Patent Number: 044473885
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fastening apparatus particularly useful in nuclear reactor systems, and pressurized power systems. 2. Description of the Prior Art In order to ensure reliability of any structural system including bolt-fastened components, especially components of a nuclear reactor, it is common practice for the bolts to be periodically inspected for evidence of crack initiation or other failure. These bolts are often inaccessible due to radiation and/or position. It is desired to provide accurate, rapid and remote indication of bolt failure particularly for nuclear reactors. SUMMARY OF THE INVENTION A chamber or chambers is to be incorporated into the body of a bolt and the chamber filled with a tag gas. In the event that a crack occurs in the bolt which traverses the space between the chamber and its outside surface, the gas will be released. A gas detection system is provided in a location to which the gas will be transported by natural or forced circulation. This gas detection system will detect and identify the tag gas escaping from the cracked bolt. The detection system can be set up to operate continuously or to be turned on by a trigger gas which also would be enclosed in the bolt chamber. One or more chambers may be provided. The chamber may be coincident with the center line of the bolt where it would have a minimal effect on the strength of the bolt. Additional connected or separate chambers could be provided in the bolt. Each bolt in a circle or group of bolts can have a different tag gas to identify the cracked bolts. Also, each chamber in a multi-chambered bolt can have a different tag gas to localize the failure within the bolt.