General Electric Company

Jens G Andersen

Gary E Dix

Charles Lee Heck

James Courtney Shaug

Ingmar E Sterzing

Bharat S Shiralkar

A method and system for thermal-dynamic modeling and performance evaluation of a nuclear Boiling Water Reactor (BWR) core design is presented. A data processing system is used to execute specific program routines that simultaneously simulate the thermal operating characteristics of fuel rods (or plural groups of fuel rods) within the reactor during a transient operational condition. The data processing system is also used for compilation of a transient response histogram that incorporates the effect of inherent 'uncertainties' in various parameters of interest. In an initial phase, the method employs a multi-dimensional approach for the simulation of postulated operational events or an anticipated operational occurrence (AOO) which produces a transient condition in the reactor--such as might be caused by single operator error or equipment malfunction. In a following phase, the operating limit minimum critical power ratio (OLMCPR) of the reactor is directly evaluated from a histogram of probability calculations representing the number of fuel rods subject to a boiling transition (NRSBT) during the transient condition. The histogram may be readily displayed by the data processing system and used to statistically demonstrate an OLMCPR compliance of the reactor core design with USNRC regulations.

Method and system for direct evaluation of operating limit minimum

An apparatus and process utilizing a large water rod of a fuel bundle in a boiling water reactor fuel assembly as a radiation heat sink during a loss of coolant accident. Core cooling spray is collected at the top end of the bundle's large water rod by a collector and distributed by a distributor to coat the inside wall surfaces of the water rod. In the case of a water rod which is not bottom vented, the water rod body is modified so as to separate the downward flow of liquid water from the upward flow of steam. During normal plant operation, the large water rod serves as a water-filled moderator tube to provide a more uniform power distribution across the fuel bundle.

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Wilmington, NC, United States of America

Jens G Andersen