Synopsis and outcome of the QUENCH experimental program

The paper gives an overview of the main outcome of the QUENCH program launched in 1997 at the Karlsruhe Institute of Technology (KIT), formerly Karlsruhe Research Center (FZK). The research program comprises bundle experiments as well as complementary separate-effects tests. The focus of the experiments performed from 1997 to 2009 was on scenarios of severe accidents whereas that of the future test program will be on large-break loss-of-coolant accidents (LOCA) in the frame of design-basis accidents, and debris coolability, in the frame of severe accidents. The major objective of the program is to deliver experimental and analytical data to support the development and validation of quench and quench-related models as used in code systems that model severe accident progression in light water reactors.So far, 15 integral bundle QUENCH experiments with 21-31 electrically heated fuel rod simulators of 2.5 m length have been conducted. The following parameters and their influence on bundle degradation and reflood have been investigated: degree of pre-oxidation, temperature at initiation of reflood, flooding rate, influence of neutron absorber materials (B₄C, AgInCd), air ingress, and influence of the type of cladding alloy.In six tests, reflooding of the bundle led to a temporary temperature excursion driven by runaway oxidation of zirconium alloy components and resulting in release of a significant amount of hydrogen, typically two orders of magnitude greater than in those tests with “successful” quenching in which cool-down was rapidly achieved. Considerable formation, relocation, and oxidation of melt were observed in all tests with escalation. The temperature boundary between rapid cool-down and temperature escalation was typically in the range of 2100-2200 K in the “normal” quench tests, i.e. in tests without absorber and/or steam starvation. Tests with absorber and/or steam starvation were found to lead to temperature escalations at lower temperatures.All phenomena occurring in the bundle tests have been investigated additionally in parametric and more systematic separate-effects tests. Oxidation kinetics of various cladding alloys, including advanced ones, have been determined over a wide temperature range (873-1773 K) in different atmospheres (steam, oxygen, air, and their mixtures). Hydrogen absorption by different zirconium alloys was investigated in detail, recently also using neutron radiography as non-destructive method for determination of hydrogen distribution in claddings. Furthermore, degradation mechanisms of absorber rods including B₄C and AgInCd as well as the oxidation of the resulting low-temperature melts have been studied. Steam starvation was found to cause deterioration of the protective oxide scale by thinning and chemical reduction.The most recent topic of the QUENCH program has been investigation of the behavior of advanced cladding materials (ACM) in comparison with the classical Zircaloy-4. Although separate-effects tests have shown some differences in oxidation kinetics, the influence of the various cladding alloys on the integral bundle behavior during oxidation and reflooding was only limited.     

Portuguese research program on nuclear fusion

The Portuguese research program on nuclear fusion is presented. The experimental activity associated with the tokamak ISTTOK as well as the work carried out in the frame of international collaboration are summarized. Future plans are briefly described.     

A strategic framework for the magnetic fusion energy program

Fusion is recognized as a sufficiently abundant and environmentally attractive energy source to sustain industrial society in the 21st century and beyond. This paper outlines a strategic framework for the U.S. magnetic fusion program that builds substantially on the high-quality research and the strong scientific and technological basis that has been established during the past two decades.     

The role of radiation damage analysis in the fusion program

The objective of radiation damage analysis is the prediction of the performance of facility components exposed to a radiation environment. The US Magnetic Fusion Energy materials program includes an explicit damage analysis activity within the Damage Analysis and Fundamental Studies (DAFS) Program. Many of the papers in these Proceedings report work done directly or indirectly in support of the DAFS program. The emphasis of this program is on developing procedures, based on an understanding of damage mechanisms, for applying data obtained in diverse radiation environments to the prediction of component behavior in fusion devices. It is assumed that the Fusion Materials Irradiation Test Facility will be available in the late 1980s to test (and calibrate where necessary) correlation procedures to the high fluences expected in commercial reactors.     

Review of the magnetic fusion program by the 1986 ERAB Fusion Panel

The 1986 ERAB Fusion Panel finds that fusion energy continues to be an attractive energy source with great potential for the future, and that the magnetic fusion program continues to make substantial technical progress. In addition, fusion research advances plasma physics, a sophisticated and useful branch of applied science, as well as technologies important to industry and defense. These factors fully justify the substantial expenditures by the Department of Energy in fusion research and development (R&D). The Panel endorses the overall program direction, strategy, and plans, and recognizes the importance and timeliness of proceeding with a burning plasma experiment, such as the proposed Compact Ignition Tokamak (CIT) experiment.Presented to the Magnetic Fusion Advisory Committee (La Jolla, California, December 4, 1986)     

End product economics and fusion research program priorities

It is shown that deuterium based fusion fuels and reactors based on them face severe technological disadvantages in comparison with fission based systems as power sources for central station electric power plants. The author postulates the most plausible deuterium based fusion reactor consistent with the physics of the fusion reaction itself and compares this reactor (called OMR-DT) with existing fission reactors. Since neutrons are the main problem in fusion, the author suggests that a great deal more effort should be given to the study of non-Maxwellian plasmas with the emphasis on neutron-free fuel cycles. The author also suggests that the deuterium based fusion driver may play its best role as a fissile fuel producer.     

European passive plant program: A design for the 21st century

In 1994, a group of European utilities initiated, together with Westinghouse and its industrial partner GENESI (an Italian consortium including ANSALDO and FIAT), a program designated EPP (European Passive Plant) to evaluate Westinghouse passive nuclear plant technology for application in Europe. The following major tasks were accomplished: (1) the impacts of the European utility requirements (EUR) on the Westinghouse nuclear island design were evaluated; and (2) a 1000 MWe passive plant reference design (EP1000) was established which conforms to the EUR and is expected to be licensable in Europe. With respect to safety systems and containment, the reference plant design closely follows that of the Westinghouse simplified pressurized water reactor (SPWR) design, while the AP600 plant design has been taken as the basis for the EP1000 reference design in the auxiliary system design areas. However, the EP1000 design also includes features required to meet the EUR, as well as key European licensing requirements.     

Winding machines for the manufacturing of superconductive coils of the main European fusion research machines

The successfull construction of large magnets passes through the development and application of non-conventional manufacturing processes.A difficult and delicate step in the manufacturing of superconducting coils is the conductor winding technique. It is often a challenging and technologically advanced process, developed according to the requirements of each project.An important aspect during the winding is to avoid any deformation of the cable cross section leading to a damage of the strands and to maintain the design features of the cable.A second aspect is to assure the suitable repeatability and a production rate for an industrial process.The winding line is a system of different machines linked and tuned together properly designed for each project.An adapted software assures the overall process control.TPA realized for ANSALDO Superconduttori the winding lines for many projects: TFMC (NET-TEAM), CMS (INFN-CERN), WENDELSTEIN W7-X (Max Planck Institute, IPP), etc.The experience acquired in this field by ANSALDO Superconduttori and by TPA (as manufacturing tools and equipments supplier) has been acknowledged by CERN with “The CMS Gold Award” of the Year 2004. The paper describes the main features of the winding lines, the main problems, the technical solutions used for the above mentioned projects and the new ideas for the forthcoming ones.     

Fusion for Energy: A new European organization for the development of fusion energy

The European Joint Undertaking for ITER and the Development of Fusion Energy or (“Fusion for Energy” of F4E for short) is a new organisation that has been established with the main objective of providing Europe's contribution to the ITER International Organisation (IO) as its Domestic Agency. Fusion for Energy is also the Implementing Agency for the Broader Approach projects being carried out with Japan and, in the longer term, will prepare a programme for the construction of demonstration fusion reactors (DEMO). The threefold mission of Fusion for Energy is consistent with the fast track strategy for the realisation of fusion energy. This paper aims to provide an overview of the current status of Fusion for Energy and highlight some of the opportunities available for research organisations and industry to participate.     

Recent progress of NSTX lithium program and opportunities for magnetic fusion research

Lithium wall coating techniques have been experimentally explored on National Spherical Torus Experiment (NSTX) for the last six years. The lithium experimentation on NSTX started with a few milligrams of lithium injected into the plasma as pellets and it has evolved to a dual lithium evaporation system which can evaporate up to ～160 g of lithium onto the lower divertor plates between re-loadings. The unique feature of the NSTX lithium research program is that it can investigate the effects of lithium coated plasma-facing components in H-mode divertor plasmas. This lithium evaporation system has produced many intriguing and potentially important results. In 2010, the NSTX lithium program has focused on the effects of liquid lithium divertor (LLD) surfaces including the divertor heat load, deuterium pumping, impurity control, electron thermal confinement, H-mode pedestal physics, and enhanced plasma performance. To fill the LLD with lithium, 1300 g of lithium was evaporated into the NSTX vacuum vessel during the 2010 operations. The routine use of lithium in 2010 has significantly improved the plasma shot availability resulting in a record number of plasma shots in any given year. In this paper, as a follow-on paper from the 1st lithium symposium [1], we review the recent progress toward developing fundamental understanding of the NSTX lithium experimental observations as well as the opportunities and associated R&D required for use of lithium in future magnetic fusion facilities including ITER.     

From patronage to partnership: Toward a new industrial policy for the fusion program

This report is part of a Department of Energy assessment of the government's policy toward industrial involvement in the nation's fusion program. It was informally commissioned by the Offices of Energy Research and Magnetic Fusion Energy to seek and to evaluate the opinion of experts on the subject and to provide exposure to issues that might otherwise be obscured by the natural tendency of institutions to protect themselves and their clients. Because it was not formally chartered, it was not obliged to seek consensus. All views and opinions are solely those of its author.     

Evolution of the ITER program and prospect for the next-step fusion DEMO reactors: status of the fusion energy R&D as ultimate source of energy

An international joint project of fusion experimental reactor, the ITER (International Thermonuclear Experimental Reactor), is reviewed in view of long-range fusion energy research and development (R&D). Its purpose, goal, evolution, and the present construction status are briefly reviewed. While the ITER is a core machine in the present stage, generation of electricity is a role of the next-step fusion demonstration power plant “DEMO.” The status of designs and technology R&D for DEMO are also reviewed.     

ATCA/AXIe compatible board for fast control and data acquisition in nuclear fusion experiments

An in-house development of an Advanced Telecommunications Computing Architecture (ATCA) board for fast control and data acquisition, with Input/Output (IO) processing capability, is presented. The architecture, compatible with the ATCA (PICMG 3.4) and ATCA eXtensions for Instrumentation (AXIe) specifications, comprises a passive Rear Transition Module (RTM) for IO connectivity to ease hot-swap maintenance and simultaneously to increase cabling life cycle.The board complies with ITER Fast Plant System Controller (FPSC) guidelines for rear IO connectivity and redundancy, in order to provide high levels of reliability and availability to the control and data acquisition systems of nuclear fusion devices with long duration plasma discharges.Simultaneously digitized data from all Analog to Digital Converters (ADC) of the board can be filtered/decimated in a Field Programmable Gate Array (FPGA), decreasing data throughput, increasing resolution, and sent through Peripheral Component Interconnect (PCI) Express to multi-core processors in the ATCA shelf hub slots. Concurrently the multi-core processors can update the board Digital to Analog Converters (DAC) in real-time. Full-duplex point-to-point communication links between all FPGAs, of peer boards inside the shelf, allow the implementation of distributed algorithms and Multi-Input Multi-Output (MIMO) systems. Support for several timing and synchronization solutions is also provided.Some key features are onboard ADC or DAC modules with galvanic isolation, Xilinx Virtex 6 FPGA, standard Dual Data Rate (DDR) 3 SODIMM memory, standard CompactFLASH memory card, Intelligent Platform Management Controller (IPMC), two PCI Express x4 (generation 2) ATCA Fabric channels (dual-star topology), eleven Xilinx Aurora x1 (or other ATCA compatible communications protocol) ATCA fabric channels (full-mesh topology) and two Fast Ethernet (Precision Time Protocol – PTP IEEE1588-V2 and Lan eXtensions for Instrumentation – LXI compatible) ATCA base channels (dual-star topology).