ML19289A045
| ML19289A045 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 11/07/1978 |
| From: | Treby S NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | Kelley J NRC OFFICE OF THE GENERAL COUNSEL (OGC) |
| Shared Package | |
| ML19289A046 | List: |
| References | |
| NUDOCS 7901030025 | |
| Download: ML19289A045 (1) | |
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November 7,1978 p sg
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J James L.1;elley '
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E U.S. Nuclear Regulatory CommiTM 9
Washington, D. C. 20555 j
In the Matter of Virginia Electr' and Power Company (North Anna Nuclear Power Station, Units 1 and 2)
Docket Nos. 50-336 OL and 50-339 OL
Dear Mr.1;elley:
Enclosed are recent mernoranda discussing certain problems experienced in connection vith pipe support base plate design. The NRR Staff has informed us that the problems disc ussed in Mr. Stello's memorandum dated September 28, 1978 are applicable to the North Anna Units 1 and 2 facility, and that DSS is pres-j ently reviewing this a< pect of piping design analysis on a case-by-case basis under SRP section 3.9.3 - ASME Codes 1, 2 and 3 Ccmponents, Component Supports and Core Support Structures. If the Commission wishes additional information, please let us know.
Sincerely,
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Stuart A. TI eby ~ '/,
Assistant Chief llearing Counsel for NRC' Staff
Enclosure:
Memo 9/28/78 Stello to Grossman (w/encls) cc:
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_2 cc w/cnclosure:
Dr Paul W. Purdom M r. J a m e t 1,i. Tor son 1ir. R. B. Briggs Richard Foster, Esq.
Michael W.1.iaupin, Esq.
1,ir. Bradford Whitman Dr. l'enneth A. McCollom
),ir s. J a m e s C. A r n old Anthony Gambardella, Esq.
1.f r. Warren Warren Mrs. June Allen Atomic Safety and Licenting Mrs. Margaret Dietrich Board Panel Mr Dean P. Agee Atumic Safety and Licensing William 11. Rod gers, Jr., Esq.
Appeal Panel John J. Runzer, Esq.
Docketing and Service Section
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d, l, r F );yp MEMORANDUM FOR:
Milton J Grossman, Hearing Division Director and Chief Counsel, OELD FROM:
Victor Stello, Jr., Director Division cf Operating Reactors, NRR
SUBJECT:
BOARD NOTIFICATION - PIPE SUPPORT BASE PLATE DESIGN i
The attached memorandum to Roger l'attson, dated June 28, 1978, presents information concerning failures of safety-relatea 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 connec-tions of pipe supports, These are, 1) the design assumption that base plates perform structurally as rigid load-bearing
- r. embers when they r.ay be ficxibic members, and 2) incorrect j
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, s
' 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 fU b
Milton J. Grossir.an,
letter to each operating facility requesting detailed design, installation, and testing information of roncrete-cabedded anchor-bolted pipe supports of safety-related equipnent.
We recommend that this information be provided to the following Boards:
1.
lionticello (FTL) 2.
Indian Point 1,2,3 (Seismic Design)
We will provide an assessment of this issue upon completion of our evaluations, i
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7.,z.7: e Victor Stello, Jr., Director Division of Operating Reactors Office of fluclear Reactor
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Regulation
Enclosure:
June 28, 1978 memo, Stello to Mattson cc w/ enclosure:
D. Vassallo V. Stello R. Mattson R. Bevan L. Olshan L. Nichols V. Itoonan A. Schwencer T. Ippolito J. Fair 95 teD Os
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MEMORANDUM TOR:
B. K. Grimes, Assistant Director for Engineering and Projects, DDR D. G. Eisenhut, Assistant Director i
for Systems and Projects, DDR t
FROM:
Acitn9 Dranch Chief, Engineering Branch, DDR
SUBJECT:
PIPE SUPPORT BASE' PLATE PROBLEM The Engineering Branch, Division of Operating Recctors, has contacted Bechtel, Bergen - P] terson, 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 - Pa terson indicated they are using rigid plate assumptions for calculating bolt loads.
g Review of the support redesigns at Millstone shows a considerable
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increase in base plate thicl. ness and anchor bolt sizes over the previous design.
The original designs by Dergen - Paterson did not meet the current rigidity requirements used by Stone & Webster.
Design deficiency reports by Long Island Lighting Company on Shorchcm show that consideration of base plate flexibility has increased the pull-out loads on some bolts, and inspection of the i
supports has shown that approximately 65 percent of the anchor l
bolts had incorrect embedment lengths, Currently, ISE is considering whether Stone & Webster should be i
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 probicms.
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.
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'W D. C. Ehe nt.ut Desed on the Ltove infore..tton, the Engineering Branch reconnends that this be considered c generic itur. for all op;: rating picnts, and a vendor insp::ction program be inpitmented with !&E to review the vendor c'esign procedures used for t.nt;1yring support bese pintes utilizing dPilled tnchor bolts tiong with the ficid insteillation procedures utilized in installing the anchor tolts.
Also, the load rating techniques used by the enchor toit manufteturert, for cycite loadings chauld be rovitxed.
The Engineering Brtneh has telhed ulth ILE and consider the vendor inspection program to be the most efficient e.ethod of co.mpleting the nocesscry review.
The Engineering Dranch estir.:tes approxir.stely 15 an-veeks will be required to review design procedures used by vendors and A/E firms.
The Engindering Branch will set up e neeting with both AD's to deterr.ine the interf..cc between the Engineering Branch tnd It.E required to impiteent the review.
The Engineering Branch is in the process of preparing a feedbbek'nsoo to DSS on the base picte probica which is expected to be completed by June 9,1978.
[1xir,js.q c.ipuhZi V. S. l'ocnan, Acting Branch Chief l
Engineering Branch j
Division of Opercting Reactors cc:
V. Stollo, Jr., DDR If. Rutherford, IE U. potopaus. IE R. Ibttson, DSS J. P. Knight, DSS R. Dosnak, DSS a
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