摘要:

AbstractA new method is proposed for the analytical calculation of resonance integrals. Resonance integrals of infinite cylindric fuel cells are calculated according to a very simple analytical method with a reasonable level of accuracy. An escape probability based on a rational approximation is used to represent the neutron transport among the cell regions.The expression obtained for the resonance integral is a function of the temperature, geometry, and fuel rod composition, as well as the neutron energy. The terms of the expression are combinations of the well-known function J(ξ,β) and its partial derivatives inβ. The formulation can be used for all resonance types (narrow, intermediate, and wide). The method parameters depend on the resonance type and can be obtained as a function of a single parameter. For this parameter, a simple expression dependent on the resonance parameters is proposed.

ISSN:0029-5639    

DOI:10.13182/NSE89-A27475

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA probabilistic approach to quantifying uncertainties in the progression of severe reactor accidents is formulated and applied to the Source Term Code Package. It is shown that quantification of uncertainties at the basic level of input parameters reveals broad time-dependent uncertainties in the core melt progression, containment challenges, and fission product releases. Dominant contributors to the source term uncertainties include the core meltdown parameters, the release rate coefficients of fission products, the chemical activity coefficients during core/concrete interactions, and containment performance.

ISSN:0029-5639    

DOI:10.13182/NSE89-A27476

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractThe results from the BETA molten core/concrete interaction (MCCI) experiments conducted at Kernforschungszentrum Karlsruhe (KfK) and the associated analyses using computer models developed by KfK and by Sandia National Laboratories, i.e., WECHSL and CORCON, are described. Two important observations were made in the BETA steady-state tests:a distinctly larger downward erosion rate than previously measured in transient tests or predicteddispersion and mixing of the metallic layer in the oxidic layer at high-melt input powers and associated gas velocities.The first observation could be modeled by WECHSL and CORCON by modifications when interface heat transfer considered a“transition boiling”analogy model. The second observation was not modeled but is expected to be important during the high-temperature phase of the MCCI when fission product release is of concern. These results suggest that the BETA experiments provide necessary information to validate MCCI models for silicate (basaltic) concrete. For limestone (carbonatic) concrete, there are still open questions that further tests must address.

ISSN:0029-5639    

DOI:10.13182/NSE102-260

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA multivariable theory is applied to the design of the recirculation and feedwater control systems of a boiling water reactor. The nuclear steam supply system simulation model is represented by a set of 14 first-order nonlinear ordinary differential equations. Linearization about a steady-state operating point leads to a linear model. To reduce the computational effort, a sixth-order model is obtained by an optimal order reduction method. A robust controller is designed so that the regulation and tracking capability holds in the presence of certain perturbations and disturbances to the plant. The controller parameters are obtained by the parameter optimization method. The results of simulation show that the control system performs well and has robust stability.

ISSN:0029-5639    

DOI:10.13182/NSE89-A27478

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA number of interesting systematics and correlations have been deduced by analyzing the criticality data of special actinide nuclides using concepts embodied in the Trombay criticality formula (TCF). The k∞of fast metal actinide nuclides gives a remarkable linear correlation with the fissility parameter Z2/A. The neutron leakage probability of all fast metal cores characterized using a constant parameterσstdenables computation of the critical mass value of any unknown fissile nuclide knowing only its Z2/A value. Since the neutron leakage probability from dilute fissile solutions is primarily governed by the scattering/slowing down properties of the hydrogen present in water, critical masses and subcritical limits can be predicted for any water-reflected system at any specified hydrogen-to-actinide atomic ratio knowing only the k∞value of the given fissile solution.In the case of fast fissible actinide systems, the neutron leakage probability can be characterized by a single parameterσstd, but having a slightly different value from that of fast fissile systems. Due to their fission thresholds, however, attempts to deduce any systematics in their k∞values have not been very successful.The importance of compiling not only critical radius/mass data but also k∞, the critical surface mass density, the degree of reflection parameter Y, etc., has been clarified while preparing criticality data tabulations for ready reference. These quantities can be used along with the TCF to compute core dimensions and fissile inventories required to yield any specified safe subcritical keffvalue.

ISSN:0029-5639    

DOI:10.13182/NSE89-A27479

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractDifferential (p,xn) cross sections, d2σ/dΩdEn, from thin targets and absolute neutron yields from stopping-length targets at angles of 7.5, 30, 60, and 150 deg for the 113-MeV proton bombardment of elemental beryllium, carbon, aluminum, iron, and depleted uranium are measured. Additional cross-section measurements are reported for oxygen, tungsten, and lead. Time-of-flight techniques are used to identify and discriminate against backgrounds and to determine the neutron energy spectrum. Comparisons of the experimental data with intranuclear-cascade evaporation model calculations with the HETC code show discrepancies as high as a factor of 7 in the differential cross sections. These discrepancies make it possible to identify some of the good agreement seen in the stopping-length yield comparison as fortuitous cancellation of incorrect production estimates in different energy regimes.

ISSN:0029-5639    

DOI:10.13182/NSE89-A27480

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor