Nuclear Waste Transmutation Research Articles

RF properties of 700 MHz, β = 0.42 elliptical cavity for high current proton acceleration

BARC is developing a technology for the accelerator-driven subcritical system (ADSS) that will be mainly utilized for the transmutation of nuclear waste and enrichment of U233. Design and development of superconducting medium velocity cavity has been taken up as a part of the accelerator-driven subcritical system project. We have studied RF properties of 700 MHz, β = 0.42 single cell elliptical cavity for possible use in high current proton acceleration. The cavity shape optimization studies have been done using SUPERFISH code. A calculation has been done to find out the velocity range over which this cavity can accelerate protons efficiently and to select the number of cells/cavity. The cavity’s peak electric and magnetic fields, power dissipation P c , quality factor Q and effective shunt impedance ZT 2 were calculated for various cavity dimensions using these codes. Based on these analyses a list of design parameters for the inner cell of the cavity has been suggested for possible use in high current proton accelerator.

China Spallation Neutron Source: Design, R&D, and outlook

The China Spallation Neutron Source (CSNS) is an accelerator based multidiscipline user facility planned to be constructed in Dongguan, Guangdong, China. The CSNS complex consists of an negative hydrogen linear accelerator, a rapid cycling proton synchrotron accelerating the beam to 1.6 GeV energy, a solid tungsten target station, and instruments for spallation neutron applications. The facility operates at 25 Hz repetition rate with an initial design beam power of 120 kW and is upgradeable to 500 kW. The primary challenge is to build a robust and reliable user's facility with upgrade potential at a fraction of “world standard” cost. We report the status, design, R&D, and upgrade outlook including applications using spallation neutron, muon, fast neutron, and proton, as well as related programs including medical therapy and accelerator-driven sub-critical reactor (ADS) programs for nuclear waste transmutation.

Transmutation of nuclear wastes using photonuclear reactions triggered by Compton backscattering photons at the Shanghai laser electron gamma source**Supported by Knowledge Innovation Project of Chinese Academy of Sciences (KJCX2-SW-N13), China Postdoctoral Science Foundation, National Natural Science Foundation of China (10475108, 10605036, 10405032), One Hundred Person Project of SINAP, and Shanghai Development Foundation for Science and Technology (06QA14062)

Based on the facility of the Shanghai Laser Electron Gamma Source (SLEGS), the transmutation for nuclear wastes such as 137Cs and 129I is investigated. It is found that nuclear waste can be transmuted efficiently via photonuclear reaction triggered by gamma photons generated from Compton backscattering between CO2 laser photons and 3.5 GeV electrons. The nuclear activities of 137Cs and 129I are evaluated and compared with the results of transmutation triggered by bremsstrahlung gamma photons driven by ultra intense laser. Due to the better character of gamma photon spectrum as well as the high brightness of gamma photons, the transmutation rate of Compton backscattering method is much higher than that of the bremsstrahlung method.

Dynamic compensation of an rf cavity failure in a superconducting linac

An accelerator driven system (ADS) for transmutation of nuclear waste typically requires a 600 MeV--1 GeV accelerator delivering a proton flux of a few mA for demonstrators, and of a few tens of mA for large industrial systems. 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 trips'' should not exceed a few per year, a specification that is several orders of magnitude above usual performance. In order to meet this extremely high reliability, the accelerator needs to implement, to the maximum possible extent, a fault-tolerance strategy that would allow beam operation in the presence of most of the envisaged faults that could occur in its beam line components, and in particular rf systems' failures. This document describes the results of the simulations performed for the analysis of the fault-tolerance capability of the XT-ADS superconducting linac in the case of an rf cavity failure. A new simulation tool, mixing transient rf behavior of the accelerating cavities with full 6D description of the beam dynamics, has been developed for this purpose. Fast fault-recovery scenarios are proposed, and required research and development is identified.

Fusion–fission hybrids for nuclear waste transmutation: A synergistic step between Gen-IV fission and fusion reactors

Energy demand and GDP per capita are strongly correlated, while public concern over the role of energy in climate change is growing. Nuclear power plants produce 16% of world electricity demands without greenhouse gases. Generation-IV advanced nuclear energy systems are being designed to be safe and economical. Minimizing the handling and storage of nuclear waste is important. NIF and ITER are bringing sustainable fusion energy closer, but a significant gap in fusion technology development remains. Fusion–fission hybrids could be a synergistic step to a pure fusion economy and act as a technology bridge. We discuss how a pulsed power-driven Z-pinch hybrid system producing only 20 MW of fusion yield can drive a sub-critical transuranic blanket that transmutes 1280 kg of actinide wastes per year and produces 3000 MW. These results are applicable to other inertial and magnetic fusion energy systems. A hybrid system could be introduced somewhat sooner because of the modest fusion yield requirements and can provide both a safe alternative to fast reactors for nuclear waste transmutation and a maturation path for fusion technology. The development and demonstration of advanced materials that withstand high-temperature, high-irradiation environments is a fundamental technology issue that is common to both fusion–fission hybrids and Generation-IV reactors.

RF properties of 1050 MHz, β = 0.49 Elliptical cavity for High Current Proton Acceleration

BARC is developing technology for the accelerator driven subcritical system (ADSS) that will be mainly utilized for the transmutation of nuclear waste and enrichment of U233. Design and development of superconducting medium velocity cavity has been taken up as a part of the accelerator driven subcritical system project. We have studied RF properties of 1050 MHz, β = 0.49 single cell Elliptical cavity for possible use in High Current Proton Accelerator. Cavity shape optimization studies have been done by means of 2D cavity tuning code SUPERFISH and 3D High Frequency Simulation code CST Microwave Studio. The cavity peak electric and magnetic fields, power dissipation Pc, quality factor Q and effective shunt impedante ZT2 were calculated for various cavity dimensions using these codes. Based on these analyses a list of design parameter for the inner cell of the cavity has been suggested for possible use in high current proton accelerator.

Dynamic response of an accelerator driven system to accelerator beam interruptions for criticality

Subcritical nuclear reactors driven by intense neutron sources can be very suitable tools for nuclear waste transmutation, particularly in the case of minor actinides with very low fractions of delayed neutrons. A proper control of these systems needs to know at every time the absolute value of the reactor subcriticality (negative reactivity), which must be measured by fully reliable methods, usually conveying a short interruption of the accelerator beam in order to assess the neutron flux reduction. Those interruptions should be very short in time, for not disturbing too much the thermal magnitudes of the reactor. Otherwise, the cladding and the fuel would suffer from thermal fatigue produced by those perturbations, and the mechanical integrity of the reactor would be jeopardized. It is shown in this paper that beam interruptions of the order of 400 μs repeated every second would not disturb significantly the reactor thermal features, while enabling for an adequate measurement of the negative reactivity.

Monte Carlo studies in accelerator-driven systems for transmutation of high-level nuclear waste

A spallation neutron source was modeled using a high energy proton accelerator for transmutation of 239Pu, minor actinides 237Np, 241Am and long-lived fission products 99Tc, 129I, which are created from the operation of nuclear power reactors for the production of electricity. The acceleration driven system (ADS) is composed of a natural lead target, beam window, subcritical core, reflector, and structural material. The neutrons are produced by the spallation reaction of protons from a high intensity linear accelerator in the spallation target, and the fission reaction in the core. It is used a hexagonal lattice for the waste and fuel assemblies. The system is driven by a 1 GeV, 10 mA proton beam incident on a natural lead cylindrical target. The protons were uniformly distributed across the beam. The core is a cylindrical assembly. The main vessel is surrounded by a reflector made of graphite. The axes of the proton beam and the target are concentric with the main vessel axis. The structural walls and the beam window are made of the same material, stainless steel, HT9. We investigated the following neutronics parameters: spallation neutron and proton yields, spatial and energy distribution of the spallation neutrons, and protons, heat deposition, and the production rates of hydrogen and helium, transmutation rate of minor actinides and fission products. In the calculations, the Monte Carlo code MCNPX, which is a combination of LAHET and MCNP, was used. To transport a wide variety of particles, The Los Alamos High Energy Transport Code (LAHET) was used.

European research on HLM thermal-hydraulics for ADS applications

The objective of the European 6th framework project EUROTRANS is to demonstrate the technical feasibility of transmutation of high level nuclear waste using accelerator driven systems. Within this objective the design of a European experimental ADS should demonstrate the technical feasibilities to transmute a sizeable amount of waste and to operate an ADS safely. This ADS will be a subcritical reactor system having liquid lead–bismuth eutectic as coolant. The liquid lead–bismuth eutectic is also intended to serve as target material for the spallation reaction which forms a crucial part to the subcritical reactor core. Since lead–bismuth eutectic is used as core coolant and spallation material, knowledge of its thermal hydraulic behaviour is essential. Within the DEMETRA domain of the EUROTRANS project, basic thermal hydraulic studies in order to support the design and safety analysis of XT-ADS components and the development of measurement techniques have been started.

CFD analysis of the HYPER spallation target

KAERI (Korea Atomic Energy Research Institute) is developing an accelerator driven system (ADS) named HYPER (HYbrid Power Extraction Reactor) for a transmutation of long-lived nuclear wastes. One of the challenging tasks for the HYPER system is to design a large spallation target with a beam power of 15–25 MW. The paper focuses on a thermal–hydraulic analysis of the active part of the HYPER target. Computational fluid dynamics (CFD) analysis was performed by using a commercial code CFX 5.7.1. Several advanced turbulence models with different grid structures were applied. The CFX results reveal a significant impact of the turbulence model on the window temperature. Particularly, the k– ε model predicts the lowest window temperature among the five investigated turbulence models.

Suitability of Small Scale Linear Systems for a Fission–Fusion Reactor, Breeder, and Waste Transmutation

To date the magnetic fusion effort has been almost entirely devoted to only one application, that being a multi gigawatt central station electric plant. Given the already well established fission based industry, the likelihood that fusion will have any impact on curbing the current carbon-based energy demand in the 21st century is slim. This paper advocates that the first and primary use of fusion neutrons should be as the driver for a sub-critical fission nuclear energy system—a fission–fusion hybrid reactor. This system can also be utilized to transmute long-lived radioactive wastes, and breed fissile nuclear fuel for several additional fission reactors. A small-scale fusion system based on a reciprocating fusion cycle employing the magneto-kinetic compression of the Field Reversed Configuration (FRC) is particularly well suited for this application. The characteristics of this fusion neutron driver and the potential for transmutation of long-lived nuclear wastes and breeding of fissile nuclear fuel in a blanket are presented.

Transmutation of nuclear waste in accelerator-driven systems: Fast spectrum

The elimination of nuclear waste is currently a pressing issue in view of the global energy crisis and increasing radiotoxic waste inventories. One potential and well-researched solution to these issues is to transmute nuclear waste in a thorium-based accelerator-driven system, such as the energy amplifier. To develop this technology a prototype capable of transmuting significant quantities of radioactive waste is needed. The proposed energy amplifier demonstration facility (EADF), a lead–bismuth cooled 80 MW th device, is designed to couple all the elements of an accelerator-driven system (ADS), producing large fast-neutron fluxes capable of transmuting kilograms of individual isotopes. This paper presents an investigation of the neutronic characterisation, safety parameters, dynamic behaviour and transmutation potential of such a device when using the plutonium–uranium fuel proposed. These results are compared with those when using thorium–plutonium fuel, demonstrating the advantages of the latter in terms of waste transmutation.

Transmutation of nuclear waste in accelerator-driven systems: Thermal spectrum

The TRIGA accelerator-driven experiment is a milestone in the roadmap towards the demonstration of the transmutation of nuclear waste in accelerator-driven systems (ADSs). It is designed in such a way as to couple the different components of an ADS in a realistic environment by using an existing critical reactor adapted to the experiment’s objectives, at significant power levels. This paper summarises the neutronic characterisation of the system, an essential step in the design and licensing process. The feasibility of the experiment is demonstrated, establishing the sub-criticality levels of operation and fuel rod configurations. The analyses of the neutron distribution in space, energy and time detail the behaviour of a real-power thermal ADS and identify the extent and limitations for the experimental programme. Studies investigating the potential of such a system to transmute transuranics and long-lived fission fragments demonstrate the need to move to fast neutron systems in order to efficiently transmute these major components of nuclear waste.

Light charged-particle production in 96 MeV neutron-induced reactions on carbon and oxygen

In recent years, an increasing number of applications involving fast neutrons have been developed or are under consideration, e.g. radiation treatment of cancer, neutron dosimetry at commercial aircraft altitudes, soft-error effects in computer memories, accelerator-driven transmutation of nuclear waste and energy production and determination of the response of neutron detectors. Data on light-ion production in light nuclei such as carbon, nitrogen and oxygen are particularly important in calculations of dose distributions in human tissue for radiation therapy at neutron beams, and for dosimetry of high-energy neutrons produced by high-energy cosmic radiation interacting with nuclei (nitrogen and oxygen) in the atmosphere. When studying neutron dose effects, it is especially important to consider carbon and oxygen, since they are, by weight, the most abundant elements in human tissue. Preliminary experimental double-differential cross sections of inclusive light-ion (p, d, t, (3)He and alpha) production in carbon induced by 96-MeV neutrons have been presented. Energy spectra were measured at eight laboratory angles: 20, 40, 60, 80, 100, 120, 140 and 160 degrees. Measurements were performed at The Svedberg Laboratory (TSL), Uppsala, using the dedicated MEDLEY experimental setup. The authors have earlier reported experimental double-differential cross sections of inclusive light-ion production in oxygen. In this paper, the deduced kerma coefficients for oxygen has been presented and compared with reaction model calculations.

Reducing radiotoxicity in the long run

Stockpiles of spent nuclear fuel and weapons material are growing worldwide. So far, the only long-term strategy seriously considered is geological repository for several hundred thousand years. Transmutation is an option significantly reducing the time during which repositories have to be sealed, simplifying the task of protecting future generations from the radioactive remnants of our civilisation. This paper gives an overview of motives and priorities, and describes the main technique suggested for transmutation of nuclear waste.

Defects characterization of welded specimens by transmission electron microscopy

Austenitic Type 304L stainless steel (SS) and martensitic Alloy EP-823 have been identified as candidate structural materials to contain spallation target for transmutation of nuclear waste. Welded specimens consisting of either or both materials have been evaluated by transmission electron microscopy (TEM) to determine the dislocation density near the heat-affected-zone (HAZ) and the base material. The results indicate that the average dislocation density determined from the TEM micrographs taken at different locations was much higher near HAZ compared to that of the base material. Further, the estimated dislocation density was higher on the Alloy EP-823 side of the weld than that of the Type 304L SS side possibly due to the faster rate of solidification of the martensitic alloy. Higher dislocation density is an indication of enhanced residual stress resulting from the welding operation.

Transmutation of radioactive nuclear waste — present status and requirement for the problem-oriented nuclear data base

Transmutation of long-lived actinides and fission products becomes an important issue of the overall nuclear fuel cycle assessment, both for existing and future reactor systems. Reliable nuclear data are required for analysis of associated neutronics. The present paper gives a review of the status of nuclear data analysis focusing on the waste transmutation problem.

The GDT as Neutron Source in a Sub-Critical System for Transmutation

In the last decade, a great progress was made in developing projects of sub-critical fission systems dedicated to transmutation of nuclear waste. In contrast to a fission reactor, such a device is fed with neutrons from an outer source in order to sustain a steady-state power generation. The Budker Institute of Nuclear Physics has made the proposal of a powerful 14 MeV neutron source based on a gas dynamic trap (GDT). This neutron source is primarily thought as irradiation facility for fusion material research. So, the question raises, whether the GDT based neutron source could be a candidate to efficiently drive such a sub-critical system too. The contribution pursues this question using results of first neutron transport calculations. The calculations were made for a simplified model of an actinides burner, which has been developed for an international benchmark exercise performed under the auspices of the Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development (OECD). Important parameters of the burner are compared for two cases - when driven by a spallation or by the GDT neutron source. From this comparison some advices for further improvements of the GDT neutron source are concluded.

ICONE15-10138 PRELIMINARY ANALYSIS OF TYPICAL TRANSIENTS IN FUSION DRIVEN SUBCRITICAL SYSTEM (FDS-I)

The potential safety characteristic is expected as one of the advantages of fusion-driven subcritical system (FDS-I) for the transmutation and incineration of nuclear waste compared with the critical reactor. Transients of the FDS-I may occur due to the perturbation of external neutron source, the failure of functional device, and the occurrence of the uncontrolled event. As typical transient scenarios, the following cases were analyzed: unprotected plasma overpower (UPOP), unprotected loss of flow (ULOF), unprotected transient overpower (UTOP). The transient analyses for the FDS-I were performed with a coupled two-dimensional thermal-hydraulics and neutronics transient analysis code NTC2D. The negative feedback of reactivity is the interesting safety feature of FDS-I as temperature increase, due to the fuel form of the circulating particle. The present simulation results showed that the current FDS-I design has a resistance against severe transient scenarios.

Laboratory Portrait: The Bordeaux Nuclear Research Center

The Centre d'Etudes Nucléaires at Bordeaux-Gradignan (CENBG) is a joint research unit of the CNRS/IN2P3 and the University Bordeaux 1 “Science and Technology.” The laboratory is composed of 35 permanent researchers (half of them are employed by the University), 40 permanent engineers and technicians, and about 15 Ph.D. students, post-docs, and visitors. The scientific program covers a broad range of topics in nuclear physics, particle physics, and astroparticle physics as well as applications of subatomic physics to different multidisciplinary fields. The main research subjects are: exotic nuclei far from the valley of beta stability and rare radioactive decays, neutrino physics (type and mass of the neutrino) and double beta decay, high energy gamma ray astronomy, innovative approaches to nuclear power generation and transmutation of nuclear waste, laser-induced nuclear excitations, the effects of various environmental exposures studied via macro-, micro-, or nano-ion beams using the new platform AIFIRA and finally theoretical studies of nuclear and hadronic matter. All these activities take place within strong national and international collaborations involving the academic world and enabling the selection and training of high-quality students and post-doctoral researchers.