| Popis: |
An investigation was conducted of malfunctions of snubbers (seismic-shock arrestors) in service in nuclear power plants. The construction and use of snubbers is summarized, and the history of snubber problems in nuclear service is reviewed. Reports of many hundreds of snubber malfunctions were found in the abnormal-occurrence reports of the docket literature. The great majority of these abnormal occurrences consisted of hydraulic snubbers whose hydraulic fluid had leaked out because of deteriorated seals; snubbers that were damaged in manufacture, shipping, installation, refitting, or use; and snubbers whose performance did not match service requirements. Additional information about the failures was obtained from the reactor operators, snubber manufacturers, reactor vendors, and independent laboratories. The abnormal occurrences were classified into 12 categories. Analyses of the causes of the individual abnormalities are presented, and preliminary comments on the current state of snubber manufacture and use are made. |
