ML18030A021

Final Deficiency Rept Re Use of Hilti Hdi Shell Anchors First Reported on 800523.Project Specs Will Be Revised by 801101 to Reflect Teledyne Engineering Svcs Test Results. Insp Evaluation & Repair to Be Done by May 1981

ML18030A021
Person / Time
Site:	Susquehanna
Issue date:	11/21/1980
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, PLA-578, NUDOCS 8012020585
Download: ML18030A021 (6)

Text

REGULA T INFORMATION DISTRIBUTION TEA (RIOS)

ACCESSION NBR: 8012020585 DOC DA TE: 80/1 1/21 iiOT4R IZED: NO DOCKET Electric Stationi Jnit ii Pennsylva

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FACIL:50 387 Susquehanna Steam 05 8 50 388 Susquehanna Steam Electric Stationi Jnit 2i Pennsylva OSQQ0388 AUTH'A41E 4 J THOR 4FFIL I AT ION CUR T IS, N. ~, Pennsyl vani a Power 8 Li ght Co ~

RECIP ~ NAME REC IP IE4T AFF ILI AT I 3'J GR TER p 8~H~ Region ii Philadelphia< Office of the Director

SUBJECT:

Final deficiency rept re use of Hilti HOI shell anchors first r eoorted on 800523 Project soecs wi1 l be revised oy

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8011Q1 to ~eflect Teledyne Engineering svcs test results ~

lnsp evaluation 3 reoair to oe done by May 1981 ~

DISTRIBUTION COOK: 8019S COPIKS RECEIVED!LTR I ENCL SIZE TITLE: Construct i on Oef i ci ency Report (10CFR50.5SE')

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TWO NORTH NINTH STREETr ALLENTOWNr PA. 18101 PHONE~ t2151 821 515'I NORMAN W. CVRTIS Vice President-Engineering 8 Construction-Nuclear 821 5381 November 21, 1980 s

h Mr. Boyce H. Grier 1 I

Director, Region I U. S. Nuclear Regulatory Commission V ~g 631 Park Avenue J King of Prussia, Pennsylvania 19406 eC

~ 3 SUSQUEHANNA STEAM ELECTRIC STATION FINAL REPORT OF A DEFICIENCY RELATING TO USE OF HZLTl HDI SHELL ANCHORS ERs 100450/100508 FILE 840-4/900-10 PLA-578

References:

PLA-549 dated 09/25/80 PLA-488 dated 05/23/80

Dear Mr. Grier:

This letter serves to provide the Commission with a final report of a deficiency relating to the use of Hilti HDI shell anchors. The condition was originally reported in PLA-488. The information contained herein is submitted in compliance to the provisions of 10CFR50.55(e).

The attachment to this letter contains a description of the problem, its cause, safety impact and significance. The test programs conducted by Teledyne Engineering and Bechtel are referenced and the test reports are retained at PPSL and are available for your review. A corrective action plan is also I

described. We expect to complete Unit inspection, evaluation, and rework/

repair by May, 1981.

We trust the Commission will find the information forwarded by this letter to be satisfactory.

Very truly yours,

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\ <<s r ~

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il N. W. Curtis Vice President-Engineering 6 Construction-Nuclear Attachment go/1 FLW:mcb PENNSYLVANIA POWER 8 LIGHT COMPANY

.SDlsoaoW5

Mr. Boyce H. Grier 2 November 21, 1980 cc: Mr. Victor Stello (15)

.. Director-Office of Znspection a Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Office of Management Znfozmation & Program Control U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. Robert M. Gallo U. S. Nuclear Regulatory Commission P. O. Box 52 Shickshinny, Pennsylvania 18655

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ATTACHMENT TO P 578 FINAL REPORT ON HILTZ~I SHEE ANQKES C" PURPOSE .

The purpose of this report is to provide caaplete inforaation, persuant to 10'0.55(e), concerning RLLti shell anchors.

2 0 HILTI HDI SHEE ANCHORS Concrete expansion anchors can be broadly categorized in three types, i.e.;

wedge, sleeve and shel1. Hilti HDI anchors are af the shell type. Ghe main difference between shell and other types of anchors is that the shell anchor consists af two principal parts the she11 (including expander plug) which is a female piece, and the bolt which is a male piece.

To achieve proper installation, a the shell is s~tly dropped/inserted oversi2;ed hole is doled in the 1n the hole. 9he plug is then concrete and driven into the shell to a set ~ns5.on using an appropriate setting tool.

Driving the plug expands the shell sga1nst the surrmncUlng concrete; this provides the holding capacity to withstand the design loads. Thus, unlQ<e wedge ard sleeve anchors, no tozquiag is quired to set the shell anchors.

30 0 BACKGROUND AND CAUSE On the Susquehanna prospect, a la~e number of Hilti shell anchors have been used to attach supports for mainly electrical items such as conduits, Junction boxes and wireway gutters ard also 1nstrumentat1on tub1ng.

Prospect Specification 8856-C-72 is the governing document for the design, procurement, installation anl 1nspection of all types of 'expansion anchors "by Bechtel field personnel. Table 4.1 of the Specif1cation vied.ch is ccnmnn for all types of anchors, provides the de~ for enbedment, installation torque, allowable loads, etc.

. Haiti's latest published 'Anchor and Fastener Design Manual'tates that for shell anchors, anbedmnt length will be equa1 to anchor, length plus 1/8 inch. However, ccmputed recesses (defined as the distance between the top of shell and cancrete surface) based upon the values given 1n the table af the aforementioned specification are generally larger than the manufacturer's recQKRIldationse In August 1979, Bechtel prospect mgineering became aware that the actual

. recess provided generally ranged between 1/2 inch and 1 inch and in scm cases greater than 1 inch.

4.0 ANALYSIS OF SAHTX IMPLICATXQNS Under tension loading, the recess would have no beax~ on the proper func-tion~ af anchors. However, under shear loading, as the bolt is unsupported within the recess, 1t would be,sub)ected to bending @ament in addition to shear load. With greater recesses, larger axxents will result.

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In order to evaluate the above comU.tion, a static shear test prcgram was under

I Ween by Bechtel. The testing was perfozmed at the jobsite in December 1979 and a report was issued in March, 1980 (see Reference 1). Test results indicated that the recess has no bearing on the ultimate static shear capacity.

However, the anchor behavior was observed to be non-linear, even for the anchors with 1/8 inch recess.

When the, project specification was developed, the allowable loads were based upon the static shear and tension test results and sara limited data on cyclic and shear-tension test results. As the majority of the expansion anchors will be subjected to cyclic and 'cxxnbined shear tension under a seismic event, the conclusion of the above mentioned report raised a question zegarding the acceptability and structural adequacy of all Hilti shell anchors used on Susquehanna.

As noted above Hilti. shell anchors have been used to attach safety related items Thezefoze f unless further investigation is done, existing may have adverse safety impact. Accordingly, Bechtel Engineer-conditiary'nstallation ing determined this problem to be zeportable under 10CFR50.55(e) and an interim report was issued on 5-27-80.

5~0 IMMEZ)IATE ACTICN In order to prevent further usage of shaD anchors, a 'HOLD'as placed on construction by Bechtel engineering in Febzuazy 1980.

A new test prcx~n was developed to perform static and cyclic tests under shear, tension and canbined shear-tension.

6 0 NEH TEST PE@GRAM The testing was performed by Teledyne Engineering Services-,.Waltham, Mass.

in accordance with the criteria provided in technical specification 8856-C-95.

Report No. 8856-C-100 (See Reference 2) includes the details of the testing, test procedures, and test results;= and Report No. 8856-C-101 (See Reference

3) contains evaluation of the test results and also the proposed allowable loads.

As the new allowable. shear loads are significant1y smaller than those in the present design criteria, further evaluation is zequized, as described below.

7.0 With the new allowable loads which aze smaller than the present design loads, the following corrective action will be undertaken.

l. The project specification will be revised by November 1, 1980, to reflect the findings of the above test reports. I

2. As mentioned previously, the majority of Hilti Shell anchors have been used to attach electrical and instzutlntation supports.

ATTACHMENT TO PZA-578

For category IE electrical supports per drawing 8856-E-S3," there are many typical supports, for which maximum allowable loads are indicated on the design drawings. Based upon new revised allowa-ble loads for the anchors, these supports will be evaluated and categorized in two groups. Those supports for which the maximum allowable loads on the-supports still satisfy the new criteria for the anchors will be included in the first group. The second group will consist of all other supports. The category IE sup-ports in the second group including all other (electrical, instru-

-m ntation and other disciplines) supports will be inspected by Bechtel field personnel, to obtain actual loading imposed on these supports. This inspection will be performed in accordance with approved field procedure. Inspection results wil1 be evaluated, and docutrented including appropriate disposition and details of repair/rework as necessary. If this evaluation indicates that the existing anchors are structurally inadequate, the. existing support connections will be nadified either by adding mare anchors or by providing additional supports.to reduce actual loading on the supports and thus on the existing anchors.

Above noted activi.ties (inspection, evaluation and repair/rework) will be caraenced in Noveaher '1980 and are scheduled for completion by May 1, 1981, for Unit 1 and'caman, to be followed by similar action for Unit 2.

8.0 CCNCLUSICN On axttpletion of the corrective action noted in section $ .0, existing Hilti shell'nchors with 1" recess (max) will meet the new design criteria

- and thus will be structurally acceptable with adequate safety margin.

1. Gore, Aravind S., 'Shear Test Report on Hilti. HDI Shell Anchors for Susquehanna Steam Electric Station." Bechtel Powe'r Corporation, San Francisco, California in March 1980.

20 Gore f Aravind S g 'Test Report on Hilti HDI Shell Anchors for Susquehanna Steam Electric Station'eport No. 8856-C-100, Bechtel Power ~aration, San Francisco, California. October 1980.

30 Gore, Aravind S., Technical Criteria for Hilti HDI Shell Anchors for Susquehanna Steam Electric Station'. Report No. 8856-C-101, ~

Bechtel Power Corporation, San Francisco, California, October 1980..

4 ATTACHMENT TO PIA-578