A remote maintenance technology to process cooling pipes internally for the ITER (International Thermonuclear Experimental Reactor) has been developed. The fundamental welding properties of austenite stainless steel obtained by using high power YAG laser indicates the tendency of porosity increase as the welding depth increases. It is also found out that the occurrence of porosity was prevented when N2 gas was used as a shielding gas and that the material strength of weld joint is kept unchanged. Furthermore, a processing equipment that can access the cooling pipes internally has been developed. The main body of this processing equipment can be inserted into a cooling pipe and consists of an focusing optics, clamping and driving mechanism, and an optical fiber. Operational experiments of this processing equipment is carried out and the basic verification experiments such as welding and cutting tests were conducted. As a result, a good quality of pipe welding joint was obtained without any defects.
In recent years, quantum crystallography, which combines X-ray crystal structure analysis and quantum chemistry, has attracted attention.Attempts have been made to reproduce wave function from electron density obtained from experiments and to refine the crystal structure using computational chemistry [1,2].However, these attempts require a high degree of expertise and such programs are not widely used.The purpose of this study is to discuss electronic states of azo-Schiff base metal complexes based on quantum chemical calculations and to verify whether quantum crystallography can be performed easily by using conventional programs.
ITER in-vessel components such as blankets and divertors are categorized as scheduled maintenance components because they are subjected to severe plasma heat and particle loads. Blanket maintenance requires remote handling equipment and tools able to handle Heavy payloads of about 4 tons within a 2mm precision tolerance. divertor maintenance requires remote replacement of 60 cassettes with a dead weight of about 25 tons each. In the ITER R&D program, full-scale remote handling equipment for blanket and divertor maintenance has been designed and assembled for demonstration tests. This paper reviews the measurement and control system developed for full-scale remote handling equipment, the Japan Home Team contribution.
In the International Thermonuclear Experimental Reactor (ITER), in-vessel components replacement and maintenance requires that connected cooling pipes be cut and removed beforehand and that new components be installed to which cooling pipes must be rewelded. All welding must be inspected for soundness after completion. These tasks require a new task concept for ensuring shielded areas and access from narrow ports. Thus, it became necessary to develop autonomous locomotion welding and cutting tools for branch and main pipes to weld pipes by in-pipe access; a system was proposed that cut and welded branch and main pipes after passing inside pipe curves, and elemental technologies developed. This paper introduces current development in tools for welding and cutting branch pipes and other tools for welding and cutting the main pipe.
In D-T burning reactors such as International Thermonuclear Experimental Reactor (ITER), an internal access welding/cutting of blanket cooling pipe with bend sections is inevitably required because of spatial constraint due to nuclear shield and available port opening space. For this purpose, internal access pipe welding/cutting/inspection tools for manifolds and branch pipes are being developed according to the agreement of the ITER R and D task (T329). A design concept of welding/cutting processing head with a flexible optical fiber has been developed and the basic feasibility studies on welding, cutting and rewelding are performed using stainless steel plate (SS316L). In the same way, a design concept of inspection head with a non-destructive inspection probe (including a leak-testing probe) has been developed and the basic characteristic tests are performed using welded stainless steel pipes. In this report, the details of welding/cutting/inspection heads for manifolds and branch pipes are described, together with the basic experiment results relating to the welding/cutting and inspection. In addition, details of a composite type optical fiber, which can transmit both the high-power YAG laser and visible rays, is described. (author)
The ITER divertor is categorized as a scheduled maintenance component because of extreme heat and particle loads it is exposed to by plasma. It is also highly activated by 14 MeV neutrons. Reliable remote handling equipment and tools are required for divertor maintenance under intense gamma radiation. To facilitate remote maintenance, the divertor is segmented into 60 cassettes, and each cassette weighing about 25 tons and maintained and replaced through four maintenance ports each 90 degrees. divertor cassettes must be transported toroidally and radially for replacement through maintenance ports. Remote handling involving cassette movers and carriers for toroidal and radial transport has been developed. Under the ITER R&D program, technology critical to divertor cassette maintenance is being developed jointly by Japan, E.U., and U.5. home teams. This paper summarizes divertor remote maintenance design and the status of technology development by the Japan Home Team.
