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338 SUMMARY
339 The potential for using fusion energy to produce commercial electric power was first
340 explored in the 1960s. Harnessing fusion energy offers the prospect of a nearly-
341 carbon-free energy source with a virtually unlimited supply of fuel (derived from
342 deuterium in water) and, unlike nuclear fission plants, fusion power plants, if
343 appropriately designed, would not produce large amounts of high-level nuclear waste
344 requiring long-term disposal. These prospects induced many nations around the world
345 to initiate R&D programs aimed at developing fusion as an energy source. Two
346 alternative approaches are being explored: magnetic fusion energy (MFE) and inertial
347 fusion energy (IFE). This report assesses the prospects for IFE, although there are
348 some elements common to the two approaches. Recognizing that the practical
349 realization of fusion energy remains decades away, the committee judges that the
350 potential benefits of inertial fusion energy justify it as part of the long-term U.S.
351 energy R&D portfolio.
352 To initiate fusion, the deuterium and tritium fuel must be heated to over 50 million
353 degrees and held together for long enough for the reactions to take place (see
354 Appendix A). The prospects for making inertial fusion a commercial energy source
355 depend on the ability to implode a fuel target to a high enough temperature and
356 pressure to initiate a fusion reaction that releases on the order of 100 times more
357 energy than was delivered to the target.
358 The current U.S. fleet of inertial fusion facilities offers a unique opportunity to
359 experiment at “fusion scale” where fusion conditions are accessible for the first time.
360 Indeed, significant fusion burn is expected on the National Ignition Facility in this
361 decade. A key aim of this study is to determine how best to exploit this opportunity to
362 advance the science and technology of inertial fusion energy (IFE).
363
364 Current R&D Status
365 U.S. research on inertial confinement fusion (ICF)—the basis for inertial fusion
366 energy—has been supported by the National Nuclear Security Administration
367 (NNSA) primarily for nuclear-weapons stockpile stewardship applications. This
368 research has benefitted inertial fusion for energy applications, because the two share
369 many common physics challenges.
370 The principal research efforts in the United States are aligned along the three major
371 energy sources for driving the implosion of inertial confinement fusion fuel pellets.
372 These are: (1) lasers (including solid state lasers at the Lawrence Livermore National
373 Laboratory’s National Ignition Facility and the University of Rochester’s Laboratory
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374 for Laser Energetics, as well as the krypton fluoride gas lasers at the Naval Research
375 Laboratory; (2) particle beams, being explored by a consortium of laboratories led by
376 the Lawrence Berkeley National Laboratory; and (3) pulsed magnetic fields, being
377 explored on the Z machine at Sandia National Laboratory.
378 There has been substantial scientific and technological progress in inertial
379 confinement fusion during the past decade. 1 Despite these advances, the minimum
380 technical accomplishment that would give confidence that commercial IFE may be
381 feasible—the ignition 2 of a fuel pellet in the laboratory—has not been achieved as of
382 this writing. 3
383 For the first time a research facility, the National Ignition Facility4 (NIF) at Lawrence
384 Livermore National Laboratory, conducted a systematic campaign at an energy scale
385 that was projected to be sufficient to achieve ignition. The anticipated achievement of
386 ignition at NIF motivated the U.S. Department of Energy (DOE) to request that the
387 National Research Council review the prospects for inertial fusion energy in a report
388 with the following statement of task:
389 • Assess the prospects for generating power using inertial confinement fusion;
390 • Identify scientific and engineering challenges, cost targets, and R&D
391 objectives associated with developing an IFE demonstration plant; and
392 • Advise the U.S. Department of Energy on its development of an R&D
393 roadmap aimed at creating a conceptual design for an inertial fusion energy
394 demonstration plant.
395 A comparison of inertial fusion energy to magnetic fusion energy or any other
396 potential or available energy technologies (such as wind or nuclear fission), while a
397 very interesting subject of study, was also outside the committee’s purview.
398 There has been significant technical progress during the past year in the National
399 Ignition Campaign being carried out on the NIF. Nevertheless, ignition has taken
400 longer than scheduled. The results of the experiments performed to date have
401 differed from model projections and are not yet fully understood. It will likely take
402 significantly more than a year from now to gain a full understanding of the
403 discrepancies between theory and experiment and to make needed modifications to
1
Three major energy sources for driving the implosion of inertial fusion energy fuel pellets
are discussed in this report. These are lasers (including solid state lasers and krypton fluoride
gas lasers), particle beams, and pulsed magnetic fields.
2
In this report, ignition is defined as “scientific breakeven” in which the target releases an
amount of energy equal to the energy incident upon it to drive the implosion.
3
As of December 27, 2012.
4
The National Ignition Facility, which was designed for stockpile stewardship applications,
currently uses a solid-state laser driver and an indirect-drive target configuration.
2
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404 optimize target performance. 5 Box 1.2 in Chapter 1 entitled “Recent Results From
405 the National Ignition Facility” provides a detailed discussion of the most recent
406 results from the National Ignition Facility, and Appendix I provides a more technical
407 discussion of this subject.
408
409 While the committee considers the achievement of ignition as an essential
410 prerequisite for initiating a national, coordinated, broad-based inertial fusion energy
411 program, the committee does not believe that the fact that NIF did not achieve
412 ignition by the end of the National Ignition Campaign on September 30, 2012 lessens
413 the long-term technical prospects for inertial fusion energy. It is important to note that
414 none of the expert committees 6 that reviewed NIF’s target performance concluded
415 that ignition would not be achievable at the facility. Furthermore, as the ICF Target
416 Physics Panel concluded, “So far as target physics is concerned, it is a modest step
417 from NIF scale to IFE scale. 7” A better understanding of the physics of indirect-drive
418 implosions is needed, as well as improved capabilities for simulating them. In
419 addition, alternative implosion modes (laser direct drive, shock ignition, heavy-ion
420 drive, and pulsed power drive) have yet to be adequately explored. It will therefore
421 be critical that the unique capabilities of the National Ignition Facility be used to
422 determine the viability of ignition at the million joule energy scale.
423
424 As the scientific basis for inertial fusion energy is better understood, —e.g., ignition
425 is achieved, or the conditions for ignition are better understood—the path forward for
426 inertial fusion energy research will diverge from NNSA’s weapons research program
427 as technologies specific to inertial fusion energy (e.g., high-repetition-rate driver
428 modules, chamber materials, mass-producible targets) will need to receive a higher
429 priority.
430 PRINCIPAL CONCLUSIONS AND RECOMMENDATIONS
431
432 With substantial input from the community, the committee conducted an intensive
433 review of approaches to inertial fusion energy (diode-pumped lasers, krypton fluoride
5
National Nuclear Security Administration, “NNSA’s Path Forward to Achieving Ignition in
the Inertial Confinement Fusion Program: Report to Congress” December, 2012.
6
Department of Energy, Memo by D. H. Crandall to D. L. Cook, “External Review of the
National Ignition Campaign,” July 19, 2012; National Ignition Campaign Technical Review
Committee, “The National Ignition Campaign Technical Review Committee Report, For the
Meeting Held on May 30 through June 1, 2012;” National Research Council, “Assessment of
Inertial Confinement Fusion Targets,” The National Academies Press, Washington, D.C.,
2012.
7
See Overarching Conclusion 1 from the ICF Target Physics Panel’s report.
3
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434 lasers, heavy-ion accelerators, pulsed power; as well as indirect drive 8 and direct
435 drive 9). The committee’s principal conclusions and recommendations regarding its
436 assessment of the prospects for inertial fusion energy are given below. They are
437 grouped thematically under several general topic headings. A broader set of
438 conclusions and recommendations is contained in the individual chapters. Where
439 there is an overlap, the conclusions and recommendations are numbered as they
440 appear in the chapters, to point the reader to the location of more detailed discussion.
441 The recommendations are made in view of the current technical uncertainties and the
442 anticipated long timeframe to achieve commercialization of IFE.
443
444
445 Potential Benefits, Recent Progress, and Current Status of Inertial Fusion
446 Energy
447
448 Conclusion: The scientific and technological progress in inertial confinement fusion
449 has been substantial during the past decade, particularly in areas pertaining to the
450 achievement and understanding of high-energy-density conditions in the compressed
451 fuel, and in exploring several of the critical technologies required for inertial fusion
452 energy applications (e.g., high-repetition-rate lasers and heavy-ion-beam systems,
453 pulsed-power systems, and cryogenic target fabrication techniques). (Conclusion 1
454 from the Interim Report; Chapters 2 and 3 of this report)
455
456 Conclusion: It would be premature to choose a particular driver approach as the
457 preferred option for an inertial fusion energy demonstration plant at the present time.
458 (Conclusion 2 from the Interim Report)
459
460 Conclusion: The potential benefits of inertial confinement fusion energy (abundant
461 fuel, minimal greenhouse gas emissions, limited high-level radioactive waste
462 requiring long-term disposal) also provide a compelling rationale for establishing
463 inertial fusion energy R&D as part of the long-term U.S. energy R&D portfolio. A
464 portfolio strategy hedges against uncertainties in future availability of alternatives
465 due, for instance, to unforeseen circumstances. (Conclusion 1-1)
466
467 Factors Influencing the Commercialization of Inertial Fusion Energy
468
469 Conclusion: The cost of targets has a major impact on the economics of inertial
470 fusion energy power plants. Very large extrapolations are required from the current
471 state-of-the-art for fabricating targets for inertial confinement fusion research to the
472 ability to mass-produce inexpensive targets for inertial fusion energy systems.
473 (Conclusion 3-24)
8
In an indirect-drive target, the driver energy strikes the inner surface of a hollow chamber
(the “hohlraum”) that surrounds the fuel capsule, exciting X-rays that transfer energy to the
capsule.
9
In a direct-drive target, the driver energy strikes directly on the fuel capsule. The
illumination geometry of the driver beams may be oblique (e.g. from diametrically opposite
sides, called “polar direct drive”) or spherically symmetric.
4
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474
475 Conclusion: As presently understood, an inertial fusion energy power plant would
476 have a high capital cost. Such plants would have to operate with a high availability.
477 Achieving high availabilities is a major challenge for fusion energy systems. This
478 would involve substantial testing of IFE plant components and the development of
479 sophisticated remote maintenance approaches. (Conclusion 3-23)
480
481 Recommendation: Economic analyses of inertial fusion energy power systems
482 should be an integral part of national program planning efforts, particularly as more
483 cost data become available. (Recommendation 3-10)
484
485 Recommendation: A comprehensive, systems engineering approach should be used
486 to assess the performance of IFE systems. Such analyses should also include the use
487 of a Technology Readiness Levels (TRL) methodology to help guide the allocation of
488 R&D funds. (Recommendation 3-11)
489
490 Conclusion: Some licensing/regulatory-related research has been carried out for the
491 ITER (magnetic fusion energy) program, and much of that work provides insights
492 into the licensing process and issues for inertial fusion energy. The Laser Inertial
493 Fusion Energy (LIFE) program at Lawrence Livermore National Laboratory has
494 considered licensing issues more than any other IFE approach; however, much more
495 effort would be required when a Nuclear Regulatory Commission license is pursued
496 for inertial fusion energy. (Conclusion 3-20)
497
498
499 The Establishment of an Integrated National Inertial Fusion Energy Program
500 and Its Characteristics
501
502 Conclusion: While there have been diverse past and ongoing research efforts
503 sponsored by various agencies and funding mechanisms that are relevant to IFE, at
504 the present time there is no nationally coordinated research and development program
505 in the United States aimed at the development of inertial fusion energy that
506 incorporates the spectrum of driver approaches (diode-pumped lasers, heavy ions,
507 krypton fluoride (KrF) lasers, pulsed power, or other concepts), the spectrum of target
508 designs, or any of the unique technologies needed to extract energy from any of the
509 variety of driver and target options. (Conclusion 4-9)
510
511 Conclusion: Funding for inertial confinement fusion is largely motivated by the U.S.
512 nuclear weapons program, due to its relevance to stewardship of the nuclear stockpile.
513 The National Nuclear Security Administration (NNSA) does not have an energy
514 mission and--in the event that ignition is achieved--the NNSA and inertial fusion
515 energy (IFE) research efforts will continue to diverge as technologies relevant to IFE
516 (e.g., high-repetition-rate driver modules, chamber materials, mass-producible
517 targets) begin to receive a higher priority in the IFE program. (Conclusion 4-10)
518
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519 Conclusion: The appropriate time for the establishment of a national, coordinated,
520 broad-based inertial fusion energy program within DOE is when ignition is achieved.
521 (Conclusion 4-13)
522
523 Conclusion: At the present time, there is no single administrative home within the
524 Department of Energy that has been invested with the responsibility for administering
525 a National Inertial Fusion Energy R&D program. (Conclusion 4-16)
526
527 Recommendation: In the event that ignition is achieved on the National Ignition
528 Facility or another facility, and assuming that there is a federal commitment to
529 establish a national inertial fusion energy R&D program, the Department of Energy
530 should develop plans to administer such a national program (including both science
531 and technology research) through a single program office. (Recommendation 4-11)
532
533 Recommendation: The Department of Energy should use a milestone-based
534 roadmap approach, based on Technology Readiness Levels (TRLs), to assist in
535 planning the recommended national IFE program leading to a DEMO plant. The
536 plans should be updated on a regular basis to reassess each potential approach and set
537 priorities based on the level of progress. Suitable milestones for each driver-target
538 pair considered might include, at a minimum, the following technical goals:
539 1. Ignition
540 2. Reproducible modest gain
541 3. Reactor-scale gain
542 4. Reactor-scale gain with a cost-effective target
543 5. Reactor-scale gain with the required repetition rate (Recommendation 4-4)
544
545 Recommendation: The national inertial fusion energy technology effort should
546 leverage magnetic fusion energy materials and technology development in the United
547 States and abroad. Examples include: the ITER test blanket module R&D program,
548 materials development, plasma-facing components, tritium fuel cycle, remote
549 handling, and fusion safety analysis tools. (Recommendation 3-2)
550
551
552 Inertial Fusion Energy Drivers
553
554 Conclusion: There are potential advantages and uncertainties in target design as well
555 as different driver approaches to the extent that the question of “the best driver
556 approach” remains open. (Conclusion 4-5)
557
558 Laser Drivers
559
560 Conclusion: If the diode-pumped, solid-state laser technical approach is selected for
561 the roadmap development path, the demonstration of a diode-pumped, solid-state
562 laser beam-line module and line-replaceable-unit at full scale is a critical step toward
563 laser driver development for IFE. (Conclusion 2-2)
564
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565 Conclusion: If the KrF laser technical approach is selected for the roadmap
566 development path, a very important element of the KrF laser inertial fusion energy
567 research and development program would be the demonstration of a multi-kJ, 5−10-
568 Hz, KrF laser module that meets all of the requirements for a Fusion Test Facility.
569 (Conclusion 2-6)
570
571 Heavy-Ion-Beam Drivers
572
573 Conclusion: Demonstrating that the Neutralized Drift Compression Experiment-II
574 (NDCX-II) meets its energy, current, pulse length, and spot-size objectives is of great
575 technical importance, both for heavy-ion inertial fusion energy applications and for
576 high-energy-density physics. (Conclusion 2-7)
577
578 Conclusion: Restarting the High-Current Experiment to undertake driver-scale beam
579 transport experiments, and restarting the enabling technology programs are crucial to
580 re-establishing a heavy-ion fusion program. (Conclusion 2-8)
581
582 Pulsed-Power Drivers
583
584 Conclusion: There has been considerable progress in the development of efficient
585 pulsed-power drivers of the type needed for inertial confinement fusion applications,
586 and the funding is in place to continue along that path. (Conclusion 2-12)
587
588 Conclusion: The major technology issues that would have to be resolved to make a
589 pulsed-power IFE system feasible—the recyclable transmission line and the ultra-
590 high-yield chamber technology development—are not receiving any significant
591 attention. (Conclusion 2-14)
592
593 Recommendation: Physics issues associated with the MagLIF concept should be
594 addressed in single-pulse mode during the next five years so as to determine its
595 scientific feasibility. (Recommendation 2-2)
596
597 Recommendation: Technical issues associated with the viability of recyclable
598 transmission lines and 0.1 Hz, 10-GJ-yield chambers should be addressed with
599 engineering feasibility studies in the next five years to assess the technical feasibility
600 of MagLIF as an inertial fusion energy system option. (Recommendation 2-3)
601
602 Other Critical Technologies for Inertial Fusion Energy
603
604 Conclusion: Significant IFE technology research and engineering efforts are required
605 to identify and develop solutions for critical technology issues and systems, such as:
606 targets and target systems; reaction chambers (first wall/blanket/shield); materials
607 development; tritium production, recovery and management systems; environment
608 and safety protection systems; and economics analysis. (Conclusion 3-3)
609
610 Target Technologies
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611
612 Conclusion: An inertial fusion energy program would require an expanded effort on
613 target fabrication, injection, tracking, survivability and recycling. Target
614 technologies developed in the laboratory would need to be demonstrated on industrial
615 mass production equipment. A target technology program would be required for all
616 promising inertial fusion energy options, consistent with budgetary constraints.
617 (Conclusion 3-9)
618
619 Chamber Technologies
620
621 Conclusion: The chamber and blanket are critical elements of an inertial fusion
622 energy power plant, providing the means to convert the energy released in fusion
623 reactions into useful applications, as well as the means to breed the tritium fuel. The
624 choice and design of chamber technologies are strongly coupled to the choice and
625 design of driver and target technologies. A coordinated development program is
626 needed. (Conclusion 3-10)
627
628 The National Ignition Facility
629
630 Conclusion: The National Ignition Facility (NIF), designed for stockpile stewardship
631 applications, is also of great potential importance for advancing the technical basis for
632 inertial fusion energy (IFE) research. (Conclusion 4-15)
633
634 Conclusion: There has been good technical progress during the past year in the
635 ignition campaign carried out on the National Ignition Facility. Nevertheless, ignition
636 has been more difficult than anticipated and has not been achieved in the National
637 Ignition Campaign that ended on September 30, 2012. The experiments to date are
638 not fully understood. It will likely take significantly more than a year to gain a full
639 understanding of the discrepancies between theory and experiment and to make
640 needed modifications to optimize target performance. (Conclusion 2-1)
641
642 Recommendation: The target physics programs on NIF, Nike, OMEGA, and Z
643 should receive continued high priority. The program on NIF should be expanded to
644 include direct drive and alternate modes of ignition. It should aim for ignition with
645 moderate gain and comprehensive scientific understanding leading to predictive
646 capabilities of codes for a broad range of IFE targets. (Recommendation 2-1)
647
648 Recommendation: The achievement of ignition with laser-indirect drive at the
649 National Ignition Facility should not preclude experiments to test the feasibility of
650 laser-direct drive. Direct drive experiments should also be carried out because of the
651 potential of achieving higher gain and/or other technological advantages.
652 (Recommendation 4-7)
653
654 Recommendation: Planning should begin for making effective use of the National
655 Ignition Facility as one of the major program elements in an assessment of the
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656 feasibility of inertial fusion energy. (Recommendation from interim report and
657 Recommendation 4-10 from this report)
658
659 Proliferation Risks
660
661 The NRC Panel on the Assessment of Inertial Confinement Fusion Targets has
662 examined the proliferation risks associated with inertial confinement fusion systems,
663 and the panel’s analysis and principal conclusions regarding proliferation risks are
664 presented in Chapter 3 of the panel’s report. The NRC Committee on the Prospects
665 for Inertial Confinement Fusion Energy Systems concurs with the Panel’s
666 conclusions, which are reiterated below for completeness.
667
668 Conclusion: At present, there are more proliferation concerns associated with
669 indirect-drive targets than with direct-drive targets. However, worldwide technology
670 developments may eventually render these concerns moot. 10 Remaining concerns are
671 likely to focus on the use of classified codes for target design. (Conclusion 3-1 from
672 the panel report)
673
674 Conclusion: The nuclear weapons proliferation risks associated with fusion power
675 plants are real, but are likely to be controllable. 11 These risks fall into three
676 categories: knowledge transfer; Special Nuclear Material (SNM) production; and
677 tritium diversion. (Conclusion 3-2 from the panel report)
678
679 Conclusion: Research facilities are likely to be a greater proliferation concern than
680 power plants. A working power plant is less flexible than a research facility, and it is
681 likely to be more difficult to explore a range of physics problems with a power plant.
682 However, domestic research facilities (which may have a mix of defense and
683 scientific missions) are more complicated to put under international safeguards than
684 commercial power plants. Furthermore, the issue of proliferation from research
685 facilities will have to be dealt with long before proliferation from potential power
686 plants becomes a concern. (Conclusion 3-3 from the panel report)
687
688 Conclusion: It will be important to consider international engagement regarding the
689 potential for proliferation associated with IFE power plants. (Conclusion 3-4 from
690 the panel report)
691
692
10
Progress in experiment and computation may eventually result in data, simulations, and
knowledge that the U.S. presently considers classified becoming widely available.
Classification concerns about different kinds of targets may then change considerably.
11
Proliferation of knowledge and Special Nuclear Material production are subject to control
by international inspection of research facilities and plants; tritium diversion is a problem that
will require careful attention.
9
