| 摘要 |
PURPOSE:To considerably lower the probability of leakage generation and to exactly measure the flow rate of fluid by detecting the change of an abundance ratio arising from the difference in the half-life of a radioactive material from the ratio of a radiation dose. CONSTITUTION:An upper stream radiation detector 4a is disposed at a measurement point 4 on the upper stream side near the outlet side of an atomic reactor pressure vessel 1 of a main steam piping 3 for conducting the main steam from the vessel 1 to a high-pressure turbine 2. A down stream radiation detector 5a is disposed at the measurement point 5 on the down stream side near the turbine 2. These detectors 4a, 5a are respectively connected to a data processor 6. The measurement of the gamma rays from carbon-15 and the gamma rays from nitrogen-16 is executed at the measurement point 4 and the measurement point 5. The peak count rate of the gamma rays from the nitrogen-16 and the peak count rate of the gamma rays from the carbon-15 are measured by the detector 4a and the detector 5a and the time requrired for the main steam to move between the two measurement points 4 and 5 is calculated by the processor 6, by which the flow rate of the main steam is calculated.
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