| 摘要 |
<p>The internal pressure of pressurised, gastight vessels containing mass produced products, esp. nuclear fuel rods, is measured by measuring the natural vibrational frequency of the fuel can (2), which varies according to its internal pressure. Preferably, transmission elements (7,8) are located adjacent to the can (2) in the zone of the rod containing the pressurised gas. Defective fuel elements are thereby identified due to the difference in the natural frequency of the fuel can as a result of escape of gas from the can, which in turn leads to a considerable loss of internal pressure due to cooling. Alternatively, the method may used for detecting sub-standard fuel rods immediately after manufacture. The process is esp. useful for the non-destructive testing of faulty fuel rods, i.e. those having a leak in the fuel can. In particular, for example, for pressurised water reactor fuel elements which are normally pressurised internally with helium gas to approx. 30 bar. A fuel element assembly may comprise 150-200 rods. For a boiling water reactor, a fuel element assembly may comprise 30-70 rods. The method is more reliable and simpler than previous methods. The emitter and receiver required are sufficiently small to be placed in the spaces between rods while in the fuel assembly.</p> |
