摘要:

AbstractThe equations and computer algorithms are derived and developed to determine the limiting rotational and scattering angles for spherical, planar circular, and right circular cylindrical detectors. In addition, the computer algorithms developed provide most of what is required for implementing the expected value technique in analog Monte Carlo simulation. This includes providing a specific rotational angle, a specific cosine of the scattering angle, a weight factor for forcing within the limiting cosines of the scattering angle, and the direction cosines for the specific angles chosen.

ISSN:0029-5639    

DOI:10.13182/NSE87-A20436

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractOxide films on Type 304 stainless steel and carbon steel exposed to boiling water reactor primary cooling water were analyzed, and mechanisms of corrosion and60Co accumulation were proposed.Double oxide layers were observed on the stainless steel coupons. The outer layer consisted of well-developed crystals (diameter: 0.5 to 1.0νm, probable major oxide form: NiO Fe2O3), while the inner layer consisted of smaller particles [diameter: 0.1 to 0.3μm, probable major oxide form: NiO·(Cr,Fe)2O3]. The depletion of chromium and nickel and the accumulation of impurities in the water, such as60Co, zinc, and copper, were observed in the outer layer. For the carbon steel the chromium-rich layer existed at the outer/inner interface. It was considered that the outer and inner layers were a corundum-type oxide (Cr,Fe)2O3.The outer layer seemed to be formed by a wet corrosion mechanism (dissolution-precipitation of metal), while the inner layer seemed to be formed by a dry corrosion one (reaction of metal with oxygen diffused through the oxide layers from the water).More than 80% of the60Co in a coupon was included in the outer layer, and it was supposed that this was deposited mainly during wet corrosion.

ISSN:0029-5639    

DOI:10.13182/NSE87-A20437

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe physics of intermediate high-conversion water reactors is strongly influenced by two essentially independent phenomena:a spectral shift associated with the reduced scattering performance of water, which shows an increased participation of238U to the neutron slowdowna vanishing of the thermal component of the spectrum, which is due to the huge absorption resonances of plutonium in the epithermal region.The effects of these physical phenomena on the most important neutronic integral parameters, such as eigenvalue, voiding reactivity, and burnup, are investigated by means of the perturbation theory. A reference group structure adjusted to design requirements is also determined, via pattern recognition methods, and the most important physical trends of the parameters are presented, correlated by sensitivity coefficients and some practical applications.

ISSN:0029-5639    

DOI:10.13182/NSE87-A20438

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe diffusion equation for volatile radioactive fission products in sintered nuclear fuels is investigated. All known effects that may affect the rate of diffusion to the grain boundaries are taken into account: simultaneous diffusion of the radioactive precursors, radioactive decay, sink trapping, and radiation resolution.Starting from the analysis of the spatial transport equation, an expression for the boundary loss term to be used in the simpler reaction rate equation is deduced.For practical applications the boundary loss term in the absence of resolution effects can reasonably be assumed to be independent of time. This is not generally true if resolution effects are present; in this case the release calculations become more complex than it was assumed so far.Finally, a discussion on the properties of the boundary loss term as functions of the physical parameters involved follows, and details of the calculations are presented.

ISSN:0029-5639    

DOI:10.13182/NSE87-A20439

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractCross sections for the emission of protons, deuterons, and alpha particles from enriched targets of63Cu and65Cu bombarded with 9- and 11-MeV neutrons were measured. A charged-particle time-of-flight spectrometer capable of detecting particles with energies as low as 1 MeV was used to make these measurements. Cross sections and spectra are compared with statistical and preequilibrium model calculations. Level density parameters of various nuclei resulting from the best simultaneous fit to present and previous 15-MeV data are inferred.

ISSN:0029-5639    

DOI:10.13182/NSE95-296

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractNeutron resonance parameters were found for152Gd up to 2700 eV. An average s-wave spacing D0= (17.4±1.0) eV and radiation width (58.6±3.0) meV were found. The resonance contribution to the capture integral was found as (397±32) b, exclusive of a 1/v term. Resonance parameters forI54Gd were extended from 490 to 2760 eV.

ISSN:0029-5639    

DOI:10.13182/NSE87-2

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractNeutron cross sections on carbon at and above 14 MeV are of interest for a variety of applications. It is argued that the ENDF/B-V evaluation of the nonelastic cross sections is in some error; this is due in part to the“subtraction”technique used for evaluating the nonelastic cross section, and to an overreliance on old nuclear emulsion data. In addition, secondary uncharged- (and, for biomedical applications, charged-) particle spectra are important. It is shown that kerma-factor calculations are very sensitive to the secondary charged-particle spectrum. Thus an assessment of the reaction mechanisms, leading to evaluated secondary particle spectra, is also needed.

ISSN:0029-5639    

DOI:10.13182/NSE87-A20442

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE87-A20444

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor