摘要:

AbstractThe“reactivity constraint approach”is described and demonstrated to be an effective and reliable means for the automatic control of power in nuclear reactors. This approach functions by restricting the effect of the delayed neutron populations to that which can be balanced by an induced change in the prompt population. This is done by limiting the net reactivity to the amount that can be offset by reversing the direction of motion of the automated control mechanism. The necessary reactivity constraints are obtained from the dynamic period equation, which gives the instantaneous reactor period as a function of the reactivity and the rate of change of reactivity. The derivation of this equation is described with emphasis on the recently obtained“alternate”formulation. Following a discussion of the behavior of each term of this alternate equation as a function of reactivity, its use in the design and operation of a nonlinear, closed-loop, digital controller for reactor power is described. Details of the initial experimental trials of the resulting controller are given.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28488

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractReactor noise signals, as measured by neutron detectors and process sensors, contain information about the dynamics of the process and sensor characteristics. The extent of sensor characteristics that can be determined from such measurements depends on the sensor type, the property of the process noise exciting the sensor, and its location.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28489

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractRecent measurements in the zero-power physics reactor have been used to study the effects of spatial decoupling in fast reactor critical assemblies of various sizes and compositions. Flux distributions in these assemblies had varying degrees of sensitivity to perturbations. Decoupling was investigated using rod-drop, boron-oscillator, and noise-coherence techniques, which emphasized different times following perturbations. Equilibrium flux distributions were also measured for subcritical configurations with inserted control rods. For most assemblies, accurate reactivity measurements were obtained by analyzing the power history from a single detector using inverse kinetics methods, assuming an instantaneous efficiency change for the detector. The instantaneous efficiency change assumption broke down, however, in assemblies with zones in which normal plutonium fuel was replaced by 235U fuel or fuel with a high240Pu content. Flux redistributions caused by perturbations in these cores took several minutes to evolve.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28490

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractCell homogenization methods for the neutronics analysis of the blanket region of a plate-type liquid-metal fast breeder reactor critical assembly are investigated, and an improved method is proposed, which calculates cell-averaged cross sections so as to preserve groupwise reaction rates in each cell in a multidrawer cell model. The present homogenization method has been applied to the analysis of the heterogeneous fast critical assembly ZPPR-13. It was found that the keffdifference between homogeneous and heterogeneous fast critical assemblies was reduced from 0.4 to 0.2%Δk/k by using the present method.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28491

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractTwo-dimensional heterogeneity effects on cell-averaged cross sections and diffusion coefficients have been estimated. Both of the heterogeneity effects caused by the flux fine structure and the resonance shielding are taken into account. The accuracy of several one-dimensional cell models is assessed by comparing cell parameters obtained from one- and two-dimensional cell calculations. The two-dimensional cell heterogeneity effects on core performance parameters have been evaluated for the large fast critical assembly ZPPR-9. The Zebra CADENZA plate-pin experiments have been analyzed using the two-dimensional cell model, and the usefulness of the two-dimensional cell calculation is discussed.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28492

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractA refinement is proposed to the current method of evaluating lattice properties for use in calculations of Canada deuterium uranium flux distributions. This refinement, labeled the local-parameter calculation, takes into account locally appropriate values of coolant density, fuel temperature, and flux/power level where core average values were previously used. The local-parameter calculation has been implemented and tested. Results are compared to those of previous calculations and of independent methods based on in-core measurements.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28493

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractThe magnitude of differential reactivity effects that result from spectral differences in different portions of a pressurized water reactor (PWR) core is studied, and it is shown that these effects can be correlated very well with the local moderator history. The impact of these differences on physics parameters such as axial offset, isothermal moderator temperature coefficient, and differential control rod worth is shown to be significant for two PWRs of considerably different design.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28494

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractThe once-through steam generator version of the personal computer transient analyzer, PCTRAN/P, was used to simulate the overcooling event that occurred on December 26, 1985, at Rancho Seco. Loss of power to the integrated control system led to a reactor trip and overfeeding by the auxiliary feedwater with excessive steam dump. As a result, the plant cooled down rapidly in a short period. PCTRAN/P has successfully reproduced the transient using its interactive control functions. Areas of the system’s design deficiencies are thus identified and modifications can be made to prevent a similar event from recurring. The computation time on an IBM-PC/XT was∼20 min for the 50-min transient. This demonstrates that PCTRAN/P can be used as a fast-turnaround tool for conducting reactor transient analyses.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28495

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractTo ensure an optimal application of fuel behavior codes, international standard problems (ISPs) are performed by the Nuclear Energy Agency of the Organization for Economic Cooperation and Development. Calculations performed with complex fuel analysis codes consume considerable implementation and running times. To avoid the application of these codes, a fast-running deformation code was extended to a fuel behavior code called BALO-2A. With this code, two standard problems were performed: ISP-14, which is based on the bundle experiment REBEKA-6, and ISP-19, performed at the Phebus facility. In each standard problem, different methods have to be applied to obtain boundary conditions and input values. The results indicate that BALO-2A simulates fuel behavior under loss-of-coolant accident conditions quite well.

ISSN:0029-5639    

DOI:10.13182/NSE88-A28496

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor

摘要:

AbstractAn implementation of Wielandt’s method of eigenvalue shifting to accelerate the convergence of nodal expansion method (NEM) reactor calculations is presented. This particular formulation of the method greatly decreases the number of source iterations required for a particular degree of convergence while retaining most of the efficiency of a groupwise solution procedure for the inner iterations. The nature of the NEM equations causes Wielandt’s method to behave somewhat differently than when it is applied to the finite difference equations. Results are presented for well-known two- and three-dimensional benchmark problems.

ISSN:0029-5639    

DOI:10.13182/NSE88-1

出版商:Taylor&Francis    

年代:1988

数据来源: Taylor