摘要:

AbstractA computer model of the existing and possible new USAEC gaseous diffusion plants (GDP) has been developed. The model has been combined with a nonlinear optimization method which permits optimum long range operating Plans to be generated. A description of the model is presented with examples of its use in simulation and in generation of optimal long range plans.

ISSN:0550-3043    

DOI:10.13182/NT70-A28792

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractThe effect of temperature on radiation characteristics and subsequent material properties after cryogenic temperature irradiation is analyzed. To date the materials tested have included hot pressed block beryllium, Ti-5% Al-2.5% Sn ELI (Al10AT), and an aluminum alloy 2219. These materials have been irradiated at liquid nitrogen temperatures (140°R) and tensile tested without any intervening warm-up. Some of the liquid nitrogen irradiated and tested material data as well as room temperature data are presented. The properties investigated have included ultimate tensile strength, percent elongation, and fracture toughness. Usually, ductility and the decrease in the magnitude of this property as a function of irradiation is of more vital interest to the designer. The experimental program conducted for some of the NERVA candidate materials is reported and areas of additional investigations for application to advanced NERVA designs are briefly discussed.

ISSN:0550-3043    

DOI:10.13182/NT70-A28793

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractA test has been devised to detect incipient failure of relays, which does not require removal of the relay from its circuit, nor does it require any system outage time in vital reactor applications. The relay parameter, which is evaluated, is the actuation time. The distribution of actuation times has been measured for several relays, of two different types. The distribution has been shown to shift as a function of coil voltage, overall temperature, and spring tension. A large shift in the distribution was noted as a result of a destructive heating test. As a result, the use of the 90% spread points of a reference distribution is proposed as a criterion for the detection of incipient failure in a periodic multiple-test program.

ISSN:0550-3043    

DOI:10.13182/NT70-A28794

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractIn connection with fast neutron (n,α) cross-section measurements, a novel boron analysis method has been developed. The boron concentration is inferred from the mass spectrometrically determined number of helium atoms produced in the thermal and epithermal10B (n,α) reaction. The relation between helium amount and boron concentration is given, including corrections for self-shielding effects and background levels. Direct and diffusion losses of helium are calculated and losses due to gettering, adsorption, and HF-ionization in the release stage are discussed. A series of boron determination is described and the results are compared with those obtained by other methods, showing excellent agreement. The lower limit of boron concentration, which can be measured, varies with the type of sample. In, e.g., steel, concentrations below 10-5% boron in samples of 0.1 to 1 g may be determined.

ISSN:0550-3043    

DOI:10.13182/NT70-A28795

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractA remotely operated atomic absorption system was developed for the routine determination of metallic constituents at macro and trace levels in highly irradiated nuclear fuel. A special optical system in the hot-cell directs a light signal to a monochromator and associated readout equipment located outside the cell. The same monochromator and readout equipment serves an atomic absorption instrument located outside the cell for analysis of non irradiated material. The sensitivity and precisian of the two systems is essentially the same. The time required for wet chemical analyses of irradiated fuel was reduced by a factor of 8 to 10 with the remote atomic absorption system.

ISSN:0550-3043    

DOI:10.13182/NT70-A28796

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractThe hydrodynamics of coolant flow in a natural circulation, nuclear-heated boiler are dependent upon interactions of the generated heat, the available driving head of vapor in the two-phase mixture, and flow of the coolant. Where at steady operating conditions a slight increase in heat generation will induce unstable flow, circulation hydrodynamics can be investigated by small-signal techniques of control system theory. The flow-pressure interaction can be described in terms of the hydraulic impedance which is the frequency-transformed ratio of two perturbed quantities, differential pressure over flow rate. The hydraulic impedance is analogous to acoustic impedance (acoustic pressure/particle velocity) of compressible media and to mechanical impedance (force applied to structure/resulting velocity) of rigid body mechanics. Measurements of the flow-vapor interaction and of the flow-pressure interaction (hydraulic impedance) are compared to a simplified theory, to demonstrate how the impedance approach aids understanding of complex two-phase phenomena. As a practical application, the flow stability of a boiling loop is predicted by measured hydraulic impedances.

ISSN:0550-3043    

DOI:10.13182/NT70-A28797

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractThe self-absorption alpha range for the 5.5-MeV alpha emission in238PuO2was determined to be 11.7±0.2μm by measurement of the effective activity on microspkerical sources of from 150 to 250μm diameter. A function was derived and experimentally tested which related the fractional escape of the total alpha emission to the range-radius ratio of the microspherical source. An energy distribution function was also derived for the alpha emission from a microspherical source which agreed quite well with the experimentally determined spectrum above 1 MeV. It is suggested that the derwed function provides a more accurate description of the energy region below 1 MeV than the experimental data.

ISSN:0550-3043    

DOI:10.13182/NT70-A28798

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

AbstractCoefficients for the Berger formula gamma-ray buildup factor are given for ordinary, magnetite, and barytes concrete, air, sand, wood, and lithium hydride. The original data can be reproduced using these coefficients with an error for source energies greater than 2 MeV to generally less than about 5%. Errors for energies 0.5 to 2 MeV may be of the order of 20%.

ISSN:0550-3043    

DOI:10.13182/NT70-A28799

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

ISSN:0550-3043    

DOI:10.13182/NT70-A28800

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor