摘要:

AbstractOver fifty fast critical assemblies have been studied in the Zero Power Reactor - III (ZPR-III) of Argonne National Laboratory since it started operation in 1955. All of these assemblies were fueled with U235and reflected with depleted uranium; the core volumes ranged from 2 to 660 liters and the critical masses ranged from 26 to 580 kg of U235. The experimental characteristics of a representative group of 23 of these assemblies in which oxide, carbide and metallic fuels were simulated have been compared with calculated values. The parameters studied were critical size, central fission ratios, prompt-neutron lifetimes and the reactivity effects of substitution of various materials at the reactor center.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20960

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractA program was instituted to study and reproduce the in-reactor intergranular failures of Type-304 stainless steel fuel cladding found in superheated steam. The program was directed toward finding ways to eliminate the cause of failure or to use improved alloys that would be less susceptible to failure.A materials screening test was developed in the out-of-pile superheat facilities with 1.5 parts/106chloride added as sodium chloride to the recirculating water in the presence of typical boiling-water-reactor quantities of oxygen and hydrogen. During the test, the heater sheaths were exposed through several cycles to saturated steam (with its accompanying moisture carryover) and superheated steam. Failure of Type-304 stainless steel was obtained in periods of less than two weeks; the failures were predominantly transgranular. Type-347 and vacuum-melted Type-304 stainless steels failed in this NaCl-cycle test while Inconel-600, Incoloy-800, Hastelloy-X, Type-406 stainless steel, and vacuum-melted Type-310 stainless steel were acceptable.An improved chloride cycle test utilizing 0.5 parts/106chloride added as ferric chloride to the recirculating water was developed. An intergranular failure was obtained similar to that experienced in the superheat fuel cladding failures in the superheat in-pile loops in the Vallecitos Boiling Water Reactor. Sensitized Type-304 and Type-316 stainless steels failed intergranularly in this test. Inconel-600, Incoloy-800, and vacuum-melted Type-310 stainless steel did not fail when exposed to the test for much longer times.During the development and performance of the cycle runs, the superheat facilities were exposed to a myriad of conditions within the extremes of the test parameters involved. Intergranular chemical attack was experienced essentially independent of stress, but the attack was generally distributed. In the presence of high stress, the intergranular attack was more localized and advanced normal to the stress. This suggests that a definite interplay exists between chemical attack and stress, and that the application of the stress increases the rate of the intergranular attack preferentially in a direction perpendicular to the stress.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20961

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractNitrosylruthenium-dibutylphosphate complexes were prepared by the reaction of trinitrate-nitrosylruthenium with dibutylphosphoric acid and by the reaction of nitrosylruthenium hydroxide with dibutylphosphate in alkaline solutions. The products are mixtures of compounds of indefinite composition, some of which are monomeric and others polymeric. Complexes were also prepared by the reaction of trinitrato-nitrosylruthenium with monobutylphosphoric acid and dinitro-nitrosylruthenium with dibutylphosphoric acid.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20962

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractThermal stress and displacement equations are derived for an internally clad tube for which the ratio of cladding thickness to internal tube radius is small with respect to unity and in which the cladding and the basic tube have different material properties. When the difference between the cladding temperature and the average temperature of the basic tube is large enough, plastic flow is found to occur in the cladding. The corresponding solution is found by making use of the Tresca yield condition and its associated flow law.The solution is examined to guide the designer in the selection of those cladding material properties that would delay the initiation of plastic flow.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20963

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractNeutron penetration in water and in iron/water shields has been calculated using a P-3 multigroup program. The thermal-neutron flux from a point fission source in water obtained from calculation and experiment agree to within 18% in the region between 15 and 140 cm, covering more than 9 decades of attenuation. The calculated neutron spectrum compares favorably in shape and magnitude with moments-method results out to 120 cm of water. The observed variations of the thermal-neutron flux in an iron/water shield are predicted by the P-3 program. Some of the differences between experiment and the predicted thermal flux within a thick iron region are due to the single-energy-group treatment in the calculations. Uncertainties in the high-energy cross sections for iron are of sufficient magnitude to account for differences between calculation and experiment noted in the water region following iron.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20964

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractThe slowing-down times in water, toluene, and heavy water were obtained from measurements of capture-gamma-ray counting rates as a function of time after injection of a neutron burst. The times to the 1.46-eV resonance in indium were 0.75±0.5μsec, 1.5±0.3μsec, and 4.0±1.0μsec for the three moderators. The corresponding times to a 0.4-eV energy in cadmium were 1.75±0.5μsec, 3.25±0.3μsec, and 10.5±1.0μsec, respectively. Time-gated pulse-height spectra measurements in a large liquid scintillation detector were made to separate fast- from thermal-neutron interactions by taking advantage of slowing-down-time spectrometry. Steady-state pulse-height spectra measurements in water and in water plus indium illustrated the application of prompt-gamma-ray analysis to determination of capture rates.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20965

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractThe problem of adiabatic excursions in a reactor is studied in general. We let the prompt temperature reactivity feedback be an unspecified function of temperature,ρ=ρ0=ρ0+ f(T), whereρis total reactivity,ρ0initial step reactivity andf(T)the feedback function. The similarity of the behavior of the reactor for differentf(T)is established by means of a topological (qualitative) analysis. A quantitative asymptotic solution of the non-linear system ofDEdescribing the reactor is presented. In delayed critical excursions, the delayed neutrons play a determining role. In the first part of a prompt excursion, the delayed-neutron source is nil; however this is not so in the second part, where it contributes appreciably to the excursion. These conclusions are shown to be valid in general, and allow us to write down almost directly the (approximate) quantitative solution of the non-linear system forany f(T). These results are correlated with the experimental data for the adiabatic excursions of a UO2core in SPERT I; in this case the (prompt) dependence of the reactivity on energy is of the formρ=ρ0- 4.588×10-4E0.74.

ISSN:0029-5639    

DOI:10.13182/NSE19-03-329

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractNumerical solutions of the time-dependent thermalization problem in infinite 1/νpoisoned media as well as in finite media in the diffusion approximation have been obtained using an eigenfunction expansion of the neutron-density function in a discrete-energy representation. This eigenfunction method is compared with a method based on direct integration of the Boltzmann equation using a discrete-energy mesh for the scattering integral and a first-order Taylor series for the time integration. Both methods of calculation have given the same results where compared in the area of time-dependent and steady-state spectra. The Wigner-Wilkins Mass-1 and Nelkin scattering models have been used with particular emphasis on the computation of time-dependent, asymptotic, steady-state spectra and diffusion parameters and the determination of their sensitivity to the scattering kernel. It is found that time-dependent spectra are rather sensitive to the scattering kernel, particularly at times of the order of a few microseconds after the introduction of a neutron pulse in the case of hydrogenous moderators. The eigenvalues and eigenfunctions for both realistic scattering kernels show the characteristics predicted for simpler analytic models. Both discrete and continuum eigenvalues have been found with the eigenfunctions corresponding to the continuum eigenvalues exhibiting a characteristic singular behavior. An interpolation scheme to determine steady-state spectra in hydrogenous moderators is also presented. The method, which is based on interpolating in the reciprocal of the infinite-medium neutron lifetime, gives very good agreement with directly computed spectra in the range of 200 to 15 microseconds lifetime. A perturbation method based upon the infinite-medium eigenfunctions is used to compute diffusion parameters for the decay constant in water; this method, through terms inB4, yields the decay constant to better than 1% in comparison with the exact diffusion theory result forB2= 1.0 cm-2.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20967

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractCorrections to the extrapolation distance and angular emergent distribution for the Milne problem have been obtained by means of a perturbation method. The exact solution for a simple kernel has been taken as the unperturbed state, and the method has been applied to more realistic scattering models: numerical results are given for hydrogen gas.By means of a combined use of numerical and analytical methods some very accurate values have been obtained for the emergent angular energy spectrum for the Milne problem in the case of hydrogen gas.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20968

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractThe failure of the standard slowing-down solutions to reproduce the detailed flux distribution both in and far below a resonance is discussed. To first order, the neutron distribution in energy is explicitly symmetric about the resonance center. Higher-order approximations, however, reveal the asymmetry in the spectral distribution. The direction of the spectral shift, as well as the degree of asymmetry, depends on the resonance parameters. There is, in particular, a competition between absorption and scattering in the resonance which directly affects the spectral asymmetry. The asymptotic distribution far below the resonance is unity instead of equal to the resonance escape probability. This difficulty may be overcome by formulating the problem in terms of the Placzek solution.

ISSN:0029-5639    

DOI:10.13182/NSE64-A20969

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor