Search

We are carrying out a multidisciplinary multi-institutional program to develop the scientific and technical basis for inertial fusion energy (IFE) based on laser drivers and direct-drive targets. The key components are developed as an integrated system, linking the science, technology, and final application of a 1000-MWe pure-fusion power plant. The science and technologies developed here are flexible enough to be applied to other size systems. The scientific justification for this work is a family of target designs (simulations) that show that direct drive has the potential to provide the high gains needed for a pure-fusion power plant. Two competing lasers are under development: the diode-pumped solid-state laser (DPPSL) and the electron-beam-pumped krypton fluoride (KrF) gas laser. This paper will present the current state of the art in the target designs and lasers, as well as the other IFE technologies required for energy, including final optics (grazing incidence and dielectrics), chambers, and target fabrication, injection, and tracking technologies. All of these are applicable to both laser systems and to other laser IFE-based concepts. However, in some of the higher performance target designs, the DPPSL will require more energy to reach the same yield as with the KrF laser.

Early attempts to perform successful allogeneic hematopoietic stem cell transplants were plagued by graft rejection and graft-versus-host disease, leading many investigators to lose hope that bone marrow transplantation could ever become a useful therapeutic approach in clinical medicine. Although many subsequent discoveries contributed to the successful transformation of this area of research into lifesaving therapy, there can be no doubt that the discovery of cyclosporine (CsA) constituted one of the major advances. Even today, more than 25 years after the first description of its use in humans, CsA remains one of the cornerstones of therapy for the majority of patients undergoing allogeneic hematopoietic cell transplantation (HCT). In this review we will recount the events that have established CsA as a foundation of HCT.

The National Ignition Facility (NIF) is the largest construction project ever undertaken at Lawrence Livermore National Laboratory (LLNL). The NIF consists of 192 40 cm square laser beams and a 10 m diameter target chamber. The NIF is being designed and built by an LLNL led team from Los Alamos National Laboratory, Sandia National Laboratories, the University of Rochester and LLNL. Physical construction began in 1997. The Laser and Target Area Building and the Optics Assembly Building were the first major construction activities, and despite several unforeseen obstacles, the buildings are now 92% complete and have been built on time and within cost. Prototype component development and testing has proceeded in parallel. Optics vendors have installed full scale production lines and have performed prototype production runs. The assembly and integration of the beampath infrastructure have been reconsidered and a new approach has been developed. The article discusses the status of the NIF project and the plans for completion.

The National Ignition Facility (NIF) consists of 192 forty-centimeter-square laser beams and a 10-m-diameter target chamber. Physical construction began in 1997. The Laser and Target Area Building ...

This paper reviews the leading edge of the basic and applied science that use high-intensity facilities. The more than 15 000 experiments on the Nova laser since 1985 and many thousands more on other laser, particle beam, and pulsed power facilities around the world have established the new laboratory field of high-energy-density plasma physics and have furthered development of inertial fusion. High-brightness femtosecond lasers have enabled the study of matter in conditions previously unachievable on earth. These experiments and advanced calculations have established the specifications for the National Ignition Facility (NIF) and Laser MegaJoule (LMJ) and have enhanced scientific fields such as laboratory astrophysics. Science and technology developed in inertial fusion have found near-term commercial use, have enabled steady progress toward the goal of fusion ignition and gain in the laboratory, and have opened up new fields of study for the 21 st century.

This report presents the results and recommendations of the deliberations of the U.S. Department of Energy (DOE) Fusion Energy Sciences Advisory Committee Panel on the Review of the Fusion Materials Research Program carried out during 1998. Metrics evaluated included evidence of recognition, publications per worker, new people attracted to the work and significance of recent accomplishments.

Over the past several decades, significant and steady progress has been made in the development of fusion energy and its associated technology and in the understanding of the physics of high-temperature plasmas. While the demonstration of net fusion energy (fusion energy production exceeding that required to heat and confine the plasma) remains a task for the next millennia and while challenges remain, this progress has significantly increased confidence that the ultimate goal of societally acceptable (e.g. cost, safety, environmental considerations including waste disposal) central power production can be achieved. This progress has been shared by the two principal approaches to controlled thermonuclear fusion--magnetic confinement (MFE) and inertial confinement (ICF). ICF, the focus of this article, is complementary and symbiotic to MFE. As shown, ICF invokes spherical implosion of the fuel to achieve high density, pressures, and temperatures, inertially confining the plasma for times sufficient long (t {approx} 10{sup -10} sec) that {approx} 30% of the fuel undergoes thermonuclear fusion.

The National Ignition Facility (NIF) Project officially began in December of 1995. In October of 1996, advanced conceptual design studies, complete environmental impact study, facilitization of the manufacturing capabilities of optics vendors began. The Title I preliminary engineering design had not yet began until the end of December, but it is expected to be on schedule. It is expected that the conventional facilities design will be completed first. The Independent Cost Estimate (ICF) process will begin after the facilities design is complete. Other elements of the design will be submitted in one- or two-week intervals. This phase method of completing Title I was also used at the end of Complete Design Report and proved to be efficient. 9 refs., 11 figs.

The mission of the National Ignition Facility is to achieve ignition and gain in ICF targets in the laboratory. The facility will be used for defense applications such as weapons physics and weapons effect testing, and for civilian applications such as fusion energy development and fundamental studies of matter at high temperatures and densities. This paper reviews the design, schedule and costs associated with the construction project.

The Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program is addressing the critical physics and technology issues directed toward demonstrating and exploiting ignition and propagating burn to high gain with ICF targets for both defense and civilian applications. Nova is the primary U.S. facility employed in the study of the X-ray-driven (indirect drive) approach to ICF. Nova's principal objective is to demonstrate that laser-driven hohlraums can achieve the conditions of driver-target coupling efficiency, driver irradiation symmetry, driver pulseshaping, target preheat, and hydrodynamic stability required by hot-spot ignition and fuel compression to realize a fusion gain.The LLNL ICF Program believes that the next major step in the national ICF Program is the demonstration of ignition and moderate gain (G ≤ 10). Recent theoretical and experimental results show that the ignition drive energy threshold can be reduced significantly by operating indirectly driven targets at radiation temperatures ∼ 1.3–1.6 times higher (thereby achieving higher implosion velocity) than originally proposed for the Laboratory Microfusion Facility (LMF). (Temperatures of ∼ 1.3 times higher have already been demonstrated on Nova.) Specifically, it should be possible to demonstrate ignition and propagating with burn about 1–2 MJ of laser energy as against the 5–10 MJ necessary for the high-yield LMF. LLNL proposes to upgrade the existing Nova facility to 1–2 MJ (2- to 4-ns pulses) and demonstrate ignition and propagating burn to moderate gain with appropriately scaled hydrodynamic equivalents of high-yield targets.Once moderate gain has been demonstrated at 1–2.0 MJ on the Nova Upgrade, investigations into improving, by about 50%, the coupling efficiency between the driver and the capsule could provide gains >20 at about 1 MJ or less. A database for gain below 1-MJ driver energies could lead to a low-capital-cost Engineering Test Facility (ETF) for a first inertial fusion energy engineering reactor. Because the capital cost for both the target chamber and the driver scale with size, there is the opportunity to realize large savings by lowering the required driver energy necessary to demonstrate the technology for a first demonstration power plant. A target gain, G ∼ 25, at a driver energy, ED ∼ 0.75 MJ, would be self-sustaining for a driver efficiency of ∼10% and a thermal-to-electric conversion efficiency of ∼33% and at 12 Hz would generate ∼10 MW of gross electric power. Although the cost of electricity would be high, the combination of low capital cost and early demonstration of reactor technology would be an attractive step in the development of inertial fusion energy.

Fusion is potentially a safe clean source not limited by political boundaries. Magnetic and inertial fusion share this promise, but there are differences between them. An inertial fusion power plant is based on different physics and technology from a magnetic fusion power plant and therefore presents somewhat different benefits and challenges. The facilities required to demonstrate inertial fusion power are potentially much smaller. In this article we describe concepts for such a power plant, its beneficial features and a low‐cost reactor test facility for developing practical fusion power.

The expeditious demonstration of ignition and gain in a laboratory Inertial Confinement Fusion (ICF) target has been identified by the National Academy of Sciences (NAS) and the Fusion Policy Advisory Committee (FPAC) as ``the highest priority of the ICF Program.`` Assuming that the near-term NAS-recommended preparatory milestones are met, they also concluded that the proposed Nova Upgrade would be the most expeditious way of achieving that goal. The Nova Upgrade would consist of an advanced, cost effective Nd:glass laser that would deliver 1-2 MJ of 0.35 gm light to a target chamber for indirect drive target experiments in which as much as 20 MJ of thermonuclear yield could result. After achieving ignition and gain, further experiments on the facility will allow development of optimized targets for Inertial Fusion Energy (IFE) reactors, simulation of some aspects of ion beam targets, and development of reactor first wall concepts. The targets developed on Nova Upgrade will potentially be suitable for use in an early, low-power engineering test facility (ETF) as the next step in IFE development.

Ultimately, of course, a prototype power plant will be built at a power level appropriate for planned future commercial operations. This could use the same ETF/ DPP driver or a new one tailored to the plant size and with less experimental flexibility than the ETF driver. With the experience and data gained from a number of small demonstration reactors, and from the operation of the ETF/DPP driver and target factory, it is quite likely that a variety of plant sizes options will be available at that time.

Controlled fusion energy is one of the long term, non-fossil energy sources available to mankind. It has the potential of significant advantages over fission nuclear power in that the consequences of severe accidents are predicted to be less and the radioactive waste burden is calculated to be smaller. Fusion can be an important ingredient in the future world energy mix and can be part of an 'insurance policy' energy strategy to develop new sources as a hedge against environmental, supply or political difficulties connected with the use of fossil fuel and present-day nuclear power. Progress in fusion reactor technology and design is described for both magnetic and inertial fusion energy systems. The projected economic prospects show that fusion will be capital intensive, and the historical trend is towards greater mass utilization efficiency and more competitive costs. Recent studies emphasizing safety and environmental advantages show that the competitive potential of fusion can be further enhanced by specific choices of materials and design. The safety and environmental prospects of fusion appear to exceed substantially those of advanced fission and coal. For example, the level of radioactivity in a low activation fusion reactor at 1 year and at 100 years after shutdown is calculated to be about one-millionth of the radioactivity in a fission reactor of the same power. Likewise, the maximum plausible dose predicted at the site boundary in the case of a low activation fusion reactor is estimated to be between 100 and 500 times smaller than that estimated for a fission power plant. Clearly, a significant and directed technology effort is necessary to achieve these advantages. Typical parameters have been established for magnetic fusion energy reactors, and a tokamak at moderately high magnetic field (about 7 T on axis) in the first regime of MHD stability (β ≤ 3.5 I/aB) is closest to present experimental achievement. Further improvements of the economic and technological performance of the tokamak are possible through the following achievements: higher magnetic fields to lower the required plasma current and reactor size; higher values of the plasma beta, including reaching the second stable MHD regime, to lower the requirements on field and plasma current; and more efficient techniques to drive the plasma current. In addition, alternative, non-tokamak magnetic fusion approaches may offer substantive economic and operational benefits, although at present these concepts must be projected from a less developed physics base. For inertial fusion energy, reactor studies are at an earlier stage, but the essential requirements are a high efficiency (≥ 10%) repetitively pulsed pellet driver capable of delivering up to 10 MJ of energy on target, targets capable of an energy gain (ratio of energy produced to energy on target) of about 100, reactor chambers capable of absorbing the energy released per shot at conditions consistent with power generation, and effective means of isolating the target chamber and driver system.

The demonstration of inertial fusion energy (IFE) will require the construction of a sequence of physics and engineering test facilities. A key facility in the development path is the Integrated Test Facility (ITF). The ITF will be the first facility to integrate all the major subsystems required for an inertial fusion power plant including the driver, target production and injection systems, and reactor systems (chamber, blanket, heat removal, tritium recovery, etc.); it will demonstrate the technical feasibility of IFE. In this paper we describe the features of a heavy ion fusion ITF that takes advantage of the unique characteristics of inertial fusion in order to reduce development time and costs. Because fusion capsule ignition and burn physics are independent of the reaction chamber size, feasibility tests of various chamber concepts can be done at much smaller sizes (about 1-2 m first wall radius) and much lower powers (tens of MWs) than magnetic fusion development facilities such as ITER.

ICF (inertial confinement fusion) target design studies done for the Nova Upgrade have identified conditions under which the target ignition 'cliff' is shifted to much lower drive energy, albeit with the penalty that the gain achieved at a given drive energy is also smaller. These targets would repeatably produce the output and spectra of higher gain targets at low yield. They should thus allow building much smaller R&D reactors with full thermonuclear effects. Demonstration reactors at the 1 to 100 MW/sub e/ level appear to be feasible with driver energies of 0.5 to 2.0 MJ/pulse. These smaller, less expensive test and demonstration facilities should result in a lower IFE development cost. If the US government builds a driver and target factory, it is also conceivable that commercial organizations could build their own scaled concepts of IFE reactors using the beams and targets supplied by the government's facilities. >

Successful development of inertial fusion energy (IFE) requires that many technical issues be resolved. Separability of drivers, targets, chambers and other IFE power plant subsystems allows resolution of many of these issues in off-line facilities and programs. Periodically, major integrated facilities give a snapshot of the rate of progress toward the ultimate solutions. The National Ignition Facility (NIF) and Laser Megajoule (LMJ) are just such integrating facilities. This paper reviews the status of IFE development and projects what will be learned from the NIF and LMJ.

Inertial confinement fusion (ICF) research in the United States is in a dramatic upswing. Technical progress continues at a rapid pace and with the start of the construction of the National Ignition Facility (NIF) this year the total U.S. budget for ICF for fiscal year 1997 stands at $380 million. The NIF is being built as an essential component of the U.S. Stockpile Stewardship and Management Program which has been formulated to assure the continued safety, reliability, and performance of the downsized nuclear weapons stockpile in the absence of nuclear tests. This paper will discuss some of the directions that the ICF research is now taking. (AIP)

Controlled fusion energy is one of only a few energy sources available to mankind in the future. Progress in fusion reactor technology and design is described for both magnetic and inertial confinement fusion energy. The projected economic prospects show fusion will be capital intensive and the historical trend is towards greater mass utilization efficiency and more competitive costs. Recent studies emphasizing safety and environmental advantages show that fusion’s competitive potential can be further enhanced by specific material and design choices. Fusion’s safety and environmental prospects appear to substantially exceed those of advanced fission and coal but will not be achieved automatically. A significant and directed technology effort is necessary. Typical parameters have been established for fusion reactors, and a tokamak at moderately high magnetic field (about 7 T on axis) in the first regime of MHD stability (s ≤ 3.5 I/aB) is closest to present experimental achievement. Directions to further improve economic and technological performance include the development of higher magnetic fields to lower the required plasma current and reactor size, improvement in the beta value in the second stable MHD regime to lower requirements of field and plasma current, and improvement in techniques for plasma current drive to efficiently achieve steady-state plasma operation. For inertial confinement, reactor studies are at an earlier stage but two essential requirements are a high-efficiency (> 10%) repetitively pulsed pellet driver capable of delivering up to 10 MJ of energy on target, and targets capable of yielding an energy gain (ratio of energy produced to energy on target) of 100.

Fifteen ICF power reactor design studies published since 1980 are reviewed to illuminate the design trends they represent. There is a clear, continuing trend toward making ICF reactors inherently safer and environmentally benign. Since this trend accentuates inherent advantages of ICF reactors, we expect it to be further emphasized in the future. An emphasis on economic competitiveness appears to be a somewhat newer trend. Lower cost of electricity, smaller initial size (and capital cost), and more affordable development paths are three of the issues being addressed with new studies.

The U.S. Department of Energy sponsored a series of nine field experiments (Burro series) conducted jointly in 1980 by the Naval Weapons Center, China Lake, California, and the Lawrence Livermore National Laboratory to determine the transport and dispersion of vapor from spills of liquefied natural gas (LNG) on water. The spill volume ranged from 24 to 39 m3, the spill rate from 11.3 to 18.4 m3/min, the wind speed from 1.8 to 9.1 m/s, and the atmospheric stability from unstable to slightly stable. An extensive array of instrumentation was deployed both upwind and downwind of the spill pond. Wind speed and direction, gas concentration, temperature, humidity, and heat flux from the ground were measured at different distances from the spill point and at different elevations relative to ground level. The wind and gas-concentration data were analyzed to further define the fluid dynamic and thermodynamic processes associated with the dispersion of the gas cloud. Data pertaining to differential boiling of LNG and observed rapid phase-transition explosions were also analyzed. The principal conclusions are summarized as follows: The turbulent processes in the lower atmospheric boundary layer dominated the transport and dispersion of gas for all experiments except Burro 8. Burro 8 was conducted under very low wind-speed conditions, and the gravity flow of the cold gas displaced the atmospheric flow, causing the wind speed within the cloud to drop essentially to zero. This has profound implications for hazard prediction from large accidental spills. High-frequency (3–5 Hz) gas-concentration measurements indicate that peak concentrations within the flammable limits are common with 10-s-average concentrations above 1%. This implies a larger flammable extent than averaged data or calculations would indicate. Differential boiloff of LNG was observed with resultant enrichment of ethane and propane in the cloud at later times. This ethane-enriched region propagates downwind and represents an additional hazard since it is more easily detonated than the methane-rich region. Energetic rapid phase transition (RPT) explosions, though not expected, did occur under at least two different circumstances during the Burro 6 and 9 tests. These explosions were large enough to damage the facility and raise questions about the coupling of the RPT-produced shock wave into the ethane-rich region of the cloud.

Owing to the inherent difficulties of recording upper esophageal sphincter pressure, little is known about normal upper esophageal sphincter physiology. In this study we used a modified sleeve device to record upper esophageal sphincter pressure continuously in 8 normal volunteers. Intraesophageal pH and electroencephalogram activity were also recorded to document the occurrence of spontaneous gastroesophageal reflux and sleep. After an hour of baseline recording, the subjects ate a meal. Recording was then resumed for an additional 7 h during which period the subjects slept part of the time. The mean upper esophageal sphincter pressure was measured for each 10-min epoch. Electroencephalogram recordings were read blindly for the presence and stage of sleep. Periods of sleep were then correlated with the manometric tracings. Mean upper esophageal sphincter pressure during wakefulness, stage 1 sleep, and deeper sleep was 40 +/- 17 (SD), 20 +/- 17, and 8 +/- 3 mmHg, respectively. A significant change in upper esophageal sphincter pressure did not occur postprandially or during episodes of spontaneous gastroesophageal reflux. Upper esophageal sphincter pressure was observed to increase transiently with each inspiration during periods of restfulness and sleep, a response consistent with the hypothesis that one function of the upper esophageal sphincter is to exclude air from the esophagus during respiration. The demonstration that upper esophageal sphincter pressure falls markedly during sleep may have significance in that this diminishes the barrier to nocturnal regurgitation and potential aspiration.

The goal of the US ICF Program is to obtain a high-yield (100 to 1000 MJ) and high-gain (about 100) thermonuclear fusion capability in the laboratory. It has long been recognized that before such a laboratory facility is constructed, it must be demonstrated that laboratory conditions can be created that will, with high probability, lead to high gain if a driver of sufficient energy is built and that such a facility can be built at reasonable cost. Thus, the two major aspects of the US program address target physics and driver development. Four main driver candidates are actively being pursued: solid state lasers (principally Nd:glass), KrF gas lasers, light ion beams (Li ions accelerated by ion diodes), and heavy ion beams )A /approximately/200, accelerated by linear induction accelerator). The target physics aspect of the program is further divided into indirect and direct drive targets. In indirect drive targets the driver beams are aimed at a material near the capsule to generate x-rays, which then are absorbed in the fusion capsule ablator to produce the implosion. In direct-drive targets, the driver beams are aimed at the surface of the capsule. However, even in this case it should be recognized that themore » beam energy is deposited in the plasma surrounding the capsule, then transported to the ablation surface by electrons. Experimental target physics results recently obtained, principally for indirect-drive targets, have led to high confidence that a suitably-shaped 10 MJ pulse is sufficient to achieve high-gain and yields of 100 to 1000 MJ will result. 7 figs.« less

The authors discuss the role of inertial fusion in relationship to defense activities as well as in relation to energy alternatives. Other general advantages to inertial fusion besides maintaining the system more cheaply and easily, are discussed such as certain designs and the use of very short wavelength with a very modest laser intensity. A discussion on the direct illumination approach is offered. The progress made in high-gain target physics and the potential for development of solid-state lasers as a potential multimegajoule driver and a potential high-rep-rate fusion driver are discussed. Designs for reaction chambers are examined, as is the heavy-ion fusion program. Light-ion accelerators are also discussed.

Accidents in which large quantities of liquified natural gas (LNG) or other combustible materials are spilled can potentially lead to disastrous consequences, especially if the dispersing combustible cloud finds a suitable ignition source. So far, very little is known about the detailed behavior of a large burning cloud. Full-scale experiments are economically prohibitive, and therefore one must rely on laboratory and field experiments of smaller size, scaling up the results to make predictions about larger spill accidents. In this paper we describe our laboratory-scale experiments with a combustible propane/air mixture in various partially confined geometries. We summarize the experimental results and compare them with calculated results based on numerical simulations of the experiments. Our observations suggest that the geometry of the partial confinement is of primary importance; turbulence-producing obstacles can cause acceleration in the flame front and, more important, can cause a faster bu...

Serious planning for the Laboratory Microfusion Facility (LMF), in which the ICF program plans to achieve high gain, has begun. An inter organization DOE group has studied the design requirements for such a facility. That group concluded that the required missions of the LMF include: (1) obtain high gain (10-100), (2) conduct weapons physics (yields of 100-1000 MJ), (3) conduct weapon effects (same yields), and (4) assess ICF's potential for electric power. This paper describes the design implications of meeting these requirements.

We studied the mechanism of belching with specific attention to the upper esophageal sphincter (UES) in 14 normal volunteers. Belching occurred by the following sequence of events: lower esophageal sphincter relaxation; gastroesophageal gas reflux, recorded manometrically as a gastroesophageal common cavity phenomenon; UES relaxation; esophagopharyngeal gas reflux; and restoration of intraesophageal pressure to baseline by a peristaltic contraction. Upper esophageal sphincter relaxations comparable to those associated with belches were induced by abrupt esophageal distention with air boluses. In contrast, fluid boluses injected into the midesophageal body either had no effect on UES pressure or increased UES pressure. Thus, the UES responded to esophageal body distention in two distinct ways: abrupt relaxation in response to air boluses and pressure augmentation in response to fluid boluses. Mucosal anesthesia did not alter the UES response to esophageal boluses of gas or liquid thereby making it unlikely that these substances are differentiated by a mucosal receptor. Rapid distention of the proximal esophagus with a cylindrical balloon (15 cm long) elicited UES relaxation. These findings suggest that the rapidity and spatial pattern of esophageal distention, rather than discrimination of the type of material causing the distention, determines whether or not UES relaxation occurs.

Lawrence Livermore National Laboratory (LLNL) is conducting safety research under the sponsorship of the US Department of Energy (DOE) to determine the possible consequences of liquefied natural gas (LNG) spills. The LLNL program includes both the collection of data from various size experiments and development of an ensemble of computer models to make predictions for conditions under which tests cannot be performed. In spills of 40 cubic metres (m/sup 3/) of liquefied natural gas onto water done at the Naval Weapons Center (NWC), China Lake, California in 1980 and 1981, data was collected on gas cloud dispersion and combustion and rapid phase transition (RPT) explosions. Analysis of the data from these tests, including comparisons between the predictions of various models and the data, are presented. The results suggest that large-scale spills may be more hazardous than would have been predicted based on earlier small-scale tests.

We have conducted parametric economic studies for heavy‐ion‐fusion electric power plants. We examined the effects on the cost of electricity of several design parameters: cost and cost scaling for the reactor, driver, and target factory; maximum achievable chamber pulse rate; target gain; electric conversion efficiency; and net electric power. Using the most recent estimates for the heavy‐ion‐driver cost along with the Cascade reactor cost and efficiency, we found that a 1.5 to 3 GWe heavy‐ion‐fusion power plant, with a pulse rate of 5–10 Hz, can be competitive with nuclear and coal power plants.

The objectives of the Inertial Confinement Fusion (ICF) Program at LLNL are to understand, develop, and utilize the science and technology associated with the ICF concept. The current emphasis and the largest fraction of our effort is on understanding fundamental target physics and driver/target interactions, learning how to fabricate targets of various design, and developing a driver capable of igniting a high-gain target. These activities are appropriate for both the military and civilian applications. Smaller efforts are devoted to near-term military uses of the laser facilities that have little applicability to the civilian goals and, conversely, to nonoverlapping civilian-oriented development. Thus, while it can be said that more than 3/4 of our effort is devoted to military applications, it is also true that more than 3/4 of our effort is devoted to the civilian applications.

We have conducted parametric economic studies for heavy-ion-beam fusion electric power plants. We examined the effects on the cost of electricity of several design parameters: maximum achievable chamber pulse rate, driver cost, target gain, and electric conversion efficiency, and net electric power. We found with reasonable assumptions on driver cost, target gain, and electric conversion efficiency, a 2 to 3 GWe heavy-ion-beam fusion power plant, with a chamber pulse rate of 5 to 10 Hz, can be competitive with nuclear and coal power plants.

Lawrence Livermore National Laboratory (LLNL) is conducting safety research under the sponsorship of the U.S. Department of Energy (DOE) to determine the possible consequences of liquefied natural gas (LNG) spills. The LLNL program includes both the collection of data from various size experiments and development of an ensemble of computer models to make predictions for conditions under which tests cannot be performed. In spills of 40 cubic metres (m3) of LNG onto water done at the Naval Weapons Center (NWC), China Lake, California in 1980 and 1981, data was collected on gas cloud dispersion and combustion and rapid phase transition (RPT) explosions. Analysis of the data from these tests, including comparisons between the predictions of various models and the data, are presented. The results suggest that largescale spills may be more hazardous than would have been predicted based on earlier small-scale tests. Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.

Concern has been expressed in recent years that the development of fusion power may require a series of facilities that are so expensive as to be unaffordable even if the end design of a power station appears to be attractive. Of course, the perception of what is affordable depends a great deal on the national urgency attached to the program at any given time. Just a few years ago, after a decade of fuel shortages, gas lines, and the energy “crisis”, Congress passed a bill that seemingly guaranteed virtually unlimited funds for an accelerated magnetic fusion development program. In the few years since, the support for such an approach has disappeared and now the program is even considering abandoning the technological approach all agree has the best chance of producing a burning plasma soonest, in favor of riskier approaches that may have less expensive development steps. In view of the fact that the perception of what is affordable can change so quickly, some advocate waiting until the climate changes back, confident in their expectation that the present glut of energy will fade and that the national resolve will return to development of fusion power. This may happen, of course, but it would seem somewhat foolish to plan on it. When the glut fades, as it surely will, many factors will determine the national response to it. Energy conservation technology is now a dynamic force in many sectors of our economy.

The International Atomic Energy Agency convened, in the framework of its Fusion Technology and Engineering Programme, the 4th Technical Committee and Workshop on Fusion Reactor Design and Technology at Yalta, USSR, from 26 May – 6 June 1986. This report contains all summaries of sessions that were organized during the workshop. The papers presented at the meeting are being published by the Agency in its Proceedings Series.