ML20147C762

Forwards Recent Memo Discussing Problems W/Pipe Support Base Plant Design Applicable to Subj Facil.W/Encl ANO: 7811020332,7811020343 & 7811020336

ML20147C762
Person / Time
Site:	05000471
Issue date:	11/22/1978
From:	Beverly Smith NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD)
To:	Calliham A, Cole R, Luton E Atomic Safety and Licensing Board Panel, UNION CARBIDE CORP.
References
NUDOCS 7812180396
Download: ML20147C762 (8)

Text

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l November 22, 1978 1:00y Edward Luton, Esq., Chairman Dr. Richard F. Cole Atomic Safety and Licensing Board Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Washington, D.C.

20555 Dr. A. Dixon Calliham o

Union Carbide Corporation P. O.

Box Y Sdho Oak Ridge, Tennessee 37830 h-ghy L q

In the Matter of~

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Boston Edison Company, et al.

(Pilgrim Nuclear Generating Statiiiii, Unit 2)

Docket No. 50-471

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Gentlemen:

Enclosed are recent memoranda discussing certain problems experienced in connection with pipe support base plate design. The NRR Staff has informed us that the problems discussed in Mr. Stello's memorandum dated September 28, 1978 are applicable to the Pilgrim facility, and that DSS is presently reviewing this aspect of piping design analysis on a case-by-case basis under SRP section 3.9.3 - ASME Codes 1, 2 and 3 4

Components, Component Supports and Core Support Structures.

The Board and the parties will be advised when additional information is available.

Sincerely,

}$n Barry H. Smith Counsel for NRC Staff

Enclosure:

Memo 9/28/78

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Stello to Grossman (w/encls) cc w/ enclosures:

George H. Lewald, Esq.

Jonathan Brant, Esq.

Dale G. Stoodley, Esq.

Atomic Safety and Licensing 4

Henry Herrmann, Esq.

Board Panel Mr. and firs. Alan R. Cleeton Atomic Safety and Licensing The Board of Selectmen Appeal Board Panel William S. Abbott, Esq.

Docketing and Service Section Mr. Lester B. Smith Laurie Burt, Esq.

Charles Corkin, II, Esq.

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v BEP 2a p MEMORANDUM FOR:

Milton'J. Grossman, Hearing Division Director an.d C.hief Counsel, OELD FROM:

Victor Stello, Jr,, Director Division of Operating Reactors, NRR

SUBJECT:

BOARD NOTIFICATION - PIPE SUPPORT BASE PLATE DESIGN The attached memorandum to Roger Mattson, dated June 28, 1978, presents information concerning failures of safety-related pipe supports at Millstone 1 and design deficiencies on similar equip-ment at Shor'eham 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 perform structurally as rigid load-bearing members when they may be flexible members, and 2) incorrect l

anchor bolt torquing.

l Recent audits of Architectural Engineering firms and assessments of the actions taken at Millstone, as noted in the attachment, provided the following general information:

1.

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

2 Past-and current des.ign 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.

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We have concluded that the more detailed information required must be obtained from each operating facility, We are preparing a generic g

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Milton J. Grossman.

letter to each operating facility requesting detailed design, installation, and testing information of concrete-embedded anchor-bolted pipe supports of safety-related equipment.

We recommend that this inforrhation 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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f Ai y. cr <9 Victor Stello, Jr., Director Division of Operating Reactors Office of Nuclear Reactor Regulation

Enclosure:

June 28, 1978 memo, Stello to Mattson cc w/ enclosure:

D. Vassallo V. Stello R. Mattson R. Bevan' L. 01shan-L. Nichols V. Noonan A. Schwencer T. Ippolito J. Fair

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JUN 2 g 197g MEMORAf10UM FOR:

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

Victor Stello, Jr., Director

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Division of Operating Reactors

SUBJECT:

OPERATIflG EXPERIEl!CE MEMORAf10UM ti0.13 PIPE SUPPORT BASE PLATE PROBLEM PROBLEM Recently during inservice inspections at Millstone Unit 1, structural failures of rigid pipe supports for class 2 safety equipment were observed.

These inspections, recently implemented at Millstone, were conducted ih 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 properly embedded; and, in some cases the anchor bolts were completely pulled out and no supporting function was provided.

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

Inspection of anchor bolt installaticns at Shoreham has shown over fifty percent of the bolt installations were deficient.

Supports for both piping systems and electrical raceways have been reported as deficient at'Shoreham.

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

First, the design assumption that the base plates perform structurally as rigid instead of flexible members may provide low estimates of imposed loads on the supports.

Secondly, incorrect anch'Br bolt embedment may also contribute to insufficient support.

The attached memorandum from V. Noonan to B. Grimes, dated g 72 0 'a $

o June 2, 1978, provides additional information.

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2 SAFETY SIGflIFICANCE Depending on equipment layout, improperly designed or installed anchor supports could:

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result in loss of support function in some cases; and, l

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

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

These changes include increased base plate thickness and larger anchor bolts for failed supports.

Shoreham in conjunction with Stone and Webster is evaluating both piping and electrical type supports.

The review is scheduled to be completed by December, 1978.

DOR ACTION The Engineering Branch will review the design procedures used on operating plants to determine anchor bolt loads, the techniques used 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 started during early July, 1978 We anticipate that criteria will be developed for design and installation of base plate-anchor bolt assemblies, and those operating plants requiring corrective action will be identified.

Additionally EB staff will further assess the occurrence and corrective actions taken at Millstone.

REC 0!?.E.k!DATIONS

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We recommend that this problem be addressed on all CP and OL reviews.

At this time it appears that consicerations 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 bolt size and embedmant to properly cope with loads imposed on the supports.

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It rnay be appropriate to require that applicants provide for review thefr:

1.

methods for determining base plate thickness and anchor bolt loads; 2.

criteria for anchor bolt installation; and, 3.

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

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

Supplemental information will be provided.

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Vic' tor Stello, Jr., Director M

Division of Operating Reactors PRMCIPAL DOR PERSONNEL Reviewer:

J. Fair I

Enclosure:

Memorandum dated 6/2/78 cc:

w/ enclosure E. G. Case S. Hanauer R. S. Boyd

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

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J. Fair W. Nichols W. Rutherford J. Sniezek E_

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,SW p W3 HEMORANDUM FOR:

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

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FROM:

Acitng Branch Chief.

Engineering Branch, D0R

SUBJECT:

PIPE SUPPORT BASE ' PLATE PROBLD4 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 boltepull-out loads within the past couple of years and are now considering this in current designs.

Gilbert and Bergen - Paterson indicated they are using rigid plate assumptions for calculating bolt loads.

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

The original designs by Bergen - Paterson did not meet the current rigidity requirements used by Stone & Webster.

Design deficiency reports by Long Island Lighting Company on Shoreham show that consideration of base plate flexibility has increased the pull-out loads on some bolts, and inspection of the supports has shown that approximately SS percent of the anchor bolts had incorrect er.:bedment lengths.

Currently, i&E is considering whether Stone & Webster should be 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 ano anchor bolt design problems.

Since the anchor bolts were never tested for cyclic loadings, and the lines at Millstone experienced flow induced ylbrations, the capability of tne anchor bolts to withstand cyclic loadings should be addressed, 3(o y

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~ v..u. t.2sonnus .' T .. + - Based on the above infomation, the Engineering Branci peccmends that this be considered a pneric item for all operati.g plants, and a vendor inspection program be inplemented with ILE to review the vendor design procedures used for analyzing support base plates utilizing drilled enchor bolts alon'g with the field instal 11ation procedures utilized in installing the anchor bolts. Also, the lo'ad rating techn'iques used by the anchor bolt canufacturers for cyclic loadings should be reviewed. The Engineering Branch has talked with I&E and consider the vendor'in' pection program to be the cost s efficient nethod of completing the necessary review. The Engineering Branch esticates approximately 15 man-weeks will be required to review design procedures used by vendors and A/E fires. The Engineering Branch will set up a maeting with both AD's to detemine the interface between the Engineering Brench and I&E required to i implement the review. I The Engineering Branch is in the process of preparing a fceokck memo to DSS on the base plate problem which is expected to be completed 'by June 9,1978'. m pqis, imp _.E}P9$,M.i V. S. Hoonan, Acting Brench Chief Engineering Branch a Division of Operating Reactors cc: V. Stello, Jr.. DDR W. Rutherford. IE U. Potopous, IE R. Mattson, DSS J. P. Knight, DSS R, Bosnak, DSS \\ .'\\ O e 9 _ _ _ _, _ _. _ _ - _ _ - - - - - - - - - - - - - -}}