摘要:

AbstractTwo methods of sensitivity theory, i.e., the Direct Sensitivity Approach and the Adjoint Sensitivity Method, have been successfully applied to a simplified problem of transient, one-dimensional, composite region of single-phase and homogeneous equilibrium two-phase flow within a uniformly heated channel subjected to an exponential inlet flow decay. In both methods, exact analytical solutions for all elementary sensitivity coefficients at each point in space and time are obtained. A general procedure for the construction of the sensitivity equations' boundary conditions at the moving boundary between the two phases has been developed and applied. Discontinuities in the velocity and quality sensitivity coefficients across the moving boundary have been obtained. The enthalpy sensitivity coefficients are found to be continuous. The behavior of the sensitivity coefficients has been investigated. This investigation provides insights into the relative importance of the input parameters and the nature of the propagation of uncertainties in space and time in two-phase flow systems.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17880

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractAerosol release is expected from a pool of molten corium that is agitated by gases that would emerge from concrete during the core/concrete interactions phase of a core meltdown accident in a light water reactor. A corium flow-regime-dependent model is developed for aerosol generation by mechanical breakup of the melt by the flowing vapors. Previous work reported in the literature is used to identify the dominant corium gas/liquid flow regimes and to formulate the flow/regime transition criteria. Models are presented for the calculation of an aerosol entrainment rate under conditions of bubbly- and churn-turbulent, two-phase pool conditions.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17881

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractA proposed fuel freezing mechanism for molten UO2fuel penetrating a steel channel was investigated in the course of liquid-metal-cooled fast breeder reactor hypothetical core disruptive accident safety studies. The fuel crust deposited on an underlying melting steel wall was analyzed as being subjected to two stresses, one due to the pressure difference between the flowing fuel and the stagnant molten steel layer, and the other resulting from the temperature variation through the crust thickness. Analyses based on the proposed freezing mechanism and comparisons with fuel freezing experiments confirmed that fuel freezing occurs in three modes. For initially low steel wall temperatures, the fuel crust was stable and grew to occlude the channel. At high steel wall temperatures (above 1070 K), instantaneous wall melting leading to steel entrainment was calculated to occur with final penetration depending on the refreezing of the entrained steel. Between these two extremes, the stress developed within the crust at the steel melting front exceeds the critical buckling value, the crust ruptures, and steel is injected into the fuel flow. Freezing is dominated by the fuel/steel mixture. The theoretical penetration distances and freezing times were in good agreement with the experimental results with no more than 20% error involved.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17882

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Abstract60Co accumulation on boiling water reactor (BWR) primary cooling pipings. To demonstrate the treatment effect, test specimens, which had been exposed to simulated BWR water in an autoclave (temperature, 286°C; pH, 7; oxygen concentration, 200 ppb) for up to 200 h, were installed in the Hatch-2 inplant loop and their60Co deposition amounts were compared with those of as-received specimens. Preoxidation treatment for 200 h resulted in deposits of about one-fourth those of as-received specimens. It was estimated that the maximum amount of60Co deposited on primary piping during the entire plant operation life (30 yr) would be reduced to about one-half of that without preoxidation treatment if the60Co concentration in the reactor water was constant.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17883

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractThree-dimensional numerical computations of negatively buoyant cold jet injected into hot water flowing in a pipe are presented for various hot-to-cold flow rate ratios. A fine nodalization with a newly modified skew upwind differencing scheme is employed. The adoption of this scheme results in a significant reduction of the numerical diffusion errors. Under certain conditions of the jet Froude number, the hot water penetrates upward into the injector, resulting in a recirculatory flow region. Such penetration and recirculation enhance the mixing process, thus helping mitigate the pressurized thermal shock concern. A satisfactory agreement between the numerical temperature predictions with available experimental data is obtained.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17884

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractNeutron capture measurements were made on a sample of fission product palladium at the Oak Ridge Electron Linear Accelerator time-of-flight facility. One hundred thirty resonance peaks were parameterized up to 3.5 keV and the average cross section from 3 to 600 keV was derived. The data exceed the ENDF/B-Vevaluation by∼25% in the 3- to 300-keV range but drop steeply below it at higher energies where neutron inelastic-scattering competition becomes important. The Maxwellian average cross section for kT = 30 keV is calculated as 1.34±0.06 b, and the dilute resonance capture integral as 108.1±4.3 b.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17885

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractAbsolute differential cross sections for the n0and n1neutron groups for the reaction10B(p, n)10C and the n0, n1, n2, n3, (n4+ n5), n6, and n7neutron groups for the reaction11B(p, n)11C have been measured at incident proton energies of 14.0, 14.3, and 14.6 MeV in the angular interval 20 to 160 deg along with excitation curves atθlab= 30 deg from Ep= 13.7 to 14.7 MeV.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17886

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractThe process of neutron slowing down in a nonabsorbing medium is reviewed, and the distinction between average energy or lethargy after n collisions and the average number of collisions to reach a given energy is emphasized. Fermi's remark about neutron slowing down in hydrogen is explained and rederived.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17887

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractA two-group, one-dimensional formulation of a coupled-core system is proposed as a revision of the one-group response function method by Shinkawa et al. The coupling coefficient of the Kyoto University Critical Assembly symmetric coupled-core loading is revised. In such a light-water-coupled system, the fast-to-fast coupling,Δ11proves the greatest, the fast-to-thermal,Δ12, the second, and the thermal-to-thermal,Δ22, the smallest component within the quantity; at the core distance of 10 cm,Δ12= 0.68Δ11andΔ22= 0.028Δ11. Beyond 20 cm, bothΔ11andΔ12decrease approximately by the fast-neutron relaxation length of water. The effectiveness of the incoming neutrons is considerably dependent on the thickness of the core that receives them.

ISSN:0029-5639    

DOI:10.13182/NSE85-A17888

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE85-A17889

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor