ML20150D250

Forwards Recent NRC Memos Re Problems Associated W/Pipe Support Base Plate Design Which Apply to Subj Facil.W/Encl ANO:7811020332,7811020343 & 7811020336

ML20150D250
Person / Time
Site:	Seabrook
Issue date:	11/09/1978
From:	Brenner L NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD)
To:	Buck J, Mike Farrar, Rosenthal A NRC ATOMIC SAFETY & LICENSING APPEAL PANEL (ASLAP)
References
NUDOCS 7812050082
Download: ML20150D250 (9)

Text

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,[k . NUCLEAR REGULATORY COMMISslON h .%j f.y[ R( 7 ] WASWNGTON, D. C. 20555 NRC PUBLIC DOCUMENT ROOM

• ,,,..# November 9,1987 Alan S. Rosenthal, Esq., Chainnan Dr. John H. Buck Atomic Safety and Licensing Atomic Safety and Licensing Appeal Board Appeal Board U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Conmission Washington, D.C. 20555 Washington, D.C. 20555 Michael C. Farrar, Esq. 4 Atomic Safety and Licensing g Appeal Board Dp#o \

U.S. Nuclear Regulatory Commissfor -

Washington, D.C. 20555 Q- N O V f ,y g g y as%,

In the Matter of J.

Public Service Company of New Hampshire, et a og (Seabrook Station, Units 1.and 2) -

Docket Nos. 50-443 and 50-444 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 Seabrook facility, and that the Staff is presently reviewing this aspect of piping design analysis on a case-by-case basis under Standard Review Plan 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, cu.O-4.kycja.s '

Lawrence Brenner Counsel for NRC Staff

Enclosure:

Memo 9/28/78 Stello to Grossman (w/encis) cc: (w/ enclosure) John A. Ritsher, Esq.

Ivan W. Smith, Esq. horman Ross, Esq.

Joseph F. Tubridy, Esq. E. Tupper Kinder, Esq.

Dr. Marvin M. Mann Laurie Burt, Esq.

Dr. Ernest 0. Salo Karin P. Sheldon, Esq.

Dr. Kenneth A. McCollom Atomic Safety and Licensing Robert A. Backus, Esq. Board Panel Thomas G. Dignan, Jr., Esq. Atomic Safety and Licensing A I

Docketing and Service Section Appeal Board 78120500 W

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SUBJECT:

BOARD NOTIFICATIO1 - PIPE SUPPORT BASE PLATE DESIGN i

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 Shoreham Unit 1. As indicated in the attachment, two factors appeared to contribute to failure of anchor-bolt connee-tions of pipe supports. Theseare,1) the design assumption that base plates perform structurally as rigid load-bearing members when they may be flexible members, and 2) incorrect anchor bolt torquing.

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 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 obtained from each operating facility. We are preparing a generic

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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 information be provided to the following Boards:

1. Monticello (FTL)

2. Indian Point 1,2,3 (Seismic Design)

We trill 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 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 e.

A. Schwencer T. Ippolito J. Fair 1

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'. y o 7 j7B MEMORANDUM 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, DDR

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-out loads within the past couple of years and are now considering this in current designs. Gilbert a nd Bergen - Paterson indicated they are using rigid plate assumptions .

for calculating bolt loads.

g 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 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 55 percent of the anchor bolts had incorrect embedment lengths.

Currently,1&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 l support plates were pulled cut to be a combination of base plate i

flexibility and anchor bolt design problems. Since the anchor bolts were never tested for cyclic loadings, and the lines at Millstone experienced flow induced vibrations, the capability of the anchor bolts to withstand cyclic loadings should be addressed, 1

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Based on the above information, thri Engineerir.g Ortnca recormends that this be con ic'cred a generic itun for all operating plants, and a vendor inspection program be implemented with I&r to review the vendor design procedures used for analyzing support base plctes ,

utilizing dfilled enthor bolts along with the field instal 11ation procedures utilized in installing the cochor bolts. Also, the load rating techniques used by the enchor fralt canufacturers for cyclic ,

loadings should be revicwed. The Engineering Branch has talked trith I&E and consider the vendor inspection program to be the cost efficient rnethod of completin0 the necessary review. The Engineering Branch estimates approximately 15 man-weeks will be required to ' review design procedurts used by vendors and A/E firms. The Engineering Branch will set up a treeting with both AD's to detemine the interfece between the Engineering Branch and ILE required to impice nt the review.

The Engineering Branch is in the process of preparing a feedback' memo to DSS on the base plate prob 1cc which is expected to be completed by June 9,1978, ftr.in,in g M sup4Pli -

V. S. floonan, Acting Branch Chief

( [ngineering Brcnch Division of Operating Reactors cc: V. Stello, Jr., 00R II. Rutherford, IE U. Potopous, IE R. Mattson, DSS J. P. YJ11ght, DSS R. 00snak, DSS i

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d MEMORANDUM FOR: R. J. Mattson, Director ,

Division of Systems Safety FROM: Victor Stello, Jr., Director Division of Operating Reactors

SUBJECT:

OPERATIl4G EXPERIENCE MEMORANDUM NO. 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 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 Lew 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 installations at Shoreham has shown over fif ty percent of the bolt installations were deficient. Supports for both piping systams and electrical raceways have been reported as deficient at Shoreham.

I PRESUMED CAUSE It is currently believed that two interacting factors contribute to the tailure 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 anchor bolt embedmont may also contribute to insufficient support.

The attached memorandum from V. Noonan to B. Grimes, dated June 2, 1978, provides additional information.

. 2-S(3FETY SIGNIFICANCE Depending on equipment layout, improperly designed or installed anchor '

supports could: <

1. re.sult in loss of support function in some cases; and,

2. result in high stressing of piping systems 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 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 Decembcr,1978. ,

DDR ACTION i The Engineering Branch will review the design procedures used on operating plants to determine anchor bolt loads, the techniquas 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 durin; 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 corre'ctive actions taken at Millstone. ,

RECOM.P.Ef!D ATIONS ,"

He recomnend that this problem be addressed on all CP and OL revicws.

At this tine 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 bolt size and embedmont to properly cope with loads imposed on the supports.

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, -3 It inay be appropriate to require that applicants provide for review their: ,

1. rnethods for determining base plate thickness and anchor bolt loads; 1, 2. criteria for anchor bolt installation; and, 3 criteria for load rating techniques for anchor bolts, including cyclic loads.

L'e shall coordinate our meetings, discussions and evaluations of this issue with your staff. Supplcmantal information will be provided.

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.. '1 Vic .:sStello,

. tor  ! Jr., Director Division of Operating Reactors 1 ~

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