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[en] FAIR - the Facility for Antiproton and Ion Research is a new international accelerator facility which is built in Darmstadt, Germany. The core machines of the project are the superconducting synchrotron SIS100 and the superconducting fragment separator Super-FRS. Design and construction of superconducting machines require a comprehensive study of cases when the superconducting state is lost (quench). This dissertation covers two subjects. The first subject aims the development of a novel calculation tool (called GSI quench software) dedicated to the quench study of the FAIR magnets. Quench calculations done with the GSI software serve as an input for the proper design of SIS100 and Super-FRS quench detection and energy extraction systems. The software uses the unconditionally stable implicit scheme for the solution of the partial-differential equations that describe the thermal model of the coil. An innovative adaptive time stepping algorithm is used in order to limit the maximum temperature increase of the individual mesh elements to a predefined level. The thermal model of the coil gives the possibility to include the cooling by a liquid helium bath. The electrical circuit topology including the magnet protection system (energy extraction resistors and/or by-pass diodes) is implemented. The properties of the magnet's yoke are taken into account in the inductance function Ld(I). The implemented electro-thermal model was verified and validated by comparison to quench measurements conducted on SIS100 dipole and Super-FRS dipole prototypes. The testing campaign on the SIS100 dipole prototype (magnet training, quench propagation velocity, hot-spot temperature, MIITs, RRRCu, inductance, splice resistance, current leads) was performed in the scope of this work. The quench measurements on the Super-FRS dipole prototype were received from the FAIR China Group. The results of calculations performed with the GSI software are either in good agreement with the measurement data or they represent the worst case scenario, e.g. the calculated hot-spot temperature or quench voltage is higher than measured. The second subject concerns the design challenges of the SIS100 quench detection system. An outstanding cycling rate of the dipole circuit (4 T/s), high voltage (U0/U=1 kV/2 kV), radiation hardness required for the equipment to be installed in the accelerator tunnel (≥1 MGy) and long signal lines between the magnets and quench detection racks (up to 200 m) implies a customised design of the key components of the system. Selected contributions to the SIS100 quench detection system, concerning the reduction of the parasitic capacitance in the main magnet circuits (by utilising magnetic amplifiers and a new overlapping structure of balance bridges) and the development of a quench detector dedicated to corrector magnets (mutual inductance detector) are presented.
[en] After a presentation of some key figures characterising the organisation and process of the public debate launched by the French government on the Energy Multi-Year Programming (PPE), a first document describes the debate process and context (recall of the PPE, role of the public debate, preliminary meetings, limited means for the public debate, fruitful initiatives of the Commission, lessons learned from technical work groups, documentation published by interest groups, disputes about the Commission). Results are then discussed by describing how the law on energy transition is facing difficulties for its application, and how the law and associated authorities (ADEME, Ministry) have been disputed, and by outlining that, while suggesting improvement, the public kept on giving importance to the compromise present within the law. Recommendations are then made to the Ministry. Then, about two hundred documents are proposed, each one being a 'cahier d'acteur' (actor leaflet) published by the Commission, each issue being written by an actor involved in the energy sector (industrial actor, environmental association, and so on) and giving its opinion and propositions regarding the energy issue.
[en] Graphene oxide (GO) with a large surface area was synthesized by the direct growth of GO on porous alumina using chemical vapor deposition to study the Cs adsorption mechanism in aqueous solutions. Electronic structure analysis employing in situ near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy measurements clarifies the Cs atoms bond via oxygen functional groups on GO in the aqueous solution. The Cs adsorption capacity was found to be as high as 650–850 mg g−1, which indicates that the GO/porous alumina acts as an effective adsorbent with high adsorption efficiency for radioactive nuclides in aqueous solutions. (author)
[en] The main principles of the Finnish radioactive waste management program were fixed already in 1983 in a decision in principle (DiP) of the ministry of trade and industry. This Dip fixed the overall responsibilities, schedule and reporting principles of the radioactive waste producers covering the operational waste, spent nuclear fuel and decommissioning. One key principle of the decision was that the waste producers are themselves responsible for management of all the radioactive waste they produce, including the costs. The status of the program today is such that all the facilities are ready on site of the Nuclear Power Plants (NPPs) in Olkiluoto and Loviisa for management of the operational radioactive waste. Both nuclear power plant operators have their own waste treatment and storage facilities as well as own Low and Intermediate Level Waste (LILW) repositories in operation. The spent nuclear fuel is stored at the NPP sites as well. The spent fuel management program is organized through Posiva, a private company owned by the NPP operators Fortum and TVO. Just recently Posiva got a construction license for spent fuel encapsulation and final disposal facility. Decommissioning plans have also been prepared as requested by the DiP. Money for decommissioning is reserved in the radioactive waste fund and the aim is to dispose all decommissioning waste to the existing LILW repositories on site of the NPPs. In Finland the decommissioning plans cover only the radioactive parts of the NPPs. This paper summarizes the status of the radioactive waste management program in Finland, with the main focus on the radioactive waste and spent fuel produced at Loviisa NPP. It also presents some highlights of research and development program on radioactive waste management and gives an overview of the plans for the future decommissioning. (author)
[en] The Nuclear Waste Management Organization of Japan (NUMO) was established in October 2000 based on the 'Specified Radioactive Waste Final Disposal Act' as the authorized implementing entity approved by the Minister of Economy, Trade and Industry (METI). Our mission is the 'Realization of the Geological Disposal of Radioactive Waste'. Since its establishment, NUMO has been engaging in communication and research and development (R and D) to fulfill the mission. As a new initiative for enhancing the site selection process of geological disposal, Japanese government is now preparing for an announcement of the 'Nationwide Map of Scientific Features for Geological Disposal', which categorizes all areas in Japan into four categories. In such a situation, NUMO is working on raising awareness and enhancing understanding of the geological disposal project among the public. NUMO is also making efforts to listen to the opinions of the public on geological disposal to understand what the public concerns are. NUMO has been carrying out PR activities such as advertising on TV commercials and newspapers to raise public awareness of geological disposal. We are currently focusing on face to face communication activities such as holding seminars with small group discussions and outdoor events with a communication vehicle, 'Geo Mirai'. Utilizing other measures including cross-media advertisement, opinion surveys and press releases allows us to reach out a wide range of stakeholders in Japan. (author)
[en] We succeeded in growing single crystals of EuCu2(Ge1−xSix)2 (x = 0–1) by the Bridgman method using a Mo crucible and measured the electrical resistivity, specific heat, magnetic susceptibility, and magnetization, together with the electrical resistivity under pressure. EuCu2(Ge1−xSix)2 compounds follow the Doniach phase diagram as a function of the x content. Namely, EuCu2(Ge1−xSix)2 compounds exhibit antiferromagnetic ordering at a Néel temperature of TN = 15 K in EuCu2Ge2 (x = 0), a maximum of TN ≃ 20 K at x ≃ 0.5, TN → 0 at x ≃ 0.7, and a moderate heavy-fermion state at x = 0.8 and 1 (EuCu2Si2). The present result is reasonably consistent with the previous studies carried out using arc-melted polycrystal samples. A similar change in the electronic states was also found to be realized under pressure P for x = 0, 0.45, and 0.6. The Néel temperature of TN = 15 K for x = 0 (EuCu2Ge2) increases slightly as a function of pressure, at a rate of dTN/dP = 3.0 K/GPa, reaches a maximum of TN = 27 K at around 5–6 GPa, decreases steeply, and becomes zero at a critical pressure of Pc ≃ 7 GPa. A moderate heavy-fermion state is realized at 8 GPa. Similar results were also obtained for x = 0.45 and 0.6, with smaller critical pressures of Pc ≃ 4.5 and 2 GPa, respectively. (author)
[en] Peer Review of nuclear power plants is performed by the World Association of Nuclear Operators (WANO) and other organizations. Domestic Electric Power Companies which own PWR and Nuclear Power Training Center, Ltd (NTC) established the 'Operato performance Review Working Group' in FY2016 in order to recommendation on operator performance indicated in the peer review. The working group made the training materials on Human Performance Tools aiming the improvement of performance for the operators. We will introduce about the results of the working group and reflection to further training. (author)
[en] We developed a new technique for measuring the thermodynamic entropy as a function of the magnetic field angle. This technique enables high-resolution angle-resolved measurements of the entropy in an unprecedentedly short measuring time. When the magnetic field is rotated under adiabatic conditions, the sample temperature changes owing to the field-angle variation of its entropy, which is referred to as the rotational magnetocaloric effect. By investigating this effect along with the specific heat, the field-angle dependence of the entropy can be determined. To demonstrate this technique, we chose the spin-ice compound Dy2Ti2O7 as a benchmark and showed good agreement between the measured and theoretical entropies as a function of the field angle. This development provides a new approach to studying condensed-matter physics, in which multiple degrees of freedom play an important role. (author)
[en] Axially variable strength control rods (AVSCRs) are suggested and developed as a solution to problems related with the variation of the axial power distribution during the power maneuvering of PWRs and to accomplish the power maneuvering with only control rods and without reactivity compensation by boron concentration change. AVSCRs are control rods that, unlike conventional control rods, have axially non-uniform strength. In a typical nuclear power plant, reactor power change is caused by variation of reactivity. Two primary mechanisms for reactivity changes are control rods and soluble boron. Moderator temperature control is an auxiliary means. During the power maneuvering of a nuclear power plant, the reactor core is in a transient state and the axial power distribution should be maintained within some prescribed range in order to prevent a xenon oscillation. However, there are difficulties involved in regulating axial power distribution within the prescribed range during reactivity change using conventional mechanisms. AVSCRs are suggested as a method of ameliorating these difficulties. Control rods are classified into two types: 'multi-purpose control rod' and 'regulating control rod'. Two multi-purpose control rod banks (AVSCR1, AVSCR2) are newly developed, while conventional control rods are adopted as regulating control rod banks to minimize design change of PWRs. The newly developed AVSCRs are axially three sectioned control rods, and the worth shapes of these AVSCRs are optimized to obtain appropriate moving characteristics for power maneuvering. As analytic objective functions do not exist in the optimization of the AVSCRs, the simulation optimization methodology is used. Then, an operation strategy employing developed AVSCRs for the power maneuvering is developed. This strategy consists of simple logics and no use of reactivity compensation by boron is considered. Finally, the AVSCRs are applied to power maneuvering with a typical 100-50-100%, 2-6-2-14h pattern of daily load-follow power maneuvering and all burn-up states of the core are considered for the application. From the application results, it is shown that the use of AVSCRs makes it possible to regulate the axial offset (AO) within the target band during the power maneuvering with only control rods. Consequently, the power maneuvering of PWR is accomplished without reactivity compensation by boron concentration change. It is also identified that AVSCRs can cover the whole burn-up states of reactor core
[en] For safeguards of pyroprocessing, destructive analysis (DA) is required for nuclear material accountancy (NMA) and sampling is essential for DA measurement. However, study of sampling approach has not been performed and there are several technical issues due to the high radiation and temperature of pyroprocessing. The form of input material is SF oxide powder and samples are taken from homogenization mixer during the pre-treatment process. KAERI developed the double stage homogenization concept and the tests were performed with metal oxide powders. In this study, design requirements of sampling system and potential sampling methods for various types if sample were investigated. The design requirements of the sampling system and potential sampling methods were investigated. However, this study is a fundamental research and further research on developing the sampling methods for various forms of waste and specific conceptual design of automated sampling devices will be performed