[en] This test program was performed to investigate if significant chatter (stick-slip) would occur at the thermal barrier sliding surfaces. Given such conditions, cyclic loads could be induced in the thermal barrier attachment fixture and studs. A representative section of thermal barrier was tested with realistic HTGR temperature cycles in a high purity helium environment. No significant chatter was detected and there was no visible deterioration of the hardware after testing

No abstract available

[en] Load-deflection characteristics of alumina and alumino-silicate fibrous blankets were experimentally determined. Load retention and springback capability of combinations of these materials were measured in a 10,000-hour test at surface temperatures of 650 to 1000⁰C (1200 to 1832⁰F). Experimental results are presented and future testing plans are discussed

No abstract available

[en] A TRIGA Dual Core Reactor System has been chosen by the Romanian Government as the heart of a new fuel development facility which will be operated by the Romanian Institute for Nuclear Technologies. The Facility, which will be operational in 1976, is an integral part of the Romanian National Program for Power Reactor Development, with particular emphasis being placed on fuel development. The unique combination of a new 14 MW steady state TRIGA reactor, and the well-proven TRIGA Annular Core Pulsing Reactor (ACPR) in one below-ground reactor pool resulted in a substantial construction cost savings and gives the facility remarkable experimental flexibility. The inherent safety of the TRIGA fuel elements in both reactor cores means that a secondary containment building is not necessary, resulting in further construction cost savings. The 14 MW steady state reactor gives acceptably high neutron fluxes for long- term testing of various prototype fuel-cladding-coolant combinations; and the TRIGA ACPR high pulse capability allows transient testing of fuel specimens, which is so important for accurate prediction of the performance of power reactor fuel elements under postulated failure conditions. The 14 MW steady state reactor has one large and three small in-core irradiation loop positions, two large irradiation loop positions adjacent to the core face, and twenty small holes in the beryllium reflector for small capsule irradiation. The power level of 14 MW will yield peak unperturbed thermal neutron fluxes in the central experiment position approaching 3.0 x 10¹⁴ n/cm²-sec. The ACPR has one large dry central experimental cavity which can be loaded at pool level through a shielded offset loading tube; a small diameter in-core flux trap; and an in-core pneumatically-operated capsule irradiation position. A peak pulse of 15,000 MW will yield a peak fast neutron flux in the central experimental cavity of about 1.5 x 10¹⁷ n/cm²-sec. The pulse width at half maximum during a 15,000 MW peak pulse is about 4 msec with an integrated flux of 1.5 x 10¹⁵ nvt. The experimental facilities include a tangential and a radial beam tube from each reactor leading to an adjacent underground beam room, an underwater neutron radiography system for radiography of irradiated fuel samples and an underwater graphite thermal column. A hot cell complex for post-irradiation examination of fuel specimens is connected directly to the reactor pool by a transfer canal, permitting transfer of radioactive specimens without the need for shielded casks. The facility also has many small laboratories for preparing, analyzing, and setting up experiments. Thus, although the prime purpose of the Dual-Core TRIGA Reactor Facility is to develop power reactor fuel elements, the facility is also well-equipped for research in other areas. An extensive neutron physics program (neutron beam physics, neutron radiography and neutron physics using the thermal column) will be possible at the same time as the reactors are being used to irradiate and test fuel samples. (author)

[en] Domain walls for spin glasses are believed to be scale invariant; a stronger symmetry, conformal invariance, has the potential to hold. The statistics of zero-temperature Ising spin glass domain walls in two dimensions are used to test the hypothesis that these domain walls are described by a Schramm-Loewner evolution SLE_κ. Multiple tests are consistent with SLE_κ, where κ=2.32±0.08. Both conformal invariance and the domain Markov property are tested. The latter does not hold in small systems, but detailed numerical evidence suggests that it holds in the continuum limit

[en] The ZEUS experiment has a three-level trigger system to select electron-proton interaction events from a large anticipated background of proton beam-gas. The first level decision is formed using pipelined hardware processors clocked at the 96 ns beam crossing frequency. A vital component of this decision is discrimination against upstream events using tracking detector information. The processors use three-dimensional space points measured in the central tracking detector to find pointing tracks over most of the θ range, and include forward tracking detector information to improve the resolution and angular coverage in the proton forward direction. The processor design status and performance simulation results are presented. (orig.)

[en] The mechanical, electrical and electronic design and construction of the ZEUS central tracking detector are described, together with the chamber monitoring and environmental control. This cylindrical drift chamber is designed for track reconstruction, electron identification and fast event triggering in a high beam-crossing rate, high magnetic field application. (orig.)