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The main ideas for the Energy Amplifier (EA) are presented, as they have been developed at CERN [1]. The discussion concerns with the safety and environmental features of this new kind of reactor which are far more better than the ones of the conventional reactors. A comparison is also given with fusion reactors and other non-nuclear methods for energy production, such as coal burning.

The power amplification factor PAF of a driven subcritical system is defined as the ratio of the fission power output of the blanket to the power which the driver must deliver to sustain its neutron source intensity. This parameter decisively determines the effectiveness of the whole system independent of its special purpose as energy amplifier or as transmutation facility. The present note derives a refined analytical expression for the PAF which reveals more physical details than the expressions given by other authors. Moreover, the traditionally used forms of the static reactor eigenvalue equation and of its adjoint equation are rewritten for subcritical systems and used in the derivation of the expression for the PAF. The derived formula and the modified eigenvalue equations are discussed.

We measured integral thin target cross sections for the proton-induced production of 3He, 4He, 21Ne, 22Ne, 36Ar and 38Ar from Fe and Ni from the respective reaction thresholds up to 1.6 GeV. The production of noble gas isotopes, especially 4He, from Fe and Ni is of special importance for design studies of accelerator driven systems and/or energy amplifier, because Fe is the main structural material in almost every design study. Furthermore, the cross sections are needed to establish the first physical model calculations for the production of cosmogenic nuclides in iron meteorites. As a result of our new measurements there now exist for both target elements a complete and consistent database for the production of noble gas isotopes. The experimental data are compared to results from the theoretical nuclear model codes INCL4/ABLA and TALYS. This comparison clearly demonstrates again that experimental data are still needed because the predictive power of nuclear model codes, though permanently improving, does still not allow reliably predicting the cross sections needed for most applications and irradiation experiments remain indispensable.

The expected duration of today’s nuclear reactors, even if persisting at the present relatively low level of 5 % of the primary energy supply, is not appreciably longer than that for energy systems using natural gas and oil and is much less than that for those employing coal. There is no doubt that, for its continued usage, nuclear power must be profoundly modified. For instance, new breeding reactions based on tritium, natural uranium or thorium, which may last for many thousands of years, far beyond fossil fuels, must be pursued, together with much stricter safety levels and a deterministic safety approach. Amongst the breeding alternatives, the use of thorium represents a unique opportunity. The advantages of thorium burning are remarkable; especially if one considers that the same amount of electric energy may be produced from 3 million tons of coal, from U-235 extracted from about 200 tons of natural uranium, or from merely one ton of the vastly abundant natural thorium. Used in an accelerator-driven system, thorium opens options for a safe nuclear power, with a considerably simplified fuel cycle, significantly minimized production of long-lived nuclear waste, as well as the possibility of destroying existing nuclear waste and stockpiles of military plutonium. My own recommendation is to construct a full-scale industrial 600 MWe subcritical thorium demonstrator, along the lines of the Energy Amplifier engineering design by Aker Solutions ASA, but using salt instead of metal, and at a cost far less than 10 % of what is presently invested in the ITER (International Thermonuclear Experimental Reactor) for fusion. A simplified fuel reprocessing concept may consist of considering the spent thorium, fission fragments, and minor actinides (Pa, Np, Am, and Cm) as “waste” and uranium and plutonium as “seeds”. The duration of each fuel cycle would be about ten years and the reactor lifetime could exceed 200 years.

The international Thorium Energy Committee (iThEC) was recently created in Geneva to promote thorium-fueled accelerator-driven systems. iThEC was initiated by members of the CERN scientific community under the auspices of Carlo Rubbia, the inventor of the ADS system he refers to as the Energy Amplifier (EA). The committee also comprises business leaders, politicians, and members acquainted with public relations, in an effort aimed at broadening the support for the ADS concept. Nuclear policy today in Europe and more particularly in Switzerland has reached a point where crucial decisions must be made, affecting the security of electricity supply, the fulfillment of commitments to the Kyoto protocol for combating climate change, while addressing public concerns that increased following the Fukushima accident. Nuclear power has its advantages, yet the perennial problem of what to do with nuclear waste, the perceived risks due to criticality, and the fear of nuclear weapon proliferation have long been a thorn in the side of nuclear power, preventing it from taking its place as a core carbon-free technology of the 21st century and beyond. In addition, policy makers are generally ill-informed about alternative nuclear energy systems, such as the possibility of ADS using thorium fuel. The main purpose of iThEC is to work on reversing the current negative trends in Europe, by providing better information to the public on thorium possibilities, by supporting thorium ADS technology developments and by actively engaging the scientific, political, and business leadership. iThEC is preparing a proposal for the construction of an ADS demonstrator.

The nuclear data sensitivity in 3D Monte Carlo burnup calculations of minor actinide transmutation in Energy Amplifier Systems is assessed. Ansaldo Nucleare’s 80 MW th Energy Amplifier Demonstration Facility (EADF) design serves as a technical and geometrical platform for the analysis. The accelerator-driven EADF is a fast, subcritical system based on classical MOX-fuel technology and on molten lead–bismuth eutectic cooling. For Monte Carlo simulations, the state-of-the-art computer code package EA-MC, developed by C. Rubbia and his group at CERN, is utilised. The code offers treatment of both high-energy particle interactions and low-energy neutron transport with a sophisticated method based on a full Monte Carlo simulation, together with the option of employing different modern nuclear data libraries. In particular, the impact of nuclear data discrepancies on transmutation properties prediction with increasing exposure is examined. Monte Carlo simulation accelerator-driven systems transmutation burnup fast neutron spectrum minor actinides nuclear waste.

The experimental study on the accelerator-driven system (ADS) is conducted for the basic research of energy amplifier system and nuclear transmutation with the combined use of the core at the Kyoto University Critical Assembly (KUCA) and the fixed-field alternating gradient (FFAG; 100 MeV protons) accelerator, in the Kyoto University Research Reactor Institute. The ADS experiments with 100 MeV protons are carried out to investigate the neutron characteristics of ADS, and the static and kinetic parameters are accurately analyzed through both the measurements and the Monte Carlo simulations of reactor physics parameters. An upcoming ADS at KUCA could be carried out in the highly-enriched uranium fueled, polyethylene- and Pb-Bi zoned core, and the reaction rate analyses of nuclear transmutation could be conducted with the use of 237 Np capture and 241 Am fission reactions.

A speculative propulsion concept is presented, based on accelerating a spacecraft by impact of a stream of matter in relative motion with respect to the spacecraft. To accelerate the stream to the needed velocity, the stream mass is contained in a transit craft, launched at low velocity and hence low energy cost, and then sent on a trajectory with near encounters of the planets for gravitational assist. The mass arrives at Earth or wherever the propellant is needed at much higher velocity and kinetic energy, where it is released into an extended stream suitable for propulsion. The stream, moving at a relative velocity in the range of 10 to 30 km/s, should be capable of both high thrust and high specific impulse. Means of limiting the transverse expansion of the stream during release and for the ∼1000 s duration of impact are a critical requirement for practicality of the concept. The scheme could potentially lead to a virtually unlimited energy source. One can imagine using a portion of one stream to launch another, larger payload on a similar trajectory. This creates, in effect, an energy amplifier extracting energy from the orbital motions of the planets. The gain of the energy amplifier is only limited by the capacity to prepare mass in transit craft.

Accelerator Driven Systems (ADS) are an old technological idea: Relativistic proton accelerators deliver their beams onto massive heavy element targets, thus producing abundant neutron fluences. Placing this target into sub-critical nuclear fission assemblies is yielding substantial fission reactions, thus additional fission energy (Rubbia called such a system “Energy Amplifier”). This technology has recently attracted considerable attention due to advances in the construction of powerful accelerators. It allows the safe and cheap production of nuclear energy simultaneously with the destruction (Transmutation) of long lived radioactive waste, in particular plutonium and other minor actinides (neptunium and americium). The principles and the present-state-of-the-art are described, including first experiments to transmute plutonium this way. This technology needs, however, many more years of further “research and development” before large scale ADS's can be constructed. It may be even necessary to investigate the question, if all basic physics phenomena of this technology are already sufficiently well understood.

Progress in particle accelerator technology makes it possible to use a proton accelerator to produce energy and to destroy nuclear waste efficiently. The energy amplifier (EA) proposed by Carlo Rubbia and his group is a subcritical fast neutron system driven by a proton accelerator. It is particularly attractive for destroying, through fission, transuranic elements produced by presently operating nuclear reactors. The EA could also efficiently and at minimal cost transform long-lived fission fragments using the concept of adiabatic resonance crossing (ARC), recently tested at CERN with the TARC experiment. The ARC concept can be extended to several other domains of application (production of radioactive isotopes for medicine and industry, neutron research applications, etc.).

SummaryExperimental studies on the transmutation of some long-lived radioactive waste nuclei, such as129I,237Np, and239Pu, as well as on natural uranium and lanthanum were carried out at the Synchrophastron of the Laboratory for High Energies at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The radioactive targets (I, Np and Pu) were contained in weld-sealed aluminium holders produced by the Institute of Physics and Power Engineering, Obninsk, Russia. Spallation neutrons were produced by relativistic protons with energies in the range of 0.5 GeV≤Ep≤1.5 GeV interacting with 20 cm long uranium or lead target stacks. The metallic targets were surrounded by 6 cm thick paraffin moderators. The uranium and lanthanum samples were positioned on the outside of the moderator surface and typically contained approximately 0.5 to 1.0 gram of uranium or lanthanum. The highest fluence of spallation neutrons was observed in the region of 5 to 10 cm downstream the entrance of the primary beam into the metallic target, rather independent of the target material or the proton energy. The results obtained by nuclear chemistry methods were supplemented by SSNTD (Solid State Nuclear Track Detector) studies. Consistent and systematic results ofB-values and spectral distributions for neutrons have been found. From the experimentally observed transmutation rates one can extrapolate that in a subcritical nuclear power assembly (or "energy amplifier") using a 10 mA proton beam of 1 GeV onto a Pb-target as used here, one can transmute within one month in one gram of sample about 3 mg129I, 21 mg237Np, 3.3 mg238U, and 200 mg239Pu. Rather similar results have been found by another group for129I and239Pu. Observations show that the transmutation rates increase almost linearly with the proton energy in the energy interval 0.5 GeV up to 7.4 GeV. These findings are largely confirmed by model calculations using the LAHET- and DCM/CEM-codes.

Accelerator-driven systems for transmutation of nuclear waste have been suggested as a means for dealing with spent fuel components that pose potential radiological hazard for long periods of time. While not entirely removing the need for underground waste repositories, this nuclear waste incineration technology provides a viable method for reducing both waste volumes and storage times. Potentially, the time spans could be diminished from hundreds of thousand years to merely 1.000 years or even less. A central aspect for accelerator-driven systems design is the prediction of safety parameters and fuel economy. The simulations performed rely heavily on nuclear data and especially on the precision of the neutron cross section representations of essential nuclides over a wide energy range, from the thermal to the fast energy regime. In combination with a more demanding neutron flux distribution as compared with ordinary light-water reactors, the expanded nuclear data energy regime makes exploration of the cross section sensitivity for simulations of accelerator-driven systems a necessity. This fact was observed throughout the work and a significant portion of the study is devoted to investigations of nuclear data related effects. The computer code package EA-MC, based on 3-D Monte Carlo techniques, is the main computational tool employed for the analyses presented. Directly related to the development of the code is the extensive IAEA ADS Benchmark 3.2, and an account of the results of the benchmark exercises as implemented with EA-MC is given. CERN's Energy Amplifier prototype is studied from the perspectives of neutron source types, nuclear data sensitivity and transmutation. The commissioning of the n_TOF experiment, which is a neutron cross section measurement project at CERN, is also described.

Transmutation rates of 239Pu and some minor actinides (237Np, 241Am, 245Cm and 246Cm), in two accelerator-driven systems (ADS) with lead or graphite moderating environments, were calculated using the LAHET code system. The ADS that were used had a large volume (∼32 m3) and contained no fissile material, except for a small amount of fissionable waste nuclei that existed in some cases. Calculations were performed at an incident proton energy of 1.5 GeV and the spallation target was lead. Also breeding rates of 239Pu and 233U as well as the transmutation rates of two long-lived fission products 99Tc and 129I were calculated at different locations in the moderator. It is shown that an ADS with graphite moderator is a much more effective transmuter than that with lead moderator.

The LAHET code system is used to study the behaviour of the spallation neutrons resulting from the interaction of 2.5 GeV/c protons with a massive lead target within a large (∼32 m3) lead and graphite moderating environments. The spatial and energy distribution of the neutrons with presence and absence of a fissile material in Accelerator Driven Systems (ADS) are investigated. It is shown that the energy spectra of the neutrons in graphite and lead moderators are very different and such difference is expected to result in noticeable differences in the nuclear waste transmutation abilities of the ADSs that use graphite and lead for neutron moderation and storage.

We summarize here the results of the TARC experiment whose main purpose is to demonstrate the possibility of using Adiabatic Resonance Crossing (ARC) to destroy efficiently Long-Lived Fission Fragments (LLFFs) in accelerator-driven systems and to validate a new simulation developed in the framework of the Energy Amplifier programme. An experimental set-up was installed in a CERN PS proton beam line to study how neutrons produced by spallation at relatively high energy ( E n ⩾1 MeV ) slow down quasi-adiabatically with almost flat isolethargic energy distribution and reach the capture resonance energy of an element to be transmuted where they will have a high probability of being captured. Precision measurements of energy and space distributions of spallation neutrons (using 2.5 and 3.5 GeV/c protons) slowing down in a 3.3 m×3.3 m×3 m lead volume and of neutron capture rates on LLFFs 99Tc, 129I, and several other elements were performed. An appropriate formalism and appropriate computational tools necessary for the analysis and understanding of the data were developed and validated in detail. Our direct experimental observation of ARC demonstrates the possibility to destroy, in a parasitic mode, outside the Energy Amplifier core, large amounts of 99Tc or 129I at a rate exceeding the production rate, thereby making it practical to reduce correspondingly the existing stockpile of LLFFs. In addition, TARC opens up new possibilities for radioactive isotope production as an alternative to nuclear reactors, in particular for medical applications, as well as new possibilities for neutron research and industrial applications.

The Transmutation by Adiabatic Resonance Crossing (TARC) experiment was carried out as PS211 at the CERN PS from 1996 to 1999. Energy and space distributions of spallation neutrons (produced by 2.5 and 3.57 GeV/c CERN proton beams) slowing down in a 3.3×3.3×3 m3 lead volume and neutron capture rates on long-lived fission fragments 99Tc and 129I demonstrate that Adiabatic Resonance Crossing (ARC) can be used to eliminate efficiently such nuclear waste and validate innovative simulation.

In order to improve the safety characteristics of nuclear systems, accelerator driven assemblies have been proposed for energy production and for the incineration of the residuals of the back-end of the nuclear fuel cycle like plutonium, minor actinides and long-lived fission products. For the neutron physics analysis of such source driven systems calculation procedures have been established and qualified at FZK. Necessary extensions to the conventional methods for fission reactors are discussed in some detail, especially for the spallation processes initiated by protons with energies of about 1 GeV. The application of these methods in an IAEA benchmark for an energy amplifier type of ADS identified the problem of the unfavorable power distribution in such sub-critical systems. In order to improve the power distributions the application of multiple sources, radial distributed over the reactor assembly has been proposed. Investigations for an ADS with three proton beams are performed with respect to the capability of incineration of plutonium and minor actinides.

Suggestions for superpowerful linear accelerators for electronuclear setups and high-intensity neutron generators are reviewed. The most important technical solutions, the characteristic features, and the state of the projects for linear accelerators with average accelerated beam power from 1 to 100 MW are examined: APT, SNS, JAERI/KEK, TRISPAL, TRASCO, ESS, KOMAC, Energy Amplifier, IFMIF, joint proposal by the Institute of Theoretical and Experimental Physcis, the Moscow Radio Electronics Institute, the Institute for High-Energy Physics, and other nuclear centers. 8 figures, 3 tables, 74 references.

The Feynman-alpha and Rossi-alpha formulae are derived analytically for subcritical systems driven by a multiple emission source,i.e. one that emits several neutrons on each source emission event. The prime example of such sources is a spallation source, which will be used in future accelerator driven subcritical systems (ADS) such as the energy amplifier. Such formulae for ADS have been derived recently but in simpler neutronic models. In this paper six groups of delayed neutron precursors are taken into account, and the full joint statistics of the prompt and all delayed groups is included. Thus the present results are generalisations of earlier ones. The involved problems that are encountered are solved with a combination of effective analytical techniques and symbolic algebra codes.

The conceptual Fast Energy Amplifier, proposed by Rubbia et al. consists of a combination of a U-233/Th-232 fuelled fast-neutron subcritical facility with a proton accelerator. An intense beam of 1 GeV protons is injected into liquid lead at the core centre and drives the reactor by producing spallation neutrons. The burst of spallation neutrons produced by a single proton alters the basic neutron statistics which are well known for thermal neutrons in conventional nuclear reactors. A short assessment of standard neutron noise analysis methods is made with respect to monitoring neutron parameter data.

We investigate a compact, pulsed racetrack microtron as an energy amplifier and bunch compressor to produce bunch charges of ∼100 pC in beams with a peak current of ∼30 A or more having longitudinal emittance of 50 keV × deg and transverse emittance of 5–15π mm × mrad with energies from 5 to 35 MeV selectable in 2.5 MeV steps.

A uranium thermometer has been designed and built in order to make local power measurements in the First Energy Amplifier Test (FEAT). Due to the experimental conditions power measurements of tens to hundreds of nW were required, implying a sensitivity in the temperature change measurements of the order of 1 mK. A uranium thermometer accurate enough to match that sensitivity has been built. The thermometer is able to determine the absolute energetic gain obtained in a tiny subcritical uranium assembly exposed to a proton beam of kinetic energies between 600 MeV and 2.75 GeV. In addition, the thermometer measurements have provided information about the spatial power distribution and the shape of the neutron spallation cascade.

The feasibility of cyclotrons to produce high power beams is discussed based on the experience gained with the operation of the upgraded 590 MeV cyclotron facility at PSI in Villigen (Switzerland) at a beam power level up to 0.9 MW. In view of new applications of particle beams in neutron spallation sources, energy amplifier and transmutation technologies a possible design of a 1 GeV cyclotron is presented that would be capable to deliver a 10 MW beam, based on the same contruction principles as used in the PSI 590 MeV Ring cyclotron. Questions concering power conversion efficiency, beam loading and space charge forces are discussed. Space charge effects are not expected to be a major problem in the high energy cyclotron, but they play an important role in the preaccelerator and further studies are needed to propose an optimized configuration.

A fission detector developed for the first energy amplifier test made at CERN-PS during the period September–October 1994 [1,2] will be described. The device is a small dimension high pressure argon gas ionization chamber with high background rejection and very high efficiency on 2π for fission fragments. The number of fissions produced in a fissile target allows the neutron flux measurement.

A new view upon an energy amplifier (based on a subcritical reactor driven by an accelerator motivated source of neutrons) as a system united by the energy flow between the accelerator and the subcritical reactor is given in the paper. A new approach to the calculation of the gain of the energy amplifier using the neutron balance equation is also introduced. The expression for the gain obtained here is compared with an expression derived earlier [C. Rubbia et al.: Rep. ISC 93-31, ISC/P 57, CERN, 1993].

An already existing, sub-critical arrangement made of natural uranium and water moderator has been exposed to a low intensity (≈ 109 ppp) proton beam from CERN-PS at several kinetic energies from 600 MeV to 2.75 GeV. The energy delivered by the hadronic cascade induced by the beam in the device has been measured by the temperature rise of small sampling blocks of uranium located in several different positions inside the device and counting the fissions in thin probe foils of natural uranium. We find typically G ≈ 30 in reasonable agreement with calculations, where G is the ratio of the energy produced in the device to the energy delivered by the beam. This result opens the way to the realisation of the so-called Energy Amplifier, a practical device to produce energy from thorium or depleted uranium targets exposed to an intense high energy proton beam. Results show that the optimal kinetic is ≥ 1 GeV, below which G decreases but is still acceptable in the energy range explored

The problem associated with the current NPP is the generation of nuclear waste and some elements in the waste have very long time of radioactivity. This paper reviews some concepts of nuclear energy generation with less nuclear waste. A concept of accelerator driven system (ADS) or energy amplifier (EA) was proposed by Carlo Rubbia, recipient of 1984 Nobel Prize in particle physics. The system is supposed to generate nuclear energy with radioactive waste of much less and shorter lifetime than those generated by present generation of nuclear power reactors. Less radioactive waste will also be generated by fusion reactions, either in hot fusion of high temperature plasma confined in a very strong magnetic field, or in cold fusion conceptually happens in muon-catalytic and lattice-trap fusions. A concept of neutronless nuclear reaction, hence activating no radioisotopes, to generate nuclear power was proposed. Present nuclear power reactors based on fission are also the source of very large number of electron neutrinos, which can be used to study neutrino oscillations.

International audience; We explore the potential of Nd:YAG single-crystal fibers for the amplification of passively Q-switched microlasers operating below 1 ns. Different regimes are tested in single or double pass configurations. For high gain and high power amplification this novel gain medium provided average powers up to 20 W at high repetition rate (over 40 kHz) for a pulse duration of 1 ns. As an energy amplifier, Nd:YAG single-crystal fiber delivered 2.7 mJ, 6 MW 450 ps pulses at 1 kHz. The extraction efficiencies vary from 8% to 32.7% following the configurations.

We investigate pulse shaping and optimization for a laser amplifier. Due to the complex character of the nonlinear PDE dynamics involved in the laser model, it is of interest to consider non-model based methods for pulse shaping. We determine input pulse shapes for an unknown laser dynamics model using iterative learning control (ILC) and high-dimensional extremum seeking (ES), which is a real-time optimization strategy. We utilize ILC to obtain the input pulse shape that generates a desired output pulse shape and ES to find the input pulse that maximizes the energy amplifier gain. Both single-pass and double-pass laser models are investigated. The effectiveness of these approaches is illustrated via numerical simulations.Copyright © 2011 by ASME

We describe a new approach for commercial nuclear energy production without a long-term high-level waste stream and for transmutation of both fission product and higher actinide commercial nuclear waste using a thermal flux of accelerator-produced neutrons in the 1016 n/cm2s range. Continuous neutron fluxes at this intensity, which is approximately 100 times larger than is typically available in a large scale thermal reactor, appear practical, owing to recent advances in proton linear accelerator technology and to the spallation target-moderator design presented here. This large flux of thermal neutrons makes possible a waste inventory in the transmutation system which is smaller by about a factor of 100 than competing concepts. The accelerator allows the system to operate well below criticality so that the possibility for a criticality accident is eliminated. No control rods are required. The successful implementation of this new method for energy generation and waste transmutation would eliminate the need for nuclear waste storage on a geologic time scale. The production of nuclear energy from 232Th or 238U is used to illustrate the general principles of commercial nuclear energy, production without long-term high-level waste. There appears to be sufficient thorium to meet the world's energy needs for many millenia.

Fig 1: Closing the nuclear cycle with the Energy Amplifier, a sub-critical device with a Th _mU fissile core fed with a supply of spallation neutrons. There is no criticality , no plutonium and no problem of actinide waste. At the end of the cycle, mU and the other uranium isotopes are recycled to serve as the initial fissile part of a new load of fuel. Thorium is an abundant resource (much more than uranium) and supplies could last thousands of centuries. k= Absorption + Losses

Accelerator-driven systems for transmutation of nuclear waste have been suggested as a means for dealing with spent fuel components that pose potential radiological hazard for long periods of time. While not entirely removing the need for underground waste repositories, this nuclear waste incineration technology provides a viable method for reducing both waste volumes and storage times. Potentially, the time spans could be diminished from hundreds of thousand years to merely 1.000 years or even less. A central aspect for accelerator-driven systems design is the prediction of safety parameters and fuel economy. The simulations performed rely heavily on nuclear data and especially on the precision of the neutron cross section representations of essential nuclides over a wide energy range, from the thermal to the fast energy regime. In combination with a more demanding neutron flux distribution as compared with ordinary light-water reactors, the expanded nuclear data energy regime makes exploration of the cross section sensitivity for simulations of accelerator-driven systems a necessity. This fact was observed throughout the work and a significant portion of the study is devoted to investigations of nuclear data related effects. The computer code package EA-MC, based on 3-D Monte Carlo techniques, is the main computational tool employed for the analyses presented. Directly related to the development of the code is the extensive IAEA ADS Benchmark 3.2, and an account of the results of the benchmark exercises as implemented with EA-MC is given. CERN's Energy Amplifier prototype is studied from the perspectives of neutron source types, nuclear data sensitivity and transmutation. The commissioning of the n_TOF experiment, which is a neutron cross section measurement project at CERN, is also described.

WOS: 000185133200014, Neutron physics analysis of a dual purpose modified PACER concept has been conducted. A protective liquid droplet jet zone of 2 m thickness is considered as coolant, energy carrier, and fusile and fissile breeder. Flibe as the main constituent is mixed with increased mole-fractions of heavy metal salt (ThF4 and UF4) starting by 2 up to 12 mol.%. The neutronic model assumed a 30 m radius underground spherical geometry cavity with a 1 cm thick SS-304 stainless steel liner attached to the excavated rock wall. By a self-sufficient tritium breeding of 1.05 with 5 mol.% ThF4, or 9 mol.% UF4 an excess nuclear fuel breeding rate of 1900 kg/year of U-233 or 3000 kg/year Pu-239 of extremely high isotopic purity can be realized. This precious fuel can be considered for special applications, such as spacecraft reactors or other compact reactors. The heavy metal constituents in jet zone acts as an energy amplifier, leading to an energy multiplication of M = 1.27 or 1.65 for 5 mol.% ThF4, or 9 mol.% UF4, respectively. As an immediate result of the strong neutron attenuation in the jet zone, radiation damage with dpa < 1.4 and He < 7 ppm after a plant operation period of 30 years will be well below the damage limit values. The site could essentially be abandoned, or the cavity could be used as a shallow burial site for other qualified materials upon decommissioning. Finally, the totality of the site with all nuclear peripheral sections must be internationally safeguarded carefully, (C) 2003 Elsevier B.V. All rights reserved.

Because of the safer and more reliable mode of operation, a Superconducting Linac has been proposed as the proton beam accelerator which drives a nuclear plant based on the concept of the Energy Amplifier. An example based on the net generation of 400 MW (electric) is described. This requires a proton beam energy of 1 GeV with a continuous beam current of 10 mA, corresponding to a beam power of 10 MW. Two frequencies cases, 360 and 805 MHz, have been considered for the Linac design. Performance and cost comparison for the two cases are given.

The Sincrotrone Trieste proposal for a 100 MeV proton accelerator, driving a 1+2.5 GeV booster linac for the Energy Amplifier Project, is based on a Multi-Tank Drift Tube Linac (MTDTL) structure, since it seems to be the most simple and efficient solution for a high power, CW proton beam. The optimization of the RF system, in terms of efficiency and cost, is a crucial point in the design of the MTDTL. A possible solutions for the low level distribution and the RF power distribution are presented and analysis of the efficiencies are given.

The science and technology of proton accelerators have progressed considerably in the past three decades. Three to four orders of magnitude increase in both peak intensity and average flux have made it possible to construct high intensity proton accelerators for modern applications, such as: spallation neutron sources, kaon factory, accelerator production of tritium, energy amplifier and muon collider drivers. The accelerator design focus switched over from intensity for synchrotrons, to brightness for colliders to halos for spallation sources. An overview of this tremendous progress in both accelerator science and technology is presented, with special emphasis on the new challenges of accelerator physics issues such as: H/sup -/ injection, halo formation and reduction of losses.

For the design of the linear optics of the superconducting linear accelerator for a Full Scale Energy Amplifier, a computer code is under development for the 3-dimensional linear motion with space charge and transverse cavity effects included. A sequential matching routine allows an easy optimization of the optics for the long structure of the linear accelerator. The program is described and first results of the optics optimization for the linear accelerating structure are discussed.

The goal of this accelerator complex is to provide a 10 MW proton beam for driving the Energy Amplifier recently proposed by C. Rubbia. It is lower (by one order of magnitude) than the requirements of most of the accelerator-driven projects based on c-w linacs. Therefore, the requirements for the Energy Amplifier open an alternative solution based on ring cyclotrons producing a continuous beam. Thus taking into account the present development of high-intensity cyclotrons, a three-stage cyclotron accelerator is a possible solution. It comprises of: (1) the injector(s) which should be able to deliver a 10 mA beam in a given phase width-a solution based on two 5mA compact isochronous cyclotrons working in parallel is proposed; (2) the intermediate stage which is a four-separated-sector cyclotron accelerating the injected beam up to 120 MeV; and (3) the final booster which has ten separated sectors and six cavities raising the kinetic energy up to about 1000 MeV.