[en] The prototype ATR 'Fugen' attained the criticality in March, 1978, as a power reactor charged with uranium-plutonium MOX fuel for the first time in the world, and through the operation of 10 years thereafter, the technology of plutonium utilization and the system engineering of ATR type reactors have been verified, moreover, the improvement and development of the technologies have been positively promoted. This technological achievement is reflected to the design of a demonstration ATR carried out by Electric Power Development Co. The main achievement obtained by the operation of Fugen is shown. Fugen is a heavy water-moderated, boiling light water-cooled, pressure tube type reactor of 557 MWt and 165 MWe, and fuel exchange has been carried out twice every year. In the core, the moderator and the coolant are separated with pressure tubes and a calandria. The core characteristics, the result of irradiation of MOX fuel and its irradiation characteristics, the plant characteristics, the techniques of handling heavy water, the irradiation characteristics of pressure tubes, the development of operation and maintenance techniques and the operation management techniques are reported. (Kako, I.)

[en] Of the start-up tests of ''Fugen'', the specific items are reported in the plant equipemt performance test, plant dynamic characteristic test, chemical and radiation measuring test, overall test, and start-up test. In the plant equipment performance test, 19 items were tested under nuclear heating condition and in loaded state, and it was confirmed that the results satisfied the design performance. In the plant dynamic characteristic test, 13 items were tested under power output condition, and it was confirmed that the results satisfied the design performance. The test is roughly classified into the control characteristic test of the plant control system, transient characteristic test in operation, and transient characteristic test at the time of tripping following a plant failure. Radiochemical and radiation level measuring tests were carried out to obtain the basic data for chemical and radiation management required for smooth plant operation, under atmospheric pressure, nuclear heating and power output conditions. Next, in the final loading test a 100 % electrical output, reactor-related data of about 200 points, turbine-related data of about 70 points and generator-related data of about 70 points were measured and evaluated to ensure that the plant can be safely and continuously operated. Finally, the start-up test program, implementing organization and testing process, the inspection prior to the operation, analytical prediction and data processing, independent inspection and the investigation items during stratup test are described. (Wakatsuki, Y.)

[en] The advanced thermal prototype reactor ''Fugen'' is a heavy water-moderated, boiling light water-cooled power reactor with electric output of 165 MW, which has been developed since 1966 as a national project. The start-up test was begun in March, 1978, being scheduled for about one year, and in March, 1979, it passed the final pre-use inspection and began the full scale operation. In this paper, the result of the start-up test of Fugen is reported. From the experience of the start-up test of Fugen, the following matters are important for the execution of start-up test. 1) Exact testing plan and work schedule, 2) the organization to perform the test, 3) the rapid evaluation of test results and the reflection to next testing plan, and 4) the reflection of test results to rated operation, regular inspection and so on. In the testing plan, the core characteristics peculiar to Fugen, and the features of heavy water-helium system, control system and other equipment were added to the contents of the start-up test of BWRs. The items of the start-up test were reactor physics test, plant equipment performance test, plant dynamic characteristic test, chemical and radiation measurement, and combined test. The organization to perform the start-up test, and the progress and the results of the test are reported. (Kako, I.)

[en] The facilities of reactor auxiliary systems for the advanced thermal prtotype reactor ''Fugen'' were manufactured in factories since 1972, and the installation at the site began in November, 1974. It was almost completed in March, 1977, except a part of the tests and inspections, therefore the outline of the works is reported. The ATR ''Fugen'' is a heavy water-moderated, boiling light water reactor, and its reactor auxiliary systems comprise mainly the facilities for handling heavy water, such as heavy water cooling system, heavy water cleaning system, poison supplying system, helium circulating system, helium cleaning system, and carbon dioxide system. The poison supplying system supplies liquid poison to the heavy water cooling system to absorb excess reactivity in the initial reactor core. The helium circulating system covers heavy water surface with helium to prevent the deterioration of heavy water and maintains heavy water level by pressure difference. The carbon dioxide system flows highly pure CO₂ gas in the space of pressure tubes and carandria tubes, and provides thermal shielding. The design, manufacture and installation of the facilities of reactor auxiliary systems, and the helium leak test, synthetic pressure test and total cleaning are explained. (Kako, I.)

No abstract available

[en] Highlights: •Evacuation time of long cryogenic pipes was calculated. •The outgassing rate in the calculations was based on the experiment. •Outgassing should be suppressed to evacuate long cryogenic pipes. •Evacuation is possible within 1 week even for the 10 km cryogenic pipe. -- Abstract: The vacuum insulation has been used for the thermal insulation of cryogenic pipes for the superconducting power transmission to reduce the heat leak from the environment at the room temperature to the low temperature parts. Since the cryogenic pipes, in particular, those for long distance power transmission, are considered to be thin long pipes, it might take a long time for evacuation. To estimate the evacuation time of the long cryogenic pipes, model calculations have been performed. According to the calculations, it is found that there is an optimum condition between the pumping speed, the diameter of the outer pipe and the length of the cryogenic pipe for efficient evacuation. It is also found that, if the outgassing is suppressed enough, the evacuation can be possible within 1 week even for the long cryogenic pipe with the length of 10 km. The reduction of outgassing is particularly important for the efficient evacuation

[en] The prototype ATR 'Fugen' developed as one of the national project has verified the performance and reliability of the advanced thermal reactor system through the operation for about eight years since 1979, and the elucidation of the characteristics in plutonium utilization and the development and verification of the utilizing techniques have been advanced. Besides, the operational results and the achievement of the technical development are successively reflected to the design of a demonstration reactor. In this paper, the outline of Fugen and the operational results are reported. The ATR Fugen Power Station is that of the prototype reactor of heavy water moderated, boiling light water cooled, pressure tube type, having the electric output of 165 MW. It started the full scale operation on March 20, 1979, and as of January, 1987, the total generated electric power reached about 7 billion kWh, the time of power generation was about 43,000 h, and the average capacity factor was 60.6 %. Plutonium utilization techniques, the flow characteristics and the dynamic plant characteristics of a pressure tube type reactor, the operational characteristics of a heavy water system and the techniques of handling heavy water containing tritium, and the operational reliability and maintainability of the machinery and equipment installed have been studied. (Kako, I.)

[en] Heavy water and helium system of the Fugen, a 165 MWe prototype of heavy water moderated, boiling light water cooled, pressure tube type reactor, has demonstrated its excellent performance and reliability through over ten years' operation. Heavy water chemistry control method was also established after a number of R and D works against degradation of purification resins with deuteriumperoxide generated from heavy water rediolysis. An overview of the ten years' operational experience is described concerning maintenance works, operational procedures, heavy water chemistry control, and radiation protection methods against tritium internal exposure. (author)

[en] In the 200 m high temperature superconducting (HTS) cable test facility at Chubu University, a coaxial power cable is used and composed of two BSCCO (Bi-2223) superconducting layers. The tapes are wound closely to reduce effects on the critical current of BSCCO at self-field. Accordingly, each superconducting layer has a different number of BSCCO tapes. Previously, we have investigated dependence of the critical current (Ic) on the gap in order to optimize the HTS DC cable design. We have been studying the effect on the performance of HTS tapes for the superconducting DC power cables by critical current measurements. In the present experiments several HTS tapes are used and set as a similar structure in the cable with a two-layer structure. The critical current of HTS tapes are measured against the gap between the tapes in the same layer. The experiments show the improvement of the critical current by optimizing the tape arrangements due to magnetic field interaction between the tapes. We will present the experimental results and discuss the design of the HTS DC cable.

[en] Symmetry-controlled ferroelectric superlattice thin films of BaZr_xTi_1-xO₃(BZT) were fabricated by a pulse laser deposition (PLD) technique. To reduce the strain effects, we used 5-layer systems of BZT with x=0, 0.25, 0.5, 0.75, and 1; we call these A, B, C, D, and E, respectively. We made two types of superlattice film, namely, ABCDE/ABCDE and ABCDE/EDCBA, where the total concentration of Zr was the same. The former exhibits symmetry breaking as in perovskite structures. In contrast, the latter has symmetry introduced by artificial structures. Superlattices show clear satellite peaks in XRD patterns and the structures are also confirmed by electron microscopy images. ABCDE/ABCDE films have larger relative permittivities than the ABCDE/EDCBA films. This property seems to be the symmetry effects in the superlattice structures. Both films have a weak temperature dependence near room temperature by the superlattice effects, which seems to be better for the application of the materials. (author)