Experimental study on improvement of inlet orifice in BWR core

M. Akiba*, Shinichi Morooka, K. Shirakawa, K. Chuman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The purpose of this study is to develop the core inlet orifice whose drag coefficient changes according to flow rate without drive parts. We improved on the conventional orifice by giving it a novel shape; the edge of the improved orifice is half-oval in shape. This improved orifice was tested under high-pressure and high-temperature (about 7.2 MPa and 570 K) simulated ABWR conditions. Test results showed that the drag coefficient of the orifice with the novel shape changed according to flow rate. It was found from these test results that drag coefficient was constant and high under ABWR natural circulation conditions and decreased by about 20% under ABWR rated power conditions. In addition, a task for the future was educed.

Original languageEnglish
Pages (from-to)793-798
Number of pages6
JournalJournal of Nuclear Science and Technology
Issue number9
Publication statusPublished - 2001 Sept
Externally publishedYes


  • Boundary-layer separation
  • Critical Reynolds number
  • Drag coefficient
  • Natural circulation
  • Orifices

ASJC Scopus subject areas

  • Nuclear Energy and Engineering


Dive into the research topics of 'Experimental study on improvement of inlet orifice in BWR core'. Together they form a unique fingerprint.

Cite this