摘要:

AbstractA method is developed to determine the optimum fuel and power distributions for a pressurized water reactor (PWR) burnup cycle. The backward diffusion calculation and the corewise Green’s function method are used for the core model, which provides analytic derivatives for solving the nonlinear optimization problem using successive linear programming methods. The solution algorithm consists of a reverse depletion strategy that begins at the end of cycle and solves simultaneously for the optimal fuel and burnable absorber distributions while the core is depleted to the beginning of cycle. The resulting optimal solutions minimize the required fissile fuel inventory and burnable absorber loading for a PWR.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23685

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractPin power reconstruction capability has recently been added to the SIMULATE-3 nodal reactor analysis code. Detailed descriptions of the models employed are presented. This reconstruction method is based on single-assembly (not colorset) form functions, and a detailed treatment of spectral interaction between assemblies is introduced. This pin power reconstruction method produces accurate calculation of pin powers throughout depletion and fuel shuffling. Comparisons with multigroup transport calculations and with measured critical assembly power distributions demonstrate that the pin power reconstruction method is comparable in accuracy to fine-mesh methods. The high numerical efficiency of the reconstruction method permits economical calculation of three-dimensional pin power distributions in light water reactors.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23686

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractThe behavior of neutron leakages between nodes is in general spatially coupled and environment dependent. To investigate this phenomenon, a new transverse leakage model characterized by the space-dependent neutron flux expanded into spatially nonseparable polynomials has been developed. The new transverse leakage model incorporated into the nodal expansion method was tested for its accuracy and applicability by performing benchmark problems and applied to a realistic pressurized water reactor core, beginning of cycle 1 of Korea Nuclear Unit 1. The results obtained for homogeneous nodal problems with the explicit representation of the baffle and water reflector show that the new method improves the reactor core physics parameters, and that it improves the nodal power distribution of the conventional models more than a factor of 2, especially in the fuel regions next to the core baffle where the material discontinuity is predominant due to the significant difference in the neutron spectrum.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23687

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA fuel assembly analysis code, VMONT, in which a multigroup neutron transport calculation is combined with a burnup calculation, has been developed for comprehensive design work use. The neutron transport calculation is performed with a vectorized Monte Carlo method that can realize speeds>10 times faster than those of a scalar Monte Carlo method. The validity of the VMONT code is shown through test calculations against continuous energy Monte Carlo calculations and the PROTEUS tight lattice experiment.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23688

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA novel one-dimensional approach, which combines the“nodal equivalence theory”and response matrix homogenization methods, is developed for generating equivalent few-group nodal diffusion parameters for the radial reflector of a pressurized water reactor. This nodal reflector model has the advantage that it is much less sensitive to reactor core conditions than conventional nodal equivalence theory models.A special one-dimensional nodal equivalence theory reflector model is described and applied in numerical experiments to investigate the significance of the environment dependence of such models. Numerical results are presented to confirm the environment insensitivity of the new model and to illustrate its feasibility for application to multidimensional nodal reactor analysis.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23689

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractAdvanced nodal methods for the solution of the multigroup neutron diffusion and transport theory equations in three-dimensional hexagonal-z geometry are described. The code HEXNOD allows an accurate and efficient calculation of three-dimensional problems for fast reactors and high converter light water reactors. A unique capability of HEXNOD is the accurate solution of global three-dimensional neutron transport problems for fast reactors with very small computing times. The accuracy of the nodal diffusion and transport approximations is demonstrated by comparison with conventional finite difference methods and Monte Carlo calculations for a number of mathematical benchmark problems. Based on numerical results, it is concluded that the code HEXNOD is well suited for three-dimensional routine analysis of fast reactors and, in particular, as the neutronics module of the generalized quasi-static kinetics program HEXNODYN, which is currently being developed as part of the European accident code EAC-2.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23690

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA nodal multigroup neutron diffusion method for modern computer architectures has been developed and implemented in the ILLICO code. Vectorization and parallelization strategies that are successful in speeding up modern nodal computations on commercially available supercomputers have been identified and applied. Realistic three-dimensional benchmark problems can be solved in the vectorized mode in<0.73 s (33.86 Mflops). Vector-concurrent implementations are shown to yield speedups as high as 9.19 on eight processors. These results demonstrate that modern nodal methods, such as ILLICO, can preserve essentially all of their speed advantages (demonstrated on scalar computers) over finite difference methods. Several ways of treating two-dimensional reactor problems with nonsquare (“jagged”) boundaries as rectangular domain problems are presented and their effectiveness evaluated. They result in nonnegligible performance improvements and can be devised so as to preserve the physics of the initial problem.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23691

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA method for solving the time-dependent diffusion and transport equations is described in which the fluxΦ(r, t) at position r and time t takes the approximate formα(t)ψ(r, t), whereα(t) depends solely on time. The treatment includes a heat transfer model, thus enabling temperature and expansion feedback effects to be incorporated into the solution.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23692

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractA superfast, multidimensional, and compact pressurized water reactor nodal code, SUPERNOVA (SPNOVA), which is much faster than conventional nodal codes and is very accurate, has been developed at Westinghouse Electric Corporation. A kinetics version of this code, SPNOVA-K, is now developed for applications to three-dimensional core kinetics analysis. The theory involved in the kinetics generalization of SPNOVA is discussed and the performance of SPNOVA-K is described. SPNOVA-K adopts the stiffness confinement method of time variable discretization. This method can provide a very stable solution against the size of the discrete time step, allowing much larger step sizes to be used.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23693

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractThe advanced nodal code SIMULA TE-3 includes the capability to generate detailed pin-by-pin power distributions. Yankee Atomic Electric Company has performed an extensive series of benchmark calculations verifying the accuracy of this capability. Fuel depletion and fuel depletion after shuffling applications were examined. Comparisons were made among SIMULATE-3, higher order transport theory calculations, and calculations performed using fine-mesh finite difference diffusion theory. Detailed pin power data from multiassembly (colorsets) and quarter-core geometries were compared. The results demonstrate the accuracy of SIMULA TE-3 relative to currently accepted methods of generating pin power data.

ISSN:0029-5639    

DOI:10.13182/NSE89-A23694

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor