Void measurement in boiling water reactor rod bundles using high resolution gamma ray tomography


Void measurement in boiling water reactor rod bundles using high resolution gamma ray tomography

Bieberle, A.; Hoppe, D.; Zippe, C.; Schleicher, E.; Tschofen, M.; Suehnel, T.; Zimmermann, W.; Hampel, U.

We present a high resolution gamma ray computed tomography (CT) system for the measurement of the void distribution in sub-channels in an electrically heated fuel rod bundle at the thermal hydraulic test loop KATHY (AREVA NP GmbH, Germany). This measurement system generates cross-sectional void fraction profiles through the pressure vessel for true-to-scale fuel rod bundles operating under typical nuclear reaction conditions and in steady state. Measurements are non-invasive, thus the two-phase flow in the bundle is not influenced. The gamma ray computed tomography system consists of a collimated 137Cs isotopic source, a gamma radiation detector arc including 320 single elements and a pulse processing unit. The average spatial resolution of the CT system is about 3 mm in plane and 8 mm axial. The thermal design of the detector arc is optimised to keep the temperature of internal components constant under changing environmental conditions. A specially developed gantry was constructed to realise vertical positioning and continuous rotation of the CT system. To determine the void fraction distribution a two-point calibration method is used. Here, data sets at zero and one hundred percent void fraction are required. The non-superposed slice image is generated using the filtered back projection reconstruction algorithm.

Keywords: high resolution gamma ray tomography; void fraction determination

  • Contribution to proceedings
    XCFD4NRS - Experiments and CFD Code Applications to Nuclear Reactor Safety, 10.-12.09.08, Grenoble, France
    PaperNo BOI-06
  • Lecture (Conference)
    XCFD4NRS - Experiments and CFD Code Applications to Nuclear Reactor Safety, 10.-12.09.08, Grenoble, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-11241
Publ.-Id: 11241