Structural materials assessment

The selection of first wall and structural materials is strongly dependent on the proposed design of breeding blanket components and the targets for a fusion reactor development. An envelope of parameters which have to be covered in future R and D activities and which have been adapted in different proposals has been compiled. A short description of interesting material groups like ferritic-martensitic steels, vanadium alloys and ceramic composites, major criteria for their selection and a survey on existing irradiation data is given. This is followed by a comparative assessment of relevant properties and an identification of major issues for each material group. A more detailed proposal for the future R and D activities is then developed for the ferritic-martensitic steels, the present reference material for the European Breeding Blankets. It describes different phases of development necessary for the qualification of this material for DEMO and gives time schedules which are compatible with parallel component developments. A more selective strategy is proposed for the development of vanadium alloys and the ceramic composite material SiC/SiC. For these alternatives work should be concentrated on identified high-risk issues, before a comprehensive development programme is started. The necessity of efficient irradiation facilities to study the irradiation behaviour of the materials under simulation - and realistic fusion conditions is discussed. The availability of high flux fission reactors and necessary extensions of irradiation rigs for the next decade is stressed. Finally it is shown that for the qualification of materials under realistic fusion conditions a high-energetic, high-flux neutron source is mandatory. An accelerator-driven d-Li neutron source (IFMIF) can fulfil essential users requirements as test bed for materials and can technically be made available in due time. In combination with ITER and DEMO, where a concept verification and full scale reliability tests of breeding blanket components can be performed appropriate and efficient tools would be available to develop materials and components towards a fusion reactor. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6332) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Einfluss von Deltaferrit und Karbiddendriten auf die Zug- und Kerbschlageigenschaften martensitischer Chromstaehle

Martensitic chromium steels with high content of chromium incline to form deltaferrite frequently accompanied by massive dendritic carbide precipitations. Both phases mostly influence the mechanical properties of this steel in countercurrent manner. The relative weak deltaferrite causes an increase of ductility and toughness, whilst the brittle carbide dendrites decreases both. Both phases mostly decrease the strength of the steel. One or the other influence will dominate in dependence of the quantitative relation of the two phases. This is the cause for very different statements in the literature. The carbide dendrites should be avoided using a cooling rate of more than 10"3 K/min after the austenitization, becauce this phase mostly impairs the mechanical properties of the steel. However, the deltaferrite without carbide dendrites can be tolerated mostly. (orig.)Martensitische Chromstaehle mit hohem Chromgehalt neigen haeufig zur Bildung von Deltaferrit, der zusaetzlich von massiven dendritischen Karbidausscheidungen umgeben sein kann. Beide Phasen beeinflussen die mechanischen Eigenschaften des Stahles meist in gegenlaeufiger Weise. Der relativ weiche Deltaferrit verursacht eine Erhoehung der Verformbarkeit und Zaehigkeit, waehrend die sproeden Karbiddendriten beides erniedrigen. Auf die Festigkeit des Stahles dagegen wirken beide Phasen eher negativ. Je nach dem Mengenverhaeltnis beider Phasen und der Pruefmethode dominiert der eine oder andere Einfluss. Dies ist der Grund fuer die sehr unterschiedlichen Angaben in der Literatur. Da die Karbiddendriten so gut wie immer die mechanischen Eigenschaften des Stahles verschlechtern, sollten sie durch eine Abkuehlgeschwindigkeit nach dem Austenitisieren von mindestens 10"3 K/min weitgehend vermieden werden. Der Deltaferrit dagegen kann allein meist toleriert werden. (orig.)11 refs.Available from TIB Hannover: ZA 5141(5727) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Verification of a fracture mechanics concept for the cleavage fracture behaviour of RAFM steels using local fracture criteria Final report for task TW2-TTMS-005/D3

An effort is made within the European Fusion Technology Programme framework to obtain a fracture mechanics description of the material behaviour in the ductile to brittle transition-regime using local fracture criteria. In a companion report, the necessary procedural steps towards the development of an according design code scheme were described. The present report contains application examples and verification results of the different procedural steps and identifies limitations of the approach for the two reference RAFM steels F82Hmod and EUROFER97. (orig.)Available from TIB Hannover: ZA 5141(6794) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

State-of-the-Art of high power gyro-devices and free electron masers. Update 1999. Status der Entwicklung von Hochleistungs-Gyro-Roehren und Frei-Elektronen-Masern. Stand: Ende 1999

Gyrotron oscillators (gyromonotrons) are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD) and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. 110 GHz (118 GHz, 140 GHz, 170 GHz) gyrotrons with output power P_o_u_t=0.55 MW (0.40 MW, 0.55 MW, 0.45 MW), pulse length #tau#10.0 s (15.5 s, 3.0 s, 8.0 s) and efficiency #eta#=30% (30%, 36%, 30%) are commercially available. Total efficiencies around 50% have been achieved using single-stage depressed collectors. Diagnostic gyrotrons have also been successfully used in materials processing. Such technological applications require gyrotrons with the following parameters: f#>=#24 GHz, P_o_u_t=10-50 kW, CW, #eta##>=#30%. This paper gives an update of the experimental achievements related to the development of high power gyrotron oscillators for long pulse or CW operation and pulsed diagnostic gyrotrons. In addition, this work gives a short overview of the present development of coaxial cavity gyrotrons, gyrotrons for technological applications, relativistic gyrotrons, quasi-optical gyrotrons, fast- and slow-wave cyclotron autoresonance masers (CARMs), gyroklystrons, gyro-TWT amplifiers, gyrotwystron amplifiers, gyro-BWO's, gyropeniotrons, magnicons, gyroharmonic converters, free electron masers (FEMs) and of vacuum windows for such high-power mm-wave sources. The highest CW powers produced by gyrotron oscillators, gyroklystrons and FEMs are, respectively, 340 kW (28 GHz), 10 kW (94 GHz) and 36 W (15 GHz). The IR (3.1 #mu#m) FEL at the Thomas Jefferson National Accelerator Facility obtained a record CW power of 1.72 kW. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6418) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

State-of-the-art of high power gyro-devices and free electron masers update 2002

Gyrotron oscillators (gyromonotrons) are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. The maximum pulse length of commercially available 1 MW gyrotrons employing synthetic diamond output windows is 5 s at 110 GHz (CPI and JAERI-TOSHIBA), 12 s at 140 GHz (FZK-CRPP-CEA-TED) and 9 s at 170 GHz (JAERI-TOSHIBA), with efficiencies slightly above 30%. Total efficiencies of 45-50% have been obtained using single-stage depressed collectors (for energy recovery). The energy world record of 160 MJ (0.89 MW at 180 s pulse length and 140 GHz) at power levels higher than 0.8 MW has been achieved by the European FZK-CRPP-CEA-TED collaboration at FZK where the pulse length restriction to 180 s is due to the HV power supply at I_b_e_a_m #approx# 40 A. At lower beam current (I_b_e_a_m = 26 A) it was even possible to obtain 506 MJ (0.54 MW for 937 s). The longest shot lasted for 1300 s at 0.26 MW output power. These very long pulses were limited by a pressure increase in the tube. A maximum output power of 1.2 MW in 4.1 s pulses was generated with the JAERI-TOSHIBA 110 GHz gyrotron. The Russian and the Japan 170 GHz ITER gyrotrons achieved 0.5 MW at 80 s pulse duration and 0.3 MW at 60 s, respectively. Diagnostic gyrotrons deliver P_o_u_t = 40 kW with #tau# = 40 #mu#s at frequencies up to 650 GHz (#eta# #>=# 4%). Gyrotron oscillators have also been successfully used in materials processing. Such technological applications require gyrotrons with the following parameters: f #>=# 24 GHz, P_o_u_t = 10-50 kW, CW, #eta# #>=# 30%. This paper gives an update of the experimental achievements related to the development of high power gyrotron oscillators for long pulse or CW operation and pulsed gyrotrons for plasma diagnostics. In addition, this work gives a short overview of the present development status of coaxial cavity gyrotrons, gyrotrons for technological applications, relativistic gyrotrons, quasi-optical gyrotrons, fast- and slow-wave cyclotron autoresonance masers (CARMs), gyroklystrons, gyro-TWT amplifiers, gyrotwystron amplifiers, gyro-BWO's, gyropeniotrons, magnicons, gyroharmonic converters, free electron masers (FEMs) and of vacuum windows for such high-power mm-wave sources. The highest CW powers produced by gyrotron oscillators, gyroklystrons and FEMs are, respectively, 340 kW (28 GHz), 10 kW (94 GHz) and 36 W (15 GHz). The IR (3.1 #mu# m) FEL at the Thomas Jefferson National Accelerator Facility obtained a record average power of 2.13 kW with an efficiency of 3.5% (with energy recovery). (orig.)Available from TIB Hannover: ZA 5141(6815) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Zug- und Kerbschlageigenschaften des Stahles EUROFER '97 (Vergleich mit OPTIFER)

Im Rahmen des Projektes Kernfusion wurde der Stahl EUROFER '97 in der OPTIFER-Reihe entwickelt und als Grosscharge mit hohen Reinheitsanforderungen erschmolzen. Die mechanischen Eigenschaften entsprechen den besseren OPTIFER-Staehlen und sind vermutlich noch etwas verbesserungsfaehig. Sie koennen durch Variation der Anlass- und der Austenitisierungstemperatur in einem weiten Bereich zwischen hoher Festigkeit und hoher Zaehigkeit variiert werden. (orig.)In the frame of the european fusion technology program the steel EUROFER '97 has been developed following the OPTIFER-steels. It was melted as a large heat with a high demand in purity. The mechanical properties correspond to the improved OPTIFER-steels, but it may be improved. The mechanical properties may be varied in a wide range between high strength and high toughness by varying the austenitizing temperature and the tempering temperature. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6551) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

State-of-the-art of high power gyro-devices and free electron masers. Update 2001

SIGLEAvailable from TIB Hannover: ZA 5141(6708) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Proceedings of the IEA-technical workshop on the test cell system for an international fusion materials irradiation facility, Karlsruhe, Germany, July 3-6, 1995 IEA-implementing agreement for a programme of research and development on fusion materials

After a Conceptual Design Activity (CDA) study on an International Fusion Material Irradiation Facility (IFMIF) has been launched under the auspices of the IEA, working groups and relevant tasks have been defined and agreed in an IEA-workshop that was held September 26-29 1994 at Karlsruhe. For the Test Cell System 11 tasks were identified which can be grouped into the three major fields neutronics, test matrix/users and test cell engineering. In order to discuss recently achieved results and to coordinate necessary activities for an effective design integration, a technical workshop on the Test Cell System was initiated. This workshop was organized on July 3-6 1995 by the Institute for Materials Research I at the Forschungszentrum Karlsruhe and attended by 20 specialists working in the fields neutronics, fusion materials R and D and test cell engineering in the European Union, Japan, and the United States of America. The presentations and discussions during this workshop have shown together with the elaborated lists of action items, that has been achieved in all three fields, and that from the future IFMIF experimental program for a number of materials a database covering widerspread loading conditions up to DEMO-reactor relevant end-of-life damage levels can be expected. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(5633) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Cryosorbent characterization of activated charcoal in the COOLSORP facility Final report on Subtask 8 of task VP1: cryopump development and testing (ITER task no. 448)

At Forschungszentrum Karlsruhe, a special cryovacuum pump system is being developed for use in the ITER nuclear fusion reactor. At the operation temperature of about 5 K, practically all gases can be condensed easily, except of helium and hydrogen isotopes. To bind these species as well, the panels are coated with sorbent materials. Best pumping characteristics are achieved with activated charcoal. For the basic design of such cryosorption pumps, isotherm data are strongly needed, which are extremely scarce, especially at temperatures between 4.2 K (LHe) and 77.3 K (LN2). Therefore, the novel continuous sorption device COOLSORP was developed to measure sorption characteristics up to atmospheric pressure under variable temperature cryogenic conditions. The facility is based on a commercially available pore-analyser (continuous sorption method), upgraded by a heatable closed He cycle two-stage Gifford McMahon refrigerator. This report gives an overview about the experimental programme performed over the last two years. For qualification of the new facility and for comparison reason, standard measurements with nitrogen at 77 K were performed. However, the emphasis of the experimental was placed on low temperature sorption isotherms (experimental and correlated data) of gases with special relevance for cryosorption vacuum pumping, like helium and hydrogen, in both the sub- and the supercritical temperature range, whenever possible. The parametric measurements were focussed on a special, commercially available, granular coconut-shell based charcoal (CHEMVIRON SC 2), which was shown to have excellent vacuum pumping performance and, thus, has become the candidate for nuclear fusion application (ITER reference material). Prior to the measurements, preliminary tests were driven to set the facility into operation properly, to confirm the applicability of the experimental method used and to calibrate the measuring instruments. Pore size information was then derived from the measured isotherms. The standard models (Langmuir, Brunauer, Emmett and Teller, Dubinin-Radushkevich) were applied for analysis of the measurement data (micro- and mesopore volume, surface area). The Density Functional Theory approach was employed to derive pore size distributions from the 77 K nitrogen isotherms. It is revealed how the accessible pore size and volume depend on the adsorptive under investigation. It is also shown that the use of standard models (recommended for nitrogen) may produce ambiguous results when applied to other gases such as helium or hydrogen. The experimental results presented in this report are especially needed to have a data base which could be used for benchmarking any new sorbent material for cryosorption pumping use. (orig.)Available from TIB Hannover: ZA 5141(6745) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Status report on experiments and modelling of the cleavage fracture behaviour of F82Hmod using local fracture grid Task TTMS-005

Within the European Fusion Technology Programme framework, a fracture mechanics description of the material behaviour in the ductile to brittle transition-regime is developed using local fracture criteria. Based on experimental results using axisymmetrically notched and pre-cracked specimens together with a numerical stress analysis at fracture load, a statistical evaluation of cleavage fracture parameters can be performed along the lines described in various code schemes such as the British Energy R6-Code or the ESIS P6 procedure. The report contains results of the experimental characterization of the deformation and fracture behaviour of the fusion candidate RAFM steel variant F82Hmod, details and background of the numerical procedure for cleavage fracture parameter determination as well as additional statistical inference methods for transferability analysis. Fractographic results give important information about fracture mode and fracture origin sites and their location. Numerical prediction of fracture origin distribution is an important tool for transferability assessment. Future issues comprise constraint effect and ductile damage as well as incorporation of irradiation effects, which are topically addressed. The methodology developed and described in the present report will be applied to characterize material behaviour of future RAFM variants as the EUROFER 97, for which analysis is currently under way. (orig.)Available from TIB Hannover: ZA 5141(6388) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman