Analysis of abnormalities of snubbers in nuclear-reactor service (Report 1)

Abstract

INTRODUCTION 1 2. SNUBBERS IN CENERAL 4 Funccional Requirements 4 Hydraulic Snubbers S Mechanical Snubbers Typical Character1stics of Snubbers 11 3. REVIEW OF SNUBBER PROBLEM Documentation 14 Abnomality Analysis 17 Sumary 18 4. COMMENTS AND CONCLUSIONS 2» 5. REFERENCES 2"» APPENDIX A. NSIC BIBLIOGRAPHY OF FAILURES OF SHOCK ABSORBERS AND OTHER SUPPORT STRUCTURES (FAILURE ABSTRACTS) APPENDIX B. PRINTOUT OF RECON SEARCH OF SSA 6 APPENDIX C. RO BULLETIN NO. 73-3 APPENDIX D. RO BULLETIN NO. 73-4 APPENDIX E. IE BULLETIN NO. 7S-0S 71 APPENDIX F. QUESTIONNAIRE SENT TO RFACTOR OPERATORS AiALYCiS J: A^.NJSKAL TILLS JF SHUBBESS IT. " irXLEAJt-rAACT'Jr. CZ.T.I7E J. H. iutler ?. X.-'Kara. Jr. An investigation war cor.iuctei of rs.tifur.ct ions cf snutters 'seisrdc-shock arresters in ser/ice ir. nuclear power plants. The construction and use of snutfcers ir s-jrrtarizei here, and the history of snubber problems ir. nuclear service is revieve.:. Reports of sany hundreds of snubber aalfunctions were found in the atnoraal-occurrer.ee reports of the iocket literature. The great sajority of these atnorsal occurrences consisted of hyirauiic snubbers whose hydraulic fluid had leaked out because of deteriorated seals; snubbers that were iacaged in aanufacture, shipping, installation, reflttir^, or use; and snubbers whose performance did not match sex-.'Ice requJresents. Addi tional inforaatior. about the failures was obtained froc the re actor operations, snubber ssanufacturers, r"*actor vendors, and independent laboratories. The abnormal occurrences were clas sified into 12 categories. Analyses of the causes of the indi vidual abnormalities are presented, ttrA preliminary consents on the current state of snubber aanufaevor* and use axe made.

Analysis of owner design specifications for snubbers. Report 2

“…If this limit is exceeded, the snubber locks and temporarily * The author wishes to recognize the following individuals who con tributed to this report: E. R. Dobyns, formerly of ITT Grinnell, J. Boyd of ITT Grinnell, and J. E. Clouser of Pacific Scientific Co. provides rigid support for the component ur.ril the force acting on it ceases (see Report 1 of this series for a more detailed description of snubber design). 1 Initially, since all snubbers operated on hydraulic principles, it was natural that the machine tool industry, which was already equipped to manufacture hydraulic cylinders, would also produce these new devices. Unfortunately, this industry was accustomed to a different application for their product and cou^d not anticipate many of the more esoteric questions which would arise as a result of struc tural design considerations.…”