Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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 160F had been performed, and
that the compounds had shown significant loss of strength at temperatures
above 120F.
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 73F and
125F; ASTM C 884 in a different test calls for cycling between 73F
and -6F.
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.
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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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