| 摘要 |
PURPOSE:To enable a highly accurate measurement of dimensions in a liquid by providing a water-sealed container with a nozzle which jetting a liquid along the length of an object to be measured to water layer near the boundary an area where a laser flux is shielded by the object being measured and an area through which it passes. CONSTITUTION:A nuclear fuel rod 5 is located at the specified position in a hole section 1a of a water-sealed container 1 placed horizontally with a guide mechanism 4, a laser flux 2a is transmitted from a transmitter 2 and received with a receiver 3. On the other hand, water is jetted upward continuously to a water layer near the boundary between an area where a laser flux 2a from a nozzle 7 is shielded by the nuclear fuel rod 5 and an area through which it 2a passes. As a result, the water layer which is changed in the density due to a decay heat scatters near the nuclear fuel rod 5 with a continuous jet of water from the nozzle 7, which removes changes in the density of water near the nuclear fuel rod 5. Thus, the laser flux 2a passing there is received with the receiver 3 without being refracted thereby enabling a highly accurate measurement. |
