ML19282C886

Forwards Memos Re Problems of Pipe Support Base Plate Design

ML19282C886
Person / Time
Site:	05000580, 05000581
Issue date:	04/05/1979
From:	Barth C NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD)
To:	Bowers E, Cowan F, Shon F AFFILIATION NOT ASSIGNED, Atomic Safety and Licensing Board Panel
References
NUDOCS 7905070225
Download: ML19282C886 (21)

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f UNITED STATES y\\

9f'g NUCLEAR REGULATORY COMMISslON

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DTC Doeg37pg Elizabeth S. Bowers, Esq., Chairman Dr. Frederick P. Cowan Atomic Safety and Licensing Board Apt. B-125 U.S. Nuclear Regulatory Commission 6152 N. Verde Trail Washington, D.C.

20555 Boca Raton, Florida 33433 A. -

Mr. Frederick J. Shon Atomic Safety and Licensing Board

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Ohio Edison Company, et al.

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(Erie Nuclear Plant, Units 1 and 2)

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Dear Members of the Board:

Enclosed are recent 'emoranda discussing certain problens experienced in connection with pipe support base plate design.

The NRR staff has informed us that the problems discussed in Mr. Stello's rcemorandum dated Scptember 28, 1978 are applicable to the Erie facility, and that DSS is presently reviewing this aspect of piping design analyis on a case-by-case basis under SRP section 3.9.3 - ASME Codes 1, 2 and 3 Components, Component Supports and Core Support Structures.

If the Board or any of the parties wish additional information, please let us know.

Sincerely, 8M Charles A. Barth Counsel for NRC Staff

Enclosure:

As Stated cc:

(See Page 2) 7 905 07 02ff

2-cc:

(w/ enclosure)

Thomas A. Kayuah, Esq.

Jay Silberg, Esq.

Mr. Robert W. Tufts Atomic Safety and Licensing Board Panel Atomic Safety and Licensing Appeal Board Docketing and Service Section

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October 11, 1978 1

i Note to Domenic Vassallo, Assistant Director for Light Water Reactors Attached is a memorandum dated September 28, 1978 from Stello to Grossman requesting that we inforn the Boards in the two operating reactor proceedings of the pipe. support base plate design problem.

We are proceeding to inform the Boards as requested by Mr. Stello.

1 The problem appears to be relevant to the facility under the cognizance of the Division of Pro;ect Macgement.

Please inform p

us as promptly as possible as to,d:ctiier or not you chonse to inform the Licensing Boards in thnse proceedings of this problem, l

And, please identify appropriate facilities.

It appears from reading Mr. Stello's memorandum and the attachments thereto that it will be necessary to assure that thedhoreha:(

Board is informed, if they have noCxalready t ertise beeginf'ormed.

Depu'ph 7. ScintotyQhiefHearinoCou

.e Attachment cc: R. Hoefling B.Paton/

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14EliORAi!DUI1 FOR:

fiilton J. Grossman, Hearing Division Director and Chief Counsel, OELD l

FR0!):

Victor Stello, Jr., Director Division of Operating Reactors,flRR

SUBJECT:

BOARD i;0TIFICATION - PIPE SUPPORT BASE PLATE DESIG!!

The attached r,emorandum to Roger itattson, dated June 28, 1978, presents information concerning failures of safety-related pipe supports at.liillstone 1 and design deficiencies on similar equip-I ment at Shoreham Unit 1.

As indicated in the attachment, two factors appeared to contribute to failure of anchor-bolt connec-tions of pipe supports.

These are, 1) the design assumption that base plates perforn structurally as rigid load-bearing inenbers when they raay be flexible nun.bers, and 2) incorrect anchor bolt torquing.

Recent audits of Architectural Engineering firms and assessments of the actions taken at liillstone, es noted in the attachment, l

provided the following general information:

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1.

During the last few years, the A/Es have changed their design and installation procedures for concrete embedded pipe supports.

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Past end current design and installation procedures vary among the A/Es.

3.

In the past many of the pipe support designs have been con-tracted, and were done with methods not known by the principal A/Es, We have concluded that the more detailed information required must be obtai.ned from each operating facility. We are preparing a generic r/

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letter to each operating facility requesting detailed design,

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/f installation, and testing information of concrete-embedded d

anchor-bolted pipe supports of safety-related equipment.

We recommend that this information be provided to the following Boards:

1.

Monticello (FTL) 2.

Indian Point 1,2,3 (Seismic Design)

We will provide an assessment of this issue upon completion of our evaluations.

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Victor Stello, Jr., Director Division of Operating Reactors Office of !!uclear Reactor Regulation

Enclosure:

June 28, 1978 memo, Stello to i'attson

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D. Vassallo V. Stello R. Mattson R. Bevan i

L. Olshan I

L. flichols V. iioonan A. Schwencer i

T. Ippolito J. Fair O

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J Ull 2 g 197 g liEMORAftDUM FOR:

R. J. Mattson, Director Division of Systems Safety FROM:

Victor Stello, Jr., Director Division of Operating Reactors i

SUBJECT:

OPERATIriG EXPERIEllCE l',EMORA!!DUM ti0.13 f

PIPE SUPPORT DASE PLATE PROBLEM i

PROBL E_M_

Recently during inservice inspections at Millstone Unit 1, stradural failures of rigid pipe supports for class 2 safety ecuipment were observed.

These ' inspections, recently irsplemented at Millstone, were conducted in accordance with Section XI of the ASME Code, as endorsed by regulation, 10 CFR 50.55 a(g), in February 1976.

Several base-plate anchor bolts of pipe supports in the Core Spray and the Low Pressure Coolant Injection Systems at Millstone were not l properly embedded; and, in scre cases the anchor bolts viere completely l

pulled out and no supporting function was provided.

l Deficiency reports, in cccordance with 10 CFR 50.55(e), filed by Long Island Lighting Company, on Shorehm Unit 1, indicate that design of base plates with drilled anchor bolts using rigid plate assuraptions has resulted in underestimation of loads on some anchor bol ts.

Inspection of anchor bolt installations at Shoreham has shown

, over fif ty percent of the bolt installations were deficient.

Supports j

for both piping systens and electrical raceways have been reported -

as deficient at Shoreham.

PRESUMED CAUSE It is currently believed that tuo interacting factors contribute to the failure of the supports.

N rst, the design assumption that the base plates perform structurally as rigid instead of flexible members may provide low estimates of ir: posed loads on the supports.

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Secondly, incorrect anchor bolt embedment may also contribute W ['

to insufficient support.

's' The attached memorandum frem V. fbonan to B. Grimes, dated June 2, 1978, provides additional information.

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Depending on equipment layout, improperly designeo or in" tailed anchor supports could:

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result in loss of support function in some cases; and, 2.

result in high stressing of piping systens during a seismic event or during a significant flow transient.

REPAIR liillstone with assistance from Teledyne Engineering has completed design modifications and repairs.

These changes include increasco base plate thickness and larger anchor bolts for failed suppori.s.

Shoreham in conjunction with Stone and l!cbster is evaluating both piping and electrical type supports.

The review is scheduled.to be

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completed by December,1978.

DDR ACTION The Engineering Branch will revie. the design procedures used on operating plants to determine anchor bolt loads, the techniques used

.s to determine load ratings for anchor bolts, and the installation procedures.

This review will be done through an A/E vendor inspection audit in conjunction with IE.

These A/E audits will be. tarted during early July, 1978, 1,'e anticipate that criteria will be developed for design and installation of base plate-anchor boit assemblies, and those operating plants requiring corrective action will be identified.

Additionally EB staff will furthe. assess the occurrence ar.d corre'ctive actions taken at f4illstone.

RECO,T.EMDAT10!1S We recommend that this problem e' addressed on all CP and OL reviews.

At this time it appears that considerations should be given to the analytical methods used to. determine whether or not base plates behave as flexible or rigid members.

This in turn may effect the anchor i

bolt size and embedment to properly cope with loads imposed on the g

supports.

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f OItmaybeappropriatetorequirethatapplicantsprovideforrevie their:

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methods for determining base plate thici: ness and anchor bolt loads; 2,

criteria for anchor bolt installation; and, 3.

criteria for load rating techniques for anchor bolts, including cyclic loads.

i Ue shall coordinate our meetings, discussions and evaluations of this issue with your staff.

Supplemntal information will be provided.

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Vic' tor Stello, Jr., Director Division of Operating Reactors PRll,'CIPAl. DDR_PERS0i!!!EL Reviewer:

J. Fair i

E A nclosure:

Ifi V emorandum dated 6/2/78 s

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w/ enclosure E. G. Case S. Hanc R. S. E d

H. R. Denton F. Schroeder DSS AD's DDR AD's F

00R BC's I

DDR SL's J. Fair W. Nichols W. Rutherford J. Sniezek f

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31 02 MEMORAriDUM FOR:

B. K. Grimes, Assistant Director for Engir.eering and Projects, DDR D. G. Eisenhut, Assistant Director for Systems and Projects, DDR

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FROM:

Acitng Branch Chief, Engineer ag Branch, DDR

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SUBJECT:

PIPE SUPPORT BASE PLATE PROBLEM The Engineering Branch, Division of Operating Reactors, has contacted Bechtel, Bergen - Paterson, Gilbert, and Stone & Webster in regard to their past and current design procedures for support base plates utilizing drilled anchor bolts.

Bechtel and Stone & Webster indicated that they became aware of. base plate flexibility effects on anchor bolt. pull-cut loads within the past couple of years ano are now considering this in. current designs.

Gilbert and Bergen - Paterson indicated they are using rigid plate assumptions i

for calculating bolt loads.

Review of the support redesigns at Millstone shows a considerable increase in base plate thickness and anchor bolt sizes over the previous design.

The original designs by Bergen - Paterson c'id j

not neet the current rigidity requircments used by Stone & i.'ebster.

Design deficiency reports by Long Island Lighting Company on Shorehan show that consideration of base plate flexibility has increased the pull-out loads on so r.e bolts, and inspection of the supports has shown that approximately 55 percent of the anchor bolts had incorrect embedment lengths.

Currently,1&E is considering whether Stone & Webster should be k

investigated for a Part 21 deviation and will be further investigating this matter.

The Engineering Branch considers the problem at Millstone where several support plates were pulled out to be a combination of base plate flexibility and anchor bolt design problems.

Since the anchor bolts were never tested for cyclic loddings, and the lines at Milistone experienced flow induced vibrations, the capability of the anchor bolts to withstand cyclic loadings should bt addressed,

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Based on the cbove infomation, the Engineering Branch recomends I

that this be considered a generic item for all operating plants, and a vendor inspection program be iuplcmented with 1&E to review the vendor design procedures used for nnelyzing support base plates utilizing dfilled enchor tolts clong with the field instal 11ation procedures utilized in installing the anchor bolts.

Also, the load rating techn ~iques used by the anchor lelt manufacturers for cyclic g

loadings should be revicwed.

The Engineering Branch has talked r

8 with ISE and consider the vendor inspection procrata to be the most efficient cathod of completing the necessary review.

The Engineering Branch estimates approxir.ately 15 nan-weeks will be required I

to review design procedurcs used by vendors and A/E firms.

Tha Engincering Branch will set up a nseting with both AD's to determine l

the interface between the Engineering Bronch cnd I&E required to I

implement the review.

l The Engineering Branch is in the process of preparing a feedbeck merso to DSS on the base plate probica which is expected to.be completed

.by June 9,1978.

prJn,ir3 p)PS$ DU 1

i V. S. !?conan, Acting Brcnch Chief i

Engincertog Branch l

Division of Optrating Reictors

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V. Stello, Jr., DDR U. Rutherford IE U. potopous, IE R. liattson, DSS J. P. Knight, DSS R. Bosnak, DSS

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