摘要:

AbstractA loss-of-coolant accident (LOCA) is one of the most severe accidents for a nuclear power plant. To demonstrate inherent safety characteristics incorporated into small high-temperature gas-cooled reactor (HTGR) designs, LOCA simulation tests have been conducted at the Arbeitsgemein-schaft Versuchsreaktor (AVR), the German pebble-bed high-temperature reactor plant. The AVR is the only nuclear power plant ever to have been intentionally subjected to LOCA conditions without emergency cooling.The planning and licensing activities including pretest predictions performed for the LOCA test are described, and the conduct of the test and experimental results are presented. The LOCA test was planned to create conditions that would exist if a rapid LOCA occurred with the reactor operating at full power. The test demonstrated this reactor’s safe response to an accident in which the coolant escapes from the reactor core and no emergency system is available to provide coolant flow to the core. The test is of special interest because it demonstrates the inherent safety features incorporated into optimized modular HTGR designs.The main LOCA test lasted for 5 days. After the test began, core temperatures increased for∼13 h and then gradually and continually decreased as the rate of heat dissipation from the core exceeded the simulated decay power. Throughout the test, temperatures remained below limiting values for the core and other reactor components.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15725

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractWith appropriate approximations, the delayed gamma dose rate problem can be formulated in terms of the effective delayed gamma production cross section. The coupled neutron-delayed gamma transport equations take the same form as the coupled neutron-prompt gamma transport equations and they can, therefore, be solved directly in the same manner. This eliminates the flux coupling step required in conventional calculations and makes it easier to handle complex, multidimensional problems, especially those that call for Monte Carlo calculations. Mathematical formulation and solution algorithms are derived. The advantages of this method in complex geometry are illustrated by its application in the Monte Carlo solution of a practical design problem.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15726

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractDevelopment of a knowledge-based system for supervision of a continuous process requires, on the one hand, efficient and flexible knowledge structuring and, on the other hand, overall system control, which provides coherence between the diagnosis task (deduction) and the prediction task (simulation). The development of a reasoning method that combines qualitative and quantitative analysis approaches is described. This method is integrated into an overall computational system for a knowledge-based supervisor. The prototype was tested by simulating the transient behavior of the auxiliary feedwater system of a pressurized water reactor. The preliminary results indicate the feasibility of the methods and their potential for industrial applications.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15727

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractA adaptive interface KNOWBOT®was designed to solve some of the problems that face the users of large centralized data bases. The interface applies the neural network approach to information retrieval from a data base. The data base is a subset of the Nuclear Plant Reliability Data System. The interface KNOWBOT preempts an existing data base interface and works in conjunction with it. By design, KNOWBOT starts as a tabula rasa but acquires knowledge through its interactions with the user and the data base. The interface uses its gained knowledge to personalize the data base retrieval process and to induce new queries. The interface also forgets the information that is no longer needed by the user. These self-organizing features of the interface reduce the scope of the data base to the subsets that are highly relevant to the user needs. A proof-of-principal version of this interface has been implemented in Common LISP on a Texas Instruments Explorer I workstation. Experiments with KNOWBOT have been successful in demonstrating the robustness of the model especially with induction and self-organization. This paper describes the design of KNOWBOT and presents some of the experimental results.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15728

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractAn adaptive predictive control system (APCS) is applied to the design of the recirculation and feedwater control systems of a boiling water reactor. The APCS uses the dead zone method to modify the adaptive law; thus, it is stable in the presence of unmodeled dynamics and bounded disturbances. Two single-input/single-output control systems are used instead of a multi-input/multi-output control system in order to simplify parameter adaptation. The interactions among the subsystems are treated as unmeasured disturbances. A simulation using the reactor model shows that the dome pressure versus recirculation pump speed subsystem is a nonminimum-phase system. To handle this system, the weighting polynomials for the system input and output are incorporated to form an augmented minimum-phase system and then the augmented system is controlled. The proposed algorithm is stable, does not require persistent excitation of the reference input, and performs well, which makes it practical for implementation.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15729

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractA study of the stability of subcritical neutronic modes in boiling water reactors that can result in out-of-phase power oscillations is presented. A mechanism has been identified for this type of instability, and the LAPUR code has been modified to account for it. Numerical results show that there is a region in the power flow operating map where an out-of-phase instability mode is likely even if the corewide mode is stable.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15730

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractThe analysis of neutron spectra emitted from a 14-MeV source and streaming through a void steel duct embedded in concrete is carried out using a multigroup Monte Carlo code on a small computer. The calculated results are compared with experimental results and with other calculational analyses involving continuous energy Monte Carlo methods. The computational methods agree when the PNexpansion of the multigroup method is sufficiently extended. Some discrepancies with the experimental results, found in earlier analyses, still remain; and these are investigated with regard to the use of a new modification of the evaluated iron data, the spreading of the calculated results for comparison with experimental spectra, and various other modeling details.

ISSN:0029-5639    

DOI:10.13182/NSE91-A15731

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor