Information Notice 1988-25, Minimum Edge Distance for Expansion Anchor Bolts

Minimum Edge Distance for Expansion Anchor Bolts

ML031150192
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	05/16/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-88-025, NUDOCS 8805100246
Download: ML031150192 (7)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 16, 1988 NRC INFORMATION NOTICE NO. 88-25: MINIMUM EDGE DISTANCE FOR EXPANSION

ANCHOR BOLTS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This Information notice is being provided to alert addressees to test results

indicating that the recommended minimum edge distance for the design and instal- lation of expansion anchor bolts may be unconservative with respect to effectively

resisting the shear forces imposed on anchor bolts during a design-basis event

such as a safe-shutdown earthquake. It is expected that recipients will review

the information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in this

information notice do not constitute NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

On March 18, 1988, Hilti, Inc., informed the Nuclear Regulatory Commission (NRC),

in accordance with 10 CFR Part 21, of recent tests of Hilti Kwik-Bolts that indi- cate that the previously recommended minimum distance from an anchor bolt to an

unsupported concrete edge may be insufficient to develop 100% of the recommended

anchor capacity. In view of the foregoing, the NRC staff met with representatives

of Hilti, Inc. (Hilti) to discuss the notification.

During the meeting, the NRC staff was informed that prior to November 1985, the

edge-distance guidelines provided by Hilti for the installation of Hilti Kwik- Bolts were those of the Expansion Anchor Manufacturers Institute (EAMI). The

EAMI guidelines are used throughout the United States and recommend an edge

distance, the distance from the center of an expansion anchor bolt to an un- supported edge of a concrete support, of five anchor diameters to achieve 100%

of the recommended anchor capacity. In November 1985, Hilti revised its design

and installation guidelines and recommended a greater edge distance than the

EAMI guidelines. These conservative guidelines were adopted based on infor- mation and broader technical knowledge and experience gained as a result of

marketing Hilti bolts to foreign customers. Consequently, Hilti initiated a

testing program in 1986 to support their revised edge-distance guidelines.

8805100246 ZA-

IN 88-25 May 16, 1988 The 10 CFR Part 21 notification documents the results of this testing program

and indicates that Hilti Kwik-Bolts installed In accordance with the EAMI guide- lines have only 30% of the recommended anchor shear capacity and 78% of the, recommended tensile capacity. HIlti further Indicated that the test results

are believed to be applicable to other expansion anchor bolts that use the same

type of anchor mechanism as Hilti Kwik-Bolts.

Discussion:

The NRC staff considers the test results indicating a 70% reduction in shear

capacity to be significant and to indicate that there is a potential safety

concern that will require further NRC review. However, the test results do

not indicate an imminent safety concern for expansion anchor bolts installed

in nuclear power facilities for the reasons given below.

(1) The purpose of the Hilti edge-distance test program was to establish

design recommendations for the resistance capacity of a single bolt

as a function of edge distance. The test anchorage consisted of only

one bolt anchored to a concrete block that was not reinforced. Equip- ment or system anchorage arrangements at nuclear power facilities usually

use more than one anchor bolt and a steel bearing plate or base assembly.

Installation pretensioning torque loads applied to the anchor bolt nuts

create compressive loads and frictional resistance forces between the

bearing plate and the concrete that tend to make the anchorage and con-

-crete-support-act asrarthrgle unit and11ltigate-the-severtty-of-the sfngle- bolt edge-distance problem. If the frictional resistance forces between

the concrete support and the bearing plate are reduced due to the creep

of concrete and the relaxation of anchor bolts, the bearing plate can

still redistribute the additional shear forces, which cannot be resisted

by the edge bolts with reduced capacity, to other bolts that have no

capacity reduction due to the edge-distance problems.

(2) The test results are an acceptable basis for establishing design recommen- dations; however, they should be viewed as conservative for the installation

of bolts. The presence of steel reinforcement between the bolt and an un- supported concrete edge should increase the bolt shear capacity, depending

on the amount of reinforcement and the type of placement, and also mitigate

the consequences of the edge-distance problem. This is particularly true

for large diameter expansion bolts (greater than 3/4 -inch bolts).

Based on the NRC staff assessment of the information that has been provided

since the submittal of the 10 CFR Part 21 notification, it appears that 1) most

anchor bolts in nuclear power facilities were installed using the EAMI recom- mended guidelines and 2) the potential failure of these bolts to perform their'

intended function during a design-basis event, such as a seismic event, could

jeopardize the integrity of safety-related systems and equipment. Therefore, the NRC will continue to evaluate this issue and take appropriate regulatory

action if It is determined that a significant safety hazard exists at nuclear

power facilities. However, addressees may wish to review the information and

consider appropriate actions if this information Indicates that a significant

safety hazard exists at their facility.

IN 88-25 May 16, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: John Ma, NRR

(301) 492-1376 Jaime Guillen, NRR

(301) 492-1153 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 88-25 May 16, 1988

• In

nr 1 c...... mI , . r.gr.  : . -.

Page I of 1 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

88-24 Failures of Air-Operated 5/13/88 All holders of OLs

Valves Affecting Safety- or CPs for nuclear

Related Systems power reactors.

88-23 Potential for Gas Binding 5/12/88 All holders of OLs

of High-Pressure Safety or CPs for PWRs.

Injection Pumps During a

Loss-of-Coolant Accident

88-22 Disposal of Sludge from 5/12/88 All holders of OLs

Onsite Sewage Treatment or CPs for nuclear

Facilities at Nuclear power reactors.

Power Stations

88-21 Inadvertent Criticality 5/9/88 All holders of OLs

Events at Oskarshamn or CPs for nuclear

and at U.S. Nuclear power reactors.

Power Plants

88-20 Unauthorized Individuals 5/5/88 All holders of OLs

Manipulating Controls and or CPs for nuclear

Performing Control Room power, test and

Activities research reactors.

and all licensed

operators.

88-19 Questionable Certification 4/26/88 All holders of OLs

of Class IE Components or CPs for nuclear

power reactors.

88-18 Malfunction of Lockbox on 4/25/88 All NRC licensees

Radiography Device authorized to

manufacture, distribute, and/or operate radio- graphic exposure

devices.

OL

• Operating License

CP

• Construction Permit

IN 88-25 May 16, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: John Ma, NRR

(301) 492-1376 Jaime Guillen, NRR

(301) 492-1153 Attachment: List of Recently Issued NRC Information Notices

Transmitted by memorandum to Charles E. Rossi from Lawrence C. Shao

dated 4/20/88

• SEE PREVIOUS CONCURRENCES

~ R*C/OGCB: DOEA:NRR

CHBerl inger

05/0/88 05/09/88

• OGCB:DOEA:NRR*ESGB:DEST:NRR *SC/ESGB:DEST:NRR*C/ESGB:DEST:NRR *PPMB:ARM

JGuillen JMa DJeng GBagchl TechEd

05/03/88 05/03/88 05/03/88 05/03/88 04/28/88

IN 88-XX

May xx, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate

regional office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: John Ma, NRR

(301) 492-1376 Jaime Guillen, NRR

(301) 492-1153 Attachment: List of Recently Issued NRC Information Notices

Transmitted by memorandum to Charles E. Rossi from Lawrence C. Shao

dated 4/20/88

• SEE PREVIOUS CONCURRENCES

D/DOEA:NRR C/O B C EA:NRR

CERossi CHBerlinger

05/ /88 05/f /88

• OGCB: DOEA:NRR*ESGB:DEST:NRR *SC/ESGB:DEST:NRR*C/ESGB:DEST:NRR *PPMB:ARM

JGuillen JMa DJeng GBagchi TechEd

05/03/88 05/03/88 05/03/88 05/03/88 04/28/88

IN 88-XX

May xx, 1988 can still redistribute the extra shear force (which cannot be resisted by

the edge bolts with reduced shear capacity) to other bolts that have no

capacity reduction resulting from edge-distance problems.

(2) Since the anchor bolts were tested in concrete that was not reinforced, the test results should be viewed as the most conservative value for

design. Steel reinforcement Is typically present in concrete supports in

structures at nuclear power facilities. The presence of steel reinforce- ment between the bolt and unsupported concrete edge should increase the

bolt shear capacity. This is particularly true for large diameter

expansion bolts (greater than 3/4-inch bolts). The amount of increase

depends on the amount of reinforcement and the type of placement.

The NRC is in the process of collecting more Information that would constitute

the basis for further action and provision of regulatory guidance. The NRC

staff will issue appropriate guidelines and criteria to ensure that all sup- ports Installed in nuclear power facilities with expansion anchor bolts have

acceptable margins of safety. However, addressees are expected to review the

information and consider appropriate actions if this information indicates that

a significant safety hazard exists at their facility.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: John Ma, NRR

(301) 492-1376 David Jeng, NRR

(301) 492-0842 Jaime Guillen, NRR

(301) 492-1153 Attachment: List of Recently Issued NRC Information Notices

Transmitted by memorandum to Charles E. Rossi from Lawrence C. Shao

dated 4/20/88 ,. I 2 D/DOEA:NRR C/09L tEA: NRR

CERossi CHBe linger

05/ /88 05/ 1/88 OG NRR ESGB:DEST:NRR SC/ESG 1U[ST:NRR C/E G jDEST:NRR PPMB:ARM

JGiTn en JMaj

d' DJeng GBa56R/ TechEd

05/. J88 05/3 /88 05/' /. 05/ %7/88 04/28/88

The NRC is in the process of collecting more information that would constitute

the basis for further action and provision of regulatory guidance. The NRC

will issue appropriate guidelines and criteria to ensure that all supports

installed in nuclear power facilities with expansion anchor bolts have

acceptable margins of safety. Ever, addressees are expected to review the

information and consider appr =a% actions if this information indicates that

a significant safety hazard exias at their facility.

Charles E. Rossi, Director

DOEA

Technical Contacts: John Ma, NRR

(301) 492-1376 David Jeng, NRR

(301) 492-0842 Jaime Guillen, NRR

(301) 492-1153 OGCB:DOEA:NRR PRMB:AF41 SC/ESGB:DEST:NRR C/ESGB:DEST:NRR

JGuillen TechEdU DJeng GBagchi

4/ /88 4 /88 4/ /88 4/ /88 C/OGCB:DOEA:NRR D/DOEA:NRR

CHBerlinger CERossi

4/ /88 4/ /88