Analysis of Thermal Stratification in the Upper Plenum of the "Monju” Reactor Vessel - Effect of Chamfer of Flow-Hole on Thermal Stratification
NURETH-14 - 2011 September 25-30


Presented at:
NURETH-14
2011 September 25-30
Location:
Toronto, Canada
Session Title:
O10-1 IAEA Session on Benchmark Analyses of Sodium Natural Convection in the Upper Plenum of the Mon

Authors:
Hiroyasu Mochizuki (Research Institute of Nuclear Engineering, University of Fukui, Japan)
Masahito Takano (Research Institute of Nuclear Engineering, University of Fukui, Japan)
  

Abstract

The analysis of thermal stratification in the upper plenum of the “Monju” reactor vessel is an IAEA Coordinated Research Program (CRP).In spite of many attempts to predict the height of the thermal stratification interface, all calculated results indicated a higher height at approximately 10 minutes after the transient than what was measured at “Monju”.Hence, the present paper discusses the effect of chamfer of the flow-holes and heat capacity of the upper instrumental structure (UIS) on the height of the thermal stratification interface, using the 3D CFD code. The chamfer hypothesis stems from the engineer’s intuition that the edges of the flow-holes should have a rounded edge or chamfer.A flow-hole with chamfer exhibits a much lower local friction loss coefficient of the sodium than a straight-edge flow- hole, resulting in a flow increase from the flow-holes.The presence of chamfer is assumed although there is no direct information about them.Three cases were calculated, one case without chamfer and one case with chamfer on the flow-hole edge, to investigate the effect on the interface behavior.Third one is a calculation taking into account the chamfer on the edge and heat capacity of UIS.In the case of calculation taking into account flow-holes with chamfer and the heat capacity of UIS, the height of the thermal stratification interface is closer to the experimental result.

Individual Conference-Paper Copies (Electronic Where Available):

  • For CNS members, the first 5 copies per calendar year are free, and additional copies are $10 each.
  • For non-members, the price is $25 for the first Conference-paper copy in a request, and $10 each for additional copies of papers in the same conference and in the same request.
  • Contact the CNS office to order reprints.