摘要:

AbstractOne-dimensional two-phase flow equations, describing mass and momentum equations for two phases, are used to analyze viscous term contributions to stability problems concerning two-phase flow equation systems. When viscous terms are taken into account, characteristics of the system become real. This paper shows that viscous terms stabilize disturbances, if the ratio of the system's dimension to the wavelength is sufficiently larger than the Reynolds numbers for the two phases. Some examples show that this result holds, when differential terms are added. An example of stable systems for any wavelength perturbations is given by adding a simple wall shear-like stress term. These results are obtained by the use of a linear stability analysis.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19624

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractWater breeder reactors based on thermal water reactors have the advantages of a well-proven technology, a wide operational experience, and an acceptable safety status, the latter from using water as a coolant and having a negative void coefficient. Water breeder reactors are now in operation for the232Th-233U cycle and are being designed for the238U-Pu cycle. This paper proposes a water breeder system in which two reactors operate in symbiosis, one using238U-233U as fuel and producing plutonium, and the other using232Th-Pu as fuel and producing233U. Thus, each reactor feeds the other. From the breeding point of view, the combined system has an advantage over the separate238U-Pu and233Th-233U cycles.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19625

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractThe moderator temperature coefficients of reactivity for a pressure-tube-type reactor consisting of highly heterogeneous cells with D2O moderator, H2O coolant, and 28-pin fuel cluster contained in a pressure-tube have been measured in order to clarify their dependence on the moderator temperature.A new experimental method has been developed that is applicable to ordinary critical assemblies not equipped with any special temperature control system. In this method, temperature changes of the core, which is subjected to natural cooling that permits heat transfer from the moderator to the H2O coolant, are measured continually, together with the resultant changes in reactivity. The data are analyzed with use of least-squares fitting to nonlinear functions.It has been clarified that the moderator temperature coefficient of reactivity of this type of reactor is markedly dependent on the moderator temperature, decreasing with increase in the temperature. In a clean lattice of 1.2 wt%235U enriched UO2fuel that contains no10B in the moderator, the coefficient changes its sign from positive to negative at∼40°C. Addition of 3.9 ppm of10B into the D2O moderator of the same lattice causes the value of the temperature coefficient to shift considerably toward the positive side.Calculational results by the WIMS code reproduce quite well the experimental values of the temperature dependence of the moderator temperature coefficient of reactivity. However, their absolute values are rather small compared to the experimental ones.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19626

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractFission-product decay energy-release rates have been measured for thermal-neutron fission of235U. Spectral data were obtained using scintillation spectrometers for beta and gamma rays separately, and were processed to the form of total yield and total energy-release integrals for each set of time-interval parameters. The irradiations were for 1, 10, and 100 s, and measurements were made covering times following irradiation from 1.7 to 13 950 s. The separate beta- and gamma-ray energy-release data were summed to obtain the total (β+γ) energy-release rates for the cases studied. The data are processed to provide two standard representations of decay energy release, the one following a pulse of fissions, and the other following an infinite period of irradiation. A complete representation of estimated uncertainties is given in the form of a variance-covariance matrix. For the pulse representation of the data, diagonal components correspond to uncertainties in the range of 3 to 4%, with correlation coefficients in the range from 0.1 to 0.5. The experimental data are compared with other experimental data. The present results are generally smaller than other data, in some cases by more than the estimated uncertainties.The present results are smaller than the proposed 1973 American Nuclear Society (ANS) Decay-Heat Standard by as much as 10% for times following fission between 2 and 400 s, and are also smaller than the presently proposed (1978) ANS Decay-Heat Standard by 5 to 8% for the time interval 2 to 600 s. The reasons for these differences are discussed, and the importance for analyses using the new standard is presented.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19627

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractA separation technique that divides the transport equation into two parts is developed to analyze fusion-fission hybrid systems. The transport of fusion-produced neutrons (first generation neutrons) is separately calculated and a fission neutron source is generated. The behavior of the second and subsequent generations of neutrons is obtained using fewer energy groups and a low order treatment for scattering. As usual, integral parameters are the summation of the contributions from the two parts. A sensitivity theory consistent with the separation technique is used to evaluate the relative sensitivity coefficient of a reaction rate to perturbations in the system. Relations between different adjoint fluxes are derived in the context of the separation technique. The technique is applied to show that the use of a low-order scattering description when solving the second part of the problem leads to small errors in the value of the fissile fuel production rate in a hybrid. Variation of this production rate with time can approximately be accounted for using the beginning-of-life values of the forward flux of the first part (related to fusion neutrons), the adjoint flux of the system, and the time-dependent source of the second part (related to subsequent fission generations).

ISSN:0029-5639    

DOI:10.13182/NSE80-A19628

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractMethods of performing continuous energy or multigroup charged-particle transport in hot media are discussed. In particular, it is pointed out that if one is to properly calculate reaction and energy deposition rates, one must properly handle the temperature dependence of cross sections and emission spectra when performing transport calculations.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19629

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractThe application of the generalized variational principles to controlled thermonuclear reactor (CTR) neutronics studies has been demonstrated using the neutronics analysis for a laser-driven molybdenum-structured CTR blanket. The variational functionals could be derived and proved identical mathematically with the well-known perturbation theory. The variational and perturbational functionals are alternatively useful in a fixed adjoint source and a fixed system perturbation problem. The neutronics calculational results using these techniques show the accuracy, range of applicability, and extremum property of their applications.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19630

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE80-A19631

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE80-A19632

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE80-A19633

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor