X-ray radiography for two-phase mixture level fluctuation during boil-off in rod bundle for wide pressure range

T. Arai, M. Furuya, H. Takiguchi, Y. Nishi, K. Shirakawa

Research output: Contribution to conferencePaper

Abstract

In the case of a loss in a coolant accident when the water level of the reactor core falls below the top of active fuel (TAF), the actual water level, namely the two-phase mixture level, is an important factor to predict the coolability of the core. The two-phase mixture level depends on the liquid inventory and temporal and spatial variations of the void fraction in the core, and can be greatly affected by the system pressure. A boil-off experiment in which the water level decreased by evaporation without any water supply, was conducted using a 5×5 heated rod bundle over a wide pressure range from 0.1 to 7.2 MPa. The heated length of the rod was 3.71 m, which is equal in length to an actual fuel rod in boiling water reactors (BWRs). The 5×5 rod bundles had an axially and radially uniform power profile, and eight pairs of fine thermocouples were embedded in the heated region to acquire the axial distribution of the rod surface temperature. The temporal fluctuation of the two-phase mixture level was visualized by a linear-accelerated driven X-ray real-time radiography at 400 frames per second. The experimental results exhibit the influence of the two-phase mixture level variation on the rise of rod-temperature under boil-off conditions.

Original languageEnglish
Pages5701-5708
Number of pages8
Publication statusPublished - 2019 Jan 1
Externally publishedYes
Event18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019 - Portland, United States
Duration: 2019 Aug 182019 Aug 23

Conference

Conference18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
CountryUnited States
CityPortland
Period19/8/1819/8/23

Keywords

  • Boil-off
  • Rod bundle
  • Two-phase mixture level
  • X-ray real time radiography

ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Instrumentation

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  • Cite this

    Arai, T., Furuya, M., Takiguchi, H., Nishi, Y., & Shirakawa, K. (2019). X-ray radiography for two-phase mixture level fluctuation during boil-off in rod bundle for wide pressure range. 5701-5708. Paper presented at 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019, Portland, United States.