ML18030A022

Final Deficiency Rept,Originally Submitted on 800523,re Use of Too Large Recesses W/Hilti Shell Anchors.Caused by Erroneous Valve Bases.Hold Placed on Const & Test Program Developed for Static & Cyclic Test Under shear-tension

ML18030A022
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 8012030663
Download: ML18030A022 (6)

Text

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SUdJECt: Final defi"iency reotioriginally suomittej on 800523ire use of too large recesses w/Hilti snell anchors'ause<J by erroneous valve oases'old place'd on const 5 test orogra~

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TITLE: Construction Deficiency Reoort (10CFR50 ~ 55E)

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TWO NORTH NINTH STREET, ALLENTOWN, PA. ISIOI PHONEr t2IS) 821 S1SI NORMAN W. CURTIS trice president-Engineering IL Construction-Nuclear 821-5381 November 21, 1980 Mr. Boyce H. Grier DSrector, Region I U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 SUSQUEHANNA STEAM ELECTR1C STATION FINAL REPORT OF' DEFICIENCY RELATING TO USE OF HILTI 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 PPGL and are available for your review. A corrective action plan is also described. We expect to complete Unit I inspection, evaluation, and rework/

repair by May, 1981.

We trust the CommS.ssion will find the information'forwarded by this letter to be satisfactory.

Very truly yours, r ia ~

N. W. Curtis Vice . President-Engineering E Construction-Nuclear Attachment FLW:mcb po/7 ill PENNSYLVANIA POWER IL LIGHT COMPANY 3<2 "csurgery

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

DirectorWffice of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. G. McDonald, Director Office of Management Information a 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

ATTACHMENT TO P 78 9Xl4K HEPORT ON HILTX-HDI SKK ANCHORS 1.0

( PURPOSE The purpose of this report is to provide ccmplete information, persuant to 10CFR 50.55(e), concernizg Rilti shell anchors.

2.0 HILTI HDI SHEEL ANCHORS Concrete expansion anchors can be broadly categorized in three types, i.e.,

wedge, sleeve and shell. Hilti HDI anchors are of the'shell type. The main difference between shell ad other types of anchors is that the shell anchor consists af two p~cipal parts the she11 (1ncluding expander plug) which is a female piece, and the bolt which is a male piece.

To achieve pro+r installation, a s~tly overs&ed hole is drilled in the concr ete and the shell 1s dropped/inserted in the hole. 9he plug is then driven into the shell =to a set cUmension using an appropriate setting tool.

Driving the plug exes the shell ~p1nst the surrounding concrete;. this provides the hol~ capacity to withstand the design loads. Thus, unlace wedge ard sleeve anchors, no torquing is required to set the shell anchors.

3.0 BACKGROUND

AND CAUSE

~w On the Susquehanna prospect, a la~e number of RLLti shell anchors have been used to attach supports for mainly electrical itens such as conduits, function boxes axe wireway gutters ard also instrumntation tubing.

Prospect Specification 8856-C-72 is the governLng docunent for'he design, procureaent, installation ard inspection af all types of'expansion anchors by'Bechtel field personnel. Table 4.1 of the Specification ~ch is ccamnn for all types of anchors, provides the details for embedment, installation torque, allowable loads, etc.

(

RLLti's latest published 'Anchor and Rastener Design Manual'tates that for shell anchors, embedment length F1 be equal to anchor length plus 1/8 inch. However, ccmputed recesses (defined as the distance between the top of sheU. and concrete surface) based upon the values given in the table af the aforementioned specification are generally l~er than the manufacturer's reccaznendations.

In August 1979, Bechtel prospect engineerina; became aware that the. actual

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

4.0 ANALYSES OR SAFETY IMPLICATXQNS Under tension loading, the recess wculd have no bearing on the proper func-tioning af'nchors. However, under shear loading, as the bolt is unsupported within the recess, shear load.

it would be sub)ected to bending aament in addition to arith greater recesses, larger uxxents will result.

In order to evaluate the above corxiition, a static shear test prcgram was under

taken by Bechtel. The testing was perform d 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 sate limited data on cyclic and shear-tension test results. As the majority of the expansion anchors will be subjected to cyclic and ccnbined sHear-tension under a seismic event, the conclusion of the above mentioned report raised a question regarding the acceptability and structural adequacy of all Hilti shell anchors used on Susqueimnna. r~

As noted above'Hilti shell anchors have been used to attach safety related items. Dherefore, unless further investigation is done, existing condition/

ins~ation may have adverse safety impact. Accordingly, Bechtel Engirmer-ing detemuaed this problem to be reportable under 10CF850.55(e) and an interim report was issued on 5-27-80; 5.0 IMMY)IATEACTICN In order to prevent further usage of shell anchors, a 'HOLD'as placed on construction by Bechtel engineering in february 1980.

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

6.0, 'i& TEST PBQGRM The testing was perfornad 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 significantly smaller than those in the present design criteria, further evaluation is required, as described below.

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

1. 'Zbe project specification wi11 be revised by November 1, 1980, to reflect the findings of the above test reports.

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

ATTACHMENT TO PZA-578

For category IE electrical supports per drawing 8856-E-53< the're 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. 'Impose supports for which the maximum alliable loads on the supports still satisfy the new criteria

'or 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-rrr ntation and other disciplines) supports will be inspected by Bechtel field personnel, to obtain actual loading imposed on these supports. &is inspection will be perfonred in accordance with approved field procedure. Ins~ction results will be evaluated, and docutrented including appropriate disposition and details of repair/rew'ork as necessary. If this evaluation indicates that the existing anchors are structurally inadequate, the existing support connections will be mx3ified either by adding rrare anchors or by providing additional supports.to reduce actual loading on the supports and thus on the existing anchors.

Above noted activities (inspection, evaluation and repair/rework) will be cmaenced in November 1980 'and are scheduled for cartpletion by May 1, 1981, for Unit 1 and'cxxman, to be followed by similar action for Unit 2.

8.0 CCNCXlJSICN On ccrrtpletion of the corrective action noted in section $ .0, existing Hilti shell anchors with 1" recess (max) will meet the new design criteria and thus will be structurally acceptable with adequate safety margin.

ti Gore g Axavtnd S g Shear Test Report on Hil HDI Shel 1 Anchors for Susquehanna Steam Electric Station." Bechtel Power Corporation, 20 Steam Electric p'1R11~'

San Francisco, California in March 1980.

Station'epcrt No. 8856-C-100, Bechtel Power Corporation@

San Francisco, California. October 1980.

3~ Gore, Aravind S., Technical Criteria for Hi1ti HDI She11 Anr9mrs for Susquehanna Steam Electric Station'. Report No. 8856-C-101, Bechtel Power Corporation, San Francisco, California, October 1980..

ATTACHMENT TO PLA-578