The Fusion Energy Program: The Role of

TPX and Alternate Concepts

February 1995

OTA-BP-ETI-141

GPO stock #052-003-01403-3

iii

oreword

or over four decades the federal government has supported research to develop reactors that

harness fusion energy for commercial electric power production. However, even the most optimistic proponents of the U.S. Department of Energy’s fusion energy program note that many

scientific, engineering, and economic challenges remain. Meeting these challenges sufficiently to construct a prototype commercial fusion powerplant is expected to require tens of billions

of dollars in experimental facilities and research over the next several decades.

This background paper, responding to a request by the House Committee on Science, focuses on

the following two questions for the U.S. fusion energy program. First, what is the role of the Tokamak

Physics Experiment (TPX), an approximately $700 million fusion reactor currently awaiting a congressional decision to begin construction? This paper examines the history of TPX planning; the anticipated scientific, engineering, and institutional contributions; and the relationship between the

TPX and the next major planned tokamak facilities, the International Thermonuclear Experimental

Reactor (ITER), currently in the design stage, and the DEMO facility planned for operation in about

three decades, which would be the first fusion device to demonstrate production of electricity.

Second, what is the role of alternatives to the tokamak concept in a broad-based fusion energy program? Over the past several years the program has been narrowed substantially to concentrate on the

single most successful and furthest developed fusion energy concept, the tokamak. This narrowing,

driven heavily by budgetary reasons, has been decried by many fusion researchers as premature given

the current elementary state of fusion knowledge. This study examines the motives for pursuing alternate concepts, the steps involved and costs of alternate concept research, and the current status of

alternate concept research as conducted in the U.S. fusion energy program.

While the focus of the study is on the TPX and alternate concepts, it also provides a history of the

overall fusion energy program. With this context, the study identifies (but does not answer) some underlying questions that must be addressed. The most pressing of these are: what is the potential role of

the fusion energy program in meeting long-term energy needs? what level of research funding is justified by that role? and what are the most reasonable goals and directions for the program under scenarios of flat or declining budgets?

OTA received generous assistance from workshop participants, reviewers, and others who offered

valuable information and comments in the course of this study. To all of them goes the gratitude of

OTA and the personal thanks of the project staff.

ROGER C. HERDMAN

Director
iv

orkshop

Alan Crane, Chairman

Senior Associate

Energy, Transportation, and

Infrastructure Program

Office of Technology Assessment

Donald Correll

Deputy Program Leader for

Inertial Confinement Fusion

Lawrence Livermore National

Laboratory

David H. Crandall

Director, Applied Plasma Physics

Division

Office of Energy Research

U.S. Department of Energy

N. Anne Davies

Associate Director for Fusion

Energy

Office of Energy Research

U.S. Department of Energy

Stephen O. Dean

President

Fusion Power Associates

Robert Hirsch

Consultant

Alan Hoffman

Aerospace and Energetics

Research Building

University of Washington, Seattle

Jack Kaslow

Executive Director, Northeast

Region

Electric Power Research Institute

William D. Kay

Department of Political Sciences

Northeastern University

Dale M. Meade

Deputy Director

Princeton University

Plasma Physics Laboratory

David O. Overskei

Senior Vice President

General Atomics

John Perkins

Physicist and Group Leader

Lawrence Livermore National

Laboratory

Stewart C. Prager

President, University Fusion

Association and Professor

Department of Physics

University of Wisconsin-Madison

Paul-Henri Rebut

International Thermonuclear

Experimental Reactor

Engineering Design Activities

John Sheffield

Fusion Energy Division

Oak Ridge National Laboratory

John W. Willis

Director, Confinement Systems

Division

Office of Energy Research

U.S. Department of Energy

Note: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the workshop participants. The

participants do not, however, necessarily approve, disapprove, or endorse this report. OTA assumes full responsibility for the report

and the accuracy of its contents.
v

roject Staff

Peter D. Blair

Assistant Director

Industry, Commerce, and

International Security Division

Emilia L. Govan

Program Director

Energy, Transportation, and

Infrastructure Program

ADMINISTRATIVE STAFF

Marsha Fenn

Office Administrator

Tina Aikens

Administrative Secretary

Gay Jackson

PC Specialist

Lillian Chapman

Division Administrator

PRINCIPAL STAFF

Robin Roy

Project Director

Karen Larsen

Senior Anaylst

Richard Rowberg

Senior Specialist

Congressional Research Service

PUBLISHING STAFF

Mary Lou Higgs

Manager

Dorinda Edmondson

Typographer

Susan Hoffmeyer

Graphic Designer

Chip Moore

Production Editor

Chris Onrubia

Senior Graphic Designer
vi

eviewers and Contributors

Anna Aurilio

U.S. Public Interest Research

Group

Charles Baker

University of California,

San Diego

David E. Baldwin

Lawrence Livermore National

Laboratory

Roger Bangerter

University of California, Berkeley

Richard Brody

Office of Technology Assessment

Mark Brown

Office of Technology Assessment

E. Michael Campbell

Lawrence Livermore National

Laboratory

Valeriy Chuyanov

International Thermonuclear

Experimental Reactor

Engineering Design Activities

Thomas Cochran

Natural Resources Defense

Council

Tony Colleraine

General Atomics

Donald Correll

Lawrence Livermore National

Laboratory

David H. Crandall

U.S. Department of Energy

N. Anne Davies

U.S. Department of Energy

Stephen O. Dean

Fusion Power Associates

James F. Decker

U.S. Department of Energy

Gerald Epstein

Office of Technology Assessment

Julie Van Fleet

International Thermonuclear

Experimental Reactor

Engineering Design Activities

Robert Goldston

Princeton Plasma Physics

Laboratory

Robert Hirsch

Consultant

Alan Hoffman

Oak Ridge National Laboratory

Rush D. Holt

Princeton Plasma Physics

Laboratory

Paul Komor

Office of Technology Assessment

Grant Logan

Lawrence Livermore National

Laboratory

Bogdan C. Maglich

Advanced Physics Corp.

Dale M. Meade

Princeton Plasma Physics

Laboratory

David O. Overskei

General Atomics

John Perkins

Lawrence Livermore National

Laboratory

Stewart Prager

University Fusion Association

University of Wisconsin, Madison

Paul-Henri Rebut

International Thermonuclear

Experimental Reactor

Engineering Design Activities

Michael Roberts

U.S. Department of Energy
vii

Marshall N. Rosenbluth

International Thermonuclear

Experimental Reactor

Engineering Design Activities

Norman Rostoker

Department of Physics

University of California, Irvine

Joanne Sedor

Office of Technology Assessment

John Sheffield

Oak Ridge National Laboratory

Yasuo Shimomura

International Thermonuclear

Experimental Reactor

Engineering Design Activities

Loren Steinhaur

Redmond Plasma Physics

Laboratories

University of Washington

Ravi Sudan

Laboratory of Plasma Studies

Cornell University

Matthew Weinberg

Office of Technology Assessment

John W. Willis

U.S. Department of Energy

Note: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the reviewers. The reviewers

do not, however, necessarily approve, disapprove, or endorse this report. OTA assumes full responsibility for the report and the accuracy of its contents.
ix

1 Overview and Findings 1

Achievements and Challenges of the U.S. Fusion

Energy Program 6

Findings on TPX 9

Findings on Alternate Concepts for Fusion Energy 12

2 The Federal Fusion Energy Research

Program 17

History of U.S. Fusion Energy Research 18

The Fusion Program Goals in Law and Policy 32

Legislative Directives 36

Federal Fusion Energy Research Programs 36

Future Budget Choices 46

3 The Tokamak Physics Experiment 49

History of the TPX Decision 50

Description of TPX 53

Issues 57

4 Alternate Concepts for Fusion Energy 65

Reasons to Pursue Alternate Fusion Concepts 65

Status and Prospects of Alternate Concepts 68

Steps in Examining Alternate Concepts 76

DOE’s Program for Alternate Concepts 78

Conclusion 80

APPENDIX

A Acronyms and Glossary of Terms 81

ontents
Overview

and

Findings

or over four decades the federal government has supported

research to develop the power of fusion energy for commercial electric power production. Fusion proponents note

that the supply of fusion fuels is virtually inexhaustible,

and that environmental impacts may be far less extensive than

those of energy supplies currently in widespread use. Widely heralded experiments performed in 1993 and 1994 at the Princeton

Plasma Physics Laboratory’s Tokamak Fusion Test Reactor

(TFTR) produced unprecedented levels of fusion reactions and

continued a trend of progress in fusion research.

However, even the most optimistic proponents of fusion energy note that many scientific, engineering, and economic challenges remain to be met. Meeting these challenges sufficiently to

construct a prototype commercial fusion powerplant may require

several tens of billions of dollars in experimental facilities and

research over the next several decades. This would require a considerable increase from the U.S. Department of Energy’s (DOE’s)

current fusion energy program budget of $373 million, and a

greater level of cost-sharing through international collaboration

in fusion research and development.1

In 1987, the Office of Technology Assessment (OTA) concluded a major assessment of the fusion energy program and published the report Starpower: The U.S. and the International Quest

1 An additional $176 million is spent on inertial confinement fusion research as part of

DOE’s defense programs, much of which is relevant to fusion energy prospects.

| 1
2 The Fusion Energy Program: The Role of TPX and Alternate Concepts

The proposed Tokamak Physics Experiment (TPX).

for Fusion Energy.2 Since then, the U.S. fusion

energy program has undergone a pronounced

change as it has grappled with uncertain budgets

that have grown less quickly than the need for

larger, more capable, and more expensive machines. One result has been a substantial narrowing of efforts to concentrate on the single most

successful and furthest developed fusion concept,

the tokamak. This narrowing, driven heavily by

budgetary reasons, has been decried by many fusion researchers as premature given the current

state of fusion knowledge.

This background paper, requested by the House

Committee on Science, Space, and Technology,3

focuses on two issues in the recent and continuing

evolution of the U.S. fusion energy research and

development (R&D) program:

. What is the role of the proposed Tokamak

Physics Experiment (TPX)? TPX is an

approximately $700-million fusion reactor

currently in an advanced stage of engineering

design and awaits a congressional decision to

begin construction at the Princeton Plasma

I

●

Physics Laboratory. This paper examines the

history of TPX planning and the anticipated

scientific, engineering, and institutional contributions of the TPX. It explores the relationship between the TPX and the next major

planned tokamak facilities, the International

Thermonuclear Experimental Reactor (ITER),

currently in the design stage, and the Demonstration Fusion Powerplant (DEMO) facility,

planned for operation in about three decades,

which would be the first fusion device to demonstrate production of electricity.

What is the role of alternatives to the tokamak concept in a broad-based fusion energy

program? This paper examines the motives for

pursuing alternate concepts, the steps involved

and costs of alternate concept research, and the

current status and process of alternate concept

research as conducted in the U.S. fusion energy

program. Note that this paper does not assess

the likely attractiveness of any alternate fusion

concept, nor does it suggest the appropriate level of effort to be devoted to it. Rather, the paper

reviews the level of development, which may

not be closely related to the long-term potential

of a concept.

There are critical issues for the U.S. fusion energy program that are beyond the scope of this

background paper. Three of the most important

are noted here. First, this paper does not examine the rationale for the overall fusion energy program. In particular, the role of the fusion

energy program in meeting long-term energy

needs and the level of research effort justified

by that potential role are critical issues for the

program. Whether or when fusion will meet the

goal of becoming an economically and environmentally attractive energy option will depend on

more than just success in a continuing multidecade R&D program. It will also depend on the

pace of progress in the other energy technologies

2 U.S. Congress, Office of Technology Assessment, Starpower: The U.S. and the International Quest for Fusion Energy, OTA-E-338

(Washington, DC: U.S. Government Printing Office, October 1987).

3 Renamed the House Committee on Science.
Chapter 1 Overview and Findings | 3

with which fusion must eventually compete.

These energy technologies span a broad array,

from advanced nuclear fission reactors to renewables such as biomass, wind, and photovoltaics to

improved methods for finding, extracting, and

burning fossil fuels including coal, natural gas,

and oil. Substantial improvements in energy efficiency technologies continue as well.4 To the extent that these energy technologies continue to

improve, they present an increasingly challenging

market environment for future fusion powerplants. While progress in fusion is continuing,

other energy technologies are improving as well,

often with some federal support. The tradeoffs in

timing and choice of R&D efforts in competing

energy technologies including fusion are critical

issues for fusion research policy beyond the scope

of this paper.5

A second and related critical issue for the fusion energy program not addressed in this paper

has to do with the possibility of declining budgets.

Proposals to greatly reduce fusion energy research spending heighten the importance of

identifying possible new roles, directions, and

goals for the program under scenarios of flat or

declining budgets. This paper discusses the likely cost involved in continuing along the current

path of fusion research, and it is substantial. As

noted below, the current fusion energy program

goals and directions, including construction and

operation of large new tokamaks, are inconsistent

even with flat budgets; the possibility of declining

budgets sharpens the issue. Certainly, potentially

valuable work can be performed under a wide

range of research budgets. However, this would

call for revised goals and directions. For example,

even under substantial cuts, some see the possibility of sustaining progress by focusing on physics

issues using existing machines, increasing international collaboration, supporting a modest but

expanded effort to investigate alternate concepts,

and concentrating on materials and technology

advances that would be necessary for fusion powerplants.

An effort to identify the most productive uses

of fusion energy funds under a variety of scenarios

could provide information critical in making

budget decisions. Eventually, however, absent

novel, unexpected science developments, progress toward development of a fusion powerplant

would require a commitment to construction of

expensive new facilities. Finally, under any budget scenario, consideration must be given to existing commitments such as decommissioning

TFTR and the international agreement to complete the engineering design of ITER. These two

commitments alone total a few hundred million

dollars over the next several years.

A third critical issue for the U.S. fusion energy program that is beyond the scope of this

background paper has to do with the increasing internationalization of research.6 Due to the

very high estimated cost of some fusion facilities,

the domestic fusion energy program is pursuing

cost-sharing collaborative efforts with several

countries. ITER, with a roughly estimated design

and construction cost on the order of $10 billion,

is the leading example (see box 1-1). The institutional structure for this type of international col4 See, e.g., the following reports by U.S. Congress, Office of Technology Assessment: Energy Efficiency: Challenges and Opportunities for

Electric Utilities, OTA-E-561 (Washington, DC: U.S. Government Printing Office, September 1993); Industrial Energy Efficiency, OTA-E-560

(August 1993); Building Energy Efficiency, OTA-E-518 (May 1992); Energy Efficiency in Federal Facilities: Government by Good Example?

OTA-E-492 (May 1991).

5 See U.S. Congress, Office of Technology Assessment, Energy Technology Choices, OTA-E-493 (Washington, DC: U.S. Government

Printing Office, July 1991). The Secretary of Energy recently commissioned a review of DOE civilian energy R&D programs that will address

this issue at some level. See The Honorable Hazel R. O’Leary, Secretary of Energy, letter to George M. Scalise, Sept. 8, 1994. Also, the President’s Council of Advisors on Science and Technology will report on the fusion energy program in Summer 1995.

6 OTA is currently examining the role of international collaboration in large science projects. That effort, due for completion in summer

1995, will examine the increasingly international character of several scientific fields, including that of fusion energy research.
4 The Fusion Energy Program: The Role of TPX and Alternate Concepts

The United States, the European

Union, Japan, and the Russian

Federation are engaged in an

unprecedented collaboration on the

engineering design of the proposed

International Thermonuclear Experimental Reactor (ITER). This collaboration has its roots in discussions among

the leaders of the European Community, Japan, the Soviet Union, and the

United States in the mid-1980s. ITER’s

purpose is to establish the scientific

and technological feasibility of magnetic fusion energy as a source of

electric power by demonstrating controlled ignition and extended burn of

deuterium-tritium plasmas and to

demonstrate and test technologies,

materials, and nuclear components

essential to development of fusion energy for practical purposes. It would

not be capable, however, of actually

generating electricity. Demonstrating

the production of electricity in a magnetic fusion energy powerplant would

be left to the DEMO reactor, a device

anticipated for construction no sooner

than 2025.

The proposed lnternational Thermonuclear Experimental Reactor.

If built, ITER would be by far the largest, most capable, and costliest fusion experiment in the world.

ITER uses a tokamak design, and would stand over eight stories tall and 30 meters in diameter. The

device is intended to sustain controlled fusion reactions in a pulsed mode for periods of up to 15

minutes. ITER is expected to be capable of producing over 1,000 megawatts of thermal fusion power.

Temperatures inside the confinement chamber would be up to 1,000 degrees centigrade, and maintenance and monitoring of the radioactive containment will have to be carried out by remote methods.

The impressive scale of ITER is dictated by the physical requirements of heating and containing a

plasma to fusion conditions on a steady state basis using available technology and materials. ITER

offers not only great scientific challenges, but practical technological challenges as well. For example,

ITER’s superconducting magnetic coils will be the largest ever manufactured. Each coil will weigh over

400 tons. The amount of superconducting materials required to make them exceeds the available

manufacturing capabilities of any one party, therefore a cooperative effort is underway to coordinate the

materials manufacture, fabrication, and assembly. 

ITER is being conducted in four phases under formal intergovernmental agreements among the

parties, These are: 1) the now-completed conceptual design activities (CDA); 2) the engineering design

activities (EDA); 3) the construction phase; and 4) the operations phase. Each phase is to be governed
Chapter 1 Overview and Findings 5

by a separate agreement among the parties and costs are shared equally. The first phase of the ITER

project, CDA, was carried out from January 1988 to December 1990. All four parties contributed

personnel and support to the ITER team for development of a conceptual design, scope, and mission

for the project.

Currently, ITER is in the EDA phase, which is scheduled to continue until July 1998. Under the ITER

Agreements, each of the parties has committed the equivalent of $300 million (1993 dollars) worth of

personnel and equipment to the design effort. The purpose of the ITER EDA phase is to produce a

“detailed, complete, and fully integrated engineering design of ITER and all technical data necessary

for future decisions on the construction of ITER.” On completion, the design and technical data will be

available for each of the parties to use either as part of an international collaborative program or in its

own domestic program. Other objectives of the EDA phase are to conduct validating R&D supporting

the engineering design of ITER, to establish siting requirements, to perform environmental and safety

analyses related to the site, and to establish a program for ITER operation and decommissioning.

EDA activities are overseen by an ITER Council composed of two representatives of each party.

Decisions by the Council are based on consensus. Under the Council, the ITER Director is responsible

for coordinating the activities of the Joint Central Team—an international design team composed of

scientists, engineers, and other professionals assigned to the ITER project by the parties. The Joint

Central Team activities are carried out at three Joint Work Sites—Garching, Germany; Naka, Japan; and

San Diego, California. Each work site team is responsible for a different aspect of ITER design. The

work of the Joint Central Team is supported by R&D activities by the “home country” fusion programs.

Tasks are assigned and coordinated by the ITER Director in consultation with the ITER Council, the Joint

Central Team, and each party’s designated “Home Team” Leader.

The next major step in the ITER process will be the negotiation of a process for deciding on a host

site for ITER. Exploratory discussions on a site selection process are currently underway. Site selection

will have to be accomplished so that the EDA team can complete specific site-related safety, environmental and economic analyses, and design work for the ITER facility. Following site selection, a

decision on whether to proceed to ITER construction and operations phases is scheduled to be made

before 1998 and would require a new international agreement.

The ITER construction phase is tentatively planned to start in 1998 and to be completed by 2005.

Initial estimates of ITER construction cost had been $6.9 billion in July 1993 dollars; some analysts have

projected ITER costs of between $8 billion to $10 billion. Detailed cost estimates for this one-of-a kind

research facility await completion of ITER engineering design work. Interim design and cost analyses

are expected in mid-1995. Final design and cost estimates are due in January 1998, assuming site

selection has been completed.

The fourth or operating phase of ITER is proposed to begin in 2005 and run through approximately

2025. The early phases of ITER operation would be dominated by a focus on the physics issues relating

to achieving and sustaining an ignited plasma. A more intense engineering phase will follow. As an

engineering test facility, researchers would be able to install, test, and remove numerous ITER components, experimental packages, and test modules to test materials properties, component characteristics, performance, and Iifetimes in an environment approximating the conditions of an operating fusion

powerplant. This experience would aid efforts at design and development of a demonstration fusion

powerplant.
6 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

laboration in the construction and operation of

large facilities remains to be developed, and its ultimate success will require dedication, flexibility,

and innovation. This paper does examine one current case in the coordination of the domestic

fusion energy program in the increasingly international fusion arena—the methods by which TPX

is coordinated with ITER, and the potential contribution of TPX to that much more ambitious facility. It does not, however, examine the methods

by which ITER can be successfully developed,

nor does it evaluate key issues in the ITER program as it relates to the broader fusion energy development effort, such as project scope and

timing. Further, it does not examine how the overall U.S. fusion energy program, including alternate concepts research, could be more fully

integrated into the world effort.

ACHIEVEMENTS AND CHALLENGES OF

THE U.S. FUSION ENERGY PROGRAM

Fusion reactions, which power our sun and the

stars, occur when the nuclei of two lightweight

atoms (e.g., isotopes of hydrogen such as deuterium and tritium) combine together, or fuse, releasing energy (see figure 1-1). Understanding and

controlling the conditions that allow practical fusion to occur on earth, such as temperatures of

about 100 million degrees Celsius, present great

scientific and technical challenges. At such high

temperatures, matter exists as plasma (a state in

which atoms are broken down into electrons and

nuclei) that cannot be contained by any solid

container.

Primary responsibility for fusion energy development rests with DOE and its Office of Energy

Research. Most effort in fusion energy research

has been devoted to the magnetic confinement approach, which uses magnetic fields to control the

range of motion of the plasma. Several different

magnetic fusion energy (MFE) confinement concepts have been investigated, the most advanced

of which is the tokamak reactor. Considerable effort has also been devoted to inertial confinement,

in which a pellet of fusion fuel would be heated

and compressed by intense lasers or ion drivers to

such high densities that the fuel’s own inertia is

sufficient to contain it for the very short time needed for fusion to occur. Inertial confinement fusion

research mimics, on a very much smaller scale,

processes in the hydrogen bomb, and to date,

much of the research relevant to inertial fusion energy (IFE) has been performed by DOE’s Office of

Defense Programs for its applications to nuclear

weapons physics and stockpile stewardship responsibilities.

The ultimate goal of DOE’s fusion energy program is “to demonstrate that fusion energy is a

technically and economically viable energy

source.” DOE’s primary emphasis in fusion energy is on developing the tokamak, and devotes by

far the largest share of the current fusion energy

budget to support design of two planned tokamak

reactors. Of the $373 million requested budget for

fiscal year 1995, 41 percent was for direct and indirect design and support of ITER, and 33 percent

was intended for design, construction, and support of TPX.7 Another 14 percent was to support

operations of the largest operating U.S. tokamak,

TFTR. The remainder of the fusion energy budget

is devoted to such diverse activities as advanced

materials development, fusion technology development, and study of alternate concepts including

IFE. In addition, in fiscal year 1995 the Office of

Defense Programs devoted $176 million to inertial confinement fusion research, much of which is

relevant to IFE.

Much progress has been made in fusion energy research over the past few years, but far

more remains to be done. Most notably, recent

experiments at TFTR attained a record in fusion

energy production of 10.7 megawatts (MW),

7 U.S. Department of Energy, “Fusion Energy Program,” briefing package presented by N. Anne Davies to Office of Technology Assessment staff, Apr. 28, 1994. Note that of the $152 million related to ITER, $81 million was for a diverse array of “support” activities rather than

direct ITER design and R&D work. Similarly, of the $118 million related to TPX, $56 million was for support.
Chapter 1 Overview and Findings 7

I

● ●

I

\

Reaction conditions

(density, temperature, time)

I

Neutron

Products 14.1 MeV

Helium

3.5 MeV

Proton MeV = Million electron volts

Neutron

SOURCE: Office of Technology Assessment 1995, based on figure from U.S. Department of Energy, Office of Fusion Energy.

amounting to a factor of about 100 million in- times higher than energy input to create the reaccrease in fusion power production over 20 years of tions) and ignition (the point at which a reaction is

research. However, even the tokamak, the most self-sustaining even when external heating is

advanced fusion energy concept, faces scientific turned off) in a steady state (continuous, rather

and engineering challenges. Scientific challenges than intermittent, operation).8 However, even

remaining to be met for MFE include achieving breakeven (the Point at which the energy produced

high energy gain (energy output that is many

8

Fusion scientists typically have defined scientific feasibility as attainment of high energy gainer ignition. Steady state operation is generally not included in definitions of scientific feasibility, although it presents an important scientific challenge that must be met by any MFE powerplant.
8 The Fusion Energy Program: The Role of TPX and Alternate Concepts

The Tokamak Fusion Test Reactor (TFTR) at the Princeton

Plasma Physics Laboratory set world records for fusion

reactions using dueterium-tritium fuel in 1993 and 1994.

TFTR, the largest U.S. tokamak, is scheduled to be shut

down in 1995.

by fusion reactions equals the energy input to heat

the plasma9

) has remained beyond the reach of current facilities.10 The highly successful TFTR

experiments of the past year, for example, reached

just over one-quarter of breakeven--about 40

MW of external power were introduced to the

plasma to create about 10.7 MW in fusion reactions. This fusion energy production lasted for

only a few moments. If constructed, ITER would

be the first MFE device expected to achieve ignition, and to operate for long pulses of several

hundred to over one thousand seconds.

Developing a commercial prototype fusion

powerplant requires more than merely meeting

scientific challenges. It further requires meeting a

series of engineering challenges, including development of materials, components, and systems for

operating fusion reactors. According to DOE, the

main scientific and technological

MFE effort are the following:

issues for the

1. ignition physics (e.g., understanding the properties of a self-sustaining fusion reaction);

2. magnetic confinement configuration optimization (i.e., determining how best to shape the

magnetic fields confining the plasma);

30 fusion nuclear technology (engineering systems to fuel, maintain, and recover energy from

a fusion reactor); and

4. low activation materials development (development of materials that will not become highly radioactive in a fusion reactor).

Meeting these challenges, by their very nature, requires abroad-based program of scientific, technical, and industrial R&D.

Under plans established a few years ago, tens

of billions of dollars and about three decades of

continued successful R&D will be needed before the science and technology are sufficiently

advanced to enable construction of DEMO following ITER, and a subsequent commercial

prototype may be operational only by around

2040. It is worth noting that fusion researchers

have long suggested a three-decade horizon for

development of fusion energy. As budgets have

not met the expectations of researchers, and as the

science has proven challenging, the horizons have

continued to recede.

Congress will face tough decisions about

budget priorities for the fusion energy program over the next few years, as current plans

for pursuing the tokamak imply a doubling or

more from fiscal year 1995’s funding of $373

million (see figure 2-8 in chapter 2). The budget

increase has not been explicitly stated in previous

9 Note that the amount of power consumed in heating the plasma is only part of the power actually consumed by the entire experiment.

Losses incurred in generating the heating power and delivering it to the plasma are not included, nor is the power needed to operate systems such

as the magnets and the vacuum system. 10 In discussing results of scientific experiments, fusion scientists often use the term “equivalent plasma conditions.’’ This term refers to the

development of a plasma not composed of fusion fuel (e.g., a mixture of deuterium and tritium, D-T) but rather of a plasma that is easier to work

with (e.g., deuterium alone). While fusion reactions can occur in the deuterium-only plasma, far less energy is produced than with D-T. Thus,

equivalent breakeven conditions refers to temperatures, densities, and confinement times in a plasma that would have resulted in true breakeven

had such conditions been attained with fusion fuel. Using this definition, Europe’s large tokamak, JET, has achieved the breakeven level in an

equivalent deuterium plasma.
Chapter 1 Overview and Findings | 9

DOE budget submissions, but is implied by new

facilities identified by DOE and continuation of

the base program. Fusion researchers have long

identified the need for substantially larger research budgets, but congressional priorities have

varied with changing energy markets and other

factors, leading often to uncertain and fluctuating

budget prospects. For example, the Secretary of

Energy’s Fusion Policy Advisory Committee indicated in 1990 that the fusion energy budget

would need to be increased to about $700 million

annually in fiscal year 1990 dollars (not including

the Defense Programs research in inertial confinement fusion) to meet program goals, but the budget since then has been at only about one-half that

level (see figure 2-1 in chapter 2).

By far the greatest single budgetary requirement for the fusion energy program over the

next decade will come from ITER, if current

plans are pursued. No decision has been made

by the ITER partners on whether to proceed beyond engineering design and to actually build the

device. However, if ITER is pursued according to

the current proposed schedule, the U.S. contribution to construction alone could require nearly a

doubling of the current total fusion energy program budget over the next few years. For example,

although construction costs remain uncertain, assuming the United States bears a one-quarter share

to build an approximately $10 billion ITER over

an eight-year construction horizon implies an average ITER construction budget alone that is over

$300 million annually, or over 80 percent of the

entire current U.S. fusion energy program budget.

Unless the budget is greatly increased, it will not

be possible to complete the ITER project as currently envisioned.

Finally, the information and analyses needed to

support congressional decisions on fusion energy

budgets and policy are not readily available. Despite congressional requirements in the Energy

Policy Act of 1992, as of December 1994, DOE

has not issued a strategic management plan for

the fusion energy program by which the program’s progress can be judged. The management plan was required to be prepared by April

1993 and progress reports on meeting the plan

milestones were to be updated biennially. The

plan is to include specific program objectives,

milestones, schedules, and cost estimates for

technology development, program management

resource requirements, and an evaluation of international fusion programs.

Undoubtedly one of the greatest challenges to

developing the strategic management plan is the

need to address the longstanding divide between

the expected budgetary requirements of the fusion

energy program and the history of funding at substantially lower levels. Because pressures to contain and reduce overall federal spending are likely

to continue, the budgets needed to carry out the fusion energy program as currently envisioned may

not be realized. Without substantial funding increases, the program will have to change significantly from the current direction and new

goals will be have to be set.

FINDINGS ON TPX

TPX is intended to provide scientific and technical advances that are clearly necessary to the

ultimate realization of a tokamak powerplant.

With regard to scientific issues, TPX is designed

to demonstrate and operate at long-pulse or nearsteady state conditions, essential for an eventual

powerplant. TPX is also designed to explore advanced operating modes or regimes that, if successful, would allow increases in confinement

efficiency and power density in future tokamaks,

and ultimately reduce the size and cost of a tokamak fusion energy reactor. With regard to technological advances, TPX would be the first large

fully superconducting tokamak (i.e., the magnets

will be superconducting, greatly reducing the

amount of electrical power they consume). This

would be a substantial achievement, and is essential for steady-state operation of an MFE powerplant. TPX would also allow investigation of a

variety of configurations for the divertor, a major

component essential in any eventual tokamak energy powerplant for removing both reaction products (e.g., helium “ash” produced by fusion) and

heat. Remote handling, necessary for maintenance in a radioactive environment created by fu-
10 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

sion reactions, would also be developed for

maintenance of mildly radioactive equipment

where limited human intervention will still be

possible.

TPX is also intended to maintain the

strength of the U.S. magnetic fusion energy

program after TFTR retires in 1995. There are

several other U.S. tokamaks operating currently,

the largest of which are the DIII-D at General

Atomics in San Diego and Alcator C-Mod at the

Massachusetts Institute of Technology. However,

absent TPX, there will be no new U.S. tokamak

under development. To support a strong MFE research and development capability, TPX has been

organized as a national facility with design and

operation guided by members from various universities, national laboratories, and U.S. industries. Proponents note that experience with

building major TPX systems such as the superconducting magnets could give U.S. industry a

firmer base in competing to construct ITER. They

also note that both Japan and Europe have large tokamaks that can continue operations for several

years beyond the retirement of the U.S.’ TFTR,

supporting their base tokamak programs until the

next steps are decided for ITER. Note, however,

that TPX would not be operational before the year

2000, and so could provide design and construction benefits but not experimental benefits before

them.

TPX is not scheduled to provide any unique

scientific and technological advances essential

to ITER. Indeed, when the ITER conceptual design activity was completed in 1991, DOE had no

formal plans to build TPX or a device like it, although a steady-state advanced tokamak was recommended by the Fusion Policy Advisory

Committee as one of four major facilities needed

prior to the construction of a demonstration fusion

reactor. Also, under current plans, TPX will become operational only after the start of ITER

construction, greatly reducing the ability to transfer TPX experimental results to ITER design. No

other partner in the ITER project has found it essential to pursue a device with TPX’s capabilities

as part of the program for successful development

of ITER.11 The ITER design group indicates that

it intends to provide the flexibility in ITER to examine most of the technology and science areas to

be examined by TPX. The ITER interim design,

expected in June 1995, should allow a better assessment of whether this is indeed the case.

One area in which TPX may produce unique

scientific benefits concerns the investigations

of specific steady-state, advanced operating

modes. Currently, ITER is being designed with

more conservative operating modes than TPX.

However, the ITER design group has indicated its

intent to maintain the flexibility to examine a

range of advanced modes approaching those of

TPX in the later phases of its experimental effort.

Building in this flexibility may be expensive,

though, as significant upgrades to auxiliary systems may be required. Again, the ITER interim

design should allow a better assessment of the degree of flexibility and its costs. Whatever the extent of flexibility built into ITER, TPX could

provide unique benefits. To the extent that ITER’s

flexibility is limited, TPX could play an important

scientific role in examining the advanced operating mode issue. On the other hand, even if wide

flexibility would be built into the ITER design,

TPX results may help identify certain unpromising approaches and thereby help avoid performing

unpromising retrofits or upgrades to ITER. This

could be important since testing in ITER of some

advanced operating modes examined in TPX

could require a potentially costly reconfiguration

of ITER.

11 The Japanese have also carried out a conceptual design of a superconducting machine called the JT-60 Super Upgrade (JT-60SU). It

would have many of the features planned for TPX and would be larger and more powerful. However, construction has not been approved, and is

not expected prior to decisions about siting and construction of ITER. Note also that both Europe and Japan currently have large, relatively

young tokamaks that will continue to provide a major focus for their own programs for several years. In contrast, the largest U.S. tokamak,

TFTR, is scheduled to retire in 1995.
Chapter 1 Overview and Findings | 11

TPX’s primary expected contribution to

ITER would be the ability to perform experiments on a device that is smaller, more flexible,

and less costly to operate. Because of the scheduling overlap between the projects, it will be impossible to take full advantage of the potential

TPX results in the design and construction of

ITER. For example, as noted above, some potentially costly decisions to build flexibility into

ITER design allowing examination of advanced

operating modes will be made long before TPX

experimental results would be available. There

may be some construction benefits as, for example, industrial experience gained from TPX

construction may be useful preparation for ITER

construction.

A more important potential benefit concerns

decisions on possibly costly retrofits to ITER to

examine advanced operating modes, as discussed

above. There are other potentially important benefits in the area of ITER operations. For example,

TPX experiments in long-pulse operation may

shorten the needed schedule for such experiments

at ITER, allowing ITER to move more quickly

into research areas for which it is uniquely suited.

The cost and schedule savings could be substantial, given ITER’s likely high operating costs and

lower flexibility relative to TPX. For example,

annual operating costs for ITER, while still undetermined and highly uncertain, may be on the order of several hundred million dollars. However,

the likely acceleration in the ITER operating

schedule enabled by TPX remains speculative.

Overall, while the potential benefits of TPX to

ITER can be real, their magnitude is uncertain, and DOE has not estimated their value.

Further, there are no plans to account for the

benefits of TPX to ITER as part of the direct

contribution to the U.S. commitment to

ITER.12

Unless tested in ITER, there will likely be

considerable uncertainty of the transferability

of TPX results to DEMO. There is no question

that successful achievement of many of the goals

to be investigated by TPX—steady-state operation, superconducting magnets, remote handling,

and advanced divertor design in particular—will

be necessary if a tokamak-based fusion power

reactor is to become a reality. These areas can be

incorporated in ITER from the start or be integrated into it after testing in TPX or elsewhere. Integration of advanced tokamak operations results

into ITER, however, may be more limited and require significant upgrades. Since successful demonstration of these operations can have significant

consequences for the economics of a fusion power

reactor using the tokamak concept, it will be important to build them into the DEMO design. To

the degree that advanced regime operation will not

have been tested in a long-pulse ignited device, a

difficult decision will eventually be needed to balance the scientific risk of incorporating that feature in an expensive facility such as DEMO

against the benefits of smaller size and lower cost.

The value of TPX to the magnetic fusion

energy program could increase if ITER is

delayed. The physics and technology TPX would

investigate are fundamental for the development

of any tokamak powerplant, but the prospects for

success are by no means certain. However, incorporating the results of the TPX advanced operating mode experiments in the design of ITER

would require a several-year delay of ITER design

and construction. While many of the steady-state

and advanced operating regime issues to be investigated by TPX are unique to the tokamak concept,

the results of technology development could also

be useful to other MFE concepts. For example,

operation of superconducting magnets, divertors,

and remote handling will be necessary on any

eventual MFE reactor.

Overall, TPX is a costly undertaking that continues to receive considerable congressional

attention. However, it presents only the most im12 This is consistent with the policy of the ITER partners that physics research performed by the partners in support of ITER is not counted

against commitments to ITER design and construction.
12 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

mediate example of a series of difficult decisions

that Congress and DOE will have to make about

the fusion energy program. Its budget of about $2

billion including construction and operation over

the next 15 years13 represents only about 5 to 10

percent of the likely total U.S. MFE research

budget needed to enable a commercial prototype

tokamak powerplant by the year 2040. Regardless of decisions on TPX, the overall tokamak

fusion energy effort will require justifying a series of expensive research activities, of which

the U.S. contribution to ITER presents the

largest single budgetary requirement in the

near future.

FINDINGS ON ALTERNATE CONCEPTS

FOR FUSION ENERGY

Over the past several decades, the tokamak has

clearly emerged as the most scientifically successful MFE concept with unmatched plasma temperatures, densities, and confinement times. It is the

focus of U.S. and world fusion energy programs.

There are, however, a number of alternate fusion

concepts14 for which the knowledge base is more

limited (as shown in table 4-1 in chapter 4). These

include several non-tokamak MFE concepts,

some of which have been extensively pursued—

such as the stellarator, a close variation of the tokamak.15 Several other MFE concepts including

mirrors, reversed field pinch, and the field reversed configuration have been examined less

thoroughly. Scientific exploration of IFE concepts has been extensively pursued primarily for

reasons related to nuclear weapons. However, the

total research effort devoted to inertial fusion, including both defense and civilian programs,

makes IFE the largest alternate approach to fusion

in the United States. A number of more novel fusion energy concepts have been suggested that

take fundamentally different, and more speculative, approaches including muon catalysis, electrostatic confinement, and colliding beams.

Over the past several years, the fusion energy program was substantially narrowed to focus on the tokamak primarily for budgetary

rather than technical reasons. This narrowing

was partly a response to congressional pressure.16

As noted by DOE in its fiscal year 1993 budget

request:

. . . [F]iscal constraints have required the program to prematurely narrow its focus to the

tokamak concept, including tokamak improvement activities, and to eliminate major alternate

magnetic confinement program elements.

Operation of several existing experimental devices was halted or minimized. In one example,

construction of the LSX, a $14-million device to

test the field reversed configuration, was completed in 1990 followed by encouraging startup

tests, but funding to continue confinement experiments was not available. In another example,

construction of a 75-percent-complete, $75-million device to test another promising concept, the

reversed field pinch, was canceled in 1990. Similarly, in fiscal year 1994, the civilian IFE budget

was reduced by 50 percent to $4 million, well be13 The total construction cost of TPX, estimated to be $694 million in as-spent dollars, was planned to be spent by fiscal year 2000, with a

peak of about $130 million to $140 million each in fiscal years 1996 to 1998. However, while Congress appropriated funds in fiscal year 1995

for acquisition of major TPX systems, it restricted funds to begin construction. As of December 1994, DOE had not identified the impact of the

restriction on the overall cost and schedule of TPX. DOE projects annual operating costs of about $150 million in fiscal year 2000 dollars for the

10-year life of the facility once operations begin.

14 In this report, the term “alternate concept” has the meaning “nontokamak concept.”

15 Japan is currently completing the construction of a stellarator, the Large Helical Device, at a total cost of about $1 billion. Germany is

pursuing a stellarator of similar size and cost.

16 See, e.g., “Conference Report on the Energy and Water Development Appropriations,” H. Rept, 103-292, Congressional Record

139:H7906, at p. H7948, Oct. 14, 1993 (daily ed.).
Chapter 1 Overview and Findings | 13

low the level needed to continue work developing

a planned heavy ion driver device despite successful operations on a smaller test facility.17

There were, of course, technical reasons that

the tokamak was retained as the primary focus—

none of the alternate MFE concepts had attained

similar performance, and a variety of technical

challenges and uncertainties remained. However,

there is a widely held view that the narrowing

of the fusion energy program was premature

and did not reflect the benefits of pursuing alternate concepts. The view that examination of

alternate fusion confinement concepts is an important component of a fusion energy program is

held even by many supporters of the tokamak, including DOE. There are clear reasons for supporting an alternate concepts program as part of the

fusion energy program. Among them is that pursuit of promising alternate concepts, including

novel ones, may provide a fusion energy option

should the tokamak prove technically infeasible or commercially unattractive. It is important

to note, however, that in many cases the knowledge base is not adequately developed to determine whether some alternate concept is likely to

exceed the performance of the tokamak. Data and

theory do not currently support large-scale experimentation for any alternate MFE concept

other than the stellarator.

The necessary dependence on experimental facilities and research to verify theory can make

fusion energy concept development expensive.

DOE suggests that a “healthy, but constrained” alternate concepts program would

require about $100 million per year. This effort

would include construction and operation of some

intermediate-scale facilities. However, a substantial amount of information that provides a

firmer basis for making future alternate concept decisions could be developed with a far

more modest program. For example, some fusion researchers have proposed a broad-based

theoretical study of a wide range of alternate concepts that could be performed for less than 1 percent of the fusion energy program budget. This

could help in identifying attractive prospects for

additional development efforts, or for discarding

some concepts as not showing substantial promise

as the most attractive fusion energy device. While

each alternate concept has its own development

profile, next steps need not necessarily cost a substantial fraction of the fusion energy program

budget. For example, experiments on existing reversed field pinch and field reversed configuration

devices could be resumed and increased for under

$5 million dollars, providing considerable insight

into the prospects for these promising but still

speculative concepts. Also, next steps on intermediate-scale facilities need not necessarily be

conducted by the United States alone, but might

be undertaken through collaborative international

efforts.

IFE using a heavy ion driver is widely considered the primary alternate concept, and involves

the costliest next steps. However, proponents

suggest a development path for the heavy ion

driver IFE concept leading to a demonstration

powerplant that could be substantially more

flexible and less costly than that planned for

the tokamak development effort. There is considerable scientific and technical uncertainty with

IFE, and development costs are uncertain as well.

Overall, some IFE proponents envision a $4-billion civilian effort (with another $4 billion from

defense programs) spread over a number of moderate-cost facilities resulting in a demonstration

powerplant. In contrast, design, construction, and

operation of ITER alone is expected to cost well in

excess of that amount, and is only one of the major

future research activities involved in the tokamak

development program. There remain considerable

scientific and technical challenges with heavy ion

IFE, however, and the estimated cost of the effort

17 The budget for the DOE Defense Program inertial confinement fusion program, which performs much of the research relevant to IFE, was

not affected.
14 The Fusion Energy Program: The Role of TPX and Alternate Concepts

A conceptual inertial fusion energy powerplant using a heavy-ion induction Iinear accelerator.

could rise significantly as more experience is

gained.

One critical issue with IFE is its relationship to

the considerably larger inertial fusion program

now included within the nation’s nuclear weapons

programs. This relationship provides an advantage for the IFE effort, in that much of the funding

for basic scientific research needed has come under DOE’s defense program. The next major step

in IFE development is to explore ignition physics,

a topic also relevant to maintaining nuclear weapons expertise. The IFE development plans assume

completion of the National Ignition Facility

(NIF), a proposed $1-billion research facility being considered under the Defense Program at

DOE as part of the stockpile stewardship program

to maintain expertise in nuclear weapons physics.

Whether NIF is constructed will probably depend

more on weapons-related reasons, including its

role in maintaining nuclear weapons design expertise and the potential effects on weapons proliferation, and budget considerations rather than its

benefits for the fusion energy program.18

In summary, while alternate concepts provide no panacea for fusion energy development, there is merit in examiningthem as part

of a broad fusion program Relative to the expected costs of the tokamak effort, a great deal of

exploratory work can be conducted at modest

cost. Assuming some of the concepts prove technically promising, however, further development

1 8 In October 1994, the Secretary of Energy approved NIF for engineering design (Key Decision 1,or KD-1). The primary mission of NIF is

to demonstrate inertial fusion ignition and modest energy gain.
Chapter 1 Overview and Findings | 15

may require larger budgets for construction of expensive facilities. As with the tokamak effort, the

potential role of the overall fusion energy program

in meeting long-term energy needs, and the level

of research effort justified by that potential role,

are critical issues for the direction of alternate concepts research.
The Federal

 Fusion Energy

 Research

 Program

fter more than 40 years of federally supported research

into fusion energy, researchers have made substantial

strides in the understanding of plasma physics and in the

design and operation of controlled fusion reactions in the

laboratory. Many more scientific and technical challenges remain

to be overcome before fusion energy’s scientific and engineering

feasibility can be conclusively established. Most researchers believe that, even if current research and development (R&D) plans

are fully funded and technically successful, commercial generation of electricity from fusion powerplants still remains decades

away.1 Even then, fusion’s economic feasibility as a power source

will be determined in large part by the availability, costs, and public acceptability of competing fossil, fission, and renewable energy technologies.

The U.S. Department of Energy (DOE) sponsors fusion research under two separate programs on magnetic fusion and inertial confinement fusion. DOE’s fusion energy research programs

have been heavily reviewed over the years. Most reviews have

complimented the steady technical and scientific progress

achieved. Over the past decade, however, several major reviews

have expressed concern about the narrowing scope of the magnetic fusion energy program, the lack of support for research on alternate concepts, and the adequacy of funding to carry out even

narrow program objectives on the scales and schedules proposed.

Fusion’s potential attractiveness as an energy source has contin1Commercial power generation has been a major goal of government fusion research

almost from the beginning, however, other potential applications of fusion technology

have been suggested, such as space propulsion, for example.

| 17
18 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

ued to garner political and financial support in the

United States and in foreign nations, despite its

uncertain future.

The Energy Policy Act of 1992 committed the

nation to a five-year “broad-based” fusion energy

program “that by the year 2010 will result in a

technology demonstration which verifies the

practicability of commercial electric power production.”2 The DOE magnetic fusion program has

proposed moving forward with a major new domestic fusion experiment, the Tokamak Physics

Experiment (TPX), the first new U.S. tokamak in

two decades. The United States has also been

engaged in an ongoing collaboration on the engineering design of the International Thermonuclear Experimental Reactor (ITER), a machine

that is intended to reach the critical milestone of an

ignited fusion plasma and provide an engineering

test bed for reactor components needed to design a

demonstration fusion powerplant. Design and

construction costs for the ITER facility are currently estimated on the order of $10 billion; more

precise preliminary cost projections for building

and operating ITER are scheduled to be available

in summer 1995. Final cost estimates will not be

made until after a site has been selected. Under the

current ITER agreement, there is no commitment

by any of the parties to proceed beyond the engineering design activities phase. If constructed,

ITER would be funded, built, and operated as an

equal partnership with the Japanese, Russian, and

European Community fusion programs and marks

an unprecedented level of cooperation in a large

science and technology project. Recently, the

ITER parties have begun discussions on a possible

collaboration on a fusion materials irradiation

facility.

This chapter provides an overview of the federal fusion research program, its history, legislative

authority, goals and organizational structure.

HISTORY OF U.S. FUSION

ENERGY RESEARCH

❚ Early Years: 1950 to 1970

U.S. research on controlled fusion for energy purposes began in 1951 as an offshoot of classified

weapons-related research under the Atomic Energy Commission’s Project Sherwood. Over the

decade, federal dollars supporting research in fusion and the new “plasma physics” grew and research programs were established at national

laboratories, universities, and several private

companies.3 Initially, fusion research was pursued with the objective of using fusion reactions

to produce plutonium and tritium for nuclear

weapons, but later discovery of ample domestic

uranium resources eliminated this objective.

However, early on, many scientists became intrigued with the prospects of fusion as a nearly inexhaustible energy source. Researchers of the

time believed that harnessing fusion would not be

an especially difficult challenge, requiring perhaps one or two decades to develop a fusion reactor. The key would be discovering a “magnetic

bottle” that could contain the fusion reaction. During the 1950s, several magnetic confinement approaches were investigated, including mirrors,

stellarators, and pinches, but, in all of them, researchers encountered instabilities in the plasmas

that limited the confinement times, temperatures,

and pressures. It also became more widely apparent that progress in the science of fusion plasmas and development of a commercial fusion

2 Public Law 102-486, Oct. 24, 1992, 106 Stat. 2776, at section 2114, 106 Stat. 3073-3074 (codified as 42 U.S.C. 13474).

3For more on the history of the fusion program, see U.S. Congress, Office of Technology Assessment, Starpower: The U.S. and the International Quest for Fusion Energy, OTA-E-336 (Washington, DC: U.S. Government Printing Office, October 1987), ch. 3; and Committee on Magnetic Fusion in Energy Policy, Energy Engineering Board, Commission on Engineering and Technical Systems, National Research Council,

Pacing the U.S. Magnetic Fusion Program (Washington, DC: National Academy Press, 1989).
Chapter 2

power reactor would be a long and expensive undertaking.

In 1958, the United States declassified fusion

research as a result of the Second Geneva Convention on the Peaceful Uses of Atomic Energy and

opened the door to international cooperation

among U.S., Soviet, and European fusion researchers. Since then, international cooperation

has grown from informal contacts among scientists and exchanges between research laboratories

to formal collaborative agreements between government programs and to the ongoing collaboration on the design of ITER.

During the 1960s, research continued on plasma physics and ways of overcoming instabilities

in the plasma to improve confinement times and

densities, but progress was very slow. By the second half of the 1960s, government and private interest in fusion R&D was waning. Then, in the late

1960s, the Russians announced significant advances in confinement conditions using their tokamak concept. Conflation of the tokamak

results gave renewed impetus to fusion energy research activities overall and resulted in a redirection of research efforts in the United States,

Europe, and Japan. The United States converted a

stellarator to tokamak configuration and built several new small tokamaks at Oak Ridge National

Laboratory, Massachusetts Institute of Technology, and General Atomics in San Diego.

❚ The 1970s: Program Expansion

Fusion research funding expanded substantially

from $34 million in 1970 to over $350 million in

1979 as shown in figure 2-1. These increases were

part of the overall expansion of federal energy

R&D in response to the 1973 OPEC oil embargo

and reflected the optimism generated by the relative successes of the tokamaks and the belief that

fusion technologies ultimately could prove more

publicly acceptable on environmental and safety

grounds than competing nuclear fission reactors.

In the reordering of federal energy research activities in 1974, fusion energy research activities of

the Atomic Energy Commission became part of

the Energy Research and Development AdminisThe Federal Fusion Energy Research Program 19

Central

solenoid 

magnet 

Poloidal

field 

magnet

Toroidal ‘

field magnet 

Tokamak magnets. A tokamak uses three types of magnets.

Toroidal field magnets create a ‘container” for the plasma,

while poloidal field magnets keep the plasma centered and

stable. The central solenoid magnets induce an electric

current in the plasma.

tration, which was later absorbed into the new Department of Energy in 1977. Magnetic fusion and

inertial confinement fusion energy activities remained in separate programs.

The U.S. magnetic fusion program supported a

broad range of research activities. The tokamak

continued to be the most technically advanced of

the magnetic confinement concepts and a number

SOURCE: Office of Technology Assessment, 1995, based on historical

information from the U.S. Department of Energy, and budget documents.
20 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

of small and mid-size tokamak fusion reactors

were placed in operation in U.S. research laboratories and many continue operating today. Construction of a major new machine, the Tokamak

Fusion Test Reactor (TFTR) was begun at the

Princeton Plasma Physics Laboratory (PPPL).

The TFTR remains among the largest and most

advanced tokamaks in the world. The TFTR was

to pursue a series of experiments planned to culminate in the early 1980s in deuterium and tritium

(D-T) reactions that could approach or even reach

the key fusion milestone of breakeven. At the

same time, the program expanded the exploration

of alternative confinement concepts as well as research into the various reactor-related component

technologies and materials that would be needed

for eventual commercial fusion power systems.

Fusion energy research programs were supported

at a number of national laboratories and universities, and the program provided support for training the majority of the plasma physicists in the

United States. In 1976, design and construction

began on a second major fusion experiment, the

Mirror Fusion Test Facility B (MFTF-B) at Lawrence Livermore National Laboratory, that was intended to compete with the tokamak concept.

The 1970s also marked the beginning of ambitious fusion R&D programs in Japan and the

European Community with commitments to construction of major new tokamak facilities and

significant increases in research budgets. International collaboration among fusion researchers

also expanded during this period, setting the stage

for future cooperative efforts.

Even as the U.S. fusion program was expanding rapidly during the 1970s, concern was expressed that funding for the fusion energy

program could not support the design, construction, and operation of several major fusion experimental machines as competitors to the tokamak,

and that the focus on tokamaks was prematurely

narrowing the search for an attractive commercial

reactor confinement concept.4 Although the tokamak was delivering promising results in the laboratory, questions raised about its ultimate

acceptability as a design for a commercial power

reactor continued to spur interest in development

of alternative concepts. An outside review of the

ambitious DOE fusion energy research plan in

1978 supported the redirection of the program

toward development of fusion power reactor

technology and endorsed the concept of a “twohorse race” between the tokamak and mirror concepts that could be expanded to include other

serious contenders as they emerged.5 A 1980 review by the DOE Energy Research Advisory

Board (ERAB) recommended that the fusion program should proceed to development of a nextstep engineering test reactor and called for a

doubling of the magnetic fusion budget over the

next seven years. These recommendations were

subsequently embodied in the Magnetic Fusion

Energy Engineering Act of 1980.6

❚ The 1980s: Technical Progress and

Declining Budgets

In the 1980s, the sense of urgency generated by the

1970s “energy crisis,” which had pushed the program to develop a fusion demonstration powerplant, rapidly abated, and funding began to

decline. Policy shifts and growing budgetary pressures contributed to a de-emphasis on research on

alternative concepts and the cancellation, mothballing, or shut-down of a number of major experimental facilities. Throughout the 1980s, the

magnetic fusion program underwent a series of

management reviews and redirections as budgets

4 See, e.g., U.S. Congress, Office of Technology Assessment, Comparative Analysis of the 1976 ERDA Plan and Program, OTA-E-28

(Washington, DC: U.S. Government Printing Office, May 1976), pp. 98-102; and reports cited in Committee on Magnetic Fusion in Energy

Policy, op. cit., footnote 3, pp. 18-39.

5Committee on Magnetic Fusion in Energy Policy, op. cit., footnote 3, citing U.S. Department of Energy, Review Committee on the Magnetic Fusion Energy Program, “Final Report,” DOE/ER-0008, June 1978.

6 For a discussion of this act, see the next section of this chapter.
Chapter 2 The Federal Fusion Energy Research Program | 21

continued to decline in real terms. As a result, the

program began to be increasingly focused on gaining approval and funding for an advanced tokamak successor to the TFTR and for its

involvement in an international collaboration to

build an ignition tokamak. That focus continues

today.

The Reagan Administration held markedly different views of the appropriate role of federal energy R&D activities than did its predecessors, and

sharply reduced the budgets of many energy research programs. However, because it was undeniably targeted at high-risk, long-term research,

the magnetic fusion program fit more closely with

the new administration’s priorities than fossil, renewable, and energy-efficiency research projects

that were focused on nearer term commercial efforts. Consequently, the fusion budgets fared better than some other programs during the Reagan

years. The fusion program budget actually increased in nominal dollars to peak at $468 million

in fiscal year (FY) 1984 before it began its decline.

(According to an analysis by DOE using special

“high energy physics” equipment and construction indices, the fusion program funding peaked in

real terms in 1977 and thereafter failed to keep

progress with inflation. By 1988 the magnetic fusion program funding had effectively been cut to

half of what it was at its 1970s peak).

DOE’s 1983 Comprehensive Program Management Plan (CPMP) for the fusion program

(required by the Magnetic Fusion Energy Engineering Act of 1980—MFEEA) reflected the

Reagan policies and explicitly ruled out a government-built demonstration reactor. The CPMP

defined the mission of the fusion program as supporting research that would allow selection of a

confinement concept for further development by

the private sector and to allow a decision to build

an engineering test reactor by 2000.

The CPMP was strongly criticized by the fusion technical advisory committee of ERAB in its

first triennial review of the fusion program required under MFEEA. The panel concluded that

program budgets would not allow the CPMP

goals to be met, and that the proposed schedule

would force a premature choice between the competing mirror and tokamaks concepts, and could

delay progress on tokamak advances. Moreover, it

called for construction of an engineering test reactor (ETR) before necessary technology would be

available. The panel recommended a redirection

of the program to delay construction of an ETR,

allow construction of a tokamak successor to

TFTR to study ignition and burning plasma physics issues, and to maintain a strong innovative

program in plasma physics, technology development, and alternate confinement concepts.7

In 1985, responding to these criticisms and others, DOE issued a revised Magnetic Fusion Program Plan (MFPP) that states that “the goal of the

magnetic fusion program is to establish the scientific and technological base required for fusion energy.”8 This goal has remained the central mission

of the fusion program ever since. The MFPP reduced the emphasis on reactor development that

had characterized the 1983 plan and concentrated

on the science and engineering requirements. It

laid out several key technical issues to be resolved

by the fusion energy program, recommended

construction of a compact ignition tokamak (CIT)

to explore the physics of ignited plasmas, and established a goal of international collaboration

rather than international leadership. Like the

CPMP, it too, precluded government construction

of a demonstration reactor. ERAB’s second triennial review of the fusion energy program endorsed

the direction and strategy in the 1985 plan. The

panel raised concerns over the potential impacts

7 Technical Panel on Magnetic Fusion of the Energy Research Advisory Board, Magnetic Fusion Energy Research and Development, final

report, DOE/S-0026 (Washington, DC: January 1984).

8 U.S. Department of Energy, Office of Energy Research, Magnetic Fusion Energy Program Plan, DOE/ER-0214 (Washington, DC: February 1985), executive summary.
22 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

on the program of proceeding to construct the CIT

under constrained budgets and recommended that

the CIT be funded as an increment to the MFE

budget.

By 1986, budget constraints were already taking their toll on the breadth of the fusion program

leading to project cancellations and cutbacks (see

figure 2-2). The huge $330-million tandem mirror

experiment at Lawrence Livermore National Laboratory, the MFTF-B, was mothballed almost immediately after its completion in 1986 without

ever operating as a fusion facility. DOE determined that it could not operate both the MFTF-B

and its competitor, the TFTR at Princeton, with

available funds.9 Earlier, DOE canceled the Fusion Materials Irradiation Test Facility at Hanford, Washington, which was to support advanced

materials development. Funding constraints also

led DOE to defer the start of the critical D-T experiments in the TFTR. In 1987, construction was

completed on the Advanced Toroidal Facility

(ATF) at Oak Ridge National Laboratory, then the

world’s largest stellarator, but funding problems

limited the extent of its experimental operations

from the start. Work was allowed to continue on

construction of a smaller, and less-expensive, reversed field pinch device at Los Alamos National

Laboratory.

During the 1980s, international collaboration

efforts grew as DOE pursued the negotiation of an

international initiative for the joint design,

construction, and operation of an engineering test

reactor as equal partners with the Japanese, Soviet, and European Community fusion programs.

The ITER effort began as a result of discussions

between President Reagan and Soviet Leader Gorbachev at the 1985 Geneva summit. An agreement

to work jointly on a conceptual design for ITER

was concluded in 1988 among the four governments.10

OTA’s 1987 report, Starpower: The U.S. and

the International Quest for Fusion Energy,11 examined the magnetic fusion program and noted

the substantial progress that had been made in the

scientific and technical challenges of proving the

feasibility of fusion power. Starpower found that

most researchers expected that at least three decades of additional R&D would be required before

a prototype commercial fusion reactor could be

demonstrated. Meeting even this schedule, however, would require a substantial increase in U.S.

fusion research budgets or a dramatic expansion

of international collaboration in fusion research.

The OTA report emphasized that important scientific uncertainties and technological challenges

remained to be resolved before fusion’s commercial potential could be assessed. The report further

cautioned that it was still too early in the research

program to determine which confinement concept

would be most likely to form the basis of an attractive commercial fusion reactor, and whether once

developed, fusion reactors would be economically competitive with other energy sources. These

conclusions still hold today, especially as the increased funding required to pursue scientific and

technical issues have not received a high priority

in an era of tight federal budgets.

The impacts of funding constraints on the

fusion program did not escape the attention of

congressional committees. During the FY 1988

appropriations process, Congress directed DOE to

submit a five-year flat budget plan that detailed

how the program would support D-T experiments

on the TFTR, construction of the proposed CIT,

and participation in ITER conceptual design acti9 At the time, there were concerns about the potential technical performance of MFTF-B because of the difficulties encountered by smaller

mirror experiments in meeting their performance targets. However, budget constraints seemed to have been the decisive factor in sealing the

fate of the MFTF-B.

10 For more on ITER, see box 1-1 in ch. 1 of this report.

11 Office of Technology Assessment, op. cit., footnote 3.
Chapter 2 The Federal Fusion Energy Research Program 23

I I I

J

ITER CDA

begun ,

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94

Fiscal Year

KEY:

BPX/CIT=Buming Plasma Experiment/Compact Ignition Tokamak

DT=Deuteriurn-Tritium

EBT=Elmo Bumpy Torus

EBT-P=Elmo Bumpy Torus-P

FMIT=Fusion Materials Irradiation Test Facility

ISX=lmpurity Studies Experiment (a tokamak)

ITER CDA=lnternational Thermonuclear Experimental Reactor Conceptual Design Activities

ITER EDA=lnternational Thermonuclear Experimental Reactor Engineering Design Activities

LANL RFP=Los Alamos National Laboratory Reverse Field Pinch

LCT=Large Coil Test Facility (superconducting magnets)

LLNL=Lawrence Livermore National Laboratory

LSX=Large S Experiment (afield-reversed compact toroid device)

MFTF-B=Mirror Fusion Test Facility-B

MIX= Microwave Tokamak Experiment

ORNLATF=Oak Ridge National Laboratory Advanced Toroidal Facility (a stellarator)

PDX=Princeton Divertor Experiment

TFTR=Tokamak Fusion Test Reactor

TPX=Tokamak Physics Experiment

SOURCE: U.S. Department of Energy, 1994.

5
24 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

vities under constant dollar funding of about $360

million annually.

In testimony, DOE explained that CIT design

and ITER activities were being funded by stretching out the CIT construction schedule, eliminating the mirror program for budgetary not technical

reasons, and “taxing” the balance of the programs’

work on alternate concepts and theoretical physics.12 In the meantime, internal reviews showed

the projected costs of the CIT growing from an estimated $360 million in FY 1986 to almost $1 billion due to design changes to give greater

assurance of reaching ignition and a stretch out of

the completion schedule.13

DOE absorbed the initial budget pressures in

the 1980s by cutting back sharply on new construction and mothballing or delaying new initiatives. This allowed the program to continue to

fund the mainline tokamak projects, while still

supporting some research on alternative concepts,

basic plasma physics, and technology development. However, a sharp drop in the fusion budget

in FY 1989 forced the program to cut into its base

program and tokamak activities to continue progress on high-priority items such as TFTR and the

ITER collaboration.

Budget pressures, a change in administrations,

and internal reviews led to more program reviews

and budget reductions. In 1989, DOE decided to

defer the CIT as then planned while conducting a

transport initiative, sponsored by taxing other

projects, in an attempt to resolve the physics issue

of heat loss from tokamaks.14 Secretary Watkins

also proposed a head-to-head competition between magnetic fusion (i.e., tokamaks) and inertial fusion (see figure 2-3).

These shifts were met with criticism from

many in the fusion community and Congress.15

Among the criticisms were that the focus on a

tokamak/inertial fusion energy competition and

discontinuance of a broader program of complementary investigation of physics issues on alternative concepts, and supporting work on plasma

physics and materials and technology development created an imbalance in the fusion program

and would not assure a well-defined path to commercial fusion. In effect, the proposed competition would limit the comparison to the

performance of two devices, the proposed CIT

and the Laboratory Microfusion Facility, each of

which were designed primarily to study narrow

physics issues. Neither reactor would be prototypical of power reactors to follow and neither device

would be intended to or capable of answering

many questions needed to be addressed in selecting a future line of approach to fusion energy. According to its critics, the competition as posed

would not serve its purpose and the delay in CIT

construction would idle many fusion researchers

and engineers.16

Secretary Watkins responded by calling for

another high-level review panel to recommend a

new policy direction for the fusion energy program. The panel was also tasked with conducting

the third triennial review of the magnetic fusion

12 See testimony of James F. Decker, Acting Director, Office of Energy Research, U.S. Department of Energy, and supplemental materials,

in U.S. Congress, House of Representatives, Committee on Science, Space, and Technology, Subcommittee on Energy Research and Development, “Hearing on Fiscal Year 1989, Department of Energy Authorization (Magnetic Fusion Energy), “ 100th Congress, 2d sess., Mar. 30, 1988,

vol. vi , pp. 11-22, 97-98.

13 David Crandall, U.S. Department of Energy, Office of Fusion Energy, personal communication, November 1994.

14 Testimony of Robert O. Hunter, Jr., Director, Office of Energy Research, U.S. Department of Energy in U.S. Congress, House of Representatives, Committee on Science, Space, and Technology, Subcommittee on Investigations and Oversight, “Hearings on Fusion Energy Program: Status and Direction,” 101st Congress, 2d sess., Oct. 5, 1989, pp. 297-317.

15 U.S. Congress, House of Representatives, Committee on Science, Space, and Technology, “Hearings on Fusion Energy Program: Status

and Direction,” 101st Congress, 2d sess., Oct. 5, 1989.

16 Statement of Senator Frank Lautenberg, in debate on the FY 1990 Energy and Water Appropriations Bill, Congressional Record (daily

ed.), S8947, July 27, 1989.
Chapter 2 The Federal Fusion Energy Research Program 25

Compact ignition

tokamak (CIT)

1989 1992

Engineering test Engineering prototype

facility (ETF) reactor (EPR)

2004 2012 2016 2025

Laboratory micro-fusion

facility (LMF) /

 Decision to proceed with device

I

▼ Operation of device 1989 1992 1998

◆ Selection

SOURCE: Testimony of Robert O. Hunter, Jr., Director, Office of Energy Research, US. Department of Energy, Attachment, in US Congress, House

of Representatives, Committee on Science, Space, and Technology, Subcommittee on Investigations and Oversight, “Hearings on Fusion Energy

Program. Status and Direction, ” 101st Congress, 2d sess., Oct. 5, 1989, p. 335.

program required under the 1980 Act. The Fusion

Policy Advisory Committee (FPAC) reported

back in September 1990 supporting a “responsible, goal-oriented fusion energy development

program” directed at achieving the goals of “at

least one operating Demonstration Power Plant by

2025 and at least one operating Commercial Power Plant by 2040.”17 The committee expressed its

belief that the U.S. fusion energy program was

“technically ready” to construct devices to demonstrate significant fusion power production in a

burning tokamak plasma and ignition in an inertially confined pellet. The committee noted that

attaining its conceptual goals would require an

immediate ramp up in funding and, recognizing

the tight budget climate, provided a number of

next-step options with lower immediate effects on

the fusion budget. The committee cautioned,

however, that “the first funding increments for

new facilities in the constrained program are essential for fusion to be an energy program. If these

increments are not forthcoming, the program

would remain only a research effort without rea17 Letter from H. Guyford Stever, Chairman, Fusion Policy Advisory Committee to Admiral James D Watkins, Secretary Of Energy, Sept.

25, 1990, transmitting the committee report, reprinted in U.S. Department of Energy, Fusion Policy Advisory Committee (FPAC), Report of the

Technical Panel on Magnetic Fusion of the Energy Research Advisory Board, Final Report, DOE/S-0081 (Washington, DC: September 1990),

hereinafter referred to as FPAC 1990.
26 The Fusion Energy Program: The Role Of TPX and Alternate Concepts

Inside the vacuum vessel of the TFTR at the Princeton Plasma

Physics Laboratory Graphite and graphite composite tiles

protect the inner wall of the vessel.

sonably timed energy objectives.”18 FPAC made a

number of specific recommendations, including:

1. The United States should commit to fusion as a

potential energy source.

2. The program should support both magnetic fusion and inertial confinement fusion as distinct

and separate approaches and should plan for

major new facilities in each. In recommending

this strategy, the FPAC report observed: “The

committee affirms its belief that the two concepts are not ready for a choice of one over the

other. Pursuing both options at this time reduces technological risk.”19

3. The United States should participate actively

as an equal partner in the ITER engineering design activities (EDA) collaboration while

maintaining a strong and balanced domestic

program.

4. The U.S. fusion program should support “an

independent program of concept improvement,

including study, and where promising, development of alternative configurations that may

be more suitable for commercialization,” plus

vigorous technology and materials development.

5. The program should increase opportunities for

U.S. industry participation to allow them to

take advantage of fusion technology advances,

while continuing involvement of universities

and national laboratories.

The committee estimated that its conceptual

program would require U.S. fusion program

budgets (including the defense inertial confinement fusion program) to reach about $1 billion per

year in constant dollars over the period 1990 to

1997 to allow construction of essential new facilities. (Note that this estimate did not include the

costs of ITER construction scheduled to begin after 1998.) Constrained budget approaches and priorities were also suggested.20

At its full budget level, FPAC called for the

magnetic fusion energy (MFE) program to support participation in ITER EDA activities,

completion of D-T experiments in the TFTR,

construction of the Burning Plasma Experiment

(BPX—an outgrowth of the previous CIT design),

a modest increase in the base program, design of a

new steady-state tokamak, and increased emphasis on low activation materials and nuclear

technology. This recommendation would require

an increase in the magnetic fusion budget from

$316 million in FY 1990 to over $600 million in

FY 1996 in 1990 dollars.

At reduced budgets, FPAC gave priority to

holding the base program roughly constant, funding D-T experiments in TFTR, stretching out

construction of BPX by two years, and participation in ITER. Construction of BPX/CIT was seen

as making the United States a “strong and attractive partner in magnetic fusion research,” achieving an important milestone intermediate between

existing facilities and ITER, and re-establishing

U.S. leadership in magnetic fusion. FPAC estimated that to achieve these priorities the budget

would have to increase to about $470 million

(1990 dollars) by FY 1996.

18 Ibid.

19 FPAC 1990, p. 4.

20 Ibid., p. 5.
Chapter 2 The Federal Fusion Energy Research Program | 27

FPAC recognized that inertial confinement

fusion (ICF) would need to remain primarily a

defense program and supported as its highest

priority mission, the study of target physics leading to the demonstration of pellet ignition. FPAC

noted that ongoing ICF work on target physics and

drivers will be beneficial for advances in inertial

fusion energy (IFE). To provide more effective

support for the goal of developing IFE technology, FPAC recommended that an IFE program be

integrated into the Office of Fusion Energy as a

separate division. The new IFE program would

concentrate on efforts that would be complementary to the ICF activities—e.g., developing an efficient and low-cost driver with repetition rates of

several pulses per second,21 concurrent work on

materials and reactor designs, and investigation of

environment, health, safety, waste disposal, and

decommissioning matters related to an IFE powerplant.

FPAC endorsed a suggestion by a separate National Academy of Sciences (NAS) Panel that

DOE develop the heavy-ion Induction Linac System Experiments (ILSE) within the IFE program

and a glass laser facility in the defense program as

intermediate steps before proceeding with a proposed Laboratory Microfusion Facility.22 FPAC

noted that unlike the situation in magnetic fusion,

the U.S. program remained the world leader in

ICF offering potential opportunities to capitalize

on that position if IFE proves commercial.

FPAC offered several budget priorities for ICF

programs including upgrades to the Nova laser at

Lawrence Livermore National Laboratory and to

other existing laser facilities and continued work

on target physics at an increment of about $44 million over FY 1990 ICF budgets by FY 1991. Additional priorities, if funding were available, would

be to support IFE development work on heavy-ion

drivers, light-ion drivers, and krypton-fluoride lasers. This would increase the FY 1996 budget by

an additional $34 million to $64 million over FY

1990 levels. FPAC estimated that support of IFE

base program activities and construction of ILSE

would require about $90 million over five years.23

As for the general management of the DOE fusion program, FPAC recommended that fusion

R&D activities be conducted in a disciplined goaloriented manner with detailed development strategies, appropriate milestones, key decision

points, and “down-selection” among competing

options following adequate technical evaluations

on a path to achieve a demonstration of one or

more fusion powerplants by 2025. The magnetic

fusion path would include ITER, a burning plasma facility and support of alternate concepts, concept improvement, and materials and technology

development. FPAC also recommended that the

IFE program build on advances in target physics

under the defense programs while investigating

several competing driver technologies, including

heavy-ion drivers. An early decision would be

made to pursue either a light-ion or krypton-fluoride laser alternative driver based on technical performance. At each major step, the program should

be subject to rigorous feasibility and cost analysis

by a qualified external group prior to approval.

While recognizing that the national laboratories

would continue to have responsibility for new facilities, FPAC recommended that the labs develop

more effective mechanisms to work cooperatively

and share responsibility while providing opportunities for more university, industry, and interna21 There are several technologies under consideration as possible drivers for IFE power production including heavy-ion drivers, light-ion

drivers, and krypton-fluoride lasers. Research on light ions and krypton-fluoride lasers is supported by the ICF program because of defense-related applications and experience there could be transferred to energy applications in the future. The National Academy of Sciences has remarked favorably on the potential use of heavy-ion accelerators as IFE drivers and encouraged construction of a device that could be used to

demonstrate and experiment with the characteristics of a full-sized heavy-ion driver. ICF researchers in Europe and Japan are also exploring use

of heavy-ion drivers, but are focusing instead on using radio frequency acceleration rather than the induction Linac approach. Ibid., pp. 43-47.

22 Ibid., pp. 41-43.

23 Ibid., p. 44.
28 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

tional collaboration in the design, construction,

and operation of new facilities.

An NAS committee also released a review of

the priority and pace of the magnetic fusion R&D

program in 1990.24 The NAS panel found a loss in

U.S. leadership in MFE research due primarily to

the halving of program funding in constant dollars

since 1977, which also led to narrowing of U.S.

programs. This committee concluded that current

DOE program funding levels would be inadequate

to meet even the near-term objectives of the 1985

MFPP. The committee estimated that funding levels would have to be increased by at least 20 percent annually over 1990 levels in the early 1990s

and by an additional 25 percent in the late 1990s to

allow the U.S. program to proceed with the proposed CIT experiment and to participate in ITER

construction. The committee offered several interim recommendations for the magnetic fusion

program:

1. U.S. participation in an international collaboration on next-step major facilities as the most

cost-beneficial U.S. approach to fusion over

the next decade;

2. an increase in program funding to permit

construction of CIT to allow resolution of central scientific feasibility questions and participation in construction of ITER in the late

1990s; and

3. development of a revised program plan providing greater participation by U.S. companies in

activities such as design and construction of

major systems and subsystems.

The committee noted that these recommendations were made without consideration of competing demands for resources from other energy

technologies or national programs. The NAS panel commented on the absence of any comprehensive comparative assessment of the energy,

environmental, health, safety, economic, and

institutional aspects of various competing alternative future energy technologies on which to base

informed choices for overall U.S. energy research

priorities.

❚ The 1990s: Growing Internationalization

and Tough Budget Choices

Secretary Watkins adopted the FPAC findings

“subject to existing budget constraints.” But the

funding increases recommended by FPAC and the

NAS panel did not win support within DOE or in

Congress. Indeed, fusion budgets continued to diminish. Budget cuts driven by deficit reduction

and reprogramming took the MFE program from

$316.7 million in FY 1990 to $273.6 million in

FY 1991. According to the then-director of the Office of Energy Research:

This translated into terminating work on alternative confinement concepts and pursuing

only the tokamak concept within the magnetic

fusion energy program as a precursor to a Burning Plasma Experiment (BPX) that would be integrated into a larger international fusion energy

program.25

Even in the face of these budget cuts, the Bush

Administration released its National Energy

Strategy (NES), which adopted fusion energy as

an important long-range element incorporating

the recommendations of FPAC. The NES fusion

goals were to prove fusion energy to be a technically and economically credible energy source,

with an operating demonstration plant by about

2025 and an operating commercial plant by about

2040. This would be accomplished by developing

both magnetic and inertial confinement approaches to fusion separately until sufficient R&D

exists to make a choice, and also by achieving early industrial involvement. The NES called for

continued international collaboration and cost24 Committee on Magnetic Fusion in Energy Policy, op. cit., footnote 3.

25 William Happer, “Charge to the Fusion Energy Advisory Committee,” Sept. 24, 1991, reprinted as app. E in Fusion Energy Advisory

Committee, Report on Program Strategy for U.S. Magnetic Fusion Energy Program, DOE\ER-0572T (Washington, DC: U.S. Department of

Energy, Office of Energy Research, September 1992.) Hereinafter referred to as FEAC, September 1992.
Chapter 2 The Federal Fusion Energy Research Program | 29

sharing in the magnetic fusion program. The NES,

however, explicitly recognized that:

The technical complexity associated with fusion development is such that substantial investments are required for new experiments, design

facilities, and test facilities. This implies the

need for long-term growth in research and development funding. 26

In September 1991, Secretary Watkins followed a Secretary of Energy Advisory Board

(SEAB) Task Force recommendation that the proposed BPX project not be funded because of

growing cost estimates and anticipated budget

constraints. This cancellation left the U.S. fusion

program potentially bereft of any large-scale fusion experimental facility after the scheduled closure of the TFTR in FY 1994. Actual funding for

the magnetic fusion program in FY 1992 was

$337.1 million and restored much of the funding

loss in FY 1991, but funding demands to support

TPX design and ITER activities resulted in a continued narrowing of the program

Once again, DOE turned to an advisory committee for assistance in setting priorities. In response to the request, the Fusion Energy Advisory

Committee (FEAC) issued a series of reports27 reviewing the physics and engineering/technology

requirements for meeting the 2025 goal for a

Demonstration (DEMO) reactor under four alternative future budget scenarios and indicated their

recommended priorities under each.28

FEAC strongly concluded that:

 Reaching the goal of an operating DEMO by

2025 is the approximate target date required if

fusion is to be a significant contributor to U.S.

energy supply by the middle of the 21st

century.

 Fusion program budgets will have to increase

at least 5 percent per year in real terms over the

FY 1993 total of $337.9 million with an additional increment for ITER construction to be

plausibly consistent with the DEMO target

date.

 Highest priority should be given to completion

of D-T experiments in the TFTR and participation in ITER EDA under all budget scenarios.

Under its first or “reference” scenario, the panel

called for an annual increase in the magnetic fusion program budget of 5 percent over inflation

over the FY 1993 level of $330.7 million, or an increase to about $420 million in FY 1998 (in 1993

dollars). In addition to support for D-T experiments and participation in ITER, the panel recom26 National Energy Strategy, Powerful Ideas for America, First Edition 1991/1992 (Washington, DC: U.S. Government Printing Office,

February 1991), pp. 130-131.

27 FEAC, September 1992; Fusion Energy Advisory Committee, Advice and Recommendations to the U.S. Department of Energy in Response to the Charge Letter of September 18, 1992, DOE/ER-0594T (Washington, DC: U.S. Department of Energy, Office of Energy Research,

June 1993), hereinafter referred to as FEAC 1993. Fusion Energy Advisory Committee, Advice and Recommendations to the Department of

Energy in Partial Response to the Charge Letter of September 24, 1991: Part D, DOE\ER-0555T (Washington, DC: U.S. Department of Energy,

Office of Energy Research, June 1992). FEAC was established to advise the Director of the Office of Energy Research/Assistant Secretary for

Energy Research.

28 Two scenarios requested in the charge to the committee were a constant dollar budget for magnetic fusion through FY 1996 and increasing the budget at 5 percent real growth per year through FY 1996. FEAC’s report included four scenarios:

 The “SEAB Task Force Scenario”—increasing the MFE budget in FY 1994 by 5 percent in real terms over the FY 1993 request ($360

million) and annual growth at 5 percent per year in real terms thereafter;

 The FEAC “Reference Scenario”—increasing MFE funding at 5 percent in real terms above inflation starting from the appropriated FY

1993 level ($339.7 million);

 The Constant or “Flat Budget Scenario”—allowing adjustments only for inflation for fiscal years 1993-96; and

 The “Declining Budget Scenario”—in which the MFE budget is frozen at the FY 1993 level in as spent dollars and declines at the rate of

inflation (assumed at 3.1 percent per year).

See FEAC, September 1992, pp. 1-16.
30 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

mended construction of the TPX (steady-state

advanced tokamak),29 upgrades to the General

Atomics DIII-D tokamak to support TPX and

ITER, and restart of the ATF stellarator. The panel

also recommended modest enhancements of the

fusion materials program and of the fusion development and technology base programs to support

ITER activities and student training in various

areas of fusion engineering, and maintaining research in applied plasma physics at least at present

levels. The panel did not include any allowance

for expected increases in funds needed to complete ITER EDA activities over the levels originally agreed to among the four parties in 1992.

TPX construction costs were then estimated at

about $500 million in FY 1989 dollars. Noting the

persisting scientific uncertainties in extrapolation

of the tokamak to a competitive commercial reactor despite its scientific successes to date, the committee suggested establishment and maintenance

of a concept improvement program to investigate

both tokamak and nontokamak confinement concepts as part of the U.S. fusion program as a matter

of policy.30

The committee report contrasted the reference

scenario with the budget levels recommended by a

1991 SEAB task force of a 5 percent annual increase above inflation over the FY 1993 budget request or an increase to $360 million in FY 1993

rising to about $460 million in FY 1998 (in 1993

dollars). SEAB had concluded that such an increase would be required to restore the program

balance to a healthy base of activity. At a base of

$20 million over the reference scenario priorities,

FEAC recommended studying a U.S. site for

ITER, enhancing the U.S. ITER EDA support activities, and enhancing activities on improved

tokamaks and other concepts, fusion theory, computation, materials research, and technology development. The FEAC panel concluded that even

this higher budget, while meeting recommended

priorities, “would jeopardize U.S. ability to compete in hosting a site for ITER and require that

base programs be held at levels lower than FEAC

believes is appropriate given their importance.”31

Under a flat budget scenario approximately

$337.9 million per year in constant 1993 dollars)

in FY 1993-FY 1998, adjusted for inflation,

FEAC recommended proceeding with TPX on an

extended construction schedule by prematurely

terminating the Princeton Beta Experiment Modified (PBX-M) tokamak at the Princeton Plasma

Physics Laboratory (PPPL) and delaying design

of the 14 MeV neutron source.

Under the declining budget scenario, the annual program budget would remain at $337 million

in 1993 dollars unadjusted for inflation over five

years. FEAC concluded that TPX could not be

built, nor could design of the 14 MeV neutron

source materials test facility begin until after FY

1997. Planned upgrades of existing facilities to

support ITER would have to be stretched out.

With shutdown of TFTR, the U.S. program would

be faced with the loss of critical personnel and

PPPL’s position as a world leader in experimental

confinement physics research would be threatened. According to FEAC, the primary consequences of such a strategy would be to severely

undermine the U.S. fusion program and its ability

to participate effectively in ITER. It is unlikely

under this scenario that the United States could

participate in ITER construction and operation.32

29 After cancellation of the BPX, a planning effort directed by the Princeton Plasma Physics Laboratory resulted in the proposal to build a

smaller successor to the TFTR as a steady-state advanced tokamak machine with superconducting magnets and divertor designs that would be

complementary to ITER. For more on the history and design of TPX, see ch. 3 of this report.

30 FEAC, September 1992, p. 10.

31 Ibid., pp. 11-13.

32 Ibid., pp. 15-16.
Chapter 2 The Federal Fusion Energy Research Program 31

● Toroidal

field magnet

Major components of the proposed ITER.

Another FEAC panel report made recommendations for IFE activities and indicated budget priorities, emphasizing research needs supporting

heavy-ion drivers, and reiterated many of the conclusions of FPAC on the attractiveness of IFE. 33

In all cases the panel called for a balance among

experimental and analytical program support for

IFE, accelerator development, and beam physics.

Three budget cases set by DOE were reviewed.

According to the panel, the most significant development since the 1990 FPAC review was a re33 FEAC 1993.

vacuum vessel

Vertical access

point

Central

solenoid

Blanket/shield

Plasma

chamber

Port to provide acce

to plasma chamber

Poloidal field

magnet

Vacuum pump

duct for exhaust

ss

Scale: The ITER

device will be

about 30 meters

high--or roughly

as tall as a ninestory building.

duction in the estimated cost for building ILSE to

$45 million because of technical advances, design

changes, and availability of an existing site and facilities. 34At an annual budget level of $17 million

(1992 dollars), the panel gave highest priority to

ILSE construction and experiments along with

supporting work on accelerator theory, reactor

system studies, and technology development. At a

middle funding level of $10 million/year, the panel concluded that it would not be possible to com34Ibid., pp. 9-10. Estimate of $45 million for ILSE costs is from U.S. Department of Energy comments on OTA draft report, November

1994.
32 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

plete the integrated ILSE demonstration project as

proposed. The panel recommended that the program proceed with scaled up accelerator experiments in the low energy part of the ILSE plan and

continue support in accelerator and beam physics.

At a low funding level of $5 million annually, the

panel concluded that a U.S. program would not

support a “credible” heavy-ion fusion development program and suggested that advocates of the

heavy-ion program enter negotiations with other

offices in DOE that might be more receptive to

their work.

The Energy Policy Act of 1992 (EPACT), included a mandate for a five-year fusion energy research program. EPACT called for a broad-based

program with participation in ITER activities,

construction of a new major U.S. fusion machine,

development of a heavy-ion driver experiment,

and increased industrial participation. EPACT

also imposed additional administrative and management requirements on DOE’s fusion program.

❚ The Fusion Program Today

In the 1990s, the magnetic fusion program continues to evolve and redirect its activities in response

to the suggestions of FPAC, FEAC, and congressional appropriations committees and the requirements of the fusion energy provisions of EPACT.

The Office of Fusion Energy’s magnetic fusion activities have been narrowed to an even greater focus on tokamak concepts, national facilities, and

greater reliance on international collaboration to

move toward achievement of the next milestones

in fusion energy development. The result is that

work has been drastically curtailed on exploration

of alternative confinement concepts that might

have more attractive characteristics as a commercial energy source than tokamaks. Even more significantly to some in the fusion community, little

progress can be expected at current funding levels

on the development of low activation and other

advanced materials and on fusion powerplantrelated technologies that will be needed under

virtually all magnetic confinement approaches,

including the tokamak.

The Bush and Clinton administrations sought,

and Congress provided, increases in fusion funding in fiscal years 1993 to 1995 primarily to support participation in ITER, and design, but not

construction of the TPX. The modest increase in

funding has not been sufficient to offset the continued narrowing of the program as alternative

concepts research and base program activities

have been squeezed to keep major tokamak experiments operating. Despite EPACT’s endorsement of a broad-based fusion program and the

strong recommendations of several outside advisory reviews to support investigation of alternative concepts, budget pressures, combined with

explicit directions from appropriations committees to give highest priority to full funding of major tokamak projects and ITER, have resulted in

curtailment of work on alternates to the tokamak.

THE FUSION PROGRAM GOALS

IN LAW AND POLICY

Fusion energy research is carried out under various grants of authority and congressional mandates. The most important sources of general

authority for the fusion program are EPACT,35

The Magnetic Fusion Energy Engineering Act of

1980,36 and the Atomic Energy Commission Act

of 1954.37 These laws are summarized in box 2-A.

EPACT directs the Secretary of Energy to conduct a five-year fusion energy program to result in

a technology demonstration by 2010 verifying fusion’s “practicability’’ for commercial power production. EPACT’s general goals for fusion energy

research include: 

35 Public Law 102-486, section 2114, Oct. 24, 1992, 106 Stat. 3073-3074, 42 U.S.C. 13474.

36 Public Law 96-386, Oct. 7, 1980, 94 Stat. 1539, 42 U.S.C. 9301.

37 Act of Aug. 30, 1954, ch 1073, 60 Stat. 921, as amended, 42 U.S.C. 2011 et seq.
Chapter 2 The Federal Fusion Energy Research Program 33

The Energy Policy Act of 19921 (EPACT) directs the Secretary of Energy to conduct a fusion energy

program resulting in a technology demonstration by 2010 to verify fusion’s “practicability” for commercial

power production. EPACT set forth general goals for a broad-based fusion energy research effort and

established several new management and reporting provisions including a requirement for a comprehensive fusion management plan and biannual reports. The Act also (under sections 3001 and 3002) applies

general provisions relating to cooperative energy research and cost sharing to fusion research activities. To

support this program, EPACT authorizes appropriations of $339.7 million for fiscal year 1993 and $380

million in fiscal year 1994.

Under EPACT, DOE’s fusion energy research programs also are intended to support more general goals

for federal energy supply R&D including: reducing oil import dependence, increasing the energy efficiency

of the U.S. economy, stimulating economic growth, stabilizing and reducing greenhouse gas emissions,

promoting environmental protection, developing more environmentally sustainable energy systems, enhancing technological competitiveness, fostering international cooperation and technology transfer, creating new market opportunities for American industry, and contributing to advancing fundamental scientific

knowledge.

The Magnetic Fusion Energy Engineering Act of 1980 (MFEEA)2 also sets forth policy goals and

management requirements for the fusion energy program. The act called for an aggressive magnetic fusion

R&D program with the goals of establishing engineering feasibility by 1990, and developing an operating

magnetic fusion device by 1990 and an operating magnetic fusion demonstration plant for electric power

production “by the turn of the 21st century. ” Section 4 directs the Secretary to maintain a “broadly based

research program on alternative confinement concepts and on advanced fuels” in addition to “an aggressive plasma confinement research and construction program on the current lead concept, ”3 The program

was to promote broad participation of industry and greater public understanding of fusion energy. The act

also provided for continued cooperation in international fusion research and maintaining U.S. leadership in

magnetic fusion.

The MFEEA requires the Secretary of Energy to prepare a comprehensive fusion program management

plan, create a national fusion engineering center, establish a technical advisory panel on magnetic fusion

to review the program and advisory committees for each fusion laboratory or facility, and report on

program activities annually. The required management plans were issued in 1983 and revised in 1985 to

reflect comments of a technical review panel and the changing energy research policy of the Reagan

Administration. Triennial reviews were conducted in 1983, 1986, and 1990.

The MFEEA goals and program structure reflected the “energy crisis” mentality of the times and

adopted the recommendations of the fusion technical review panel for a shift in the program from a

focus on fundamental fusion science and plasma physics to technology development. The act called

for substantial increases in annual appropriations for fusion research in later years to achieve these

ambitious goals. These increases were not provided.

1 Public Law 102-486, section 2114, Oct. 24, 1992, 106 Stat 3073-3074, 42 U S C 13474.

2 Public Law 96-386, Oct. 7, 1980, 94 Stat. 1539, 42 U.S.C. 9301.

3

42 U.S.C. 9303.

(continued)
34 The Fusion Energy Program: The Role of TPX and Alternate Concepts

DOE’s fusion energy research activities are also conducted under the Atomic Energy Commission Act

of 1954,4 which provides basic authority for federal nuclear R&D activities and regulation. The act carried

on many provisions of the prior act of August 1, 1946 under which fusion research was supported by the

Atomic Energy Commission (AEC) and its successors. Most of the AEC’s nuclear research responsibilities

were transferred to the new Energy Research and Development Administration in 1974.5 In 1977 these

duties were vested in the newly formed Department of Energy.6

Among the purposes of that act are: to assist R&D to “encourage maximum scientific and industrial

progress, ” to aid education and training, promote widespread participation in development of peaceful

uses for atomic energy;7 and to encourage international cooperation.8 The federal government is authorized to support a broad range of research activities relating to nuclear processes, atomic energy theory

and production, use of nuclear energy or materials for generation of usable energy, and for commercial

and industrial applications.

The AEC was authorized to make grants and other contributions to the construction and operation of

reactors and other facilities at educational and charitable institutions for education and training purposes,9

and to conduct research activities and studies in its own facilities.10 The AEC Act thus provides additional

legislative authority for DOE support of fusion-related nuclear physics (including plasma physics) and the

engineering education and training missions of the Office of Fusion Energy and Defense Programs.

4 Act of Aug. 30, 1954, ch 1073, 60 Stat 921, as amended, 42 USC 2011 et seq.

5 Public Law 93-438, Oct 11, 1974

6 Department of Energy Organization Act, Public Law 95-91, Aug. 4, 1977.

7Atomic energy is defined as all forms of energy released in the course of nuclear fission or nuclear transformation. 42 U.S.C. 2014

Transformation is interpreted to include fusion.

8

42 U.S.C 2013

9

42 U.S.C. 2051(c).

1042 U.S.C. 2052

support of a broad-based fusion energy pro- ■ R&D on inertial confinement fusion energy,

gram;

participation in the ITER engineering design

activities and related efforts;

development of a technology for fusion power,

and industrial participation in technology development;

design and construction of a major new machine for fusion research and technology development; 38 and

and development of a heavy-ion inertial confinement fusion experiment.

EPACT’s reference to a broad-based fusion

program echoes the language of MFEEA, which

requires a “broadly based research program” on

attractive alternate concepts and alternate fuels

while also aggressively pursuing scientific progress via the tokamak path. The EPACT language is

38The major new machine has been interpreted by some as authorization for the proposed TPX, but others maintain that construction of the

facility has yet to be authorized specifically.
Chapter 2 The Federal Fusion Energy Research Program | 35

cited by proponents of alternate fusion concepts as

requiring DOE to support a more active and varied

alternate concepts research program. Fusion program officials at DOE, however, interpret this directive as requiring them to support a broad range

of research activities conducted by a variety of research institutions.

The comprehensive management plan for the

fusion energy program required under EPACT is

to include specific objectives, milestones, schedules, cost estimates, program management resource requirements, and an evaluation of the

appropriate extent of participation by universities

and the private sector in fusion activities. The plan

must evaluate the requirements needed to build

and test an inertial fusion energy reactor for purposes of power production. The plan also is to describe proposed U.S. participation in the design,

construction, and operation of ITER and include

an evaluation of international cooperative agreements on fusion research and of the need for

strengthening existing agreements or negotiating

new ones. The management plan was to have been

completed within 180 days of passage of EPACT,

i.e., by April 1993, however, DOE had not completed it as of December 30, 1994.39

EPACT also requires DOE to issue a report detailing fusion program organization staffing,

funding, and expenditures, and describing the program’s progress in achieving the specific objectives, milestones, and schedules in the fusion

management plan as part of the energy technology

inventory and status report for the management

plan on energy research, development, demonstration, and commercialization under section

2304.40 The first report was to have been submitted by October 1993. Updates on the progress

of the fusion plan are to be included in subsequent

reports every two years; by December 30, 1994,

the first periodic progress report had yet to be delivered.

DOE has been slow to implement the new management and reporting requirements for the fusion

program established by EPACT. Various reasons

have been suggested for the lack of progress in issuing a comprehensive management plan for the

future development of fusion power and for participation in ITER. The most important factors

contributing to the delay appear to be the uncertainty over future budget levels for the fusion research program (under the current policy of level

spending in discretionary programs) and a lack of

key decisions about the priority to be accorded to

fusion power among competing federal energy

and science research programs, including decisions about ITER. These policy decisions are not

made at the Office of Fusion Energy level and explain in part the absence of an updated management plan for fusion development. At the same

time, there does not yet appear to be any public

analysis of alternative long-term paths for federally sponsored fusion energy research efforts under

constrained funding. Several developments may

advance the opportunities for a reconsideration of

fusion research policy. The Office of Fusion Energy recently reconstituted FEAC. Over the next

year, the fusion research efforts are also likely to

come under review by one or more panels convened by the Secretary of Energy. These include

SEAB, the Task Force on Strategic Energy Research and Development, and the task force reviewing the work of the national laboratories.

39 DOE has released two reports relevant to some of the planning material requested. On November 21, 1994, Secretary Hazel O’ Leary

transmitted to several congressional committees the “Interim Report to the Congress on Planning for International Thermonuclear Experimental Reactor Siting and Construction Decisions,” in partial response to requests for a detailed ITER siting and development plan in the FY 1993

and FY 1994 Energy and Water Development Appropriations conference reports. The Secretary advised the committees that a more complete

response could not be provided until the ITER Interim Design Report is completed and accepted by the parties. In August 1994, the Department

of Energy released for comment a draft of “A Management Plan for the Conduct of Research, Development, Demonstration, and Commercial

Application of Energy Technologies” required under section 2304 of EPACT. The appendix to the draft contains a very brief one-page figure on

fusion technology issues, performance goals, benefits/leverage, and technology readiness dates.

40 42 U.S.C. 13523(c).
36 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

LEGISLATIVE DIRECTIVES

Priorities for the fusion energy programs are

shaped by directives contained in appropriations

acts and reports and pending legislation. In some

instances, DOE has given greater weight to the

directions of appropriations committees than to

the recommendations of its technical reviewers

and to more general provisions of law. For example, the FY 1994 Energy and Water Appropriations Conference Report directed DOE to:41

 focus the DOE magnetic fusion program on elements that further the design, construction, and

operation of ITER and a future demonstration

fusion reactor;

 set priorities for the domestic fusion energy

program identifying elements that contribute

directly to development of ITER or DEMO;

 provide a plan describing: 1) a selection process

for a U.S. host site for ITER; and 2) the necessary steps by the international partners for selecting a final ITER host site and for the design,

construction, and operation of ITER by 2005,

including relevant milestones and budget estimates;

 begin evaluation and selection of a U.S. ITER

host site;

 give highest priority in the national program in

FY 1994 to D-T experiments in the TFTR at

PPPL; and

 proceed with design and R&D tasks on TPX,

upgrades of the DIII-D tokamak, and an aggressive program on low activation materials to be

tested in ITER and used in DEMO, and provide

a $500,000 increase in funding for the IFE

program.

Effectively, the appropriations conference report applied many of the provisions of S. 646, a

bill passed by the Senate in June 1993, that would

have focused the magnetic fusion program almost

exclusively on activities in support of ITER and

TPX tokamak approaches and eliminated investigation of nontoroidal concepts. This approach

was highly criticized by many in the fusion research community.

In contrast to the appropriations directives and

S. 646, the House passed H.R. 4908, the Hydrogen, Fusion, and High Energy and Nuclear Physics Research Act of 1994 in August 1994. H.R.

4908 would have supported ongoing TPX and

ITER activities. It also would have restored research activities on alternative fusion confinement concepts through establishment of a separate

program that would have responsibility for advancing heavy-ion inertial fusion energy and other

alternate concepts. It is expected that similar legislation will be introduced in the 104th Congress.

Attempts to cut the fusion energy program

budget to produce savings for deficit reduction

and support of competing renewable and energy

efficiency technologies also were before the

House of Representatives in the 103d Congress.

In November 1993, the proposed Penny-Kasich

amendment to H.R. 3400, the Government Reform and Savings Act of 1993, included a provision rescinding $70 million from the fusion

energy program.42 During consideration of the FY

1995 Energy and Water Appropriations Act in the

House, an amendment to strike the $67-million

funding for TPX construction was defeated.43

FEDERAL FUSION ENERGY

RESEARCH PROGRAMS

DOE supports a variety of R&D activities related

to fusion energy in its science and defense programs. Primary responsibility for fusion energy

science and technology development rests with

the Office of Fusion Energy (OFE) in the Office of

Energy Research. OFE oversees most of the civilian research efforts involving plasma physics,

confinement concepts, reactor studies, and related

41Conference Report on H.R. 2445, H. Rept 103-292, 103d Cong., 1st sess., at 139 Congressional Record H7948, Oct. 14, 1993 (daily ed.)

42 See 139 Congressional Record H10479, Nov. 20, 1993 (daily ed.).

43 See 140 Congressional Record H4431-4439, June 14, 1994 (daily ed.).
Chapter 2 The Federal Fusion Energy Research Program | 37

technology development. The Office of Defense

Programs sponsors research on ICF science and

technology for potential applications in meeting

its nuclear weapons and stockpile stewardship responsibilities as well as for long-term energy potential. OFE also supports R&D on the energy

applications of fusion technologies developed under the separate weapons-related inertial confinement fusion program.

Fusion research activities are carried out at national laboratories, universities, and private companies. Figure 2-4 shows the distribution of major

fusion research facilities funded by OFE. In FY

1994, DOE’s magnetic fusion program was budgeted at about $347.6 million with much of that

funding going to support fusion activities at

PPPL, Oak Ridge, Lawrence Berkeley, and Lawrence Livermore National Laboratories, and at

General Atomics in San Diego and various universities. The Defense Program’s ICF program

was funded at $169.2 million in FY 1994 with activities concentrated at Livermore, Sandia, and

Los Alamos National Laboratories, the Naval Research Laboratory, and the Laboratory for Laser

Energetics at the University of Rochester.

❚ Program Goals

Goals for the DOE fusion energy program are set

by legislation and/or presidential or secretarial decisions, and the program offices have little leeway

to change them. Thus, fusion program goals have

remained relatively constant in objectives and

schedules and untempered by budget constraints

that could hamper their timely achievement. The

FY 1995 DOE budget request for the magnetic fusion energy program states that “the overarching

goal of the program is to demonstrate that fusion

energy is a technically and economically viable

energy source.” More specifically, according to

DOE, the major long-term goals of the magnetic

fusion energy program are to establish the “practicability of electric power production by 2010” (as

called for in EPACT); to show the engineering and

economic feasibility of fusion power production

by having an operating demonstration reactor by

(around) 2025, to be followed by an operating

commercial prototype reactor by (around) 2040

(as set out in the 1990 NES and FPAC recommendations). Other goals for the program include the

education and training of fusion scientists and engineers, and encouragement of international collaboration. DOE’s FY 1995 budget request admits

that “budgetary constraints over the past few years

may mean that the schedule for meeting such objectives is delayed.”44

DOE has developed more detailed goals and

strategies that it has relied on in setting priorities

for its magnetic and inertial fusion energy research and technology development programs

Magnetic Fusion

For the magnetic fusion program, among the most

important scientific and technical issues that must

be addressed to achieve the program’s goals are

ignition physics, fusion nuclear technology, magnetic confinement optimization, and development

of low activation materials.45 The budget request

outlines the four major elements of DOE’s magnetic fusion activities directed at resolving these

issues.

1. Study of D-T-fueled reactions in the TFTR.

Beginning in FY 1994, D-T fuel was introduced

into the TFTR to allow experiments to increase

the amount of energy obtained from fusion reactions and to verify of extrapolations made from

nontritium reactions such as D-D or a mix of deuterium and helium3 (D-He3). The goal of the

TFTR experiments is the production of 10-million

watts of power for one second. (This will move

laboratory production of fusion power approximately 30 percent of the way toward achievement

of the goal of breakeven). TFTR’s D-T experi44 U.S. Department of Energy, Office of the Chief Financial Officer, “FY 1995 Congressional Budget Request: vol. 2, Energy Supply Research and Development,” DOE/CR-0021, 1994, p. 425.

45 Ibid., p. 426.
38 IThe Fusion Energy Program: The Role of TPX and Alternate Concepts

University of Rochester,

Laboratory for

PNL University of Laser Energetic

LBL

LLNL

SNLL

UCLA

UCSD

GA

ITER JCT LANL

SNLA

A

●

■

o

 University of

National laboratory Texas

Private industry

University

ITER EDA site

KEY

ANL= Argonne National Laboratory

GA= General Atomics

INEL= Idaho National Engineering Laboratory

ITER JCT= ITER Joint Central Team

LANL= Los Alamos National Laboratory

LBL= Lawrence Berkeley Laboratory

LLNL=Lawrence Livermore National Laboratory

MlT=Massachusetts Institute of Technology

ORNL=Oak Ridge National Laboratory

PNL=Pacific Northwest Laboratory

PPPL= Princeton Plasma Physics Laboratory

SNLA=Sandia National Laboratory-Albuquerque

SNLL=Sandia National Laboratory-Livermore

UCLA= University of California, Los Angeles

UCSD=University of California, San Diego

SOURCE: U.S. Department of Energy, 1994
Chapter 2 The Federal Fusion Energy Research Program 39

ments will be the first to generate important data

and experience on plasmas with internally generated heat from alpha particles. Attainment of alpha particle heating will be critical for

self-sustained fusion reactions in future development steps such as ITER and for eventual fusion

powerplants.

2. Participation in the ITER international collaboration. ITER is intended to demonstrate the

scientific and technical feasibility of fusion by

producing over 1,000 MW of fusion power under

ignition conditions and serving as a test bed for fusion technology in support of a demonstration

powerplant--e.g., remote handling, divertor, fuel

injection, heat transfer, maintenance, materials,

and blankets.

3. Development, construction, and operation

of a new domestic advanced tokamak device. The

Tokamak Physics Experiment to be sited in the

TFTR test cell at PPPL will be the first major new

U.S. fusion facility in over a decade, if it is

constructed. The proposed TPX will provide the

opportunity to study long-pulsed advanced tokamak operations and is designed to take advantage

of the TFTR site and much of its existing equipment. TPX is intended to significantly improve

the physics results of tokamak reactors by exploring advanced operating modes with the potential

for better confinement conditions, higher pressure

limits, and efficient steady-state current drive.

TPX would be built using superconducting magnets and thus would contribute to U.S. industry

experience with key components also needed for

the ITER project. TPX also would provide critical

operating experience in the steady-state/longpulse mode that will be the focus of a later ITER

nuclear testing phase.

4. Maintenance of a base program of fundamental physics and technology research. OFE

will continue to maintain a range of base program

activities required to support development of

ITER, TPX, and DEMO, and operation of existing

major U.S. tokamaks, DIII-D and AlcatorC-Mod. The base program funds research on fuInside the vacuum vessel of the DIII-D tokamak.

sion theory and modeling, fusion computing

systems, and development of low activation materials.

These elements are spread over several subprograms and support what is now characterized as

the mainline magnetic fusion energy development

program shown in figure 2-5. This long-term

strategy was developed in consultation with the

fusion community, generally reflecting priorities

established in the fusion program in the

mid-1980s as modified to take into account

changing budget conditions and the recommendations of FPAC and FEAC.

Under this magnetic fusion development strategy, research will progress through a number of

critical steps and new facilities to result in eventual demonstration of commercial power production by the middle of the 21st century. The

pathway reflects a heavy reliance on the success of

the tokamak confinement approach as the most

likely (and only available) technology to meet key

development milestones for fusion power.
40 The Fusion Energy Program: The Role of TPX and Alternate Concept

I I I >

I

Blanket

development

I I I Time | I I I >

1990 2000 2010 2020

SOURCE: U.S. Department of Energy, 1994.

●

■

●

■

■

■

Key elements shown are:

D-T experiments and alpha heating in the

m ,

demonstration of ignition, long-pulse, and

technology testing in ITER,

achievement of steady-state/advanced tokamak

reactor conditions in TPX,

development of low activation materials for

fusion reactors in a 14 MeV materials test facility,

possible development of a blanket test facility,

and

maintaining balance in the rest of program.

lnertial Fusion Energy

Major goals for the civilian energy aspects of the

inertial confinement fusion energy program are

development of components for fusion energy

systems and reactor systems that can take advantage of the target physics developed by the Defense Programs’ ICF research. Activities include

continuing support for the investigation and development of a high-efficiency, high-repetition

driver, targets, and reactor concepts that are particularly important to energy applications of ICF, but

not of concern in weapons stewardship/research.

The current IFE program emphasizes support for
Chapter 2 The Federal Fusion Energy Research Program 41

Gas laser

Nike

(direct drive)

Glass laser High-yield microOmega Upgrade fusion capability

(direct drive) Gain>50

Yield = 0.2-1 GJ

Glass/advanced National Ignition

solid-state laser Facility (NIF)

Nova Gain = 1-10

(indirect drive) Yield = 1-20 MJ

Light ions Engineering Demonstration

PBFA II power

(indirect drive) (ETF) plant

FY

NIF

I I I I I

KD=O 1 23 4

1990

I I 5-year plan FY 2000 FY 2004 FY 2010 FY 2025

Target physics -

Ignition and Defense and Electric

and driver gain energy power

development demonstration applications production

KEY

KD=Key Decision

SOURCE U S Department of Energy.

development of the heavy-ion accelerator driver

approach, and development of IFE target designs

with features of high gain and ease of production

The IFE program plan relies heavily on progress

in the ICF program, such as the proposed National

Ignition Facility (NIF), to achieve key IFE milestones and experience to allow a decision to proceed with an IFE engineering test facility.

Cutbacks in alternate concepts research in the

MFE program have left inertial confinement as

the only alternative fusion technology sufficiently

advanced to compete with the tokamak concept

when the key decision for choice of a demonstration fusion reactor concept is made. The long-term

development path for demonstration of commercial power production using inertial confinement

fusion technologies is shown in figure 2-6. Critical technology development for IFE along this

path includes: achievement of ignition in the proposed NIF, development of an efficient repetitive

driver, improvements in target design and

manufacture, and development of a fusion energy

target chamber and energy extraction technology

for use in a IFE engineering test facility.
42 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

This strategy parallels the path and key decision points for magnetic confinement fusion in the

competition between MFE and IFE that was

adopted as the future fusion strategy in 1990. A

proposed change in the ICF plan could permit an

alternative development path with fewer major facilities by integrating the IFE engineering test facility and the laboratory microfusion facilities

using separate target chambers but a common

driver.46 It should be noted, however, that many

questions concerning the detailed cost estimates

and choice of technologies for an IFE development path remain to be resolved.47

❚ OFE Program Structure

The Office of Fusion Energy under the Assistant

Secretary for Energy Research has three operating

divisions—Confinement Systems, Applied Plasma Physics and Technology, and ITER and

Technology—roughly corresponding to its budgetary subprograms: Confinement Systems, Applied Plasma Physics, and Technology and

Development.48 The discussion here is organized

according to the budgetary subprograms used in

appropriations requests.

The Confinement Systems Subprogram supports the planning, design, and operation of existing and new reactors and facilities to improve the

tokamak concept through research to achieve a

more detailed understanding of fusion plasmas in

reactor-like conditions. The goal of this research

is to develop technically and economically credible fusion power reactors for commercial energy

production in the 21st century. Major areas of research include: energy confinement, plasma heating, fuel injection, power handling and particle

control, current drive, and alpha particle heating

and its impacts on confinement and stability. The

division also conducts physics R&D on existing

machines for ITER EDA activities. The FY 1995

budget request reports that budget- and policydriven program redirection in the past decade have

reduced the number of operating fusion facilities

supported by the programs as activities are increasingly concentrated on ITER, TPX, and highpriority issues. The division has tried to offset

some of the impacts of this redirection by encouraging the scientific staff of the affected laboratory

and university programs to collaborate at facilities

with operating fusion devices, including international collaborations in Germany, France, England, and Japan. Total funding for the confinement

systems subprogram in FY 1994 was $168 million

with 45 percent going to operation of the TFTR,

40 percent to operation of base toroidal facilities

(e.g., DIII-D and Alcator C-Mod), 11 percent to

TPX design activities, and 4 percent for advanced

toroidal facilities (i.e., the ATF stellarator). More

than half of the subprogram’s budget is dedicated

to programs at the Princeton Plasma Physics Laboratory. The subprogram’s FY 1995 budget request was $150.5 million.

The Applied Plasma Physics and Technology Subprogram supports research to improve understanding of fusion principles and to investigate

innovative techniques leading to improved plasma confinement conditions. Responsibility for

this budget subprogram rests with the Applied

Plasma Physics and Technology Division. This

division oversees work on experimental plasma

research, fusion theory and computing, theoretical and experimental physics, and analysis and de46 Alex Friedman, Lawrence Livermore National Laboratory, personal communication, Aug. 11, 1994; and C. Olson et al. “ICF Diverse

Strategies for IFE,” paper presented at the International Atomic Energy Agency Technical Committee Meeting, Paris, Nov. 14-18, 1994.

47 Some researchers have proposed an alternative path to the mainline ITER-DEMO tokamak-based development path for magnetic fusion.

See, e.g., Stephen O. Dean, “Fusion Power Development Pathways,” Journal of Fusion Energy, vol. 12, 1994, pp. 415-420; and Stephen O.

Dean et al., “An Accelerated Fusion Power Development Plan,” Journal of Fusion Energy, vol. 10, 1991, pp. 197-206.

48 The operating divisions were reorganized in 1992 to reflect the growing concentration on ITER and to aggregate longer term issues in an

Advanced Physics and Technology Division covering materials, systems studies, alternative fusion concepts (including IFE), exploratory toroidal improvements, and theory. The budgetary subprograms remained unchanged, however.
Chapter 2 The Federal Fusion Energy Research Program | 43

sign supporting major devices. The program also

is responsible for developing diagnostics, plasma

heating and control concepts, and data necessary

to design and run major experiments. A major initiative of this subprogram in recent years has been

support of development of computer codes and capabilities for simulating plasma confinement

conditions on high-performance computers and

establishment of improved computer networks

linking major energy research centers and fusion

facilities in the United States and overseas. With

1990s program redirection, primary emphasis is

given to research activities in support of ITER and

TPX design.

This division also administers OFE’s modest

program to support innovative nontoroidal confinement methods research as recommended by

FPAC and FEAC. Through a process of solicitation of proposals, several researchers are given

grants on a three-year basis for small-scale, proof

of concept experiments for innovative tokamak

improvement concepts and unconventional toroidal concepts. A total of $1.2 million per year was

allocated to this initiative. Not included in this

program are the funds used for work in alternative

toroidal concepts, such as the reversed field pinch,

and on physics issues that are complementary to

and supportive of work on the tokamak confinement concept.

Funding for plasma physics activities in FY

1994 was $59 million with about 31 percent going

to plasma theory, 44 percent to support experimental research, and 25 percent to MFE computing. Lawrence Livermore National Laboratory,

which operates a major fusion computer center,

received about 17 percent of total funding under

this program in FY 1994. The FY 1995 request

was $54.3 million.

The Technology and Development Subprogram supports work on the design and technology

development for ITER; the development of

technologies needed for TPX, DIII-D, and other

fusion experiments; and studies of future fusion

systems. (Subprogram responsibilities are mainly

carried out under the ITER and Technology Division.) Projects are organized in three technical

areas: ITER, plasma technologies, and fusion

technologies.

The ITER technical area includes funds for the

U.S. share of ITER design and development work,

except for the advanced materials, theory, and

diagnostics research activities funded under the

applied plasma physics and confinement systems

subprograms. Funds are used to pay for ITER

technology development tasks negotiated with the

ITER Director and approved by the ITER Council. Total operating funds for ITER activities under this program were $62.4 million in FY 1994

with an increase to $68.6 million requested for FY

1995.

The plasma technologies activities include developing technologies for forming, confining,

heating, and sustaining a reacting fusion plasma

such as magnet systems, heating systems, fueling

systems, and materials in the plasma environment. A major focus of these efforts has been directed at development of reliable high-field

pulsed and steady-state superconducting magnet

systems for ITER and TPX. These efforts were

funded at $5.8 million in FY 1994, with a request

for $5.3 million for FY 1995

The fusion technologies activity supports research that is important for TPX, ITER, and future

power reactors, including materials development

and long-term waste issues, safety and environmental considerations, component reliability, tritium fuel breeding and processing, and power

extraction. This area also has supported scoping

studies for a high-energy neutron irradiation test

facility, which is critical to the development of

low activation materials for future devices, and

cooperative work under ITER, the International

Atomic Energy Agency (IAEA), and U.S.-Japan

bilateral agreements on blanket engineering, and

Tritium Systems Test Assembly. Fusion system

studies activities support analytical, engineering,

and computational studies of fusion systems to

identify potential problem areas and to provide future program direction. The FY 1994 funding for

various fusion technologies activities was about

$12 million. The FY 1995 request of about $15
44 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

million accommodates an increase in funding for

advanced materials activities.

Total funding for the Development and

Technology Subprogram in FY 1994 was about

$80 million. Major funding recipients included

Argonne, Lawrence Livermore, Los Alamos,

Sandia, Pacific Northwest, and Oak Ridge National Laboratories. DOE has requested $89 million for this subprogram in FY 1995.

❚ The Defense ICF and IFE Programs

The ICF program is part of DOE’s nuclear weapons research and technology development activities under the Office of Defense Programs. ICF is

supported because of the ability to produce pure

thermonuclear burn in a laboratory environment

to study weapons physics and effects as an alternative to underground testing and to provide the research base for longer term fusion energy

applications. The primary emphasis of the program is on demonstrating ignition in a laboratory

microfusion device and developing both direct

and indirect driver technologies. Related work focused solely on energy aspects of ICF is supported

under the Office of Fusion Energy Applied Plasma Physics and Technology Division. Following

significant accomplishments in target physics in

the late 1980s that supported the scientific feasibility of ICF, the ICF program began to focus on

appropriate drivers primarily intended for defense

and ICF physics purposes and to proceed with the

design of the proposed NIF. In December 1993,

Energy Secretary Hazel O’Leary declassified portions of the Defense Programs relevant to IFE.

Thus, results from the experiments with ignition

of ICF plasmas may be used for energy applications.

Research on systems to explore the development of IFE as a potential civilian energy source is

carried out as a separate subprogram of OFE. The

primary technology activity has been support for

the development of a heavy-ion driver and study

of inertial fusion energy targets. IFE subprogram

activities are closely coordinated with the Defense

ICF Programs. In fact, work on inertial fusion energy in OFE is often closely tied to projects supported by the Defense ICF Program. Work on ICF

physics, and target design benefits energy applications. Researchers from both programs maintain

close professional contact.

The Defense ICF Program was funded at $169

million in FY 1994 and at $176 million in FY

1995. Inertial fusion energy programs received $4

million in FY 1994—half the level of the

program’s fiscal year 1993 budget—reflecting a

decision by DOE to defer consideration of

construction of the accelerator for the Induction

Linac Systems Experiment.

❚ Fusion Program Budgets

The FY 1995 DOE budget request sought $372.6

for the Magnetic Fusion Energy Program. The request supported U.S. direct and indirect activities

for ITER, TPX design and construction startup activities, and continuing analysis of data from the

TFTR D-T experiments following shutdown in

FY 1994 to allow the test cell to be prepared for

TPX construction. The request also called for

hardware upgrades to DIII-D to support its capabilities to address key issues in design and operation of ITER and next generation machines. In

addition, funding was sought for the base physics

program, including support of ITER, and tokamak

improvements, along with modest increases in

funds to support materials development for future

fusion devices (including preliminary work on design of a neutron source facility as an international

collaboration through IAEA coordination, much

like early phases of ITER project development).

Congress appropriated the full requested

$372.6 million for the Office of Fusion Energy activities.49 However, the conferees declined to ap49Conference Report on H.R. 4506, The FY 1994 Energy and Water Appropriations Act, H. Rpt. 103-533, S. Rpt. 103-291, 103d Cong., 2d

sess., Aug. 3, 1994, published in 140 Congressional Record H6888, Aug. 4, 1994 (daily ed.) Subsequent general reductions in the DOE budget

have left $364.563 million for fusion program expenditures in FY 1994.
Chapter 2 The Federal Fusion Energy Research Program | 45

prove construction spending for TPX, but did

allow DOE to continue with TPX engineering design and R&D ($42 million) and to purchase longlead-time superconducting materials (up to $2

million). The conferees directed DOE to use standard phased industrial contracts for TPX design

activities to provide for future construction approval, when and if authorized by Congress.

The conferees also provided $65 million for

continuation of additional D-T experiments in the

TFTR until such time as TPX construction is approved and TFTR activities are wound down.

Without these additional funds, TFTR was scheduled to be shutdown at the end of FY 1994 to make

funds available for TPX activities. Senate and

House members called for legislation explicitly

authorizing TPX construction. An additional $8

million was provided for operation of the PBX-M

tokamak facility at PPPL and $8.7 million was

provided for IFE energy development activities to

allow progress on the ILSE heavy-ion driver. Additionally, the conference report calls on the President’s Council of Advisors on Science and

Technology (PCAST) to review the magnetic fusion energy and inertial confinement fusion energy development programs and to report to

Congress on their future direction given the large

sums required for program expansion.50 PCAST

is expected to begin their review of the fusion program early in 1995 and to complete their recommendations by June 1995, according to DOE. 51

The FY 1995 budget provides adequately for

ITER activities and in that respect is in agreement

with FEAC, FPAC, congressional recommendations, and the DOE request. Delays in construction of TPX are not consistent with the schedules

recommended by the advisory panels and will

eventually add to its cost. (Preliminary estimates

of the cost of the one-year delay have not yet been

made public.) The budget increases restore some

funding for development of ILSE in the IFE program but are still less than reviewers recommendations.52 TPX and ITER supporting research and

development activities continue to absorb most of

the rest of the fusion program budget given the

directives of the FY 1993 conference report (see

figure 2-7).

Overall the FY 1995 budget is approximately at

the levels and priorities analyzed by FEAC for

magnetic fusion, but is less than the funding level

suggested for IFE. Appropriations levels and intra-program allocations have continued to fall far

short of the recommendations of FPAC for both

programs. It is probably too early to determine

what effect, if any, the project delays and decreased funding of basic program components

may have on attainment of the ultimate goal of developing a technically viable demonstration fusion reactor by 2025.

To the extent that ITER and TPX become the

exclusive driving focus of the magnetic fusion

program, FEAC and FPAC hopes that recommended budget increases would restore balance to

the program in support of basic physics, alternative concepts, and materials and technology development have not been met.

ITER and TPX-related budget demands will

continue to create budget pressures on other program elements. TFTR decommissioning expenses will absorb much of the roll off from

shutting down TFTR operation for several years.

Over the next few years, DOE and the program

will need to obtain additional increments required

for TPX construction and operation, ITER final

design and siting activities, ITER construction,

and development of heavy-ion drivers. FPAC estimated that these increments could increase the to50 Conference Report on H.R. 4506, at 140 Congressional Record H6942, Aug. 4, 1994 (daily ed.)

51 “Curtis Warns New Congress, Tight Budget Will Harm Fusion Program,” Inside Energy with Federal Lands, Dec. 5, 1994, p. 11.

52The status of ILSE is still uncertain. The Office of Energy Research has suggested that Lawrence Berkeley Laboratory scale back the ILSE

project and proceed with construction of the first third of the proposed project on a stretched out schedule and call it “ELISE.” Roger Bangerter,

Lawrence Berkeley Laboratory, personal communication, Nov. 17, 1994.
46 The Fusion Energy Program: The Role of TPX and Alternate Concepts

Demonstration

power plant studies*

$2.7 Low activation materials*

\ /

$10.3

$70.0 ‘ \ $49.0

TPX direct

$42.0

FY 1995 $365.7 million

● base program activities

NOTE: Total funding for fusion activities reflects the Office of Fusion Energy share of the general reduction in DOE spending of $8 million from the FY 1995 appropriation of $3726 million. Activity categories reflect DOE program managers’

assessments of how fusion funds are allocated among R&D activities and are not identical with budget categories used

in appropriations requests

SOURCE: Office of Technology Assessment, 1995, based on information from the U.S. Department of Energy

tal fusion program budget to $1 billion per year by

the late 1990s and that annual budgets of at least

this amount will be needed to support activities

needed to enable informed decisions on selection

and design of a demonstration reactor to be operational by about 2025.

FUTURE BUDGET CHOICES

To meet the magnetic fusion program’s fusion energy development path laid out in prior program

plans calling for maintenance of a base program,

construction of TPX and participation in ITER

EDA activities, funding would have to rise from

the current level of $372 million in FY 1995 to almost $550 million in FY 1998. A decision to proceed with ITER construction could require annual

increments above 1998 levels rising from about

$50 million in FY 1999 to about $400 million in

FY 200153 and higher as construction activity increases (see figure 2-8). This estimate assumes

53 Estimates are from figures prepared by DOE for remarks of N. Anne Davies, Director, Office of Fusion Energy, presented to the Fusion

Energy Advisory Committee, Dec. 1, 1994. The estimates are based on internal planning documents of OFE and are not reflected in DOE outyear budget estimates included in the President’s FY 1995 budget request to Congress.
Chapter 2

1,000 ,

o

0

400

200

0

1990 92 94 96 98 2000

Fiscal year

NOTE: This figure IS based on internal Off Ice of Fusion Energy planning

estimates and the funding levels shown are not reflected in FY 1995

budget request documentation The increase in base program funding

in FY 1997-2001 reflects increased activity in support of TPX and ITER

and for a proposed fusion materials test facility

SOURCE: Office of Technology Assessment, 1995, based on information from the U.S. Department of Energy

that ITER is not located in the United States, thus

avoiding a possible host country premium.54

However, present budget plans calling for flat

budgets for discretionary programs would seem to

rule out any real increase in the fusion program

budget without a substantial justification for it and

a corresponding reduction in another program.

The fusion program would seem to have several options under a five-year flat-budget horizon. It

The Federal Fusion Energy Research Program 147

could try to meet direct funding needs for EDA activities and a stretched out construction schedule

for TPX by cutting more deeply into base programs. How viable such an approach would prove

is questionable, since a significant portion of the

base program activities underwrite research programs that lend indirect support to ITER and TPX

projects or are complementary to them. Cutting

into the base program would make it even harder

to fund initiatives to expand consideration of

alternative nontokamak confinement concepts,

including inertial fusion energy and the development of advanced materials and reactor technologies necessary for progress toward DEMO. Such a

funding scenario might also call into question the

rationale for proceeding with a major new domestic tokamak and ITER while substantially weakening the domestic base program and the research

and industrial infrastructure that is intended to

benefit from these activities.

As difficult as the problems for the fusion program seem under a future flat-budget scenario,

proposals to cut energy research spending dramatically, including fusion, may trigger further debate

about the appropriate role and direction for the fusion program under lower budgets. Some members of the fusion research community question

whether a low budget path would be warranted at

all, except perhaps to document the state of fusion

research for future generations or perhaps to allow

U.S. researchers to participate at some level in the

fusion research programs in Japan, Europe, and

Russia—assuming of course that those nations

elect to continue their efforts in the absence of an

active United States program. Others are not nearly so pessimistic, although they too would express

disappointment if the U.S. were not to participate

directly in the next “big step” fusion project.

Among this latter group, some see the possibility

54In discussions investigating issues related to ITER siting, representatives of the parties and observers have suggested that the host country

for ITER could be requested to pay an additional ‘“premium” or contribution to ITER costs in recognition of the economic benefits that might

flow to the local economy from hosting such a large construction project and research facility. A precedent for such a premium is the arrangement that led to the Joint European Torus (JET) facility being located at Culham, United Kingdom, where the British Government agreed to pay

more than its proportional share of the costs for this European fusion program facility.
48 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

of sustaining progress in fusion research by focusing on physics issues using existing smaller machines, increasing international collaboration, a

modest effort in investigating alternative concepts, and concentrating on materials and technology advances that would be necessary for fusion

power reactors. Eventually, however, progress

toward development of a fusion powerplant will

require a commitment to construction of very expensive new facilities.
The

 Tokamak

 Physics

 Experiment

n the fiscal year 1993 budget request to Congress, the U.S.

Department of Energy (DOE) asked for $20 million for

“conceptual design and R&D” for a tokamak physics experiment (TPX) “to address the physics of tokamak improvements.”1 This request was the culmination of an effort

started in 1991 by DOE, in the wake of the cancellation of the

Burning Plasma Experiment (BPX), to come up with a new experimental device to follow the completion of work on the Tokamak Fusion Test Reactor (TFTR). If completed, TPX would be

the first large experimental magnetic fusion device built and operated in the United States since TFTR operation began in 1982.

The principal focus of TPX is to examine a range of physics and

engineering issues whose successful resolution could greatly reduce the cost and complexity of a commercial fusion powerplant

based on the tokamak concept.2 In addition, TPX is intended to

support design and operation of the International Thermonuclear

Experimental Reactor (ITER).

The principal features of TPX are to be its ability to explore advanced operating regimes that could substantially improve tokamak powerplant performance, and to operate at near steady-state

conditions with a design plasma pulse length of 1,000 seconds.3

TPX is to be built at the Princeton Plasma Physics Laboratory in

the area currently occupied by TFTR. The most recent estimate of

1 U.S. Department of Energy, FY1993 Congressional Budget Request, DOE/CR-0006

(Washington, DC: January 1992), vol. 2, p. 390.

2 U.S. Department of Energy, Tokamak Physics Experiment, UCRL-TB-114199

(Washington, DC: March 1993).

3 Ibid.

| 49
50 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

total project cost—construction plus associated

operations during construction—is $694 million.4 If TPX construction starts by the end of

1995, completion is expected in 2001. Once completed, operating costs are expected to be $150

million per year for the project’s 10-year lifetime.5

This chapter presents an analysis of the TPX

project. The chapter starts with a description of the

process leading up to the TPX decision. Next, a

description of the machine is given including its

scientific and technical goals. Several of the issues

about TPX emerge from this analysis.

HISTORY OF THE TPX DECISION

The roots of TPX lie in the 1990 report of the Fusion Policy Advisory Committee (FPAC) to

DOE.6 That report set forth a series of recommendations to guide the future of the U.S. fusion energy program. The committee recommended that

the United States “commit to fusion as a potential

energy source,” that the program should be directed toward energy production, and that it

should set as a specific goal the construction of a

demonstration powerplant (DEMO) by 2025.7

The committee also recommended that to achieve

these goals, DOE needed to start four new facilities in the 1990s including: a burning plasma

experiment, ITER, a steady-state advanced tokamak, and a neutron source for materials development. These facilities would be necessary to

investigate a series of important scientific and

technical issues that needed resolution if magnetic

fusion energy was to become a reality.

At the time of the FPAC report, DOE was proceeding with conceptual design of BPX and was a

partner with Japan, the European Union, and Russia in the conceptual design activity of ITER. BPX

was to be a moderately sized tokamak with very

high magnetic fields. It was to be capable of

achieving ignition (reaching the point where the

fusion reaction becomes self-sustaining) for the

purpose of investigating the properties of burning

(self-heated) plasmas,8 particularly behavior of a

plasma dominated by alpha particle heating.9

Such heating is expected to be the principal source

of heating in a deuterium and tritium (D-T) fusion

plasma once ignition is achieved. These results

were expected to provide “valuable” input to

ITER and ultimately, along with ITER, to be essential to reaching a DEMO by 2025. While BPX

was expected to achieve a large net energy gain, it

was not being designed for steady-state operation.

That task was to be left to other, unspecified

experiments, although the FPAC report did rec4 This cost estimate was made prior to DOE’s submission of its fiscal year 1995 budget request. Since Congress did not grant approval for

DOE to begin construction of TPX in fiscal year 1995, the cost estimate will probably increase.

5 U.S. Department of Energy, FY1995 Congressional Budget Request: Project Data Sheets, DOE/CR-0026 (Washington, DC: February

1994), vol. 2., p. 90.

6 U.S. Department of Energy, Final Report, Fusion Policy Advisory Committee (FPAC), DOE/S-0081 (Washington, DC: September 1990).

7 Ibid., p. 3.

8 U.S. Department of Energy, FY1988 Congressional Budget Request, DOE/MA-0274 (Washington, DC: January 1987), vol. 2, p. 327.

9 One of the products of the fusion reaction between deuterium and tritium is the helium-4 nucleus, an alpha particle. These alpha particles,

in turn, possess energy from the fusion reaction. The alpha particles are also subject to confinement by the external magnetic field, although they

eventually diffuse out of the fusion plasma. While confined, the alpha particles can give up their energy by collisions with the deuterium and

tritium in the plasma, helping to heat these ions to the point where they will undergo fusion reactions. Eventually, there will be sufficient heating

in this manner to sustain the fusion reaction and ignition will be reached. There is speculation that the presence of large quantities of alpha

particles may cause instabilities to appear in the plasma leading to excessive energy loss. Since no fusion plasma has reached ignition yet, investigation of such alpha particle instabilities has not been possible. Observations on TFTR where substantial fusion power has been produced,

however, have indicated that such instabilities do not occur.
Superco 

solenoid

Chapter 3 The Tokamak Physics Experiment 51

Superconducting

Cryostat

Major TPX components.

ommend the construction of a steady-state tokamak.10

In 1991, however, it became clear that BPX

would not be built. The estimated cost of the facility had reached $1.4 billion and the Secretary of

Energy Advisory Board (SEAB) Task Force on

Energy Research Priorities recommended that

DOE not proceed with BPX but concentrate on

ITER.ll Secretary of Energy Watkins ordered the

cancellation of the project. Without the operation

Divertor

(TF)

Superconducting

poloidal field (PF)

magnet

umpduct

of a BPX, it became necessary to transfer its areas

of investigation to ITER. In other words, ITER

would have to be a test bed for examining the

physics of burning plasmas in addition to its other

missions. It appeared that the demise of BPX

meant an extension in the physics operating phase

of ITER.

In addition, the added responsibilities would

increase the overall project risk. Since ITER’s

principal function was to be an engineering test fa10A number of proposals for steady-state tokamaks had been put forward by different researchers. See for example, General Atomics and

Lawrence Livermore National Laboratory, Technology and Physics in the Tokamak Program: The Need for an Integrated, Steady-State R&D

Tokamak Experiment,” GA-A19305, UCID-21404, May 1988.

11 Ronald C. Davidson, memorandum to John Sheffield, Oct. 30, 1991.
52 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

cility, it depended on most if not all of the physics

being resolved prior to its operations. If there were

substantial, unexpected problems with burning

plasma stability—most likely as a result of the

presence and actions of the alpha particles created

by the D-T fusion reactions, a considerable delay

in investigating the engineering issues of a fusion

reactor would result. Nevertheless, the decision to

cancel BPX plus the likelihood that no other ITER

partner would build a burning plasma facility,

made it necessary that ITER perform that role.

Also contained in the Task Force report was the

suggestion that DOE look for a “less costly follow-on device” once TFTR concluded its experiments.12 This charge was passed on to the Fusion

Energy Advisory Committee. The committee accepted the Task Force recommendation to terminate the BPX program, and recommended a new

experimental facility to follow TFTR. The recommendations of the two advisory groups focused on

a device costing “in the $500 million class” that

would “investigate improvements in the tokamak

concept,” support the ITER project, and maintain

the scientific momentum of the U.S. program.13

The SEAB report specifically requested that the

new device investigate improvements “that could

suggest new operating modes for ITER. . . .”14

One of the major concerns of DOE at the time was

that when TFTR finished its work in the

mid1990s, there would be a decade at least in

which there would be no major facility for U.S. fusion researchers to have access. ITER is not scheduled for completion until 2005 at the earliest.

Upon receiving the recommendations, DOE

began to plan for the new machine. It set up a National Task Force on Post-TFTR Initiatives to develop a set of the most promising design options

for more detailed study and to identify the preferred design options. The New Initiatives Task

Force was asked to solicit a broad range of input

from the fusion research community, including

forming groups from the advocates of the various

options. The Task Force was asked to provide

DOE with guidance on the critical physics and

technology issues that could be investigated by

this new machine. While the Task Force was given

considerable scientific and engineering latitude,

the constraint that the construction cost of any

new facility should be in the $500-million range

was firm.

The Task Force finished its work in March

1992.15 It recommended that the new facility be a

long-pulse tokamak capable of investigating advanced operating regimes. It defined a long pulse

as that required to ensure conditions within the

plasma had reached a steady state, and that all

equipment—power supplies, particle exhaust,

etc.—would have to operate in a steady-state

mode. In essence, this facility would fulfill the

third of the four facilities recommended by FPAC,

a steady-state advanced tokamak (SSAT). The

Task Force recommended that the new facility

limit most of its operations to deuterium plasmas,

since providing the facility with the capability of

extensive D-T operation at high energy gain

would force the costs to go well beyond the

$500-million limit. Finally, in a follow-on report

in May 1992, the Task Force recommended superconducting magnets for the machine. All of this

12 Ibid.

13 Ibid.

14 Charles H. Townes, letter to Secretary James D. Watkins, Oct. 20, 1992.

15 J. Sheffield et al., “Report of the New Initiatives Task Force,” Mar. 10, 1992.
Chapter 3 The Tokamak Physics Experiment | 53

could be accomplished, according to the Task

Force, within the $500-million total project cost

limit.16 The recommendation was accepted by

DOE and design has proceeded. The TPX proposal at an estimated construction cost of $597 million (in as spent dollars) was endorsed by the

SEAB Task Force.

DESCRIPTION OF TPX

❚ Scientific Features

The New Initiatives Task Force report identified

the class of initiatives it reviewed as TPX. That

name has now been adopted for the SSAT recommended by the Task Force. The mission of TPX is

to “develop the scientific basis for an economical,

more compact, and continuously operating tokamak fusion reactor.”17 Its principal feature will be

its ability to operate at near steady-state conditions. TPX is being designed to achieve plasma

pulse lengths of 1,000 seconds. This time is sufficient to ensure that the plasma has come to a

steady-state equilibrium, both internally and with

the surrounding vacuum vessel. To achieve this

pulse length, a plasma current driven by the plasma itself—the “bootstrap” current—must be generated. In addition, current drive is to be assisted

by the external heating mechanism. The bootstrap

current, however, will make up about 70 to 90 percent of the total plasma current. While bootstrap

current fractions in this range have been generated

in some existing tokamaks, none of the experiments lasted long enough to reach a condition of

steady-state equilibrium, which is one of the goals

of TPX.

TPX will also attempt to operate in an advanced

tokamak regime. This regime can be characterized

by parameters that measure the potential power

density of the fusion plasma if operated with deuterium and tritium, and the efficiency of the confinement system.18 Higher values of the potential

power density permit a tokamak operating with

deuterium and tritium and generating a given

amount of fusion power to be smaller and/or require a lower magnetic field, and, therefore, to be

less costly. Higher confinement efficiency is also

important because it allows the device to be smaller and/or operate with a lower magnetic field

while confining the energy from the fusion reactions sufficiently long to produce significant energy gain.

TPX is being designed to operate in a regime,

defined by these two parameters, well beyond that

of largest existing machines—JET and JT-60U

(upgrade)—and greater than that assumed in the

ITER design. Existing tokamaks with configurations closer to that proposed for TPX (most notably the DIII-D device at General Atomics) have

achieved values of potential power density and

confinement efficiency near that planned for TPX

but not under steady-state conditions. Figure 3-1

shows the goals for TPX, their relationship to the

other three machines and representative data

points from the DIII-D device. The quantities on

the two axes have no dimensions and are proportional to the parameter beta. As one moves up the

16 The original charge to the Task Force (Davidson, op. cit., footnote 11) specified that the new device should be “in the $500 million” range.

Although no indication was given in the memorandum about the reference point for those dollars, a September 1992 report by the Fusion Energy Advisory Committee on Program Strategy for U.S. Magnetic Fusion Energy Research stated that the amount was in “as-spent” dollars. The

Task Force in its March 1992 report on the SSAT, estimated the cost of the machine at $429 million in fiscal year 1992 dollars. In its fiscal year

1995 budget submission to Congress, DOE gave a cost estimates of $597 million for total facility cost (actual construction cost) and $694 million for total project cost. These figures are in as spent dollars as calculated using DOE construction cost escalation rates. That is, this number is

the sum of the dollar amounts in the years the money is actually spent. Taking the Task Force estimate and projecting it forward using the same

rates yields a figure of about $540 million. Therefore, the original cost estimate was reasonably close—within 10 percent—to that determined

after substantially more engineering design.

17 The scientific features of TPX are described in detail in Princeton Plasma Physics Laboratory, “TPX: A National Facility for Steady-State

Advanced Tokamak Research,” briefing paper prepared for OTA, July 13, 1994; and see footnote 29.

18 Both of the potential power density and confinement efficiency are characterized by a parameter called beta, which is the ratio of pressure

exerted by the hot plasma to the pressure exerted by the external magnetic field.
54 The Fusion Energy Program: The Role of TPX and Alternate Concepts

0.04

■

TPX

 0.03- DIII-D

----> ■

 0.02–

JET OO ITE R

o

 0.01- JT-60U

Potential power density

SOURCE: Office of Technology Assessment, 1995

vertical scale at a given point on the horizontal

axis, the magnetic field and/or machine size required to achieve a given fusion power gain decrease. Moving in the horizontal direction at a

given point on the vertical scale allows a machine

to produce a given amount of fusion power at a reduced magnetic field and/or size. In either case,

the cost per unit of fusion power would decrease

because of the importance of the magnetic field

size to machine cost. The parameters selected for

TPX are those that, if achieved, could considerably reduce the cost of an eventual tokamak fusion

powerplant.

While the TPX design values have been

reached on other experimental devices, they have

not been matched at steady-state conditions. Indeed, in cases where similar values of beta-about

5 to 6 percent—have been reached, the plasma has

proved unstable after a few seconds. A key goal of

TPX is to investigate the physics necessary to

eliminate this instability and allow the parameters

to be held continuously as will be required in a tokamak fusion power reactor. Theoretical predictions show that these instabilities can be

controlled by adjusting the shape of the main tokamak current. Such changes will be made on TPX

with the external heating mechanisms (see below). Machines where the instability has been observed do not yet have as much flexibility for

changing plasma current shape as is planned for

TPX.

Reaching the parameters planned for TPX requires the ability to form the cross-section of the

plasma into a shape resembling the letter D. This

change has been shown to improve both confinement efficiency and potential power density. In

short, such shaping allows a tokamak plasma to

operate at a higher beta value than if it had a circular cross-section. Figure 3-2 shows cross-sections

of various tokamak plasmas now in operation

comparted to that proposed for TPX. Note the Dshapes for DIII-D and TPX compared to the circular cross section for TFTR. There are two

parameters that characterize the plasma cross-section: elongation (referring to the stretching of the

plasma) and triangularity (referring to the approximate triangular shape). A circular plasma crosssection has an elongation of 1 and a triangularity

of 0. TPX is being designed to have an elongation

of 2 and a triangularity of 0.8. These parameters

are similar to those on the DIII-D device.

TPX will have three heating options. The plasma can be heated by injecting energetic beams of

neutral particles-+ ailed neutral beam injection

heating—as is now done on TFTR, or it can be

heated by pumping electromagnetic power into

the plasma. If the frequency of the electromagnetic power resonates with a characteristic frequency

of the ions in the plasma, heating can take place.

Two such frequencies are particularly useful.

These methods are called ion cyclotron radiofrequency heating and lower hybrid current drive

heating. External heating will also contribute to

the steady-state current in the plasma and to shaping the plasma current for stability purposes as

discussed above. As with the other characteristics

discussed above, these heating methods have been

applied to other tokamaks with success. Operating
High-Current Coils

that produce the magnetic 

fields that keep the plasma

centered in the chamber

Ports

where diagnostics

are mounted to

measure plasma

properties

Plasma

high-temperature

ions that fuse

Chapter 3 The Tokamak Physics Experiment 55

High-currant Coils

that generate the high

currents in the plasma that

produce a plasma stabilizing

magneticfield

/

High-CurrsntColls

magnetic field (toroidal field)

 that suspends the hightemperature plasma away

 from the vacuum vessel

Vacuum Vessel

to prevent air form

contaminating the

fusion fuel (plasma)

High-Temperature Armor 

 Divertor

~- removes heat and exhausts

to protect the vacuum vessel from particles from plasma

the hot plasma

Diagram of General Atomics DIII-D Tokamak showing major components.

these heating methods in a steady-state environment, however, remains to be investigated.19

TPX will operate with deuterium to form the

plasma since it is more desirable than hydrogen

for achieving advanced operating conditions.20

The use of deuterium, however, will produce fusion reactions and a significant quantity of neutrons (although considerably fewer than would

result if deuterium and tritium were used). The

presence of neutrons will require remote handling

and shielding that would not be necessary if only

hydrogen were being used. To achieve the performance sought for TPX with hydrogen, however,

would require a much larger machine and neutral

beam system than with deuterium alone. The net

result of these two competing cost factors is a less

costly machine with deuterium.

1 9 It should be noted that current reactor design studies conclude that neutral beam heating and lower hybrid current drive are not likely to be

practical for fusion powerplants. 20 Robert Goldston, Princeton Plasma Physics Laboratory, personal communication, July 13, 1994.
56 The Fusion Energy Program: The Role of TPX and Alternate Concepts

2m

1m

o

-1m

DIII-D = General Atomics, USA;

JET = Joint European Torus, European Community, Culham Laboratory, U. K.;

JT-60U = JT-60 Upgrade, Japanese Atomic Energy Research Institute, Japan;

TFTR = Tokamak Fusion Test Reactor, Princeton Plasma Physics Laboratory, USA;

TPX = Tokamak Plasma Experiment, Princeton Plasma Physics Laboratory, USA

SOURCE: Office of Technology Assessment, 1995, based on a figure provided by David Overskei, General Atomics.

❚ Technological Features

There are several important technology issues that

will be investigated on TPX.21 First, TPX will be

a fully superconducting tokamak. That is, all of

the external magnet systems will be superconducting. While other tokamaks have had superconducting magnets, they have been confined to

the main toroidal (donut-shaped) fields. The other

major magnet system, called the poloidal field

system, which is responsible for inducing the initial plasma current and shaping the plasma crosssection, has not been superconducting on any

previous tokamak. The second feature will be the

requirement that the superconducting magnets be

capable of running essentially steady state. Because TPX will be operating with current pulses

1,000 seconds or longer, the toriodal magnetic

field must be on continuously. Previous superconducting tokamaks have only had plasma pulse

lengths of up to 60 seconds. It should be noted,

however, that the superconducting toroidal field

coils of the Tore Supra tokamak (a large tokamak

21 For a discussion of the technological features, see Sheffield et al., op. cit., footnote 15.
Chapter 3 The Tokamak Physics Experiment | 57

operating in France) have been kept on for eight to

10 hours at a time.

Full-power operation of TPX is now projected

to be about 200,000 seconds (55 hours) per year.

While a small fraction of the total number of hours

in a year, this period is considerably greater than

current tokamaks. The limiting factor will be the

degree of human access required for maintenance

in the region outside the vacuum vessel. Because

the vessel will become radioactive as a result of

being struck by neutrons from the plasma, such

access will require that the flux of neutrons be kept

below a certain level, hence a limitation on the

number of hours the machine can operate. This

feature will be discussed more completely below.

Not all of TPX experimental runs would be at the

full 1,000-second pulse. Rather, runs with pulse

lengths on the order of 100 to 200 seconds would

be made testing various operating conditions.

Only for those conditions that appear to be particularly interesting in terms of the TPX goals would

1,000-second or longer pulses be operated. Finally, the machine will be designed to operate for

500,000 seconds (about 140 hours) per year at reduced power. It is expected that these conditions

will be used during startup of the machine.

Another critical area of investigation for TPX

will be the divertor. Interaction between the plasma and the wall of the surrounding vacuum vessel

takes place at the divertor. In any tokamak plasma,

energy eventually escapes through the loss of the

energetic particles making up the plasma and by

radiation. The divertor is designed to capture and

cool these escaping particles. The charged particles are also neutralized at the divertor and the

resultant gas is exhausted from the vacuum chamber. Because the heat and particle load leaving a

typical fusion reactor plasma will be very large,

design of a divertor that can withstand such a load

is critical. It is one of the factors that will determine the size of the tokamak. The higher the heat

load that can be handled by a given divertor, the

smaller the entire machine can be for a given power output. TPX is being designed to test different

configurations. The TPX divertor system will be

completely replaceable using remote handling

technology. The divertor design is being made as

flexible as possible. Finally, the steady-state nature of TPX is critical to investigating the steadystate behavior of various divertor arrangements.

Remote handling is another technological area

that will be investigated on TPX. As described

above, there will be significant numbers of neutrons formed during TPX operations. It will be

necessary, therefore, to be able to make changes

within the machine remotely using robotics. Since

such handling will also be necessary on any fusion

power reactor, the ability to test and develop these

remote handling capabilities is a key feature of

TPX. The radiation environment inside the machine will be kept low enough, however, to allow

limited human access. The vacuum vessel, and

many of its internal components, will be

constructed of a material that produces a low

quantity of radioactive byproducts when subjected to the flux of neutrons. Such materials are

called low-activation materials. It is also possible

that TPX can be a test facility for exposing different kinds of low-activation materials to a steadystate tokamak environment. Similarly, shielding

in the wall of the vacuum vessel surrounding the

plasma will be necessary to keep neutrons from

the superconducting magnets. If neutrons reach

the magnets in sufficient numbers, the resultant

heating would cause them to heat up and lose their

superconductivity. Testing shielding technologies

will be useful for eventual fusion power reactors.

ISSUES

❚ Relation to Existing Tokamaks

TPX is being designed as a national facility.22 The

design team is made up of members from various

universities, other national laboratories, and representatives of industry. Once completed, TPX

operations will be guided by an oversight council

22 U.S. Department of Energy, op. cit., footnote 2.
58 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

with similar representation. Experiments will be

performed by researchers from participating institutions throughout the nation under the guidance

of this council. TPX will be integrated into the national information infrastructure so that researchers can perform experiments from their home

institution. This situation is being created in order

to facilitate one of the principal functions of

TPX—that it be a centerpiece in maintaining a

strong national research capability in fusion science and engineering.

The New Initiatives Task Force made an assessment of several existing tokamaks to see if the

goals of TPX could be met on one of them.23

There are two other large, superconducting tokamaks in existence, the Tore Supra in France and

the T-15 in Russia. Both devices have superconducting toroidal coils like TPX, but neither have

superconducting poloidal coils. The Tore Supra

appears to have the potential for long-pulse (about

600 second) operation. Both, however, have fusion plasmas with circular cross-sections and,

therefore, are incapable of achieving the advanced

operating parameters designed for TPX. The DIIID device at General Atomics in San Diego has the

necessary plasma shaping capability to test the advanced features and create the high bootstrap current fractions that are features of TPX. The

DIII-D, however, cannot maintain the long pulses

because its current magnet power supply configuration and plasma heating supplies are incapable

of operation for the long periods needed for the

1,000-second pulses. Also, the DIII-D device cannot accommodate the large divertors planned for

TPX without a significant reduction in plasma

size.

The remaining large tokamaks are JET,

JT-60U, and TFTR. None of these machines operates with superconducting magnets. Further, both

JET and TFTR are committed for investigation of

D-T plasma operation for the rest of their operational life. While capable of operating in advanced

modes, as seen in figure 3-1, JT-60U will not be

able to match the planned operating conditions of

TPX, nor of sustaining very long pulses. Based on

the capability of its magnet system, pulses of 45

seconds are about as long as could be expected on

that machine. The Japanese have also carried out a

conceptual design of a superconducting machine

called the JT-60 Super Upgrade.24 It would have

many of the features planned for TPX and would

be larger and more powerful. Construction has not

been approved, however, and its fate may depend

on funding resources in Japan and whether TPX is

built. In any case, the JT-60 Super Upgrade is seen

as possible by Japanese research funding authorities only if ITER is not sited in Japan.

Finally, none of the current machines can

match the planned, high-duty cycle of TPX. A key

parameter in determining duty cycle is the annual

flux of neutrons produced by fusion reactions of

the deuterium used for TPX plasma. These neutrons will impinge on the inner wall of the vacuum

vessel and on the divertor resulting in a steady

buildup of radioactive material in these structures.

In addition, neutrons that escape the ports in the

vacuum vessel will activate structures outside the

vessel. To keep the activation levels of such material below that which can be handled without costly procedures puts a upper limit on the neutron

flux that can strike these structures. Also, DOE’s

site boundary dose limits (30 times lower than

background) must be observed. TPX is being designed to accept an annual neutron flux of 6x1021

neutrons. The other machines are limited to neu23 Sheffield et al., op. cit., footnote 15, ch. 3.

24 H. Ninomiya et al., “Conceptual Design of JT-60 Super Upgrade,” paper presented at the 15th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Seville, Spain, Sept. 26 - Oct. 1, 1994.
Chapter 3 The Tokamak Physics Experiment 59

The JT-60U tokamak in Japan.

tron fluxes 10 to 100 times less than TPX design

because of their structural materials. Table 3-1

summarizes the principal parameters of the tokamaks discussed in this section compared to

TPX. 25

❚ Relation to ITER

The FPAC report included both an engineering

test reactor and a steady-state advanced tokamak

among its recommended facilities. Much of the

conceptual design activity (CDA) work on ITER

was complete before the TPX initiative began,

however, and the final report of the CDA was

vague about whether a TPX-like machine would

be operative in time to provide ITER with any design or operational guidance.26 Indeed, it was assumed at the time that a burning plasma facility

would be the one constructed. The ITER CDA report did define physics and technology R&D that

would be needed to “validate the scientific and

technical basis and assumptions” for the ITER design.27 Included were several of the areas that are

planned to be investigated by TPX such as longpulse operation, improved divertor performance,

25 Sheffield et al., op. cit., footnote 15, ch. 3; and Princeton Plasma Physics Laboratory, op. cit., footnote 17.

26 International Atomic Energy Agency, ITER Conceptual Design Activities: Final Report, ITER Documentation Series, No. 16 (Vienna,

Austria: 1991).

27 Ibid., p. 14.
60 The Fusion Energy Program: The Role of TPX and Alternate Concepts

TORE

Parameter TPX SUPRA T-15 DIII-D JT-60U JET

Major radius (meters) 2.25 2.38 2.43 1.67 3.4 3.1

Minor radius (meters) 0.5 0.75 0.70 0.67 0.85 1.1

Toriodal field (T) 4 4.5 3.5 2.1 4.2 3.4

Plasma current (MA) 2 2 1.4 2.1 6.0 6.0

Elongation 2 1.0 1.0 2.0 1.6 1.8

Pulse length (see) 1,000 20 ? 10-60 20-30 15-30

Neutron budget (ns/yr) 6x102 I 1.2X1020 ? 3X1018 <1021 >1021

Country Proposed U.S. France Russia Us. Japan U.K.

KEY

JET = Joint European Torus

MA = mega-amperes

ns/yr = neutrons per year

T = tesla

TPX = Tokamak Physics Experiment

SOURCE: J. Sheffield et al., “Report of the New Initiates Task Force,” Mar. 10, 1992.

superconducting magnets, remote handling, and

plasma heating and current drive systems. The

ITER CDA assumed that this research and development (R&D) would be done on existing tokamaks and that ITER would be responsible for

integrating all these features along with its other

goals. 28 On that basis, one could conclude that the

ITER project was proceeding under the assumption that no steady-state advanced tokamak would

be built.

While it is planned that TPX will investigate

many of these ITER CDA R&D needs, operation

is not scheduled to begin until ITER construction

is underway according to the current plans. This

situation was recognized by the team that developed the report on TPX (SSAT) to the New Initiatives Task Force early in 1992. The report stated

that TPX operations would be able to provide

valuable operating experience on long-pulse,

high-duty factor operation for later operations of

28 Ibid.

ITER.29 In addition, construction of the superconducting magnets would give U.S. industry important experience as a prelude to the task of

constructing the ITER magnets. Finally, TPX

would serve as a central research facility for U.S.

researchers while ITER was under construction.

The ITER design activity seems to be attempting to make a greater connection between it and

TPX. There have been discussions between TPX

and ITER design teams about divertor systems.

Currently, the two machines are using different

divertor designs with ITER proposing a more conservative configuration. TPX, however, has the

capability of investigating the divertor configurations planned for ITER. Comparison of the different designs should permit TPX to make important

contributions to the divertor choice for DEMO. A

more important connection concerns the advanced operating mode investigations of TPX.

29 Keith Thomassen et al., Lawrence Livermore National Laboratory, Steady State Advanced Tokamak (SSAT); The Mission and the Machine (Springfield, VA: National Technical Information Service, March 1992).
Chapter 3 The Tokamak Physics Experiment | 61

Currently, ITER is being designed fairly conservatively in terms of the confinement efficiency

and potential power density parameters. From figure 3-1 above, it lies considerably below the design variables for TPX. Originally, ITER was to

be configured to operate in a regime closer to that

of TPX. These parameters were changed because

such operation would have entailed more risk for

ITER, since the fusion power produced would

have taxed the limits of the materials used for the

vacuum vessel. While TPX proposal did not spark

these changes, results from TPX related to the advanced operating regimes, as discussed below,

would be useful for ITER.

The ITER design group recently indicated its

desire to maintain the flexibility of performance in

steady-state advanced tokamak regimes in the later phases of its operation to permit study of advanced operating regimes in ITER. Significant

upgrades to auxiliary systems may be required for

these tests, but it appears that ITER could ultimately approach TPX conditions in a D-T plasma

operating at high energy gain. A major question is

the cost involved. To build in the flexibility so that

ITER could fully explore this advanced, steadystate regime may be very expensive. Recent work

has shown that while ITER is being designed for

lower elongation and triangularity (see figure 3-1)

than TPX, calculations indicate that values approaching those of TPX can be attained in ITER at

reduced plasma current.30 At this time, the ITER

design team seems intent on preserving this capability. The ITER interim design, expected in June

1995, should allow a better assessment of whether

this is indeed the case.

Achieving the ideal operating conditions will

require optimizing several parameters. Whether

TPX, with its ability to shape the plasma crosssection to a greater degree than ITER, is more successful than ITER at reaching these conditions

remains to be determined by experiment. Results

from TPX in this context should be valuable for

ITER.

In addition, in many of the technology areas—

such as superconducting magnets and remote handling and shielding—ITER will have to be

operating at least on par with TPX if not in

advance of it, since ITER demands will be substantially greater due to its D-T operation. Experimental results on TPX, if they precede ITER

operation by a sufficient period, could be of value.

Unless they can be tested in ITER, there will

likely be considerable uncertainty about integrating TPX results with those from ITER in designing and building DEMO. There is no question that

successful achievement of many of the goals to be

investigated by TPX—steady-state operation, superconducting magnets, remote handling, and advanced divertor design in particular—will be

necessary if a tokamak-based fusion power reactor is to become a reality. As discussed above,

these areas can be incorporated in ITER from the

start or be integrated into it after testing elsewhere,

preferably on TPX. Integration of advanced tokamak operations results into ITER, however, may

be more limited and require significant upgrades.

Since successful demonstration of these operations can have significant consequences for the

economics of a fusion power reactor using the tokamak concept, it will be important to build them

into the DEMO design. Indeed, if operation in the

advanced regimes has not been demonstrated, the

economics of a tokamak fusion powerplant may

be not be attractive enough to be accepted by the

market. Demonstrating advanced operations may

be the most important contribution of TPX. TPX,

therefore, is designed to be upgradeable for operation with deuterium and tritium. Doing so, however, would eventually add to the cost of TPX.

Such expenditures may prove beneficial since

D-T operation in TPX could complement D-T experiments in ITER and provide important data for

30 W. Nevins et al., “ITER Steady-State Operation and Advanced Scenarios,” IAEA-CN-60/E-P-5, paper presented at the 15th International

Conference on Plasma Physics and Controlled Nuclear Fusion, Seville, Spain, Sept. 26-Oct. 1, 1994.
62 The Fusion Energy Program: The Role of TPX and Alternate Concepts

The DIII-D Tokamak at General Atomics in San Diego.

DEMO. It is likely that DEMO will be designed

rather conservatively because of the potentially

high cost of that machine. To the degree that advanced operation has not been tested in a D-T,

steady-state device such as ITER, the risk of incorporating that feature into DEMO may be too

great.

❚ Stand-Alone Machine

Supporters of TPX argue that the machine’s value

is not dependent on the ITER even though many

of the scientific and technical issues that TPX will

investigate are important for ITER. They say that

some of the results from TPX will be useful regardless of the path fusion power development

takes. In particular, operation of superconducting

magnets and remote handling will be necessary on

arty magnetic fusion reactor. In addition, there will

be need for a divertor or similar device to remove

heat and particles from a burning plasma. Theresults of physics investigations on steady-state and

advanced operations can also be useful to a variety

of other magnetically confined concepts since

they, too, will have to operate continuously and

will be concerned with some of the same issues

about power density and confinement efficiency

gain. Much of the steady-state and advanced operation issues to be investigated by TPX, however, are unique to the tokamak concept. For that

reason, the results of the advanced operation experiments may be essential in evaluating the tokamak against alternative concepts should the latter

fusion program be redirected toward more effort

on such concepts.

Another important function of TPX, as described above, is to serve as a national facility.

Without such a machine, there does not seem any

prospect for a new large, magnetic fusion experimental facility in the United States in the next

several years after TFTR shuts down. Several other U.S. tokamaks would remain in operation,

however, the largest of which is the DIII-D facility

at General Atomics in San Diego. While possessing many of the features of TPX, DIII-D is not

now capable of steady-state operation for the reasons described above. In addition, it is not now a

national facility in the sense that TPX is intended

to be. Access to DIII-D by researchers outside of

General Atomics, however, has been quite good.

Another possible scenario for the magnetic fusion energy program is that ITER is indefinitely

postponed, but no other alternative concept

emerges to challenge the tokamak.31 In that case,

TPX could be of even more value than currently is

the case. As previously stated, the physics and

technology it is investigating are fundamental for

the development of any tokamak-based fusion

power reactor. It also seems clear that while TPX

will expand the state of knowledge about advanced tokamak operation, successful steadystate operation in that regime is by no means

certain. Particular issues that need resolution concern how steady-state operation affects density

and current profile-shaping for generating the

bootstrap current and attaining higher values of

potential power density and confinement efficiency. Similarly, there is still much R&D to be done

to come up with a divertor that can operate reliably

31 For one discussion of different timing and mix of major tokamak facilities leading to a demonstration powerplant, see Stephen O. Dean,

Fusion Power Development Pathways,” Journal of Fusion Energy, vol. 12, No. 4, 1993, pp. 415-420.
Chapter 3 The Tokamak Physics Experiment 63

160

140-

120-

$ ~ 100-

millions- 80-

40-”

20-

1993 1994 1995 1996 1997 1998 1999 2000

Fiscal year

SOURCE Off Ice of Technology Assessment, 1995

under steady-state conditions. If TPX is built and

these important physics and engineering problems are solved, the possibility of developing a

successful tokamak-based fusion power reactor

would be significantly higher.

❚ cost

As proposed in the DOE fiscal year 1995 budget

request to Congress, the total project cost estimate

of TPX is $694 million to completion. This estimate includes $597 million for actual construction and $97 million for associated research

during the construction period and other related

costs. These costs are all in as spent dollars. The

cost profile as envisioned in the fiscal year 1995

request is given in figure 3-3. This plan called for

$66.9 million in fiscal year 1995. Congress, however, appropriated $42 million and did not grant

approval to start construction. At this time, the fiscal year 1996 budget request is uncertain. In addition, the spending profile will also change, but,

assuming project construction is approved, the

annual amounts needed are not likely to decline

from those shown. Currently, DOE is projecting

annual operating costs of $150 million (in fiscal

year 2000 dollars) for the 10-year life of the

facility.

The budget requirements for TPX construction

when combined with DOE commitments to the

ITER program, even before its construction,

would result in a large increase in the total MFE

budget unless the base program is greatly reduced.

While some reduction can be expected as TFTR

operations are phased out, it is not likely to be sufficient to keep the total budget requirements from

growing sharply. At the same time, there have

been calls to reduce the magnetic fusion energy

budget by as much as 50 percent. It is clear, therefore, that gaining approval to begin TPX construction is likely to be difficult. Given the Japanese

interest in a machine with similar characteristics—the JT-60 Super Upgrade—it may be desirable to explore the possibility of making TPX an

international venture just as the ITER project, or

otherwise integrating it more fully into the international fusion energy effort.
Alternate

 Concepts for

 Fusion

 Energy

ver the past several decades, the tokamak has emerged as

the most scientifically successful fusion energy concept,

and is emphasized in U.S. and world programs. There

are, however, a number of alternate concepts (i.e., nontokamak) for fusion energy for which the knowledge base is more

limited (see table 4-1). Some of these may have potentially attractive characteristics. In the past several years, alternate concepts

have received a declining fraction of the federal fusion energy

program budget, leading to the current state in which nearly all

emphasis is placed on the tokamak. This chapter addresses the

following questions regarding alternate concepts:

 What is the rationale for pursuing alternate concepts as part of

a fusion energy program?

 What is the current status of knowledge for alternate concepts?

 What activities are involved in pursuing an alternate concept?

 What is the Department of Energy’s (DOE’s)

current program for alternate concepts?

REASONS TO PURSUE ALTERNATE

FUSION CONCEPTS

There is widespread agreement that examination of alternate fusion confinement concepts is an important component of a fusion

energy program. The Office of Technology Assessment’s 1987

report found that “the characteristics, advantages, and disadvantages of various confinement concepts need further study”1 for

1 U.S. Congress, Office of Technology Assessment, Starpower: The U.S. and the International Quest for Fusion Energy, OTA-E-336 (Washington, DC: U.S. Government

Printing Office, October 1987), p. 11.

| 65
66 The Fusion Energy Program: The Role of TPX and Alternate Concepts

Low density magnetic confinement

Tokamak

Field reversed configuration

Spheromak

Spherical tokamak

Reversed field pinch

Stellarator

Inertial fusion energy (l FE)

Conventional IFE (e.g., heavy-ion, laser)

Advanced, decoupled-ignition, target systems

Magnetized-target IFE

Focused-ion fast ignition

Z-pinch fast ignition

High density magnetic confinement

Z-pinch

Z-Flow-through pinch

Wall-confined, magnetically insulated

Nonthermonuclear

Inertial electrostatic confinement

Colliding beam systems (e.g., MIGMA)

Coulomb barrier reduction

Muon catalysis

Others (e.g., antiproton catalysis)

SOURCE: R. Paul Drake et al., Lawrence Livermore National Laboratory, “Advanced Fusion Assessment,” Aug. 19, 1994

several reasons, including uncertainty about

which concept can form the basis of an attractive

fusion powerplant. In 1990, the Secretary of Energy’s Fusion Policy Advisory Committee (FPAC)

reported:

. . . there must be an independent program of

concept improvement, including study, and

where promising, development of alternative

configurations that may be more suitable for

commercialization. 2

Similarly, in its June 1992 report to the DOE Director of Energy Research, the Fusion Energy Advisory Committee (FEAC) recommended:

. . . a non-tokamak fusion concept program, at

some level, should be supported as a matter of

policy. FEAC recommends that DOE retain the

flexibility to test some non-tokamak concepts at

intermediate scale when warranted by their

technical readiness and promise as a reactor.3

There are several reasons for supporting alternate concepts as part of a fusion energy program,

including reducing risk, identifying more commercially attractive concepts, identifying tokamak enhancements, and promoting competition

in research. Reducing risk and identifying potentially more attractive prospects have been most

widely cited, including by FPAC, FEAC, and

OTA.

❚ Reduce Risk

The tokamak has clearly emerged as the most

scientifically successful fusion energy concept.

However, while there is widespread agreement

that a tokamak powerplant is likely to be scientifically and technically feasible, it may ultimately

prove not to be, and thus pursuit of alternate concepts reduces the risk of having no fusion energy

option should the tokamak prove infeasible. The

remaining physics challenges and uncertainties in

developing a tokamak fusion energy device are

substantial. For example, it is still to be demonstrated that a tokamak plasma can be ignited and

that an ignited plasma can be maintained in steady

state. There are extensive technology challenges

as well, such as developing a divertor (a device to

control impurities and remove reaction products)

2 U.S. Department of Energy, Fusion Policy Advisory Committee, Report of the Technical Panel on Magnetic Fusion of the Energy Research Advisory Board, Final Report, DOE/S-0081 (Washington, DC: September 1990), p. 4.

3 Fusion Energy Advisory Committee, Advice and Recommendations to the Department of Energy in Partial Response to the Charge Letter

of September 24, 1991: Part D, DOE\ER-0555T (Washington, DC: U.S. Department of Energy, Office of Energy Research, June 1992), June

1992, p. 11.
Chapter 4 Alternate Concepts for Fusion Energy 67

Characteristic Cost/performance implication

Low power density High capital cost per kW produced

High complexity Low perceived reliability/maintainability

Large unit sizes of >2 GW (thermal) Inflexible for power system planning

Deuterion and tritium fuel Not radioactively benign

Very high development costs

SOURCE: R Paul Drake et al , Lawrence Livermore National Laboratory, “Advanced Fusion Assessment, ” Aug. 19,

1994.

and developing advanced materials well suited for

the challenging environment of a magnetic fusion

energy (MFE) reactor. 4 In all, tokamak proponents suggest that meeting the existing challenges

to making a demonstration fusion powerplant will

take a continuous, high-level effort extending

more than three decades. This multidecade time

horizon for fusion energy development and the

substantial challenges ahead suggest the importance of breadth and flexibility in the program.

❚ Identify More Commercially

Attractive Concepts

Even if a tokamak energy device ultimately

proves scientifically and technically feasible

(which most observers believe is likely), it may

not be commercially attractive. There are several

tokamak concept characteristics that may lead to a

commercially unattractive reactor product. Without significant technical breakthroughs, these

characteristics could cause tokamak energy devices to have inherently high capital costs, difficult maintenance, large unit sizes, and other

unattractive features, as shown in table 4-2.5 Recent reactor studies performed for the fusion energy program indicated that the cost of electricity

from a fusion powerplant based on the tokamak

concept would be somewhat in excess of today’s

best fission powerplants, assuming all scientific

and technical feasibility challenges are met over

the next several decades.b Table 4-3 summarizes

criteria identified by electric utility industry personnel as important for practical fusion power

systems.

Pursuing alternate concepts, including novel

ones, may provide a breakthrough for an ultimately more economic fusion energy device. There are

several alternate concepts that in theory address

some of the challenges associated with the tokamak. However, their scientific and technical development remains inadequate to determine likely

feasibility. It should be noted that there is at present no alternate concept that appears superior to

the tokamak. Rather, there is insufficient information to determine the long-term prospects of many

alternate concepts. While an alternate concept

may appear promising, the relative lack of information and technical development for most

4 Many technology challenges facing the tokamak would also have to be addressed by some alternate concepts, but there are many excep--

tions. For example, by using a liquid wall of materials not subject to neutron activation or degradation, by its very nature, the inertial fusion

energy concept need not require the same advanced materials. Similarly, alternate concepts involving fusion of certain fuels other than deuterium and tritium such as helium-3 would result in less extensive production of high-energy neutrons, and thus may not require the same developments in advanced materials as needed for the tokamak.

5

L.J. Perkins et al., Lawrence Livermore National Laboratory, “Fusion, the Competition and the Need for Advanced Fusion Concepts,”

paper prepared for OTA Workshop on Fusion Energy, June 8, 1994.

6 F. Najmabadi et al., “The ARIES-I Tokamak Reactor Study,” UCLA-PPG-1323, 1991.
68 The Fusion Energy Program: The Role of TPX and Alternate Concepts

Economics-lower Iifecycle costs than competitors

Plant size flexibility

Short, simple construction schedule

Design simplicity

High reliability, availability

Low fuel costs

Long life

Low end-of-life costs

Public acceptance

Environmental attractiveness, minimal radioactive

wastes

Low costs

Maximum safety

Licensing simplicity

SOURCE: Office of Technology Assessment, adapted from Jack KasIow, Electric Power Research Institute, “Criteria for Practical Fusion

Power Systems, ” presentation to the Fusion Energy Advisory Committee, Dec. 1-2, 1994.

makes that promise speculative. In contrast, the

advanced state of development of the tokamak

makes it relatively easy to identify its likely shortcomings—less well developed alternate concepts

may well have shortcomings that will not be identified without further development efforts.

❚ Identify Tokamak Enhancements

Even if the tokamak proves to be the most commercially attractive fusion concept, research on

alternate concepts can support tokamak improvement and technology development. A current example is the field reversed configuration (FRC)

concept, a toroidal MFE concept at a relatively

low level of development. The largest FRC device, the Large S Experiment (LSX) was built by

Spectrum Technologies, Inc. between 1986 and

1990 at a cost of $14 million with a planned yearly

operating budget of about $3 million. Although

DOE decided in late 1990 to terminate funding for

LSX experiments examining the feasibility of the

FRC fusion concept (see below), LSX received

partial funding to explore its use as a technology

for refueling of tokamaks.7

❚ Promote Competition in Research

and Development

Finally, pursuing more than one fusion concept

may provide the discipline that comes with competition. Providing a competitor for the tokamak

was one of the reasons for supporting the nowabandoned magnetic mirror concept during the

1970s and early 1980s.8 Similarly, in the late

1980s, then-Energy Secretary Watkins proposed a

head-to-head competition between the tokamak

and inertial fusion energy (IFE).

STATUS AND PROSPECTS OF

ALTERNATE CONCEPTS

There are several alternate fusion concepts with a

wide range of maturity levels or development of

the information base. Over the past decades, the

primary focus of the fusion energy program has

been on several MFE concepts.9 Extensive research relevant to IFE has also been performed,

largely for its potential defense applications. As a

result, many MFE and IFE concepts generally enjoy afar more advanced knowledge base than other fusion concepts such as the colliding beam and

inertial electrostatic concepts. Past efforts have

been much less extensive both in theory and experiment, and knowledge about the prospects is

far more speculative.

The likelihood that some alternate concept may

attain and exceed the expected technical and economic performance of the tokamak remains speculative. Developing comparative information

judging the relative strengths and weakness of a

broad range of alternate concepts and assessing

7 Alan L. Hoffman, University of Washington, letter to OTA, May 9, 1994.

8 See, e.g., “Fusion’s $372-Million Mothball,” Science, vol. 238, Oct. 9, 1987, p. 153.

9 For a primer on various magnetic confinement fusion concepts, see Office of Technology Assessment, op. cit., footnote 1.
Chapter 4 Alternate Concepts for Fusion Energy 69

the information base has not been a priority of the

fusion energy program. In particular, there is no

current, published DOE-sponsored analysis of the

comparative technical prospects and challenges of

the broad array of fusion concepts including novel

ones or those previously examined and no longer

pursued. DOE has sponsored and published, however, reviews of alternate MFE concepts that discuss their relative level of development and likely

prospects, 10 and has supported some analyses of

the relative prospects of IFE.ll The lack of comparative assessment of non-MFE or IFE concepts

is consistent with the fusion energy program’s primary focus on MFE concepts rather than a broader

array of fusion concepts.

❚ MFE Concepts

Prior to the 1990s, DOE pursued a variety of MFE

concepts that use magnetic fields to control the

range of motion of the plasma. This research effort

included construction of several small and intermediate facilities to examine such diverse MFE

concepts as stellarators, mirrors, reversed field

pinch; and FRC. Notably, only the stellarator has

come close to attaining the plasma conditions

(e.g., confinement times, temperatures, and densities) attained by tokamaks. The lower levels of

performance, however, may be due to a lack of follow-through rather than a lack of potential. Many

major alternate concept experiments have been either canceled prior to completion of construction,

or kept to a limited experimental effort primarily

for budgetary reasons rather than poor technical

promise. As noted by DOE in its fiscal year (FY)

1993 budget request:

. . . fiscal constraints have required the program

to prematurely narrow its focus to the tokamak

concept, including tokamak improvement activities, and to eliminate major alternate magnetic

confinement program elements.

The Advanced Torodidal Facility Stellaratorat Oak Ridge

National Laboratory in Tennessee.

Table 4-4 shows the status of several experimental facilities for alternate magnetic fusion

concepts that were under development but were

canceled, mothballed, or operated minimally

since the mid- 1980s. The FRC case provides one

example of a technically successful alternate concept with a limited knowledge base that DOE

largely discontinued due to budgetary considerations. FRCs have highly complex effects that are

not well understood, requiring experimental work

to determine the physics of stability and confinement. If the physics turnout to be favorable, however, FRC may present an attractive reactor

concept, with high output power densities and the

potential for relatively simple engineering

compared to the tokamak (e.g., a natural divertor

to exhaust reaction products and heat, based on the

device’s linear geometry). Work on small FRCs at

Los Alamos National Laboratory and Spectra

Technology, Inc. in the late 1970s and 1980s was

promising, leading to a DOE decision to build a

larger device--the $14 mi1lion LSX to explore the

physics in a regime more relevant to reactors.

10 For example, see Fusion Energy Advisory Committee, op. cit., footnote 3; and Argonne National Laboratory, Fusion Power Program,

"Technical Planning Activity: Final Report," prepared for the U.S. Department of Energy, Office of Fusion Energy, January 1987. 11 For example, see Fusion Policy Advisory Committee, op. cit., footnote 2.
70 The Fusion Energy Program: The Role of TPX and Alternate Concepts

Construction cost

Concept Facility ($ in millions) Status

Mirror MFTF-B $372 Closed in 1986, upon completion of

construction.

Stellarator ATF $19 Operated intermittently since opening in

1990, mothballed 1994.

Field reversed configuration LSX $14 Operated minimally upon completion in

1992; being relocated since 1993 to be

used for tokamak fueling experiments.

Reversed field pinch CPRF $58 Canceled during construction, 1992.

(unfinished)

Reversed field pinch MST $4 Operated at reduced budget since opening in 1988.

Spheromak MS $4 Maryland Spheromak was phased out in

1992 without attaining anticipated performance.

Spheromak s-l $9 Constructed at the Princeton Plasma

Physics Laboratory in 1983, operated until 1987, demonstrating some fundamental

physics of the concept.

1 There are a number of alternate concepts that have been pursued in other countries in addition to the U.S. facilities Iisted here

SOURCE: Office of Technology Assessment, 1995.

However, the anticipated $3 million annual funding to conduct experiments on the LSX to explore

the prospects of FRC for a potential fusion energy

device was dropped in 1991, the year after

construction was completed. A more limited experimental course was continued at about onequarter the planned budget, examining the use of

the FRC concept for tokamak refueling.

The reversed field pinch (RFP) concept has a

limited knowledge base and has been greatly cut

back due to budgetary considerations. As with

FRC, RFP has physics challenges (primarily, poor

energy confinement) requiring experimental

work. However, if techniques can be developed to

improve confinement, RFP offers some potentially attractive features. A key benefit is that the

magnetic field required is about one-tenth that of

the tokamak, which could lead to a more compact,

high-power density fusion powerplant. In the

early 1990s, DOE canceled construction of a

$75-million RFP device, the ZT-H, that was about

75 percent complete, again for budgetary reasons.

A much smaller RFP device, MST, continues partial operation at the University of Wisconsin. Operation of an Italian RFP device called the RFX of

similar size to the ZT-H began in 1991.12

The largest fusion energy project cancellation

is the Mirror Fusion Test Facility-B (MFTF-B), a

$372-million (as spent) alternate concept device

that was mothballed due to budget constraints the

day after completing construction in 1986, but

prior to its commissioning.13 MFTF-B did face

considerable technical challenges identified during the last two years of its construction, as experiments at much smaller mirror facilities gave

12 Fusion Energy Advisory Committee, op. cit., footnote 3, p. 7.

13 “Fusion’s $372-Million Mothball,” op. cit., footnote 8, pp. 152-155.
Chapter 4 Alternate Concepts for Fusion Energy 71

disappointing results for the mirror concept generally. MFTF-B would also have been expensive to

operate, costing tens of millions of dollars annually. However, as it was never operated, MFTF-B

did not provide experimental evidence either supporting or rejecting the mirror concept. As shown

in table 4-4, several other major facilities were

built during the 1980s to test a variety of alternate

concepts, most of which were retired early or pursued a limited course of experimental studies.

Some alternate MFE concepts previously investigated and found less promising than the tokamak may warrant reconsideration, based on

improvements in technology and theoretical understanding. For example, one of the major challenges with the stellarator concept was designing

and fabricating the relatively intricate magnets required. However, advanced computer-based analytical capabilities continue to improve the ability

to design and manufacture magnets. Some of

these techniques were developed and used in producing the now prematurely retired Advanced

Toroidal Facility (ATF), the most recent stellarator.14 While the stellarator may not ultimately

prove more attractive than the tokamak, improving magnet technology continues to reduce one of

its principal drawbacks. Advantages relative to

the tokamak include that they are inherently

steady state, have no plasma current, and thus do

not suffer from disruptions and instabilities of the

plasma. The approximately $1-billion Large Helical Device (LHD), under construction in Japan, is

a superconducting stellarator similar to ATF in

concept, but closer to TPX in scope and cost. A

similar scale stellarator has been proposed in Germany. A much smaller stellarator with a cost of

about $3 million is under construction at the University of Wisconsin as part of DOE’s small program for alternate fusion concepts.

End magnets for the Mirror Fusion Test Facility (MFTF-B)

Lawrence Livermore National Laboratory

DOE last sponsored a detailed examination of

the prospects for tokamaks and alternate magnetic

confinement concepts in the mid- 1980s, which resulted in a January 1987 report, “Technical Planning Activity: Final Report” (TPA).15 While that

document remains a useful source of information,

there has been considerable change since it was

produced. For example, there have been major

advances in tokamak performance, some limited

experimental efforts on some alternate MFE concepts, and a continuing improvement in the broad

base of physics and technology related to fusion.

Thus, the TPA does not provide an entirely up-todate foundation for evaluating the current merits

of alternate fusion research efforts. More recently,

DOE’s FEAC panel on concept improvement

(FEAC panel #3) has provided a substantially less

detailed review of alternate concepts, which

makes note of the advances in MFE.

Reviews of MFE concepts have classified the

concepts according to their status or level of development. 16 For example, FEAC panel #3 di14 Following completion of construction in 1988, ATF was held to a limited operational schedule and retired prematurely for budgetary

reasons rather than poor technical performance. 15 Argonne National Laboratory, op. cit., footnote 10.

16 Ibid.; Office of Technology Assessment, op. cit., footnote 1; and Fusion Energy Advisory Committee, op. cit.. footnote 3.
72 The Fusion Energy Program: The Role of TPX and Alternate Concepts

FEAC Panel #3-concept improvement OTA Starpower report

Highly developed concepts Well-developed knowledge base

Tokamaks Conventional tokamak

Stellarators

Developing concepts Moderately developed knowledge base

Reversed field pinch Advanced tokamak

Field reversed configuration Tandem mirror

Stellarator

Reversed field pinch

Developing knowledge base

Spheromak

Field reversed configuration

Dense Z-pinch

Small scale innovative concepts

Unspecified

SOURCES: Fusion Energy Advisory Committee, Advice and Recommendations to the Department of Energy in Partial

Response to the Charge Letter of September 24, 1997: Part D, DOE/ER-0555T (Washington, DC: U.S. Department of

Energy, Office of Energy Research, 1992), p 11, and U S. Congress, Office of Technology Assessment, Starpower: The

U.S. and the International Quest for Fusion Energy, OTA-E-336 (Washington, DC: U.S. Government Printing Office, October 1987), table 1-1, p. 12.

vialed MFE concepts into three categories of development, as shown in table 4-5. The panel did

not explicitly investigate the prospects for potential fusion powerplants, but rather commented on

the current state of scientific understanding of

alternate concepts. Similarly, OTA’s 1987 Starpower report included a listing of magnetic confinement concepts then under investigation in the

United States, and their level of development

based on DOE’s TPA. The lists of concepts in the

earlier documents (i.e., OTA and TPA) are longer,

reflecting the greater variety of alternate MFE

concept research then being pursued.

❚ IFE Concepts

Considerable effort has been devoted to understanding inertial confinement, in which a pellet of

fusion fuel is heated and compressed by intense lasers or heavy-ion drivers to such high densities

that the fuel’s own inertia is sufficient to contain it

for the very short time needed for fusion to occur

(see figure 4-l). Numerous reviews have concluded that the IFE concept using a heavy-ion

driver is a promising approach to an eventual fusion powerplant.17 DOE has sponsored reactor

studies of conceptual designs of IFE powerPlants. 18 There is, however, considerable scientific and technical uncertainty with IFE. Overall,

IFE proponents envision a $4-billion civilian effort (supplemented with about $4 billion in DOE

Defense Program research) over the next 30 years

involving several new facilities to address the

scientific and technical challenges, culminating in

a demonstration powerplant. Although much

17 FFAC Panel #7 Report, “Inertial Fusion Energy,” in U.S. Department of Energy Fusion Energy Advisory Committee, Advice and Recoinmendations to the U.S. DOE in Response to the Charge Letter of Sept. 18, 1992 (Washington, DC: June 1993); and Fusion Policy Advisory

Committee, op. cit., footnote 2.

18 See, e.g., R.W. Moir et al., “HYLIFE-II: A Molten-Salt Inertial Fusion Energy Power Plant Design-Final Report,” Fusion Technology,

vol. 25, January 1994, pp. 5-25.
Chapter 4 Alternate Concepts for Fusion Energy 73

Heating Compression Ignition

Laser or particle beams Fuel is compressed by The fuel core reaches high

rapidly heat the surface rocket-like blowoff of the density and ignites.

of the fusion target, surface material.

forming the plasma envelope.

Bum

Thermonuclear burn

spreads rapidly through

the compressed fuel,

yielding many times the

input energy.

SOURCE: Lawrence Livermore National Laboratory.

scientific and technical work remains to be done

(see figure 4-2), the information base for IFE is

moderately well established, as are the next research and development steps.19

Inertial confinement research mimics, on a

very small scale, some processes in the hydrogen

bomb, and most of the research relevant to IFE has

been performed by DOE’s Office of Defense Programs for its applications to nuclear weapons and

stockpile stewardship responsibilities. The scientific feasibility of achieving high gain in an

inertial confinement fusion target has been demonstrated in underground nuclear explosion experiments at the Nevada Test Site in a program

called Halite/Centurion. The next step in examining the science of target physics and ignition depends on the National Ignition Facility (NIF),

another effort planned for the DOE Defense Program. NIF is a proposed $1-billion research facility being considered as part of the stockpile

stewardship program to maintain expertise for nuclear weapons. The scientific results that NIF or

something like it would produce are essential to

demonstrating ignition and propagating burn of

high-gain targets, and to establishing the requirements that an IFE driver would have to meet.

However, whether NIF is pursued will depend

more on weapons-related reasons, including its

role in stockpile stewardship and the potential effects on weapons proliferation rather than its

benefits for the fusion energy program. DOE announced plans to proceed with NIF in October

1994, but is also performing a detailed study of the

1 9See, e.g., B. Grant Logan et al., "The Inertial Confinement Fusion Pathway,"paper presented at the Forum on Pathways to Fusion Power,

American Nuclear Society Annual Meeting and Fusion Topical, New Orleans, LA, June 22, 1994.
74 The Fusion Energy Program: The Role of TPX and Alternate Concepts

Energy Research Activities Construction

ILSE program design

Power plant technology

Technology development

Engineering Test Facility

(ETF) and DEMO

Supporting programs >

Defense Programs Activities

Existing facilities

National Ignition Facility

Supporting programs

Nova, Omega, PBFA II, Nike

Design Construction

Ignition

demonstration

Possible Laboratory Microfusion Facility

Target physics, target fabrication . . .

1 >

1990 2000 2010 2020

SOURCE: Roger O Bangerter, Head, Fusion Energy Research Program, Lawrence Berkeley Laboratory, “Heavy Ion Inertial Fusion, ” testimony at

hearings before the House Committee on Science, Space, and Technology, Subcommittee on Energy, Aug. 2, 1994

effects of the program on nuclear nonproliferation, expected to be completed in 1995.

There are important scientific and technical

challenges for IFE that go beyond the target physics research needs shared with the Defense Program. The most important of these is development

of a driver that is both efficient and can be operated

at a high repetition rate (e.g., several times per second) for use in an eventual IFE powerplant. In

contrast, while lasers can be highly effective for

target physics research, which requires a repetition rate of one burst every several hours, they lack

the efficiency and repetition rate needed by IFE

powerplant drivers. Numerous reviews have supported development of a heavy-ion driver, which

is the most advanced concept. The heavy-ion driver concept builds on the considerable investment

in science and technology developed for the accelerators used in high-energy physics. The next step

in heavy-ion driver development is called the Induction Linac Systems Experiments (ILSE), with

an estimated construction cost of about $50 million. While heavy-ion drivers appear to be the

most advanced concepts for IFE, there are other

approaches that may eventually prove attractive as

well, including light-ion drivers and advanced

lasers. 20

Budget constraints have caused a continued deferral in the development of key research efforts

for IFE, including ILSE. Despite favorable recommendations from review committees for proceeding with ILSE, the IFE budget was reduced

from $9 million in FY 1992 to $4 million in FY

20 Charles D. Orth et al., Larence Livermore National Laboratory, “Diode-Pumped Solid-State-Laser Driver for Inertial Fusion Energy

Power Plants,” ICF Quarterly Report, vol. 3, No. 4, July-September 1993, pp. 145-154.
Chapter 4 Alternate Concepts for Fusion Energy | 75

1993. In commenting on the lack of progress in the

IFE effort, one review body found the following:

The Department of Energy has not established an IFE program that resembles remotely

the one envisioned by FPAC. Ostensibly this has

been due to stringent funding allocations for fusion as a whole.21

In general, IFE proponents suggest a development path with inherently less dependence on extremely expensive individual facilities than the

tokamak by virtue of greater modularity in experimental facilities. For example, while an ignition

facility is an expensive component of an IFE development path, that one facility could service the

research needs of several drivers. An overview of

the research needs for IFE development and a simplified development path as developed by proponents is shown in figure 4-1. In total, IFE

proponents project budget needs of about $4 billion over the next three decades to develop a demonstration powerplant (DEMO).22 This cost

estimate includes neither the anticipated $1.8 billion to build and operate NIF, nor other efforts

paid for under DOE’s Defense Program. Counting

all defense research also relevant to IFE would

add about $4 billion to the costs. Further, it must

be noted that the cost estimates are highly uncertain, and depend on such unresolved physics issues as the gain achievable with a given driver.

❚ Other Novel Concepts

A number of novel fusion energy concepts have

been suggested that take fundamentally different

approaches from those used in either MFE or

IFE.23 Relative to inertial and magnetic confinement fusion, these approaches have generally received very limited attention in the fusion energy

program, and are at an embryonic development

stage, with far less well understood and demonstrated scientific concepts. While the lack of

scientific understanding and demonstration can

be a notable shortcoming of novel concepts, some

proponents find this to be the essence of their potential benefit and justification for support. For

example, one physicist long associated with certain novel concepts notes:

If there is a route to dramatically more attractive fusion systems, it will be in the investigation of new or relatively unexplained physics

rather than in engineering refinements of present or recently terminated programs.24

Just as the scientific aspects can be highly speculative, the broader technology issues that would

have to be addressed leading to a fusion energy

powerplant based on any of these concepts have

typically not been examined in detail. However,

proponents of these concepts suggest a variety of

possible advantages relative to the tokamak, ranging from ability to use advanced fuels (e.g.,

helium-3 and deuterium, which produces less

neutron radiation than results from the deuteriumtritium reactions of tokamak and IFE) to smaller,

more flexible powerplant sizes, to lower construction and operating costs. As noted earlier, DOE

has not published an analysis of the comparative

technical prospects and challenges of novel alternate concepts.

One example of the many novel concepts is

muon catalysis, which involves using a subatomic

particle called a muon to shield the electric charge

of one of the nuclei in a fusion reaction from the

other.This shielding mitigates the repulsive forces

21 FEAC Panel #7 Report, op. cit., footnote 17.

22 Donald Correll, Deputy Program Leader, Laser Programs—Inertial Confinement Fusion Lawrence Livermore National Laboratory, fax

to OTA, July 22, 1994; and Roger O. Bangerter, Lawrence Berkeley Laboratory, “Heavy Ion Inertial Fusion” testimony at hearings before the

House Committee on Science, Space, and Technology, Subcommittee on Energy, Aug. 2, 1994.

23 For brief descriptors of a number of novel concepts, see for example, Global Foundation, Inc., “1st International Symposium on Evaluation of Current Trends in Fusion Research: Book of Abstracts,” Washington, DC, Nov. 14-18, 1994.

24 Normal Rostoker, “Alternate Fusion Concepts,” paper presented at the 1st International Symposium: Evaluation of Current Trends in

Fusion Research, Washington, DC, Nov. 14-18, 1994.
76 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

and allows the nuclei to approach closely enough

to fuse without the need for extreme temperature.

Muon-catalyzed fusion reactions have been observed in high-energy physics experiments dating

back several decades, although the number of fusion reactions produced per muon before it decays

was lower than would be necessary to make the

process worthwhile.

Inertial electrostatic confinement fusion is a

more developed, but still novel approach that has

received limited attention from the fusion energy

program. The concept involves confining the

highest energy fuel ions electrostatically, leading

to greater reactivity than found in an MFE plasma.

While some work has been performed examining

the scientific basis of the concept including at the

University of Wisconsin and the University of Illinois, the theoretical studies remain at a relatively

preliminary stage. A related concept, the colliding

beam, was largely discarded decades ago based on

theoretical and experimental results using the

migma reactor approach that indicated an inability

to develop a sufficient ion density. However, proponents of the concept suggest that developments

in the field of high-energy physics and in the accompanying technology of linear accelerators

may provide solutions to this drawback of the colliding beam concept.25

Perhaps the most widely debated and controversial novel concept has been cold fusion. In

1989, two researchers, Stanley Pons and Martin

Fleischmann, announced that they had discovered

a method of producing nuclear fusion at room

temperature using a simple electrochemical apparatus. Although some researchers reported results

supporting the claims, many of those findings

were subsequently retracted or could not be confirmed by other researchers. A 1989 DOE advisory committee of nuclear physicists and chemists

concluded that “evidence for the discovery of a

new nuclear process termed cold fusion is not persuasive.”26 Today, a handful of researchers continue to report that electrolysis of heavy water can

lead to the production of excess power. Some investigators theorize that unusual and unexplained

chemical or nuclear processes may in fact be at

work. The inability to routinely reproduce experimental findings has proven to be a continuing

challenge, and the results are still questioned by a

majority of the scientific community. However,

the Japanese agency MITI has an ongoing program examining the phenomena, with funding of

about $5 million in 1994.27

STEPS IN EXAMINING

ALTERNATE CONCEPTS

The next step that would be required in development of any alternate concept depends on its level

of maturity. While immature concepts may be

well suited to a great deal of relatively inexpensive

theoretical analysis for screening purposes, some

such as IFE are at a point where major facilities

such as ILSE and NIF are required to continue

development.

Theoretical research, modeling, and analysis

can be useful tools for examining the likely merits

of an alternate concept. These theoretical efforts

can include a wide range of expertise from

detailed physics (e.g., modeling of radiation/

magneto-hydrodynamics for high-density plasmas; modeling of particle orbits and collisional

effects) to reactor design and economic analysis

assuming favorable physics (e.g., commercial

reactor evaluations and systems modeling28).

Computational abilities continue to improve,

making theoretical studies increasingly feasible.

Even for relatively more advanced concepts,

theoretical analysis can be useful for estimating

the potential long-term attractiveness, and thus

25 B.C. Maglich et al., “Modern Magnetic Fusion,” Advanced Physics Corp. Report # SAFE-94-104, May 5, 1994.

26 Energy Research Advisory Board, “Cold Fusion Research,” a report to the U.S. Department of Energy, November 1989.

27 Nature, vol. 367, Feb. 24, 1994, p. 670.

28 These include, for example, the ARIES series of studies for tokamaks and HYLIFE-II for heavy-ion inertial fusion.
Chapter 4 Alternate Concepts for Fusion Energy | 77

help set priorities for the next, more costly experimental steps.

One team of fusion researchers at Lawrence

Livermore National Laboratory (LLNL) has proposed an “Advanced Fusion Assessment Program” intended to perform objective evaluation

and development of alternate concepts. They intend for the effort to become an effective tool for

DOE in managing the longer term fusion program, by taking good ideas far enough that DOE

can choose an appropriate organization to pursue

an experimental program.29 As envisioned by the

LLNL team, this program would encompass the

following:

 Seek out good ideas for fusion systems that offer improvements over present concepts that

approach an order-of-magnitude.

 Build appropriate teams of LLNL, U.S. scientists, and U.S. industry to evaluate both the

physics and reactor potential. Make scientific

and engineering evaluation tools available to

people with new ideas.

 Provide neutral, objective evaluation rather

than advocacy of specific ideas.

 Provide physics support as needed as such programs get underway.

The LLNL proposal emphasizes theoretical,

rather than experimental, studies. These would be

integrated studies, including a full range of analysis from basic physics to examining the likely

reactor characteristics and economics, assuming

the physics is found promising after experimental

efforts. The effort could be useful as an integrated

screening tool and may be able to sort out the truly

promising but undeveloped concepts from less

promising ones. According to LLNL team members, an initial evaluation of an undeveloped concept, including basic physics and reactor

potential, could be performed for a few hundred

thousand dollars. A full theoretical, computational, and reactor potential study would probably require a few million dollars.30 Overall, the LLNL

proposal suggests a one-year budget of about $3.5

million, or less than one percent of the fusion energy program budget.

Understanding, evaluating, and developing a

fusion concept cannot be accomplished with

theoretical work alone, however. In some areas of

fusion physics, theory and modeling capabilities

are not currently adequate for exploring fusion energy concepts. For example, existing theoretical

tools are better suited to analyzing high-density

plasmas than low-density plasmas such as tokamak. Thus, for alternate concepts involving lowdensity plasmas, experimental devices are

essential for examining the physics prospects.

Even in those cases for which analytical capabilities are well suited, the complexity of the physics

and technology requires extensive experimental

work as a concept is developed to validate the predictions of theory. The evolution of scientific and

technological understanding has typically proceeded in stages using increasingly capable, and

often larger, facilities. This evolution builds on

the empirical results from operation of previous

facilities, extrapolating the existing knowledge

base to design a more capable facility.

The necessary dependence on experimental facilities and research to verify theory can make

concept development expensive. One aspect of

the reliance on empirical results is that advanced

studies require increasingly capable and expensive facilities as a concept is developed, which can

lead to substantial budget requirements. However,

examination of a wide range of alternate concepts

does not necessarily entail an extensive series of

facilities reaching into several billions of dollars.

There are two main reasons: first, as information

is gained about a concept during earlier stages of

development, only some will be found to merit

promotion to subsequent stages of development.

Criteria for promoting a concept to a subsequent

stage (and development of more and costlier experimental facilities) may include development

29 R. Paul Drake et al., Lawrence Livermore National Laboratory, “Advanced Fusion Assessment,” Aug. 19, 1994.

30 D.E. Baldwin and John Perkins, personal communications, Aug. 11, 1994 and Nov. 17, 1994.
78 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

cost, likelihood of technical success, and likelihood that the concept, if successful, will provide a

substantial cost or performance advantage over

the tokamak. Budgetary considerations can also

be an important criterion for determining whether

the prospects of a concept justify the additional

spending for further development work.

Second, while tokamak development has involved a series of larger, more capable, and more

expensive facilities reaching on the order of $10

billion, some alternate concepts may not require

as extensive a succession. For example, a concept

with inherently higher power densities such as

FRC, if found to be technically promising based

on theoretical reviews and small experimental efforts, may require smaller and less costly facilities

relative to the tokamak. While pursuing FRC

would still require a series of theoretical and experimental efforts, including development of larger facilities if current results so warrant, its

proponents suggest that an engineering test reactor could be far smaller and less costly than

ITER.31 As noted in the previous section, IFE provides another example of a potentially less costly

and more flexible development path for a fusion

powerplant.

DOE’S PROGRAM FOR

ALTERNATE CONCEPTS

In the Energy Policy Act of 1992 (EPACT), Congress set a goal for DOE of pursuing a broad-based

fusion energy program that would, by 2010, verify

the practicability of commercial electric power

production. EPACT further directed the department to develop a comprehensive plan for the program that would “include specific program

objectives, milestones and schedules for technology development, and cost estimates and program

management resource requirements.”32 However,

DOE has not yet developed that overall plan. Nor

has it explicitly examined and justified a level of

effort and a process for identifying, evaluating,

and, where appropriate, pursuing alternate concepts, which arguably are one aspect of a broadbased fusion energy program. That is, there is no

explicit DOE analysis of the relationship between

alternate concepts and the overall fusion energy

program objective—developing a technically and

economically attractive method of electric power

production.

Although DOE has not published a strategic

plan for the fusion energy program, it has pursued

a course of greatly reducing emphasis on alternate

concepts in the past several years. With substantial cutbacks in alternate concept work in the past

several years, many fusion researchers (including

those not identified with any particular alternate

concept) perceived indifference or worse on the

part of DOE for alternate concepts. The FEAC

panel #3 on concept improvement noted the following:

. . . statements and communications by the

Department [of Energy] led to the perception in

the fusion community that proposals for research on non-tokamak concepts would not be

supported by OFE, and should not be submitted.

. . . The rationale given was that research on

competing concepts could not be supported,

since, even if the research were successful, no

funds would be available to develop the concept

to its next, more expensive state; thus it would

be best not to begin.33

Similarly, LLNL researchers have recently noted:

“There is now little focus on seeking, generating,

and objectively examining advanced ideas” and

“in fact, the current environment is rather hostile

31 Hoffman, op. cit., footnote 7.

32 Energy Policy Act of 1992, Public Law 102-486, Oct. 24, 1992, Sec. 2114.

33 FEAC Panel #3, “Concept Improvement: A Report to the Fusion Energy Advisory Committee,” May 11, 1992, p. 2, in Fusion Energy

Advisory Committee, op. cit., footnote 3, app. I.
Chapter 4 Alternate Concepts for Fusion Energy 179

to new ideas for fusion and inventors have trouble

finding support.”34

In 1992, FEAC recommended “that a small but

formal and highly visible periodic competition be

established to foster new concepts and ideas that if

verified would make a significant improvement in

the attractiveness of fusion reactors.”35 In response, DOE announced an “Innovative Concepts

Initiative” and a request for proposals “to support

innovations in tokamak improvements and new

fusion confinement systems.”36 The announcement anticipated awarding a total of $1 million to

be divided among no more than three grants. DOE

judged 15 of the 24 applications to be eligible and

provided those to a non-DOE peer review committee. A total of $1.2 million annually in fiscal

years 1993 through 1995 was provided to the three

winning applicants. Among these was a concept

closely related to FRC, called the Ion Ring.

The current level of effort devoted to alternate

concepts is widely viewed as inadequate relative

to the overall fusion energy program. While pursuit of alternate concepts is widely agreed on by

fusion proponents as one aspect of a balanced fusion energy program, the appropriate level of effort devoted to alternate concepts is less clear. In

FY 1994, about $1.2 million, less than 1/2 percent

of the total fusion energy budget, was dedicated to

the Innovative Concepts Initiative. About $4 million was devoted to inertial fusion energy, the

most developed and promising alternate concept,

an amount insufficient to proceed to the next development step, a heavy-ion driver experiment. In

fact, FEAC had in 1993 reported to DOE that

“there is no credible program for the development

34 Perkins et al., op. cit., foootnote 5.

35 Fusion Energy Advisory Committee, Op. Cit., footnote 3, p. 11.

36 Federal Register, vo1. 57, No. 244, Dec. 18, 1992, pp. 60197-60198.

The Large Helical Device (a stellarator) under construction in

Japan is estimated to cost about $1 billion.

of a heavy-ion fusion energy option” at an annual

funding rate of $5 million.37

DOE suggests that a “healthy, but constrained”

alternate concepts program would require about

$100 million per year.38 However, a substantial

amount of information could be developed with a

far more modest program that provides a freer

basis for making future alternate concept decisions. For example, pursuing an advanced fusion

assessment proposal of the type suggested by

LLNL researchers, supporting the civilian portion

of the IFE budget, repeating the DOE Innovative

Concepts Initiative, and restarting or accelerating

confinement concept experiments at existing but

underused or idled facilities such as LSX and the

ATF stellarator could cost under $20 million or

about five percent of the current fusion energy

program budget. Increased international collabo37U.S. Department of Energy, Fusion Energy Advisory Committee, Advice and Recommendations to the Department of Energy in Partial

Response to the Charge Letter of September 18, 1992, DOWER-0594T (Washington, DC: June 1993), p. 11.

38 U.S. Department of Energy, “Fusion Energy Program,” briefing package presented by N. Anne Davies to OTA, Apr. 28, 1994.
80 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

ration making use of existing alternate concept research facilities in other countries may also be a

lower cost alternative to sole U.S. funding of new

intermediate-scale facilities.

CONCLUSION

In summary, while alternate concepts provide no

panacea for fusion energy development, there is

merit in examining them as part of a broad fusion

program. Relative to the expected costs of the tokamak effort, a great deal of exploratory work can

be conducted at modest cost. Assuming some of

the concepts prove technically promising, however, further development may require larger

budgets for construction of expensive facilities.

As with the tokamak effort, the potential role of

the overall fusion energy program in meeting

long-term energy needs, and the level of research

effort justified by that potential role, are critical

issues for the direction of alternate concepts

research.
Appendix A:

 Acronyms and

Glossary of

 Terms

ACRONYMS

AEC Atomic Energy Commission

ATF Advanced Toroidal Facility,

Oak Ridge, Tennessee

BPX Burning Plasma Experiment

CDA conceptual design activity

CIT Compact Ignition Tokamak,

proposed for Princeton Plasma

Physics Laboratory, Princeton,

NJ

CPMP Comprehensive Program Management Plan

DIII-D Double III upgrade, General

Atomics, San Diego

D-D Reaction deuterium-deuterium fusion

reaction

DEMO Demonstration Fusion

Powerplant

DOE U.S. Department of Energy

D-T Reaction deuterium-tritium fusion

reaction

EDA engineering design activity

EPACT Energy Policy Act of 1992

ERAB Energy Research Advisory

Board

ETR engineering test reactor

FEAC Fusion Energy Advisory

Committee

FMIT Fusion Materials Irradiation

Test Facility

FPAC Fusion Policy Advisory

Committee

FRC field reversed configuration

ICF inertial confinement fusion

IFE inertial fusion energy

ILSE Induction Linac System

Experiments

ITER International Thermonuclear

Experimental Reactor

JET Joint European Torus

JT-60 super

upgrade Japan Tokamak 60 super

upgrade

JT-60U Japan Tokamak 60 upgrade

LBL Lawrence Berkeley National

Laboratory, Berkeley, CA

LHD Large Helical Device

LLNL Lawrence Livermore National

Laboratory, Livermore, CA

LSX Large S Experiment

MeV million electron volts

MFAC Magnetic Fusion Advisory

Committee

MFE magnetic fusion energy

| 81
82 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

MFEEA Magnetic Fusion Energy Engineering Act of 1980

MFPP Magnetic Fusion Program

Plan

MFTF-B Mirror Fusion Test Facility B

MW megawatts

NAS National Academy of Sciences

NES National Energy Strategy

NIF National Ignition Facility

OFE Office of Fusion Energy

ORNL Oak Ridge National Laboratory,

Oak Ridge, TN

PBX-M Princeton Beta ExperimentModification

PCAST President’s Council of Advisors

on Science and Technology

PPPL Princeton Plasma Physics Laboratory, Princeton, NJ

Q Energy gain

RFP reversed field pinch

R&D research and development

SSAT steady-state advanced tokamak

SEAB Secretary of Energy Advisory

Board

T-15 large superconducting tokamak,

Kurchatov Institute, Russia

TFTR Tokamak Fusion Test Reactor

TPX Tokamak Physics Experiment

GLOSSARY

Advanced fuel cycles: The use of fuels other

than D-T to sustain fusion reactions. Alternate

fuel cycles include enhanced D-D reactions, reactions of deuterium with helium-3 (D-3He), or lithium-6 (D-6Li), and proton-Boron-11 (p-11B)

reactions. Achieving fusion with these fuels

would typically require higher temperatures and

Lawson confinement parameters than required for

D-T fuels as well as substantial improvements in

available plasma technologies. The attraction of

these fuel cycles is that they require little or no tritium, and produce fewer and lower energy neutrons thus reducing radiation damage, allowing

the use of existing materials and minimizing radioactive wastes.

Advanced tokamak: A tokamak incorporating features such as steady-state current drive or

shaping of the plasma in order to attain higher

performance or more efficient operation than the

conventional tokamak. See “Tokamak” or “Conventional tokamak.”

Alpha particle: A positively charged particle,

identical to a helium-4 nucleus, composed of two

protons and two neutrons. An alpha particle is

emitted in the radioactive decay of many naturally

occurring radioisotopes such as uranium and thorium; it is also one of the products of the D-T fusion reaction.

Alpha particle heating: Heating of a fusion

plasma by alpha particles generated during the fusion reaction colliding with deuterium and tritium

in the plasma. Alpha particle heating is expected

to be the principal source of heating in a D-T fusion plasma once ignition is achieved.

Alternate concept or alternate confinement

concept: As used in this report, a nontokamak

confinement concept.

Ash: An end product of a fusion reaction. For

the D-T fusion reaction, the “ash” is helium gas.

Auxiliary heating: External systems that heat

plasmas to higher temperatures than can be

reached from the heat generated by electric currents within the plasma. Neutral beam heating and

radiofrequency heating are both examples of auxiliary heating systems.

Beta: The ratio of the outward pressure exerted

by the plasma to the inward pressure that the magnetic confining field is capable of exerting. Beta is

equivalent to the ratio of the energy density of particles in the plasma to the energy density of the

confining magnetic fields.

Blanket: Structure surrounding the plasma in a

fusion reactor within which the fusion-produced

neutrons are slowed down, heat is transferred to a

primary coolant, and tritium is bred from lithium.

Blanket test facility: A plasma-based large

volume neutron source device to be used for the

testing of blanket components and materials needed to recover the heat of fusion reactions and to

produce new tritium fuel. The need for construction of a separate blanket test facility is dependent
Appendix A Acronyms and Glossary of Terms | 83

on the timing and scope of the ITER blanket test

program.

Bootstrap current: A plasma current driven

by the plasma itself.

Breakeven: The point at which the fusion power generated in a plasma equals the amount of

heating power that must be added to the plasma to

sustain its temperature.

Breakeven-equivalent: Attainment in a nontritium-containing plasma of conditions (temperature, density, and confinement time) that would

result in breakeven if the plasma contained tritium. Because plasmas not containing tritium are

far less reactive than those containing tritium, the

actual amount of fusion power generated by a

breakeven-equivalent plasma will be far less than

would be produced under actual breakeven

conditions.

Burning plasma: A plasma in which the fusion reactions supply a significant fraction of the

energy needed to sustain the plasma.

Celsius: Centigrade.

Centigrade: A thermometric scale on which

the interval between the freezing point of water

and the boiling point of water is divided into 100

degrees with 0° representing the freezing point

and 100° representing the boiling point.

Conceptual design: The basic or fundamental

design of a fusion reactor or experiment that

sketches out device characteristics, geometry, and

operating features but is not at the level of detail

that would permit construction.

Confinement: Restraint of plasma within a

designated volume. In magnetic confinement, this

restraint is accomplished with magnetic fields.

Confinement concept: An approach to controlling the range of motion of a plasma. Due to

the extremely high temperatures needed to allow

fusion to occur, no solid container can confine a

fusion energy plasma. Instead, a variety of approaches, such as using magnetic fields or inertia

to confine the plasma can be used.

Confinement parameter: The product of

plasma density and confinement time that, along

with temperature, determines the ratio between

power produced by the plasma and power input to

the plasma. Also called “Lawson parameter.”

Confinement time: A measure of how well the

heat in a plasma is retained. The confinement time

of a plasma is the length of time it would take the

plasma to cool down to a certain fraction of its initial temperature if no heat were added.

Conventional tokamak: A tokamak device

not incorporating advanced steady-state current

drive or plasma shaping technology. See “Tokamak,” “Advanced tokamak.”

Current drive: A technique for making the toroidal plasma current using RF or neutral beam

power, i.e., without the use of an inductive transformer.

D-D reaction: A fusion reaction in which one

nucleus of deuterium fuses with another. Two different outcomes are possible: a proton plus a tritium nucleus, or a neutron plus a helium-3

nucleus.

D-T reaction: A fusion reaction in which a

nucleus of deuterium fuses with a nucleus of tritium, forming an alpha particle and a neutron and

releasing 17.6 million electron volts of energy.

The D-T reaction is the most reactive fusion

reaction.

Decommissioning: The steps taken to render a

plant, particularly a nuclear reactor, safe to the environment at the end of its operating lifetime.

Density: Amount per unit volume. By itself,

the term “density” often refers to particle density,

or the number of particles per unit volume. However, other quantities such as energy density or

power density (energy or power per unit volume,

respectively) can also be defined.

Deuterium (D or 2H): A naturally occurring

isotope of hydrogen containing one proton and

one neutron in its nucleus. Approximately one out

of 6,700 atoms of hydrogen in nature is deuterium.

Deuterium is one of the fuels (along with tritium)

needed for the D-T fusion reaction, the most reactive fusion reaction.

Diagnostics: The procedure of determining

(diagnosing) exactly what is happening inside an

experimental device during an experiment. Also,

the instruments used for diagnosing.

Divertor: A component of a toroidal fusion device used to shape the magnetic field near the plasma edge so that particles at the edge are diverted
84 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

away from the rest of the plasma. These particles

are swept into a separate chamber where they

strike a barrier, become neutralized, and are

pumped away. In this way, energetic particles near

the plasma edge are captured before they can

strike the walls of the main discharge chamber and

generate secondary particles that would contaminate and cool the plasma.

Driver: A machine that provides the energy to

heat and compress an inertially confined fusion

target in the form of intense, high-power beams of

laser light or particles.

Electron: An elementary particle with a unit

negative electrical charge and a mass 1/1837 that

of a proton. In an atom, electrons surround the

positively charged nucleus and determine the

atom’s chemical properties.

Electron volt (eV): A unit of energy equal to

the energy that can be acquired by a singly charged

particle (e.g., an electron) from a one-volt battery.

Since the temperature of a system is proportional

to the average energy of each particle in the system,

temperature is also measured in electron volts.

Energy gain (Q): The ratio of the fusion power

produced by a plasma to the amount of power that

must be added to the plasma to sustain its temperature.

Engineering feasibility: The ability to design

and construct all the components, systems, and

subsystems required for a fusion reactor.

Engineering test reactor: A next-generation

fusion experiment to study the physics of longpulse ignited plasmas, provide opportunities to

develop and test reactor blanket components under actual fusion conditions, and integrate the various systems of a fusion reactor.

Equivalent Q: For a plasma not containing tritium, a measure of what Q would have been in a

tritium-containing plasma that attained the same

temperature and confinement parameter. See

“Confinement parameter.”

Field-reversed configuration (FRC): A magnetic confinement concept with no toroidal field,

in which the plasma is essentially cylindrical in

shape. The FRC is a form of compact toroid.

Fission: The process by which a neutron

strikes a nucleus and splits it into fragments. During the process of nuclear fission, several neutrons

are emitted at high speed, and heat and radiation

are released.

Flux: The amount of a quantity (e.g., heat, neutrons) passing through a given area per unit time.

Fusion: The process by which the nuclei of

light elements combine, or fuse, to form heavier

nuclei, releasing energy.

Fusion nuclear technology: The engineering

systems needed to fuel, maintain, and recover energy from a fusion reactor.

Fusion self-heating: Heat produced within a

plasma from fusion reactions. Since alpha particles produced in fusion reactions remain trapped

within the plasma, they contribute to self-heating

by transferring their energy to other plasma particles in collisions. Fusion-produced neutrons, on

the other hand, escape from the plasma without

reacting further and do not contribute to selfheating.

Heavy ion: An ion of high mass (e.g., an electrically charged atom of an element from the

middle to the high end of the periodic table).

High-energy gain: A fusion reaction producing many (10 or so) times as much power as must

be input to the reaction to maintain its temperature.

Hydrogen (H): The lightest element. All hydrogen atoms have nuclei containing a single proton and have a single electron orbiting that

nucleus. Three isotopes of hydrogen exist, having

0, 1, or 2 neutrons in their nuclei in addition to the

proton. The term hydrogen is also used to refer to

the most common isotope, technically called

“protium,” that has no neutrons in its nucleus.

Ignition: The point at which a fusion reaction

becomes self-sustaining. At ignition, fusion selfheating is sufficient to compensate for all energy

losses; external sources of heating power are no

longer necessary to sustain the reaction.

Impurities: Atoms present in a plasma that are

heavier than fusion fuel atoms. Impurities are undesirable because they dilute the fuel and because

they increase the rate at which the plasma’s energy

is radiated out of the plasma.

Inertia: Inertia is the property of an object to

resist external forces that would change its mo-
Appendix A Acronyms and Glossary of Terms | 85

tion. Unless acted on by external forces, an object

at rest will remain at rest, and an object moving in

a straight line at constant speed will continue to do

so. Under the influence of external forces, objects

with differing inertias will respond at different

rates.

Inertial confinement: An approach to fusion

in which intense beams of light or particles are

used to compress and heat tiny pellets of fusion

fuel so rapidly that fusion reactions occur before

the pellet has a chance to expand. The pellet’s own

inertia, or its initial resistance to expansion even

when it is being blown apart, holds the pellet together long enough for fusion energy to be produced.

Instabilities: Small disturbances that become

amplified, or become more intense, once they begin. A cone balanced upside-down on its tip is

subject to an instability, since once it begins to

wobble, it will become more unbalanced until it

falls over. A stable system, on the other hand, responds to disturbances by opposing them. Small

disturbances in a stable system decrease in intensity until they die away. If a ball sitting in the bottom of a bowl is disturbed, for example, it will

eventually come to rest again at the bottom of the

bowl.

Ion: An atom (or molecularly bound group of

atoms) that has become electrically charged as a

result of gaining or losing one or more orbital electrons. A completely ionized atom is one stripped

of all its electrons.

Isotope: Different forms of the same chemical

element whose atoms differ in the number of neutrons in the nucleus. (All isotopes of an element

have the same number of protons in the nucleus

and the same number of electrons orbiting the

nucleus.) Isotopes of the same element have very

similar chemical properties and are difficult to

separate by chemical means. However, they can

have quite different nuclear properties.

Laser fusion: A form of inertial confinement

fusion in which a small pellet of fuel material is

compressed and heated by a burst of laser light.

See “Inertial confinement.”

Lawson parameter: See “Confinement parameter.”

Light ion: An ion of low mass, typically an

electrically charged atom or the bare atomic

nucleus of an element near the light end of the periodic table. In inertial confinement fusion, light

ions are typically accelerated across a small gap in

a high voltage short-pulse diode accelerator.

Linac: Linear accelerator; a device for accelerating heavy ions to drive inertial confinement fusion targets.

Low-activation materials: Materials that, under neutron irradiation, do not generate intensely

radioactive, long-lived radioactive isotopes. Examples include certain vanadium alloys and ceramics such as silicon carbide. Fusion reactors

made of low-activation materials would accumulate far less radioactivity over their lifetimes than

reactors made with more conventional materials

such as steels. Low-activation materials also produce less afterheat following a reactor shutdown

than more conventional materials.

Magnetic confinement: Any means of containing and isolating a hot plasma from its surroundings by using magnetic fields.

Magnetic field: The property of the space near

a magnet that results, for example, in the attraction

of iron to the magnet. Magnetic fields are characterized by their direction and their strength. Electrically charged particles moving through a

magnetic field at an angle with respect to the field

are bent in a direction perpendicular to both their

direction of motion and the direction of the field.

Particles moving parallel to a magnetic field are

not affected. Therefore, magnetic fields cannot

prevent plasma particles from escaping along

field lines.

Magnetic fusion energy: Energy released by a

thermonuclear reaction in the fuel of a magnetically confined plasma.

Magnetic mirror: A generally axial magnetic

field that has regions of increased intensity at each

end where the magnetic field lines converge.

These regions of increased intensity “reflect”

charged particles traveling along the field lines

back into the central region of lower magnetic

field strength.

Mirror: See “Magnetic mirror.”
86 | The Fusion Energy Program: The Role of TPX and Alternate Concepts

Muon: A short-lived elementary particle that

can be used to substitute an electron in a D-T molecule. It is much heavier than the electron thus reducing the size of the molecule and the distance

between the nuclei. This effect makes fusion of the

two nuclei much more likely to occur.

Neutral beam heating: Heating a confined

plasma by injecting beams of energetic (typically

greater than 100 keV) neutral atoms into it. Neutral atoms can cross magnetic lines of force to enter the plasma, where they transfer their energy to

plasma particles through collisions. In these collisions, the neutral beam particles become ionized,

and, like the other electrically charged plasma particles, are then confined by the magnetic fields.

Neutral beam injection: A technique of using

high-energy beams of neutral atoms to penetrate

the magnetic confinement fields of a fusion plasma for fueling, heating, and current drive. Once

inside the plasma, the neutral atoms are ionized

and are then confined.

Neutron: A basic atomic particle, found in the

nucleus of every atom except the lightest isotope

of hydrogen, that has no electrical charge. When

bound within the nucleus of an atom, the neutron

is stable. However, a free neutron is unstable and

decays with a half-life of about 13 minutes into an

electron, a proton, and a third particle called an

antineutrino.

Neutron flux: A measure of the intensity of

neutron irradiation. It is the number of neutrons

passing through one square centimeter of a given

target in one second.

Plasma: An ionized gaseous system composed

of approximately equal numbers of positively and

negatively charged particles and variable numbers

of neutral atoms. The charged particles interact

among themselves, with the neutral particles, and

with externally applied electric and magnetic

fields. The plasma state is sometimes called “the

fourth state of matter” due to the fundamental differences in behavior between plasmas and solids,

liquids, or neutral gases.

Plasma current: Electrical current flowing

within a plasma. In many confinement schemes,

plasma currents generate part of the confining

magnetic fields.

Plasma physics: The study of plasmas.

Proof-of-concept experiment: An experiment

done at a relatively early stage of development of a

confinement concept to determine the limits of

plasma stability, explore how the confinement

properties appear to scale, and develop heating,

impurity control, and fueling methods. Successful

completion of such an experiment verifies that the

confinement concept appears capable of operating

successfully on a scale much closer to that needed

in a reactor.

Proof-of-principle experiment: An experiment one stage beyond the “proof-of-concept”

stage to determine optimal operating conditions,

to establish that the concept is capable of being

scaled to near-reactor level, to extend methods of

heating to high power levels, and to develop efficient mechanisms for fueling and impurity control.

Proton: An elementary particle with a single

positive electrical charge. Protons are constituents

of all atomic nuclei. The atomic number of an

atom is equal to the number of protons in its

nucleus.

Pulsed operation: Noncontinuous operation

of a fusion reactor. This term refers to reactors that

must periodically stop and restart. In pulsed operation, individual pulses may last as long as

hours.

Reactor-scale experiment: Experiment to test

a confinement concept by generating a plasma

equivalent to that needed in a full-scale reactor.

Such an experiment must achieve reactor-level

values of beta and must demonstrate temperature,

density, and confinement times sufficient for the

production of net fusion power. Furthermore, its

heating, fueling, and other technologies must also

be able to support a reactor-level plasma.

Remote maintenance: Conducting maintenance on reactor systems or components by remote control, rather than “hands-on.” Remote

maintenance will be required in fusion reactors

and in many future fusion experiments because

the radioactivity levels near and inside the plasma

chamber will be too high to permit human access.

Reversed field pinch: A closed magnetic confinement concept having toroidal and poloidal

magnetic fields that are approximately equal in
Appendix A Acronyms and Glossary of Terms | 87

strength, and in which the direction of the toroidal

field at the outside of the plasma is opposite from

the direction at the plasma center.

Scaling: Extension of results or predictions

measured or calculated under one set of experimental conditions to another situation having different conditions. One of the most important

functions of a confinement experiment is to determine how confinement properties scale with parameters such as device size, magnetic field,

plasma current, temperature, and density. It is important to understand the scaling properties of a

confinement concept—either empirically or theoretically—to assure that future experiments have a

reasonable probability of succeeding.

Scientific feasibility: The successful completion of experiments that produce high-gain or ignited fusion reactions in the laboratory using a

confinement configuration that lends itself to development into a net power producing system.

Spheromak: A magnetic confinement concept

in which a large fraction of the confining magnetic

fields are generated by currents within the plasma.

The spheromak is a form of compact toroid.

Steady-state operation: Continuous operation, without repeated starting and stopping.

Stellarator: A toroidal magnetic confinement

device in which the confining magnetic fields are

generated entirely by external magnets.

Superconductivity: The total absence of electrical resistance in certain materials under certain

conditions. Until recently, superconductivity had

only been found to occur in certain materials

cooled to within a few degrees of absolute zero.

Since late 1986, however, a new class of materials

has been discovered that become superconducting

at temperatures far higher than the materials previously known. An electrical current that is established in a superconducting material will persist as

long as the material remains below its critical temperature, the point at which it loses all resistance

to electricity.

System studies: Studies presenting preconceptual designs for fusion reactors that serve to

uncover potential problems and determine how

changes in design choices affect reactor characteristics. System studies are particularly valuable in

guiding the research program by identifying areas

where further research and development can have

the greatest impact.

Target: In inertial confinement fusion, the

structure or object containing the fusion fuel at

which the driver beams are directed within the experimental chamber. Targets may consist of simple disks or pellets of fusion fuel or may be

complex structures with many parts.

Temperature: A measure of the average energy of a system of particles. Given sufficient time

and enough interaction among the different portions of any system, all portions will eventually

come to the same temperature. In short-lived plasmas, however, the ion and electron temperatures

usually differ because of insufficient interaction

between the two. Plasma temperatures are measured in units of electron volts, with one electron

volt equal to 11,605 K.

Tokamak: A magnetic confinement concept

whose principal confining magnetic field, generated by external magnets, is in the toroidal direction but that also contains a poloidal magnetic

field that is generated by electric currents running

within the plasma. The tokamak is by far the most

developed magnetic confinement concept. The

word “tokamak” is a Russian acronym—

TOroidal’naia KAMera s AKsial’nym magnitnym polem—meaning torodial chamber with

axial magnetic field. See also “Conventional tokamak” or “Advanced tokamak.”

Toroidal: In the shape of a torus, i.e. doughnutshaped.

Torus: The shape of a doughnut, automobile

tire, and innertube.

Tritium (T or 3H): A radioisotope of hydrogen

that has one proton and two neutrons in its

nucleus. Tritium occurs only rarely in nature; it is

radioactive and has a half-life of 12.3 years. In

combination with deuterium, tritium is the most

reactive fusion fuel.