TY - CONF
T1 - X-ray radiography for two-phase mixture level fluctuation during boil-off in rod bundle for wide pressure range
AU - Arai, T.
AU - Furuya, M.
AU - Takiguchi, H.
AU - Nishi, Y.
AU - Shirakawa, K.
N1 - Funding Information:
Part of this research was conducted as Infrastructure Development Project for Enhancement of Safety Measures at Nuclear Power Plants "Advanced Models for Thermalhydraulic Analysis during Nuclear Fuel Boil-off Process" sponsored by the Ministry of Economy, Trade and Industry. The authors would like to thank Messrs. Takio Endo, Yoshiyuki Shiratori, Yuki Miyazawa, and Shinya Ueno of Electric Power Engineering Systems Co., Ltd., for helping with these experiments.
Publisher Copyright:
© 2019 American Nuclear Society. All rights reserved.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2019
Y1 - 2019
N2 - 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.
AB - 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.
KW - Boil-off
KW - Rod bundle
KW - Two-phase mixture level
KW - X-ray real time radiography
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M3 - Paper
AN - SCOPUS:85073740210
SP - 5701
EP - 5708
T2 - 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
Y2 - 18 August 2019 through 23 August 2019
ER -