[en] This paper discusses tritium technology in the united States which has advanced considerably since the 1988 Tritium Conference in Toronto. This advance has come in facilities, processing, and safety related technologies and in an ever increasing commitment to compliance related issues. The major laboratories in the U.S. tritium programs continue to be (Westinghouse) Savannah River Site, EG and G Mound, Lawrence Livermore National Laboratory, Sandia National Laboratory and the Los Alamos National Laboratory. Each of the Laboratories have made some significant changes in their programs and/or facilities in the past four years

[en] In order to discuss the long-term reliability and safety of zirconium-cobalt alloy for tritium use, the release behavior of decay helium from ZrCo tritide has been investigated for one and a half years with a radio-gaschromatograph. In this paper, the results show that the release fractions of the total decay ³He in ZrCo tritide are less than 3% and has been almost constant for 18 months under the following conditions: the operating temperatures = 293 ∼ 523 K, the atom ratios (T/ZrCo) = 0.3 ∼ 1.4, and the number of hydrogenation-dehydrogenation cycles before tritiation = 1 ∼ 10. Moreover, residual decay ³He was not released even if ZrCo was heated to 873 K, though most of the tritium was released. It became clear that the decay ³He was quite immovable in ZrCo tritide under these experimental conditions

[en] The ITER Conceptual Design Activity (CDA) was a three-year, 400 professional-year effort to design a next step tokamak. The Activity was conducted under the auspices of the IAEA jointly by EURATOM, Japan, the USSR and USA. The main ITER parameters are summarized in the paper. An engineering design phase (EDA) lasting 5-6 years is planned to begin in 1992. Fuel Cycle design studies carried out as part of the CDA concluded that suitable options existed or could be developed to satisfy all tritium-handling requirements for the machine within the EDA time and resource framework. During the EDA, special emphasis will be required on design integration and optimization

[en] The R and D for tritium technology and studies of tritium science in Japan has been carried out in the national institutions (JAERI, PNC and others), in the universities, and in industry. In fusion fuel technology, the technological R and D of tritium processing and handling has been carried out by TPL-JAERI, including collaboration with TSTA (United States) and basic and innovative research conducted by the universities. PNC has conducted R and D and engineering studies in the heavy water quality control system for FUGEN reactor, a heavy water cooled reactor ATR, and in the tritium recovery system for the heavy water coolant. Since the last meeting in Toronto, there are many developments in the above researches which will be summarized in this paper with some results

[en] Analytical studies on a traveling wave direct energy converter (TWDEC) for D-³He fueled fusion are carried out. The energy of 15 MeV carried by fusion protons is too high to handle with an electrostatic device. The TWDEC controls these high energy particles on the base of the principle of a Linac. This traveling wave method is discussed and the details of proton dynamics and excitation mechanism of electric power are clarified. The TWEDC consists of a modulator and decelerator. The applied traveling wave potential to the modulator modulates the velocity of fusion proton beams. This modulation makes a form of bunched protons at a down stream of the modulator. The decelerator has a set of meshed grids, each of which is connected to a transmission circuit. The phase velocity of excited wave on the transmission circuit is controlled the same way as that of decelerated protons. The kinetic energy 15 MeV of proton beams changes into an oscillating electromagnetic energy on the transmission circuit. This highly efficient direct energy converter of fusion protons brings a fusion reactor with a high plant efficiency. 4 refs., 4 figs

[en] A rotational instability is observed in a field-reversed configuration plasma. Onset time, growth rate and modal frequency of the instability are measured in connection with the ion diamagnetic drift frequency over a wide rage of plasma parameters. When the plasma is stabilized by a quadrupole field, it shrinks axially with time and its particle confinement time becomes shorter than that of a nonstabilized plasma. A numerical calculation of the field profile reveals that the distortion of the confinement field by the quadrupole field at the ends of the separatrix is responsible for the degradation of particle confinement. However, the multipole field with a higher pole number than the quadrupole can stabilize the plasma without degradation of the particle confinement. 13 refs., 6 figs

[en] Confinement magnetic field of a field-reversed configuration (FRC) plasma is reduced by a factor of about 10 and plasma density is decreased by a factor of about 100 without lowering the temperature seriously by translating a theta-pinch produced FRC plasma axially into a large bore metal vessel. Reduced magnetic field brings the lower-hybrid frequency into a range easily detected by magnetic probes. Search for wave activities in the FRC plasma for a wide frequency range disclosed magnetic field fluctuations in the lower-hybrid-drift frequency range for the first time in the FRC plasma. The identification of the mode is not done yet but the fluctuation level is close to the values predicted by theories on the LHD instability. This fluctuation level is not large enough to account for the transport rate of the particles from the FRC plasma. 11 refs., 3 figs

[en] A novel slow formation method of field-reversed configuration (FRC) has been developed by magnetic reconnection of two force-free spheromaks with opposite toroidal magnetic field. The merging process cancels their opposite magnetic helicities, realizing a non-Taylor relaxation from the force-free state to the high-β FRC state with zero helicity. A significant increase in the ion temperature has been documented up to 180 eV during this fully anti-parallel reconnection. The dissipated toroidal magnetic energy of the merging toroids is transformed mostly to the ion thermal energy, revealing a unique relaxation mechanism to the high-beta equilibrium. The merging toroids are found to relax either to an FRC or to a new spheromak, depending on whether their total helicity is larger or smaller than a critical value. 10 refs., 5 figs

[en] The low-frequency stability of ion rings and previous experimental work on weak ion rings is briefly summarized. In anticipation of a new experimental thrust to create field reversed strong ion rings, numerical simulations have helped to outline the physics of ring formation by the injection of short pulse intense ion beams ( = 1 kA/cm²) into a gas filled magnetic cusp followed by solenoidal ramped magnetic field. 12 refs., 2 figs

[en] The temporal behavior of electron density profiles of edge plasmas in the Compact Helical System (CHS) during high beta discharges was measured with a thermal neutral lithium beam probe. A large outward shift of the plasma edge boundary was observed with an increase in the beta value. The position of the plasma edge boundary measured experimentally was compared with that of the last closed flux surface (LCFS) calculated by the VMEC code, and qualitative agreement was found between experimental and theoretical results. The experiment on the dynamic poloidal field control during the discharge was also performed successfully to fix the position of the edge plasma boundary when the plasma beta was raised. 10 refs., 6 figs