As fusion reactor designs continue to evolve, the need for experimental data on magnet materials covering a range of environmental conditions becomes more apparent. Early designs focused on the use of superconducting magnets with the blanket and shield thickness set to equate magnet and reactor lifetimes. Currently there is interest in magnet materials that will withstand higher radiation fields as well as higher temperatures. In this work irradiation and test data are reported for SPAULRAD-S, a high pressure laminate of polyimide resin reinforced with S-glass (boron free) cloth. This material is one which has been identified as having favorable resistance to radiation as well as good mechanical and physical properties. Specimens 11.1 mm in diameter by 0.464 mm thick were irradiated in two different facilities, the Advanced Test Reactor (ATR) at the Idaho National Engingeering Laboratory and the Intense Pulsed Neutron Source Facility at ANL.

Fusion reactor coils, located in areas where they will be only partially shielded, must be fabricated from materials which are as resistant to radiation as possible. They will probably incorporate resistive conductors with either water or cryogenic cooling. Inorganic insulators have been recommended for these situations, but the possibility exists that some organic insulators may be usable as well. Five insulator materials were investigated in this work, two containing E-glass cloth (contains B2O3) and three containing S-glass cloth (boron free). Disks of these materials were irradiated in two capsules in the Advanced Test Reactor at 325 K to a gamma dose of over 3.2 × 109 Gy, a fast neutron fluence of 3.5 × 1023 n/m2 (E > 1.0 MeV), and a total neutron fluence of 3.5 × 1024 n/m2 for the lower fluence capsule. Following irradiation, compressive fatigue tests were made at room temperature on all five candidate materials. No failures were observed for the three insulators containing S-glass when cycled to a maximum stress of 345 MPa (50 ksi) for over 1.5 × 105 cycles. In comparison, the G-11CR failed in a few cycles at the lowest stress level applied and the G-10 failed after a number of cycles which varied according to the applied stress level.

Beta-spodumene was investigated as a candidate material for use in fusion reactor environments. Properties which support the use of beta-spodumene include good thermal shock resistance, a very low coefficient of thermal expansion, a low-Z composition which would result in minimum impact on the plasma, and flexibility in fabrication processes. Specimens were irradiated in the Advanced Test Reactor (ATR) to a fluence of 5.3 × 1022 n/m2, E > 0.1 MeV, and 4.9 × 1023 n/m2 thermal fluence in order to obtain a preliminary evaluation of the impact of irradiation on the material. Preliminary data indicate that the mechanical properties of betaspodumene are little affected by irradiation. Gas production and release have also been investigated.

Recent magnet insulator studies at the Idaho National Engineering Laboratory have included work applicable to quite different magnet configurations, both the conventional wrapped conductor and the Bitter plate. These investigations have emphasized irradiation effects work in support of the Princeton Plasma Physics Laboratory (PPPL) for the Tokamak Fusion Test Reactor (TFTR) and of Massachusetts Institute of Technology (MIT) for the ZEPHYR program. Postirradiation testing included shear bond testing of specimens prepared at Princeton and compressive fatigue tests of fiberglass-epoxy disks, principally G-10, for MIT. The fatigue tests included both room temperature and liquid nitrogen temperature over a range of maximum loads. The method for determining disk failure during the fatigue test is emphasized in this report.

Recent theoretical investigations have pointed to considerable uncertainty in estimating the amount of tritium which will permeate the first wall of a fusion reactor and enter the primary coolant system due in part to the implantation of energetic ions. An experiment is being planned to study this problem in a small test reactor where the /sup 3/He(n,p)/sup 3/T reaction is used to generate protons and tritons for implantation in and permeation of a simulated first wall. By comparing the amount of tritium moving through the wall in the presence of implantation with that in its absence while maintaining the time background partial pressure and temperature, the efflct of implantation on tritium permeation will be determined. The experiment offers an interesting and important complement to similar experiments based on plasmas or ion beams.

Low-cycle fatigue and tensile tests were performed on specimens faoricated from 14-mm (0.55-in.) cross-rolled tungsten plate which was prepared by a powder metallurgy process. Tests included measurements on both as-received and recrystal1ized specimens. Data have been obtained at 1088 K (1500°F) in vacuum, and at room temperature. Low-cycle fatigue data at both 1088 K and room temperature are in fair agreement with predictions based on the “universal slopes” equation for the as-received material condition. In contrast, fatigue data for recrystal1ized specimens at 1088 K fall considerably below prediction, except in tne high cycles-to-fai1 (105 cycles) regime. Details of the test procedure as well as modification of the specimen configuration which was required for room temperature testing are reported.

The testing of fusion materials and components in fission reactors will be increasingly important in the future due to the near-term lack of fusion engineering test devices, and the long-term high demand for fusion testing when they do become available. Fission testing is capable of filling many gaps in fusion reactor design information, and should be aggressively pursued. EG and G Idaho has investigated the application of fission testing in three areas, which are discussed in this paper. First, work was performed on the irradiation of magnet insulators. This work is continuing with an improved test environment. Second, a study was performed which indicated that a fission-suppressed hybrid blanket module could be effectively tested in a reactor such as the Engineering Test Reactor (ETR), closely reproducing the predicted performance in a fusion environment. Finally, a conceptual design is presented for a fission-based Integrated Test Facility (ITF), which can accommodate entire wall/blanket (FW/B) modules for testing in a nuclear environment, simultaneously satisfying many of the FW/B test requirements. This ITF can provide a cyclic neutron/gamma flux, as well as the necessary module support functions.

Results are reported for strain-controlled low-cycle fatigue measurements on Vanstar-7, 8, and 9 in both the irradiated and unirradiated conditions, conducted at 400°C. Specimens were irradiated in the experimental breeder reactor II (EBR-II) to fluences of 0.18 to 6.37 × 1025 neutrons (n)/m2 (E > 0.1 MeV) at 410 to 450°C. The results indicate that neutron irradiation had little or no effect on the fatigue life of any of the alloys. Comparison with data for Types 304 and 316 austenitic stainless steels tested at 400°C shows that on the basis of strain range the irradiated Vanstar alloys are inferior or equivalent to the stainless steels below 10 000 cycles-to-failure but become superior above that point. Proportional limit and yield-strength information have been extracted from the fatigue data, where possible. These data indicate that radiation hardening occurs rapidly at low neutron fluences and that strengthening saturates or increases very slowly above a fluence of approximately 1 × 1025 n/m2.

In order to resolve reported differences in the compressibility of hexagonal selenium, lattice parameters have been measured at pressures up to 140 kbar. Independent measurements have been made by neutron time-of-flight and by x-ray diffraction. The results from these methods are in good agreement. The a axis is found to contract, but the c axis expands with increasing pressure. Values obtained for the average volume, a-axis, and c-axis zero-pressure compressibilities are 49.7±15, 31.9±7, and −14.3±4×10−4 kbar−1, respectively. These results compare favorably with a correlation of bulk modulus and cohesive energy. The expansion of the c axis under pressure is comparable to the contraction of the c axis with increase of temperature.

Lattice vibration frequencies of Tl at 77 and 296 K have been measured along the lines $\ensuremath{\Delta}$ and $\ensuremath{\Sigma}$ by neutron inelastic scattering. Modified axially symmetric force-constant models were fitted to the neutron data and were used to calculate phonon-dispersion curves along other symmetry directions in the crystal. Frequency distributions calculated from the 77-K models are compared with the results of superconducting tunneling experiments of Clark and Dynes.

AbstractUsing coherent inelastic neutron scattering, phonon dispersion curves for zirconium, at room temperature, were measured for two high symmetry directions, [0001] and [0110]. The data were analyzed on the basis of a six‐neighbor modified axially symmetric model. A frequency distribution calculated from the parameters obtained from the model is also presented.