摘要:

A model is presented describing the phenomenon of liquid entrainment resulting from the presence of Kelvin-Helmholtz instability at the gas-liquid interface of a sonic gas jet submerged in a mass of liquid. On the basis of this model, available experimental data regarding the rate of entrainment were correlated satisfactorily. The correlation thus obtained is of importance in deriving the heat transfer coefficient in the impingement area of a fuel pin impinged upon by a fission-gas jet released from a failed pin in a liquid-metal-cooled fast breeder reactor fuel subassembly.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26616

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

Principles from information theory are used to obtain the minimum of the average number of shutdowns needed with a trial-and-error testing procedure for identifying failed fuel in nuclear reactors, based on a priori failure probabilities of each assembly. Also presented is the average reduction in the number of shutdowns if other information about failure is incorporated, so the merit of this other information can be assessed quantitatively. Illustrative examples are given for applications involving the use of information from flux tilting in a pressurized water reactor, gas tagging in a liquid-metal fast breeder reactor, and burnup in the Experimental Breeder Reactor II.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26617

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The probability generating function of the counts obtained in an arbitrary sequence of time intervals and counters is derived in the framework of the one-velocity point-reactor model without delayed neutrons. The main feature of the method is that the multiple derivatives of the probability generating function, which provide the joint probabilities and the joint moments, can be easily calculated from recurrence relations. The procedure is well suited to computer programming, and, indeed, a Fortran IV program has been written. Some conditioned probability profiles and moments thereby obtained are reported.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26618

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The total neutron cross section of carbon was measured over the energy range 1 keV to 15 MeV, using the U.S. National Bureau of Standards electron linear accelerator as a pulsed neutron source. Neutrom energies were measured by the time-of-flight method.The measurement accuracy is estimated to be±¾% below 100 keV and±1% above .The carbon cross section was fit with a polynomial from 0.001 to 1.4 MeV with the following coefficientsσ= 4.757−3.419E + 1.548E2−0.328E3, whereσis in barns and E in MeV. Data are compared with other results.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26619

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

Recommended values for delayed-neutron data of principal interest in reactor-physics analysis are presented. These data are the absolute delayed-neutron yield, the delayed-neutron energy spectrum, and the group fractions and decay constants used to describe the time behavior of delayed-neutron production. The recommended values are the result of a review and evaluation of experimental data and empirical correlations. Use of these values is discussed, and several remaining problems are described.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26620

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

Resonance self-shielding occurs as the result of flux depressions at resonance peaks. The group self-shielding factor is defined as the ratio of the effective flux-weighted cross section to the average cross section. Given a constant background cross section,σ, as well as a temperature and an energy group, the shielding factor of an element can be approximated by simple formulas employing two- or three-group effective parameters. These areλ,η, andρ—an effective base (potential scattering) cross section, an effective peak cross section, and an effective ratio of the base cross section to the average of the resonance total cross section, respectively.The use of resonance group parameters eliminates the problem ofσ- interpolation. Furthermore, through a certain interpretation of these parameters, theσ- ambiguity is also cleared up. The constant background,σ, required to represent the actual interaction of the shielded resonance series with background resonance series, is a linear expression in the number densities and theλ’s of the background elements.Theσ- iteration technique, currently in use, is shown to be rather inaccurate.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26621

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractThe consequences of igniting a small fissionable pellet by laser-beam or relativistic electron-beam induced high density implosion-compression on future reactor technology are discussed. It is shown that with this method a highly efficient reactor system becomes possible by direct magnetohydrodynamic conversion of the expanding fireball into a magnetic cavity. The method not only will lead to an“absolutely”safe fast breeder reactor but by using hybrid pellets consisting of a combination of both fissionable and fusionable materials in addition will also lead to a combined fission-fusion energy producing system. In such a fission-fusion hybrid system, whereby the fission process produces a large amount of heat and the fusion process produces a large number of neutrons, the bootstrap coupling between the fission and fusion processes greatly increases the rate of the ensuing chain reaction and hence energy output enhancing substantially the energy yield of the micro-explosions.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26622

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractThe exponential integral functions of the first and second kinds, E1(b) and E2(b), and the secant (Siever’s) integral, F(θ0,b), are useful in calculating radiation fluxes. Values of these functions vary rapidly with the argument b, so that useful tabulations are voluminous and interpolation is difficult. Related functions have been defined whose values vary slowly with the argument b and which are readily amenable to linear interpolation. Thus, accurate flux calculations depend only on the availability of an adequate table of the exponential function e-b. Compact tables of these related functions and of three other functions useful in flux calculations are given in this Note, together with illustrations of their use in shielding formulas.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26623

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractTo resolve a discrepancy in determinations of the10B(n,α)7Li branching ratio, a new measurement has been made at the National Bureau of Standards (NBS). The measurement was made with a10BF3gas proportional counter and monoenergetic 790-keV neutrons obtained at the NBS 3-MV Van de Graaff laboratory. A branching ratio of 0.66±0.03 was obtained. This determination agrees with the measurements of Petree et al. and Davis et al.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26624

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractCross sections of58Ni for interactions of the type (n,p), (n′), (n,α), (n,n′p), (n,2n,), (n,n′α), (n,αn′), (n,αp), (n,pn′), and (n,2p) with neutrons of 14.8 and 14.0 MeV (laboratory system) have been computed using a diffused-edge optical model potential. The spin dependence, shell, and pairing energy effects in the various level-density formulas have been considered. The compound nucleus and the direct interaction contributions are calculated separately. The computed cross sections are quite suitable for direct comparison with experimental values obtained from activation techniques and energy and angular distributions. The shell-dependent Newton’s level-density formula gives better agreement for primary and secondary emission.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26625

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor