Submission Title
Instabilities in Natural Circulation Systems
Presentation Type
Keynote
Start Date
16-12-2018 9:00 AM
Abstract
Natural circulation is playing an increasingly important role as a heat removal mechanism in power generation units. Earlier it was only considered for low power reactors or for safety systems of nuclear reactors. Of late these are also considered for the main heat transport system such as for the proposed Indian Advanced Heavy Water Reactor (AHWR). The talk will present the features of the systems that operate under natural circulation. Though these systems are reliable and passive, these can develop hydrodynamic instabilities, and it is necessary to check out the location stability boundaries vis-à-vis the operating parameters before these can be implemented in real life systems. While parametric studies to understand the safety margins available for the system would usually be carried out by appropriate software tools, benchmarking of these tools is necessary to ascertain that the tools are able to predict the system behavior realistically. For this purpose, experimental data have to be generated under controlled conditions in scaled down systems which are a fair representative of the prototype. This would require establishing of scaling principles that would be employed to design the scaled down experimental models. The talk would present an overview of these principles and demonstrate its application through the example of the Parallel Channel Natural Circulation Test Facility erected at Indian Institute of Technology, Bombay (IITB). The basic objective of setting up of such a facility and conducting experimental studies is to simulate the thermal-hydraulic behavior during the start-up and powering-up operation. Several experiments that were conducted both in the single-channel and in multi-channel loops of the PCNCTF that addressed both start-up as well as flow instabilities will be presented. The results of numerical simulations carried out using RELAP5/MOD 3.2 would be also presented.
Recommended Citation
Iyer, Kannan (2018). "Instabilities in Natural Circulation Systems," Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety.
Instabilities in Natural Circulation Systems
Natural circulation is playing an increasingly important role as a heat removal mechanism in power generation units. Earlier it was only considered for low power reactors or for safety systems of nuclear reactors. Of late these are also considered for the main heat transport system such as for the proposed Indian Advanced Heavy Water Reactor (AHWR). The talk will present the features of the systems that operate under natural circulation. Though these systems are reliable and passive, these can develop hydrodynamic instabilities, and it is necessary to check out the location stability boundaries vis-à-vis the operating parameters before these can be implemented in real life systems. While parametric studies to understand the safety margins available for the system would usually be carried out by appropriate software tools, benchmarking of these tools is necessary to ascertain that the tools are able to predict the system behavior realistically. For this purpose, experimental data have to be generated under controlled conditions in scaled down systems which are a fair representative of the prototype. This would require establishing of scaling principles that would be employed to design the scaled down experimental models. The talk would present an overview of these principles and demonstrate its application through the example of the Parallel Channel Natural Circulation Test Facility erected at Indian Institute of Technology, Bombay (IITB). The basic objective of setting up of such a facility and conducting experimental studies is to simulate the thermal-hydraulic behavior during the start-up and powering-up operation. Several experiments that were conducted both in the single-channel and in multi-channel loops of the PCNCTF that addressed both start-up as well as flow instabilities will be presented. The results of numerical simulations carried out using RELAP5/MOD 3.2 would be also presented.
