Kazuyuki Furuya

Effect of triple ion beams in ferritic/martensitic steel on swelling behavior

Abstract The synergistic effects of displacement damage and atomic hydrogen and helium on swelling of the ferritic/martensitic steel, F82H, has been investigated. The irradiation was performed at temperatures between 470 and 600 °C to 50 dpa (displacement per atoms) under conditions of simultaneous ion beams consisting of Fe3+, He+ and H+ ions or Fe3+ and He+ ions. The swelling of F82H steel under triple beams with 18 appm He/dpa and 70 appm H/dpa was larger than that under dual beams with 18 appm He/dpa. The swelling in F82H under triple beams increased with decreasing irradiation temperature from 0.1% to 3.2%, while swelling under dual beams was between 0.04% and 0.08%. On the other hand, in the case of triple beam irradiation with a high ratio of gas/dpa, the swelling tended to increase with irradiation temperature. The swelling in ferritic/martensitic steels is significantly enhanced by the synergistic effect of displacement damage, hydrogen and helium atoms.

Optimization of HIP bonding conditions for ITER shielding blanket/first wall made from austenitic stainless steel and dispersion strengthened copper alloy

Abstract Optimum bonding conditions were studied on the Hot Isostatic Pressing (HIP) bonded joints of type 316L austenitic stainless steel and Dispersion Strengthened Copper alloy (DSCu) for application to the ITER shielding blanket / first wall. HIP bonded joints were fabricated at temperatures in a 980–1050°C range, and a series of mechanical tests and metallurgical observations were conducted on the joints. Also, bondability of two grades of DSCu (Glidcop Al-25 ® and Al-15 ® ) with SS316L was examined in terms of mechanical properties of the HIP bonded joints. From those studies it was concluded that the HIP temperature of 1050°C was an optimal condition for obtaining higher ductility, impact values and fatigue strength. Also, SS316L/Al-15 joints showed better results in terms of ductility and impact values compared with SS316L/Al-25 joints.

Mechanical properties of HIP bonded joints of austenitic stainless steel and Cu-alloy for fusion experimental reactor blanket

Abstract Tensile, fatigue and impact properties have been measured for hot isostatic pressing (HIP) bonded joints of type 316 austenitic stainless steel (SS316)/SS316, and of SS316/Al2O3 dispersion strengthened copper (DSCu). The HIP bonded joints of SS316/SS316 had almost the same tensile and fatigue properties as those of the base metal. The HIP bonded joints of SS316/DSCu had also almost the same tensile properties as those of the base metal of the DSCu, though total elongation and fatigue strength were slightly lower than those of the DSCu base metal. Further data accumulation, even with further optimization of fabrication conditions, is required, especially for HIP bonded SS316/DSCu joints, to confirm above data and reflect to blanket/first wall design.

Development of joining technology for Be/Cu-alloy and Be/SS by HIP

Joining of Be/DSCu and Be/SS by using HIP technique with and without various interlayers were investigated as a screening test for selecting optimum joining method and conditions. Metallurgical observation and shearing tests were performed for basic characterization of the bonded joints. For Be/DSCu, the use of Ag interlayer with 700°C HIP temperature would be a prime candidate if Cd formation under neutron irradiation would not seriously affect plasma operation and joint performance. Other than the Ag interlayer, a Cr/Cu interlayer gave relatively high joint strength in the present screening test. The lower HIP temperature, 550°C, for this joint contributes to prevent sensitization of stainless steel (SS) structural material. As for Be/SS, the highest joint strength was obtained with a Ti interlayer. The HIP temperature of 800°C or a little higher would be applied for this joint to avoid SS sensitization.

Application of HIP bonding to first wall panel fabrication made from reduced activation ferritic steel F82H

Abstract As a course of fabrication technology development of DEMO breeding blankets, fabrication of small-scaled first wall panels made from reduced activation ferritic steel F82H has been attempted by applying HIP (Hot Isostatic Pressing) method. By applying the conditions identified in the previous studies, two flat panels with ten cooling channels each have been fabricated. One of the fabricated panels was destructively tested to examine metallurgically sound HIP bonding and to characterize the change of the micro-structure of the F82H steel due to the HIP process. Destructive examination has confirmed sound bonding for all of the HIP interfaces and satisfactory dimensional tolerance, and applicability of HIP bonding to the complex component made from this steel has been demonstrated.

Ceramic breeding blanket development for experimental fusion reactor in JAERI

Abstract The ceramic breeding blanket is a promising breeding blanket concept for experimental fusion reactors, and worldwide efforts have been devoted to their design and R&D. A layered pebble bed type ceramic breeder blanket with water cooling was proposed by JAERI during ITER/CDA, and has been improved based on detailed analysis and consideration of fabricability. In this concept, beryllium and ceramic breeder pebble bed layers are arranged alternately, in which the beryllium layer works as a thermal resistance layer between the breeder layer and a cooling panel as well as a neutron multiplier. The use of the breeding material and beryllium in the form of small pebbles has been proposed to accommodate dimensional changes by irradiation effects. A wide variety of R&D has also been conducted on the design progress. The development of the fabrication technology for the blanket box structure and its mechanical testing, elementary testing on the thermal performance of the pebble bed, and engineering-oriented material tests of breeder and beryllium pebbles, such as compatibility with structural materials and thermal cycle durability, are the main recent achievements. The present paper outlines recent progress in the design of the ceramic breeder blanket in JAERI and the major results of R&D on box structure fabrication and elementary out-of-reactor testing are also described.

Microstructure and hardness of HIP-bonded regions in F82H blanket structures

Metallurgical examinations and hardness measurements were performed at hot isostatic pressing (HIP)-bonded regions in blanket structures made from F82H alloy in order to investigate the HIP-bondability and the influence on the microstructure due to the HIP and heat treatments which would correspond to the fabrication of an actual blanket. The metallurgical examination showed that the HIP-bonded interfaces were sufficiently diffusion-bonded without significant defects, i.e. voids and/or exfoliations, although grain coarsening was observed at a part of the HIP interfaces. Hardness was nearly equal in the coarsening region and a region without coarsening, but about a 10 Hv increase was found in a boundary in between the regions with and without coarsening. Microcrystallized grains were observed in a region about ∼6 μm from HIP interfaces, and the hardness increased by about 0.2 GPa in the region.

Fracture strengths of HIPed DS-Cu/SS joints for ITER shielding blanket/first wall

Abstract Fracture toughness and crack propagation tests were performed to investigate the effect of HIP temperature and fracture behavior of HIPed DS-Cu/SS joints. Test specimens of DS-Cu/SS HIPed joints were manufactured by bonding flat plates of DS-Cu and SS under HIP temperatures of 980°C, 1030°C and 1050°C. J Q of the joint at HIP temperature of 1050°C was larger than the other two joints. For the crack propagation test, two types of test specimens were prepared. One had a notch along the HIPed interface and the other in DS-Cu and normal to the interface. The crack in the former specimen propagated along the interface. On the other hand, the crack in the latter specimen propagated in the DS-Cu perpendicular to the loading direction, stopped at the interface, and then exfoliated along the HIPed interface. In the fracture tests, the crack was observed propagating in DS-Cu side at approximately 5–10 μm away from the interface.

Development of first wall/blanket structure by hot isostatic pressing (HIP) in the JAERI

Abstract In the ITER shielding blanket design, first wall coolant tubes of type 316LN stainless steel (SS) are embedded in a heat sink of Al2O3 dispersion-strengthened Cu (DSCu), which are joined to a SS shield block. Development of fabrication technology using hot isostatic pressing (HIP) for this structure, including testing, is currently being performed at JAERI. Recent progress in this development is reviewed in this paper. A simultaneous joining of DSCu/DSCu, DSCu/SS and SS/SS, especially at the first wall and the first wall to the shield block, by a solid HIP technique, has been pursued. Following the optimization of HIP conditions, mechanical tests of the HIP joints and fabrication of first wall mock-ups were performed. High heat flux tests of the first wall mock-ups resulted in their sufficient heat removal capability and integrity of the HIP joints. Small- and medium-scale mock-ups of the shielding blanket, integrated with the first wall, were fabricated to examine the applicability of the HIP technique and develop a fabrication route. As a result of these activities, fabrication technologies and the route to be applied for the ITER shielding blanket and sufficient thermo-mechanical performance of the HIP bonded structure were foreseen.

Engineering Validation and Engineering Design of Lithium Target Facility in IFMIF/EVEDA Project

Abstract EVEDA Lithium Test Loop (ELTL) has been designed and constructed, has operated a liquid lithium flow test facility with the world’s highest flow rate and has succeeded in generating a 100-mm-wide and 25-mm-thick free-surface lithium flow along a concave back plate steadily at a high speed of 20 m/s at 300°C for the first time in the world. This result will greatly advance the development of an accelerator-based neutron source to high energy and high density, one of the key objectives of the fusion reactor materials development under the BA (Broader Approach) Activities. Recent related engineering validation and engineering design of the lithium facility has been evaluated.