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Information Notice No. 83-40: Need to Environmentally Qualify Epoxy Grouts and Sealers
SSINS No.: 6835 IN 83-40 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 30555 JUNE 22, 1983 Information Notice No. 83-40: NEED TO ENVIRONMENTALLY QUALIFY EPOXY GROUTS AND SEALERS Addressees: All nuclear reactor facilities holding an operating license (OL) or construction permit (CP). Purpose: This information notice is intended to alert licensees to potential degradation of epoxy formulations by heat and radiation. No specific action or response is required. Description of Circumstances: At Watts Bar, TVA reported in September 1981 that two epoxy grouts, used to install various anchor bolts inside the containment building, had been specified by trade name without consideration of the thermal aging and radiation environment. In a followup report dated September 1982, TVA reported that tests at temperatures up to 160
F had been performed, and that the compounds had shown significant loss of strength at temperatures above 120 F. Contrary to usual IE practice, the trade names of the products are not being disclosed, because we believe that many other similar products may have similar or poorer thermal characteristics. In recent years, epoxy products have achieved widespread acceptance in concrete construction and repair. ASTM and ACI standards have been issued, but these standards address the use of epoxy in normal construction and repair, with temperatures limited to those ordinarily caused by changes in weather. For example, ASTM C 883 calls for test cycling between 73 F and 125 F; ASTM C 884 in a different test calls for cycling between 73 F and -6 F. One reference book lists 63 types of epoxy resins and 62 chemical groups which can be used for curing the resins. Further, there is a wide variety of fillers, accelerators, and other ingredients used in compounding the products. As a result, a wide variety of products can be formulated to the desired end-use characteristics. 8305110475 . IN 83-40 June 22, 1983 Page 2 of 2 Some general rules of organic chemistry can be applied in designing an epoxy compound with the desired physical and chemical Characteristics, such as strength at elevated ,temperature and resistance to radiation damage. However, full confidence in the results can only be achieved by product testing. Another characteristic which needs to be considered is the relatively low creep strength of epoxies. Where anchor bolts are bedded in epoxy grout, and tensioned to any appreciable preload, it may be important to periodically verify that the preload has not been lost by creep in the grout. TVA has halted the use of epoxy grout, and is in the process of analyzing individual past uses to determine what, if any, corrective actions are appropriate. No specific action or reply is required, If you have any questions regarding this matter, please contact the Regional Administrator of the appropriate NRC Region Office, or this office. Edward L. Jordan Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical Contact: J. B. Henderson, IE 301-492-9654 Attachment: List of Recently Issued IE Information Notices .
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