| 摘要 |
<p>Leaks of heavy water from the cooling system of a nuclear reactor vaporise immediately and so are invisible, but they transmit an ultrasonic noise. This is picked up by a wide angle sound collector, fixed vertically to the end face of the reactor. It has several reflectors, fixed at an angle relative to each other, and is long and thin. Neutrons and gamma rays are transmitted or reflected out of the system, so that only the sound wave travels down a tube (being reflected twice more, through 90 degrees) to the microphone. This is therefore protected from the dangerous radiation and high temp. at the reactor surface. A signal is transmitted from the microphone to a logarithmic amplifier, which traces the wave and so indicates where the leaks are and roughly how large.</p> |
