Search

Search Results

• 1. [Article] Scaling analysis of the Direct Reactor Auxiliary Cooling System for Gas-cooled Fast Reactors during a Depressurized Loss of Forced Convection Event

  The Direct Reactor Auxiliary Cooling System (DRACS) is a passive safety system capable of removing decay heat directly from the reactor core. Its modularity makes it scalable for use in reactors with various ...

  Citation × Citation Citation Abstract Copy Title: Scaling analysis of the Direct Reactor Auxiliary Cooling System for Gas-cooled Fast Reactors during a Depressurized Loss of Forced Convection Event Author: Blake, Grant C. The Direct Reactor Auxiliary Cooling System (DRACS) is a passive safety system capable of removing decay heat directly from the reactor core. Its modularity makes it scalable for use in reactors with various power levels. Work has previously been completed to support inclusion of the DRACS in liquid metal reactors and fluoride-salt cooled reactors. This work supports the inclusion of DRACS in gas-cooled reactors, similarly. A scaling analysis has been completed for a DRACS module. The target prototype for this scaling analysis is a DRACS for gas-cooled fast reactor (GFR), such as in the Energy Multiplier Module (EM²). The target model for the scaling analysis is a conceptual design for the inclusion in the High Temperature Test Facility (HTTF) at Oregon State University (OSU). Also included herein is the conceptual design requirements for said scaled-down DRACS module including an instrumentation plan and SolidWorks models. Python was used with Engineering Equation Solver to determine the operating characteristics. These physical dimensions and operating characteristics were used to build models in RELAP5-3D of the scaled-down and full-scale DRACS with the intent to inform the scaling analysis results. Results from the RELAP5-3D models support the scaling analysis performed. The error was analyzed between the resulting scaling for each value from RELAP5-3D and the theoretical scaling value as found in the scaling analysis. The errors found for most of the quantities were minimal, and well within reason for simulations in RELAP5-3D. There was a significant error found in the intermediate loop velocity scaling from the RELAP5-3D model results, and this error led to other errors which are dependent on the intermediate loop velocity. The scaling of the heat transfer rates in the intermediate loop also experienced an error from the theoretical results, leading to an error in the intermediate loop DRACS heat exchanger (DHX) and natural draft heat exchanger (NDHX) numbers. The velocity error is thought to be the result of an improperly scaled intermediate loop resistance number, which cannot be investigated directly from RELAP5-3D outputs. The heat transfer error is likely due to different Nusselt number correlations in the intermediate loop from those used in the direct and natural draft loops. These correlations are selected automatically by the code, and measures could be taken in a future design to correct for this. Title: Scaling analysis of the Direct Reactor Auxiliary Cooling System for Gas-cooled Fast Reactors during a Depressurized Loss of Forced Convection Event Author: Blake, Grant C. The Direct Reactor Auxiliary Cooling System (DRACS) is a passive safety system capable of removing decay heat directly from the reactor core. Its modularity makes it scalable for use in reactors with various power levels. Work has previously been completed to support inclusion of the DRACS in liquid metal reactors and fluoride-salt cooled reactors. This work supports the inclusion of DRACS in gas-cooled reactors, similarly. A scaling analysis has been completed for a DRACS module. The target prototype for this scaling analysis is a DRACS for gas-cooled fast reactor (GFR), such as in the Energy Multiplier Module (EM²). The target model for the scaling analysis is a conceptual design for the inclusion in the High Temperature Test Facility (HTTF) at Oregon State University (OSU). Also included herein is the conceptual design requirements for said scaled-down DRACS module including an instrumentation plan and SolidWorks models. Python was used with Engineering Equation Solver to determine the operating characteristics. These physical dimensions and operating characteristics were used to build models in RELAP5-3D of the scaled-down and full-scale DRACS with the intent to inform the scaling analysis results. Results from the RELAP5-3D models support the scaling analysis performed. The error was analyzed between the resulting scaling for each value from RELAP5-3D and the theoretical scaling value as found in the scaling analysis. The errors found for most of the quantities were minimal, and well within reason for simulations in RELAP5-3D. There was a significant error found in the intermediate loop velocity scaling from the RELAP5-3D model results, and this error led to other errors which are dependent on the intermediate loop velocity. The scaling of the heat transfer rates in the intermediate loop also experienced an error from the theoretical results, leading to an error in the intermediate loop DRACS heat exchanger (DHX) and natural draft heat exchanger (NDHX) numbers. The velocity error is thought to be the result of an improperly scaled intermediate loop resistance number, which cannot be investigated directly from RELAP5-3D outputs. The heat transfer error is likely due to different Nusselt number correlations in the intermediate loop from those used in the direct and natural draft loops. These correlations are selected automatically by the code, and measures could be taken in a future design to correct for this. Close