ML20154A971
| ML20154A971 | |
| Person / Time | |
|---|---|
| Issue date: | 05/06/1988 |
| From: | Berlinger C Office of Nuclear Reactor Regulation |
| To: | Rossi C Office of Nuclear Reactor Regulation |
| References | |
| REF-PT21-88 NUDOCS 8805160285 | |
| Download: ML20154A971 (6) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION WASHINGTON,0. C. 20555 l;;
p MAY 61988 MEMORANDUM FOR:
Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation THROUGH:
Carl H. Berlinger, Chief Generic Comunications Branch Division of Operational Events Assessment Office of Nuclear Reactor Regulation FROM:
Jaime Guillen, Reactor Engineer Generic Comunications Branch Division of Operational Events Assessment Office of Nuclear Reactor Regulation
SUBJECT:
MEETING BETWEEN NRC AND HILTI, INC.
Representatives of Hilti, Inc. met with the NRC staff on Tuesday, April 17, 1988 to disciass the report submitted in accordance with the requirements of 10 CFR Part 21 by Hilti, Inc. on March 18, 1988. The meeting was held at the request of the Structural and Geosciences Branch (ESGB) of NRR who is reviewing the above mentioned report. The meeting also provided the staff with additional infonnation to allow a determination as to the safety signi-ficance of the issue, its generic applicability, and the need to issue a generic communication. The individuals in attendance are listed in Enclosure 1.
The Hilti representatives reiterated some of the infonnation contained in the 10 CFR Part 21 notification and addressed the NRC staff's questions and con-Hilti indicated that before November 1985 it had been using the Expan-cerns.
sion Anchor Manufacturers Institute (EAMI) guidelines for the installation of Hilti Kwik-Bolts. These recomendations had been developed by EAMI based on tension and shear tests performed on expansion anchor bolts. These EAMI guide-lines for edge distance, the distance from the center of an expansion anchor bolt to an unsupported edge of a concrete support, are 1) intended to develop 100% of the recomended anchor capacity (both tensile and shear), and 2) used throughout the United States for the installation of anchor bolts in concrete.
Prior to November 1985, Hilti recomended to its customers that they follow an edge distance of five anchor bolt diameters, based on the EAMI guidelines.
CONTACT: Jaime Guillen, NRR 492-1153
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y&y 6 1988 Charles E. Rossi In November 1985, Hilti revised its edge distance guidelines to be compatible with those for metric expansion anchor bolts since Hilti Kwik-Bolts were being marketed outside the United States. Hilti had encountered some problems in pro-viding technical assistance to its foreign customers due to the inconsistencies /
incompatibilities in guidelines. The revised Hilti guidelines recommended greater edge distances than those specified by EAMI to achieve 100% of the recommended anchor capacity.
In 1986, Hilti initiated a testing program to support its revised guidelines. The 10 CFR Part 21 notification provides the results of this testing program and indicates that the EAMI recommended minimum edge distance of five anchor diameters from an unsupported edge is unconservative and insufficient to develop 100% of the recommended anchor capacity.
The Hilti test findings indicate that if the recommended EAMI guidelines are used in the installation of anchor bolts, there could be a 22% reduction in the tensile capacity and a 70% reduction in the shear capacity of the anchor bolts.
The Hilti edge distance test program was aimed at establishing design recom-mendations for the resistance capacity of a single bolt as a function of edge distance; therefore, the test anchorage consisted of only one bolt anchored to an unreinforced concrete block. During the Hilti tests, the bolt was pulled directly upward along the bolt axis during the tension test and the shear force was directed toward the free edge during the shear test. Although the staff feels that the Hilti test finding of a 22% reduction in tensile capacity is not significant, the tests results showing a 70% reduction in shear capacity is significant.
The Hilti tests, and those that form the basis for the EAHI guidelines, were performed on unreinforced concrete. The staff raised several questions regard-ing the applicability of these tests to bolts anchored in reinforced concrete since in almost all cases nuclear facilities anchor expansion bolts in rein-forced concrete. According to Hilti, a similar reduction in the recommended anchor capacity should be expected, based on the results reported in the 10 CFR Part 21 notification, regardless of the type of expansion anchor bolts or concrete composition. Hilti also stated that all mechanical expansion anchor bolts that use the same type of anchor mechanism as Hilti Kwik-Bolts should be looked at generically.
In response to questions raised by the NRC staff regarding the safety factor associated with Hilti Kwik-Bolts. Hilti indicated that they had recommended a safety factor of 4 for the installation of their bolts.
Hilti has begun tracing its records to identify all U.S. nuclear facilities that have been supplied Hilti Kwik-Bolts either directly or through intermediaries such as architect / engineers or other vendors. Hilti presented a partial listing at the meeting of those facilities known to have purchased Hilti expansion anchor bolts, and that possibly used the EAMI guidelines. Hilti indicated that it will continue to search its records to identify all facilities that may be affected by this issue. Hilti stated that it sells only commercial-grade bolts; however, they do maintain a traceability that meets the requirements of 10 CFR Appendix B for those bolts that are supplied to the nuclear industry.
9 MAY 61988 Charles E. Rossi
-3 Hilti agreed to work closely with the staff to resolve the issue and to perform additional tests of Hilti Kwik-Bolts, if needed, to resolve NRC concerns, such J
as the applicability of the Hilti test results to anchor bolts in reinforced 1
concrete. The staff complimented the Hilti representatives for their responsive-ness to the staff's conceros and their willingness to cooperate with the staff on the resolution of this issue.
l Jaime Guillen, Reactor Engineer i
Generic Comunications Branch Division of Operational Events Assessment Office of Nuclear Reactor Regulation
Enclosure:
As stated cc:
C. Poparad R. Wollmershauser R. Boentgen DISTRIBUTION w/ enclosure CBerlinger, NRR JGuillen, NRR EJButcher, NRR WDLanning, NRR NRC Meeting Attendees Central Files j
DCS DOEA R/F OGCB R/F JGuillen R/F b
- SEE PREVIOUS CONCURRENCES
- 0GCB:00EA:NRR 4 C/ESGB: DEST:NRR C/0GCB:DOEA:NRR JGuillen GBagchi CHBerlinger l
04/29/88 05/#/88 05/0>/88 i
MAY 6 1988 MEETItG WITH HILTI REGARDItG 10 CFR PART 21 REPORT APRIL 12, 1988 IEE CCHPATI Charlec Poparad Hilti, Inc.
Richard Wollmershauser Hilti. Inc.
Jabne Guillen NRC/NRR/DOEA Goutam Bagchi NRC/NRR/ DEST David Jeng NRC/NRR/ DEST John Ma NRC/NRR/ DEST Pei-Ying Chen NRC/NRR/ DEST Hans Ashar NRC/NRR/ DEST Norman Reeney NRC/NRR/ DEST Arnold Lee NRC/NRR/ DEST Karal Manoly NRC/NRR/ DEST Frank Rinaldi NRC/NRR/ DEST David Terao NRC/OSP/CPPD Annette Vietti-Cook NRC/0C Andrew Murphy NRC/RES Roger Kenneally NRC/RES Herran Graves NRC/RES Teun-Yung Chang NRC/RES Rudolf B entgen NRC Conultant ee.g m,n re.< w nu ROUTING - REQUEST Please REAo To EMuou h se wris A (p phk
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