摘要:

AbstractStationary experiments (subcritical and with choked flow) with strongly accelerated steamwater and air-water mixtures, assuming a broad variation of inflow conditions (m˙,p,x), were performed in a well-instrumented horizontal diffuser. The experimental setup is reported as well as the experimental program. The phenomenology of a two-phase horizontal diffuser flow is investigated.Experimental data are compared to calculations with a one-dimensional computer code (DUESE). In a systematic study, two-phase flow models (homogeneous and drift-flux) and empirical parameters in constitutive correlations of different code versions were tested. Special attention was given to the pressure rise in the diffuser, which could be calculated adequately only with the drift-flux correlation taken from the SOLA-DF code.Velocity data for choked flow conditions are compared to four different two-phase sound velocity models, which give the best agreement with the equilibrium sound velocity.

ISSN:0029-5639    

DOI:10.13182/NSE88-A29019

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractUncertainty estimates and cross correlations by range/survivor have been calculated for the Hiroshima and Nagasaki free-in-air (FIA) tissue kerma obtained from two-dimensional air/ground transport calculations. The uncertainties due to modeling parameter and basic nuclear transport data uncertainties were calculated for 700-, 1000-, and 1500-m ground ranges. Only the FIA tissue kerma due to initial radiation was treated in the analysis; the uncertainties associated with terrain and building shielding and phantom attenuation were not considered in this study. Uncertainties of∼20% were obtained for the prompt neutron and secondary gamma kerma and 30% for the prompt gamma kerma at both cities. The uncertainties on the total prompt kerma at Hiroshima and Nagasaki are∼18 and 15%, respectively. The estimated uncertainties vary only slightly by ground range and are fairly highly correlated. The total prompt kerma uncertainties are dominated by the secondary gamma uncertainties, which in turn are dominated by the modeling parameter uncertainties, particularly those associated with the weapon yield and radiation sources.

ISSN:0029-5639    

DOI:10.13182/NSE88-A29020

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractGeneralized bias operators (GBOs) can be derived from the differences in the calculations of a nuclear system by two methods. One method is accurate and expensive and the other one is less accurate and less expensive. These GBOs serve to improve the accuracy of the less accurate methods for systems similar to the original one. Two applications are discussed. In the first application, diffusion-type calculations with GBOs give transport calculations quality results. In the second application, one-dimensional calculations with GBOs replace two-dimensional calculations. The method is applied for calculating the Zion-2 core.

ISSN:0029-5639    

DOI:10.13182/NSE88-A29021

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractA study on the development of acceleration equations for boundary cells and the associated boundary conditions for the diffusion synthetic acceleration method of neutron transport problems in x-y geometry is described. Alcouffe’s algebraic manipulation of the P, equations resulting in a single diffusion equation is modified to obtain explicit acceleration equations for the boundary cells. To accomplish this, the discretization in space is performed according to the ordinary box-centered method. The resulting synthetic computation scheme is linear in its differenced form. The boundary cell difference equations are derived in a manner that exactly parallels the discretization of the diffusion equation for interior mesh cells and that of the transport equation. The importance of these equations in improving overall efficiency without sacrificing stability is discussed, as is the optimum choice of the boundary conditions associated with these equations.

ISSN:0029-5639    

DOI:10.13182/NSE88-A29022

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE88-A29023

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE88-A29024

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE88-A29025

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE88-A29027

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE88-A29028

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor