience can be used effectively in studies related to environmental, operation and maintenance, and safety aspects of fusion. The utilities can also contribute in assessing specific trade-offs that are possible among plant characteristics, such as plant size, modularity, and maintainability of future fusion plants. Much discussion has centered on the preferred utility characteristics. Take plant size for example. It seems that all the speakers today ad- dressed that. Although it is a significant system planning parameter, the optimum plant size is dependent on other factors that are system-dependent. It is not reasonable, therefore, to conclude that one size, be it small or large, is preferable to all utilities. However, there are tools which each utility has developed, specifically in power supply planning, that can aid in examining the possible trade-offs among plant size, capital cost, reserve requirements, and so forth, relative to a fusion design on a model utility system. These tools can be an important aid in examining the decisions made in carrying out fusion designs.

Serving in an advisory capacity, PSE&G has served on the Fusion Advisory Panel for the House Subcommittee on Energy Research and Production. We also served on fusion-related EPRI and Atomic Industrial Forum committees, as well as the Prince- ton Plasma Physics Laboratory Utility Advisory Committee, and as a member of Fusion Power Asso- ciates. PSE&G has also been a direct participant in a number of fusion projects, including DOE-funded design of an inertial confinement fusion central station electric power generating plant. We are currently part of the team that was awarded a Technical Sup- port Services contract from the Office of Fusion Energy, DOE.

Turning to the second point, which centers on the responsibilities being assigned to the utilities and private industry, electric utilities are expected to be supportive of fusion until it moves from the laboratory stage of development to the prototype stage, where utilities can begin to identify with the final product. Then, according to the current DOE thinking, private industry will assume the responsibility for funding the demonstration, through commercialization-size fusion power plants. Our experience leads us to believe that this will substantially increase the risk to the development of fusion. The reason is that the utilities, of necessity, are generally very conservative

when it comes to assuming risk associated with utiliz- ing a new technology. For example, the first lightwater reactor to be purchased without government incentives was Oyster Creek. Oyster Creek was not ordered until 1963. By that time, over 18 power-pro- ducing reactors had already been in operation worldwide. The experience with the HTGR program reinforces this position. Peach Bottom, a 40 megawatt HTGR, was operational as early as 1967. Even though the HTGRs have many potential advantages over the conventional LWRs, only a demonstration unit has been built and operated--that's Fort St. Vrain. A commercial HTGR has yet to be built. The Liquid Metal Fast Breeder Reactor Program offers another reason for utility caution. Here, a small size experimental reactor was operational in 1951. The first LMFBR owned and operated by a utility, the Fermi Plant, was commissioned in 1966. In spite of the operating experience gained in Europe, political diffi- culties have, in effect, closed the chapter on the Clinch River Breeder Reactor.

In view of these experiences, it may be unrealis- tic to expect the utilities and private industry to shoulder the responsibilities of getting fusion from the engineering stage to the commercialization stage. In fact, past experiences compel us to suggest that, to enhance the probability of success of the fusion program, the DOE plan should include support for fusion research and development through the commercialization stage.

In conclusion, many utilities are already inter- ested in fusion energy and are willing to fill a pre- liminary role as a sponsor, advisor, or minor participant. Active steps must be taken to maintain and increase this interest. Early participation by the ultimate user of the technology can help assure that the fusion program benefits from mistakes committed in other programs, and that the technology is success- fully commercialized. Also, there is a strong need for the DOE Program Plan to include government support of fusion R & D through the commercialization stage if fusion is to realize its promise.

REMARKS BY DANIEL COHN

I want to look at the prospects for commercialization of fusion in the context of comparison with


other energy sources. Each of the long-term energy sources has its own issues with regard to cost and environmental impact.

Fission, as is well known, has the highest power density of any of the inexhaustible energy sources and, as a result, has advantages in terms of capital cost. However, there are public concerns about safety, waste disposal, and weapons material production. In addition, in the case of fission, once one starts looking at it as a long-term energy source there are issues concerned with the fuel supply--there is a need for a breeder reactor, or some other source of fissile fuel.

If solar power were to be used as a source of central power production, one would be faced with issues connected with the very low power density and the effect on capital cost. Now', it's clear that solar power would have the environmental advantages of no radioactivity and no air pollution during operation. However, solar power has environmental ef- fects due to the very large construction material requirements. Typically, solar electric plants require 10 to 100 times more material than fission and fusion plants.

In the case of fusion, we have a potential source that has a much higher power density than solar and hence the possibility for lower cost. Relative to fission, fusion has potential advantages in terms of waste disposal, safety, and the absence of weapons material production in electric power plants.

Let me make a few comments now about the cost of electricity. The very low fuel cost for fusion plants allows a higher capital cost relative to fission plants with expensive fuel--that is, fission plants that in the long term will have to use expensive uranium or will have to rely on a different technology such as the breeder. As a rough guideline, the cost of electricity from a fusion plant would be about equal to the cost of electricity from a fission plant in the long-term if the capital cost per kilowatt electric for fusion is in the range of 1.5 to 2.0 times the capital cost for an LWR. Now this, of course, assumes equal availability; that is, the percentage of time the plant operates. It turns out that for present fusion plant designs this cost requirement is roughly satisfied.

From my point of view, the key issue concerning commercialization is the issue of high availability. Can fusion reactors be designed so that they operate a high fraction of the time? I think that the answer is, over the very long-term, yes, because there is a wide range of design space.

I also want to comment about fusion/fission systems--they tend to be somewhat overlooked these days. This potential application of fusion should certainly be considered if a major commitment is made to fission. We don't know what's going to happen in the future. Therefore we have to consider all possibilities and one possibility is that there is a major commitment to fission. If this is true, what are the consequences for fusion?

Fusion could play an important role in this scenario--in that one fusion plant could produce fissile fuel for a large number of fission plants, result- ing in a relatively low cost for fissile fuel. Based on some of the reactor design studies done at Livermore by Ralph Moir and his group, fissile fuel might be provided for $50/lb. equivalent cost of U308. This cost could be lower than that of other long-term sources. Uranium from sea water could be quite expensive because of the very large amount of sea water that would have to be processed. For the LMFBR, there is a range of equivalent costs, which include both increased costs for the reactor and re- processing costs; the range is on the order of $100/lb. to $150/lb.

If fusion could be used to produce fissile fuel it could, in addition to facilitating continued use of existing LWR plants, also provide some advantages in terms of the design of fission plants. If the breeding requirements for fission reactors could be re- moved, then fission reactors could be more readily optimized for a number of potentially desirable features; improved safety (that is, more forgiving reactors, reactors with lower potential for meltdown due to higher thermal capacity), reduced unit cost, non-electrical applications, and possible improvements in proliferation resistance.

In summary, I want to make the following points. First, we don't know what weight future societies will give to environmental impact issues vs. cost. What we're doing in developing possibilities for fusion electric power generation is providing future societies with a choice. The potential advantages in terms of environmental impact (waste disposal, safety, reduced proliferation potential) relative to fission might be considered very important by these societies.

Second, it appears that the cost of fusion power could be roughly competitive with that of fission as a long-term energy source. It may be that the environmental impact advantages will have to be maximized in order for fusion electric power to compete with


fission. On the other hand, electricity from a central solar facility could well be significantly more expensive due to the low power density.

Third, since we don't know what will happen in the future, we have to take into account the possibility that there could be a major comrrfitment to fission

power and, in that case, fissile fuel breeding could be a very important application of fusion energy.

Finally, the achievement of high availability is a critical issue. It should eventually be attainable, given the wide range of design options for fusion reactors.

fusion reactors: their commercial potential

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