Primary Loop Recirculation Research Articles

原子炉診断への応用を目的とした故障生起汎化知識の表現

A new method for diagnostic knowledge acquisition based on the generalized failure mechanism knowledge (GFMK) has been proposed in order to solve the problem of incompleteness of the diagnostic knowledgebase. The present study consists of two main issues; derivation of the GFMK from actually experienced events and the failure mode estimation based on the plant model. Failure events and objective plant are described by multi-level state transition model and multi-level, multi-attribute model, respectively. A systematic knowledge representation has been obtained through combined use of these two methods. The validity of the failure events representation method and the capability of the GFMK extraction from failure events have been demonstrated by applying proposed methodology to the actually experienced failure events. The failure mode estimation capability has been demonstrated by applying the GFMK to the primary loop recirculation system of boiling water reactor represented by the proposed model.

Centrifugal Pump Behavior in Steady and Transient Two-Phase Flow

In the event of a LOCA (loss-of-coolant accident) resulting from a hypothetical guillotine break in the suction line of the PLR (primary loop recirculation) pump for a BWR plant, the PLR pump will be reversely driven by the two-phase fluid flowing back at high speed in the line. For clarifying the two-phase flow characteristics of the PLR pump, which would be necessary for the analysis of pump behavior during LOCA, blowdown tests were conducted using three scale model pumps. The two-phase flow characteristics data for the pump were plotted with use of homologous curves method and the two-phase degradation multiplier in order to examine the effect of specific speed and void fraction. As a result of this study, it was shown that the characteristics of any pump with specific speed between N s=500 and 4,200 rpm·gpm1/2/ft3/4 can be obtained by interpolation. Experimental analyses were made using the TRAC code. Analytical results regarding pump inlet pressure, void fraction, volumetric flow rate and pump speed showed good agreement with the test results. This is a joint study of Japan BWR utilities and plant makers.

Centrifugal pump behavior in steady and transient two-phase flow.

In the event of a LOCA (loss-of-coolant accident) resulting from a hypothetical guillotine break in the suction line of the PLR (primary loop recirculation) pump for a BWR plant, the PLR pump will be reversely driven by the two-phase fluid flowing back at high speed in the line. For clarifying the two-phase flow characteristics of the PLR pump, which would be necessary for the analysis of pump behavior during LOCA, blowdown tests were conducted using three scale model pumps. The two-phase flow characteristics data for the pump were plotted with use of homologous curves method and the two-phase degradation multiplier in order to examine the effect of specific speed and void fraction. As a result of this study, it was shown that the characteristics of any pump with specific speed between N s=500 and 4,200 rpm·gpm1/2/ft3/4 can be obtained by interpolation. Experimental analyses were made using the TRAC code. Analytical results regarding pump inlet pressure, void fraction, volumetric flow rate and pump speed ...