Effects Of Nuclear Radiation Research Articles

The no effect of nuclear radiation on a computer magnetic tape and a magnetic card

The no effect of nuclear radiation on a computer magnetic tape and a magnetic card

Effect of nuclear radiation on the elastic moduli of zircon

Zircon crystals that have been damaged by a naturally occurring radioactive contaminant, referred to as metamict zircons, have density values ranging from 4.70 to 3.90 g/cm3. The present work is a study of the effect of the damage on the single-crystal elastic moduli. A systematic and very marked decrease (i.e., up to 69%) of the elastic moduli with density have been observed. All the longitudinal and the shear elastic moduli decrease with radiation damage and approach two common saturation values of 1.5×1012 and 0.49×1012 dyn/cm2, respectively. Present observation of the elastic moduli of the radiation-damaged zircon crystals confirms Warren’s theoretical predictions concerning the effect of different pore geometries on the compressibility. Qualitative correlation of the elastic moduli with the structural changes arising from radiation damage in zircon crystals suggests that the marked decrease of the elastic moduli in the radiation-damaged zircons is caused by the nonspherical defect clusters, microcracks, and pores generated during radiation damage. Thermal annealing, x-ray diffraction, elastic moduli, and density measurements on the zircon samples confirm the ’’three-stage’’ process proposed for the metamict transformation of zircons, but the final product of metamictization does not seem to be a mixture of ZrO2 and SiO2 crystallites.

Effects of nuclear radiation on the optical properties of cerium-doped glass

Some twenty types of glass containing 0.5-4% CeO 2 have been irradiated in a 60Co gamma cell and in the mixed neutron-gamma field of a nuclear reactor, at total integrated doses of up to 5 × 10 9 Rad (CH). The resulting colouration has been assessed quantitatively by measuring the light transmission with reference to air, in the range 360–510 nm. From the results, certain types of glass suitable for applications in nuclear engineering can be selected. Specifically, it was found that 1–2% CeO 2 content is usually sufficient to obtain radiation-resistant optical glass: the reduction in light transmission above 450 nm is nil at 10 8 Rad (CH), below 10% at 10 9 Rad (CH), and below 20% at 5 × 10 9 Rad (CH); the post-irradiation fading is negligible.

Effects of nuclear radiation and elevated temperature storage on electroexplosive devices

Aerospace type electroexplosive devices (EEDs) were subjected to nuclear radiation. Components and chemicals used in the EEDs were also included. The kind of radiation and total dosage administered were those which may be experienced in a space flight of 10 years duration, based on information available at this time. After irradiation, the items were stored in elevated constant-temperature ovens to accelerate early effects of the exposure to radiation. Periodically, samples were withdrawn for visual observation and testing. Significant changes occurred which were attributed to elevated-temperature storage and not radiation.

Effects of Environmental Nuclear Radiation on Optical Fibers

A comparison of the available data on environmental radiation and on the radiation damage in fibers and glasses under controlled laboratory conditions leads us to the conclusion that long-term exposure to gamma rays and neutrons in the environment does not pose a serious problem for the optical fibers.

Effects of nuclear radiation on a high-reliability silicon power diode—4. Analysis of reverse bias characteristics

We present device characteristics obtained from two-dimensional numerical simulations of asymmetric 4H-SiC gate turn-off (GTO) thyristor structures. Material parameters are discussed, and a good comparison with measured results is demonstrated. Current vs voltage characteristics indicate that typical structures have quite good electron injection from the cathode, but hole injection from the anode is weak unless the n-base layer is doped less than 1×1018 cm−3. On the other hand, lowering electron injection at the cathode/p-base junction is important to improve the turn-off gain. The 2000 V blocking structure simulated with lifetimes of τn:τp=100:50 ns does not reach its on-state for current densities less than 6000 A/cm2, but for lifetimes of 400:200 ns, this minimum is reduced to 1 A/cm2. Blocking voltages increased approximately 400 V for a 3 μm increase in the drift region length. Clamped inductive load mixed-mode simulations with a 4H-SiC flyback diode indicate that the peak power during turn-on is only slightly higher than during turn-off when switching a 4 Ω, 5 mH load. Because turn-on times are much shorter than turn-off times, much less power is dissipated during turn-on for both 27°C and 200°C ambient temperature operations.

Radiation effects on magnetic bubble domain devices

The effect of nuclear radiation on garnet film material parameters and bubble domain devices has been studied both during and after irradiation. The materials investigated include CVD grown Y 3 (FeGa) 5 O 12 , Er 3 (FeGa) 5 O 12 and LPE grown (YGdTm) 3 (FeGa) 5 O 12 films. The devices were different shift registers fabricated on ion implanted, non implanted and double layer YGdTmGaIG LPE films and GaErIG CVD films. Permanent damage on the material parameters caused by the irradiation were determined by measuring the 4\piM_{s}, \sigma_{w}, l, \mu_{w}, H_{c}, V_{s} and defect density before and after each irradiation, while the device performances were studied by comparing the propagation and annihilation margin and the detector signal. The irradiation sources included neutrons from a nuclear reactor and gamma rays from a Co60source. No significant Variation due to irradiation was found in any of the measurements for neutron irradiation up to 1015n/cm21 MeV equivalent and gamma irradiation up to 50 Mrads. Transient stability of information stored in a bubble memory was tested by writing information into different shift registers and then bombarding these registers with a high energy (∼1.5 McV) pulsed electron beam. The results indicate there is no loss of data for a dose rate of 104rads in a 30 ns pulse.

Effects of nuclear radiation on a high-reliability silicon power diode three-junction capacitance : J. F. Been and I. T. Myers. Nat. Aeronaut. Space Admin., Washington D.C., U.S.A., May (1971), pp. 19. P-176474. NASA-TN-D-6330

Effects of nuclear radiation on a high-reliability silicon power diode three-junction capacitance : J. F. Been and I. T. Myers. Nat. Aeronaut. Space Admin., Washington D.C., U.S.A., May (1971), pp. 19. P-176474. NASA-TN-D-6330

Device Degrdation from the Effects of Nuclear Radiation on Passivation Materials

Devices that utilized three different commercial passivation processes were studied in a nuclear radiation environment to determine if the passivation process influences the radiation tolerance of the device. Comparisons were made between devices obtained from the same manufacturer. The passivation processes studied featured silicon dixoide, silicon nitride and aluminum oxide. Irradiations were performed with the devices in both a biased and unbiased mode. The results show that the device with silicon dioxide passivation degraded the most. The nitride devices having beam leads showed no saturation of the induced degradation while the other processes did for a dose of 1 × 107 (Si). All devices studied showed a small bias dependence. The addition of an aluminum oxide or silicon nitride passivation layer (over the silicon dioxide surface) for an increased reliability definitely induces no increased radiation degradation.

Regenerative system for continuous measurement of internal friction and Young's modulus of alkali halide crystals

A regenerative drive system is described for kilohertz acoustic measurements in alkali halide crystals. In the system field effect transistors are used as gain control elements to keep the strain-amplitude of mechanical vibrations constant during experiments in which internal friction and modulus are changing. Discussion is given of the main features of the design of the equipment, its testing and calibration and its application to experiments involving effects of nuclear radiation on alkali halide crystals.

Effects of nuclear radiation on a high reliability silicon power diode I-Change in I–V design characteristics : J. F. Been, Natl Aeronaut. Space Admin., Washington, D.C., NASA TN D-4620, June (1968), 36pp

Effects of nuclear radiation on a high reliability silicon power diode I-Change in I–V design characteristics : J. F. Been, Natl Aeronaut. Space Admin., Washington, D.C., NASA TN D-4620, June (1968), 36pp

Transient Effects of Nuclear Radiation on the Dielectric Properties of Refractory Low‐Loss Ceramics at Microwave Frequencies

Selected ceramic materials were exposed to an intense burst of nuclear radiation to determine the transient effects of such an environment on their dielectric properties at frequencies in the L, S, and X bands. The radiation source was a pulse reactor of the swimming pool type which delivers a maximum dose of 2 × 1014/cm2 and 5 × 105 rd gamma during a 13 ms pulse. The dielectric constant and loss of the materials under test were measured before, during, and after irradiation using a resonant cavity technique successfully adapted to the unusual conditions of the experiment. The time resolution in the dielectric measurements was 10 ms. Results are reported for polycrystalline alumina, beryllia, magnesia, boron nitride, clear and opaque fused silica, and, for comparison, four organic dielectrics. Among the materials which exhibited radiation effects, changes in dielectric constant ranged from 0.001 to 0.008 and in tan δ from a factor of 2 to several orders of magnitude.

The effects of coupling nuclear radiation with static service stresses on pressure vessel material behavior

The nuclear service performance of two pressure vessel steels as influenced by the application of static stress during radiation exposure has been examined. Bar samples from an A350-LF1 (Modified) steel forging and from a heavy section A302-B steel plate were irradiated under uniaxial tension at 430°F and 550°F, respectively, together with unstressed (reference) specimens for comparisons of Charpy-V notch ductility performance. Applied stress levels were in excess of 75% of individual steel yield strengths at temperature. A brief description of the special exposure assembly and control instrumentation developed for this study is presented. Experimental data for both steels suggest no synergistic effect of applied stress and radiation on mechanical properties performance under conditions simulating nuclear service. The post-irradiation annealing response of the low alloy A302-B steel also was not found to be influenced by stress during irradiation.

Comparison of surface and bulk effects of nuclear reactor radiation on planar devices

Surface effects of nuclear reactor irradiation are separated from bulk effects, and their relative importance compared. It is shown that the rates of change of surface recombination velocity and lifetime with dose are such that at high doses surface effects have an insignificant influence on p-n junction recombination-generation currents compared to bulk effects. In particular, the degradation of current gain at low collector currents in reactor irradiated bipolar transistors is shown to be the result of increased recombination in the bulk rather than at the surface of the emitter-base depletion region, in contrast with the case of ionizing radiation alone.

Effect of nuclear radiation on the mechanical relaxation behavior of polytetrafluoroethylene

Nuclear radiation effect on structural and mechanical relaxation behavior of polytetrafluorethylene at audio frequencies

Radiation effects on creep rupture and fatigue strength of pure aluminum

Paper describes an experimental investigation on the effect of nuclear radiation on the creep rupture and fatigue strength of pure aluminum for the ratios of alternating stress to mean stress ranging from zero to infinity. It was found that not only was the strength of the material tested affected by radiation over a range of ratios of stresses, but also the brittle-ductile transition was influenced. Based upon the experimental results obtained, an analytical model was developed to correlate creep rupture, fatigue strength and radiation effect for various ratios of stresses. This information may prove to be valuable in dealing with the stress analysis of nuclear reactors.

Effects of Nuclear Radiation as Part of the Temperature-Vacuum-Power Environment

Various electronic parts were exposed to combined environments such as temperature, vacuum, and nuclear radiation. A brief summary of the total results is presented with a more detailed description of the results obtained on the 2N911 transistor.

The Design and Performance of a 1200degrees F Magnetic Flowmeter for In-Core Application in Sodium-Cooled Reactors

A magnetic flowmeter that may be used in the core of a 1200°F sodium-cooled reactor has been designed and partially tested, The flowmeter is constructed in the shape of a hexagon so that it can be completely self-contained as a part of a reactor fuel element. An integral stainless steel sheath, alumina insulated, stainless steel lead wire is provided for signal transmission. Complete construction and design details are presented. The effects of temperature and nuclear radiation on the magnet stability are considered and discussed. The preliminary test results are given and compared to the calculated performance.

EFFECTS OF NUCLEAR RADIATION

EFFECTS OF NUCLEAR RADIATION

Effects of nuclear radiation and cryogenic temperatures on nonmetallic engineering materials

Changes in physical and mechanical properties of engineering materials exposed to nuclear radiation and cryogenic temperatures