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RF simulation results for the doorknob transition design. The waveguide to coaxial transition can have either a “flat” or a circular rounded short circuit at the end of the rectangular waveguide. Simulations were made for transitions with both short circuit shapes and the results
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Accelerator Driven system (ADS) are being considered for their potential use in the transmutation of nuclear waste. Such a device typically requires a 600MeV to 1GeV accelerator delivering a high intensity beam. Because of the induced thermal stress to the subcritical core, the high-power proton LINAC will have to fulfill stringent reliability requ...
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Context 1
... optimized transition designed with HFSS ® was implemented in the CST ® code. The Figure 4 shows that simulations results, regarding the reflection (S11) and transmission (S21) coefficients are in agreements. With CST-MS ® the "reflection peak" slightly shifted to lower frequency, but the -30dB bandwidths are appreciably similar. ...
Context 2
... optimized transition designed with HFSS ® was implemented in the CST ® code. The Figure 4 shows that simulations results, regarding the reflection (S11) and transmission (S21) coefficients are in agreements. With CST-MS ® the "reflection peak" slightly shifted to lower frequency, but the -30dB bandwidths are appreciably similar. ...
Citations
... Considering that there are nuclear reactors available in different parts of the world, it is estimated that there will be problems with uranium supply in the future. Nuclear reactors in the European Union produce around 2,500 tons of nuclear spent fuel per year (The European Technical Working Group on ADS, 2001; Biarrotte et al., 2009;Bouly et al., 2009). Nuclear spent fuel from fission reactors contains uranium (about 95 wt%), plutonium (0.9 wt %), MA; Np, Am, and Cm (0.1 wt%), and fission products (4 wt%). ...
In this study, a Boiling Water Reactor (BWR) design was made using the Monte Carlo (MCNPX) method. The reactor core in the designed BWR system was divided into an 8 × 8 square lattice with a constant pitch of 30.48 cm. In this study, americium (Am), which is found in the minor actinidine (MA) of spent nuclear fuel known as nuclear waste from existing reactors, was used as fuel with the addition of oxygen and fluorine. In this study, AmO2 and AmF3 fuels at the rate of 0.02–0.1% were used as Americium Mixed Fuels, and Zircaloy-2 (Zr-2), SiC, and VC were used as clad. Neutronic calculations for certain Americium Mixed Fuels and clads were compared in the designed BWR system. In the BWR system designed in the study; keff, neutron flux, fission energy, heating, and depleted Am were calculated. The three-dimensional (3-D) modeling of the designed BWR system was performed by using MCNPX-2.7.0 Monte Carlo method and the ENDF/B-VII.0 nuclear data library.
... In the continuation of the work initiated within the FP6 EUROTRANS programme [6], a prototypical cryomodule of the medium-energy section of the MYRRHA proton linac has been developed, built and fully tested in "accelerator-like" configuration, and a few reliabilityoriented experiments have been performed in view of the foreseen MYRRHA fault-recovery procedures [2]. ...
... The operating frequency is 352 MHz, and for maximal compatibility with the fault tolerance scheme, a 2-cell cavity is a chosen. A first spoke cavity has been successfully tested at 4K and 2K in an "accelerator-like" horizontal cryostat configuration 28 , fully equipped with its tuning system, magnetic shield, RF power coupler, and fed by a 10 kW solid-state amplifier. Nevertheless, this technology is still rather young and R&D effort has to be intensively continued. ...
New generation high power hadron accelerators are more and more required to produce intense fluxes of secondary particles for various fields of science: radioactive ions for nuclear physics, muons and neutrinos for particle physics, and of course neutrons for many applications like condensed matter physics, solid-state physics, or irradiation tools. This paper will focus on the applications of such accelerators in support of nuclear energy, and in particular on the two following cases: the International Fusion Materials Irradiation Facility (IFMIF), which asks for a 10 MW, 40 MeV deuteron beam, and the ADS (Accelerator Driven System) application for transmutation of long-lived radioactive wastes, which typically requires a 600 MeV -1 GeV proton beam of a few mA for demonstrators, and a few tens of mA for large industrial systems. In this respect, the status of the accelerator proposed for the European MYRRHA project will be detailed and discussed.
... Concerning MA production rate, European sources report wordly "at present, the total park of nuclear power plants in the European Union (∼125 GW of nominal power) produces approximately 2500 tons of spent fuel are produced annually (oxygen of the oxide not being accounted for in this figure), containing about 25 tons of plutonium and 3.5 tons of the "minor actinides (MA)" neptunium, americium, and curium and 3 tons of long-lived fission products [11][12][13]." Some nuclear waste actinides ( 239 Pu, 241 Pu, 242m Am and 245 Cm) are fissile fuel under thermal neutron spectrum, and all of them become excellent fissile fuel under fast 14 MeV fusion neutron spectrum. ...
Progress on The National Ignition Facility (NIF) brings fusion a viable energy source in foreseeable future. Energy multiplication in a fusion–fission (hybrid) reactor could lead earlier market penetration of fusion energy for commercial utilization. Originally, scientists at the Lawrence Livermore National Laboratory (LLNL) have worked out a hybrid reactor design concept; the so-called Laser Inertial Confinement Fusion–Fission Energy (LIFE) engine, which has consisted of a spherical fusion chamber of ∼5 m diameter, surrounded by a multi-layered blanket with a beryllium multiplier zone after the first wall.
... The main difference lies in the diameter of the coaxial line on the cavity side which is 80 mm. The cooling of the cold outer conductor relies on a supercritical He (3 bar, 6K) counter flow heat exchanger [18]. The coupler prototypes have been build and are ready for conditioning with a 80kW IOT amplifier. ...
This paper reviews the RF power coupler developments for high intensity superconducting linacs. Pulsed high intensity proton linacs, continuous wave (CW) heavier ion linacs and energy recovery linacs (ERL) require high power couplers at various frequencies. The paper focuses on developments for which average power is mostly above 30 kW. PULSED H + /H -LINACS The development of superconducting high intensity pulsed proton linacs with duty cycles in the 1-10% range requires RF couplers to deal with high peak power, since cavities are foreseen to run at high gradient with high peak currents. The projects driving the choice of the coupler parameters are the European Spallation Source ESS [1] and the Superconducting Proton Linac Study (SPL) at CERN [2]. The average power is high enough that RF dissipation aspects have to be dealt with, both for thermal stability when the couplers are integrated on a cavity inside a cryostat, and for integrity of the components such as the ceramic window. The characteristics are more demanding than for the SNS with a nominal peak power for 550 kW, aiming to the 0.9 to 1.2 MW range. Most couplers developed as of now share common characteristics: they rely on a single coaxial RF window acting as a vacuum barrier at room temperature, also called warm window. The vacuum side of the ceramic is coated with TiN to reduce secondary electron generation in case of multipactor activity in the window and prevent charge build-up. Due to the frequency range they lie in (500 MHz to 1 GHz) a waveguide to coaxial transition ensures the connection to the power RF network rectangular waveguide. The inner conductor can be biased using DC high voltage to alter the electron activity behavior. To prevent potential problems with high power handling, bellows are generally avoided, because they are difficult to cool. Therefore active cooling of the outer conductor connecting to the cavity using He-gas is chosen to minimize the heat leak to the liquid He bath. The coupler instrumentation is of utmost importance for efficient and safe conditioning, then later for operation. During processing, the RF power increase is generally controlled comparing the pressure in the coupler to a threshold of the order of 10 -7 mbar. The pressure measurement serves as the primary interlock but is not fast enough to protect the coupler. Fast interlocks are provided by an electron pick up, and an arc detector installed close to the window. A large fraction of couplers developed at various frequencies are similar to KEK design for Tristan SC cavity later successfully adapted for KEK-B coupler which transfers daily the highest average power of 350 kW CW to a beam and operates for more than a decade [3]. Having a single warm window separated from the cavity axis by a typical distance of 0.5 m brings constraints on the design of cryomodules especially if they host more than two cavities, assembled in a clean room to form a string, together with couplers. Indeed the cavity string has to be inserted as a whole in the module vessel. This method is the most successful to avoid contamination of the SRF cavity surface which reduce their performance.
... R&D on Spoke cavities is also ongoing. A 352 MHz spoke cavity had been successfully tested at 4K and 2K in an "accelerator-like" horizontal cryostat configuration, fully equipped with its tuning system, magnetic shield, RF power coupler, and fed by a 10 kW solid-state amplifier [12]. These activities will be pursued, focusing on the detailed design of a MYRRHAlike spoke cryomodule. ...
The goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in an Accelerator Driven System (ADS) by building a new flexible irradiation complex in Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton flux of 4 mA CW operation. Such a machine belongs to the category of the high-power proton accelerators, with an additional requirement for exceptional reliability: because of the induced thermal stress to the subcritical core, the number of unwanted beam interruptions should be minimized down to the level of about 10 per 3-month operation cycle, a specification that is far above usual proton accelerators performance. This paper describes the reference solution adopted for such a machine, based on a so-called "fault-tolerant" linear superconducting accelerator, and presents the status of the associated R&D.
... The main linac is based on the combination of 352 MHz β=0.35 spokes resonators and two families of 5cell 704 MHz elliptical cavities at β=0.47 and 0.65. Prototypes of spokes and elliptical resonators have been build and tested in previous programs [56][57][58]. ...
The worldwide status of superconducting RF cavities and cryomodules for low velocity ion and proton particles is reviewed, with emphasis on the construction and tests of prototypes. A number of different multi-cell structures at a range of operating frequencies have been successfully realized. This review will cover the progress of several facilities under construction or being proposed.
World thorium reserves are approximately three times more abundant than the natural uranium reserves. Turkey is rich is thorium resources. Hence, thorium remains a potential energy source for future energy strategies in Turkey.
Large quantities of nuclear waste plutonium and minor actinides (MAs) have been accumulated in the civilian light water reactors (LWRs) and CANDU reactors. These trans uranium (TRU) elements are all fissionable, and thus can be considered as fissile fuel materials in form of mixed fuel with thorium or nat-uranium in the latter. CANDU fuel compacts made of tristructural-isotropic (TRISO) type pellets would withstand very high burn ups without fuel change.As carbide fuels allow higher fissile material density than oxide fuels, following fuel compositions have been selected for investigations: ① 90% nat-UC + 10% TRUC, ② 70% nat-UC + 30% TRUC and ③ 50% nat-UC + 50% TRUC. Higher TRUC charge leads to longer power plant operation periods without fuel change. The behavior of the criticality k∞ and the burn up values of the reactor have been pursued by full power operation for > ∼12 years. For these selected fuel compositions, the reactor criticality starts by k∞ = 1.4443, 1.4872 and 1.5238, where corresponding reactor operation times and burn up values have been calculated as 2.8 years, 8 years and 12.5 years, and 62, 430 MW.D/MT, 176,000 and 280,000 MW.D/MT, with fuel consumption rates of ∼16, 5.68 and 3.57 g/MW.D respectively. These high burn ups would reduce the nuclear waste mass per unit energy output drastically. The study has show clearly that TRU in form of TRISO fuel pellets will provide sufficient criticality as well as reasonable burn up for CANDU reactors in order to justify their consideration as alternative fuel.
