IR 05000282/1987013

Insp Repts 50-282/87-13 & 50-306/87-12 on 870803-06.No Violations or Deviations Noted.Major Areas Inspected: Licensee Action on IE Bulletin 79-02 Pipe Support Baseplate Design (& Const) of Concrete Expansion Anchor Bolts

ML20237L555
Person / Time
Site:	Prairie Island
Issue date:	09/02/1987
From:	Danielson D, Norton J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20237L546	List: IR 05000282/1987013 ML20237L541
References
50-282-87-13, 50-306-87-12, IEB-79-02, IEB-79-2, NUDOCS 8709080456
Download: ML20237L555 (6)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION III

Reports No. 50-282/87013(DRS); 50-306/87012(DRS)

Docket Nos. 50-282; 50-306 Licenses No. DPR-42; DPR-60 Licensee: Northern States Power. Company 414 Nicollet Mall Minneapolis, MN 55401 Facility Name: Prairie Island Nuclear Generating Plant, Units 1 and 2 Inspection At: Prairie Island Site, Red Wing, Minnesota Inspection Conducted: August 3-6, 1987 Inspector * . F. Norton 9/2/#7 Date

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Approved By: D. H. Danielson, Chief 9/2//7 Materials and Processes Section Date Inspection Summary

Inspection on August 3-6, 1987 (Reports No. 50-282/87013(DRS); 50-306/87012(DRS))

Areas Inspected: Announced, routine safety inspection of licensee action on IE Bulletin No. 79-02 " Pipe Support Baseplate Design (and Construction)

of Concrete Expansion Anchor Bolts." 1

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Results: No violations or deviations were identifie i i

8709000456 870902 PDR ADOCK 050002G2

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L DETAILS 1. Persons Contacted Northern States Power Company (NSP)

• C. Baltos, Nuclear Technical Services

• G.-Lenertz, General Supervisor of Plant Maintenance

• G. Miller, Supervisor of Operating Engineering

• J. Anderscn, Engineering Associate i D. Teft, Machinist P. Winberg, Lean Machinist U.S. Nuclear Regulatory Commission (USNRC)

J. Hard, Senior' Resident Inspector

• Denotes persons attending the exit intervie . Licensee Action on-IE Bulletins (Closed) IE Bulletin No. 79-02-(282/79-02-BB; IB; 306/79-02-BB; IB):

IE BuIletin No. 79-02, " Pipe Support Baseplate Design / Construction Using Concrete Expansion Anchor Bolts." A review of relevant information revealed ~that IE Bulletin No. 79-02 requirements have been fully implemented at Prairie Island Nuclear Generating Plant, Units 1 and ,

Background IE Bulletin No. 79-02 addresses pipe support baseplate design using concrete expansion anchor Teledyne. Engineering Services (TES) i was authorized by fourteen utilities (including NSP) to provide (

engineering service which would assist the utilities in responding, '

in part, to IE Bulletin No. 79-02, dated March 8, 1979. IE Bulletin No. 79-02 required response to a number of items associated with baseplate flexibility and its concomitant effect on concrete expansion anchor bolts. It was determined by the Utility /TES group that a number of items in the bulletin were generic in nature and could be addressed more substantially by combining resources and technolog The specific bulletin items addressed by the Utility /TES group were:

(1) The experimental development of shear-tension interaction curves to properly apply the bulletin safety factors for combined loadin (2) Experimental determination of the adequacy of concrete anchor I bolts that are not preloaded to withstand cyclic ioadin (3) An analytical technique for determining the effect of baseplate flexibility on concrete anchor bolt loadin l i

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i 2' The Owner's Group was responsible for directing the efforts of TES and reviewing the specific tasks as they were performed and l L

completed. On April 26, 1979, the Utility /TES group met with the J NRC in Bethesda, Maryland to discuss this generic program and its applicability to IE Bulletin No. 79-02. Representatives from I&E >

and NRR were in attendance and their general conclusion was that )

"the proposed program would address the concerns for the base plate / I anchor bolt installation in a fashion that is acceptable to the NRC." j

TES' submitted Technical Report TR-3501-1, Revision 1, dated August 30, l 197 The report presented the results of a generic problem that  !

responded,'in part, to the Bulleti Both experimental and analytical '

work was performed in this generic program. Shear-tension interaction tests and cyclic test of concrete expansion anchors were performed and a pre and post processor to an existing finite element program was i developed to facilitate baseplate analysis, Subsequently, the NRC staff performed an independent analytical verification of the techniques used to account for baseplate flexibility and its effect on anchor bold load The independent analytical verification consisted of developing an elastic beam-based '

model of an anchored plate, subjected to static combined axial and moment loadin The concrete base was represented by elastic springs ;

which were capable of sustaining compression only. The anchoring '

bolts were represented by springs which reproduced the non-linear behavior of the bults during pullout. The model also accounted for initial preload in the bolt plate assembly. The solution to a given loading condition (i.e,. bolt load vs. external load history)

was obtained through and in-house developed computer program, which calculated the non-linear behavior in an incremental approach, including equilibrium interactio Based on the review and independent verification, the NRC staff l concluded that the techniques applied by TES correctly accounted '

for pipe support baseplate flexibility and was therefore acceptabl Licensee Action In response to a request by Northern States Power Company (NSP),

Teledyne Engineering Services (TES) has conducted a study of the expansion anchor used in pipe-support structures for the Prairie ,

Island Nuclear Station Units 1 and 2. The work was performed for Seismic Category 1 pipe supports in response to NRC IE Bulletin No. 79-0 TES, under NSP Purchase Order No. MP4950, verified all of the Seismic Category 1 baseplate as-builts at the site for Units 1 and 2, performed all the baseplate / anchor-bolt analyses ,

and provided suggested modification to those that failed to meet  !'

the criteria. This effort is summarized in TES Technical Report TR-3607-1, dated April 20, 1983. There were a number of supports l which TR-3607-01 indicated required modification. TES, under NSP Purchase Order No. 028490MQ, analyzed the final "as-built" drawings sent to TES by NSP and incorporated the "as-built" analyses into the

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support packag ,

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' Technical Report No. TR-3607-01 and No. TR-3607-1 Rev. A constitutes )

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a complete summary of the evaluation of Seismic Category 1 pipe i supports in response to IE Bulletin No. 79-0 I The discussion o'f the overall project is included in Section ,

Lof TES Technical Report No. TR-3607- The purpose of TES Technical i

. Report No. 3607-1 Rev. A'is to revise the conclusions of TR-3607-1 to include the completion of the analysis'for the supports.noted as being analyzed by TES, having modifications suggested by TES. This technical report. includes an updated status of all the supports

' evaluated in this' effor ~

l i TES evaluated 1131 supports'on Unit l'and 710 supports on' Unit 2 for a total of 1841. supports. All supports evaluated passed the criteria as defined in Procedure P3607-2, " Baseplate Anchor. Bolt Adequacy Evaluation,"_which is in Section 11.0 of TES Technical Report No. TR-3607-1, Rev. TES recommended 170 support modifications for Unit 1 and 122 support modifications for Unit 2. -Therefore, the total number of supports-for which modifications'were suggested was 292 of the 1841 total ;

number of supports in Unit 1 and 2 or 15.9L ' All Seismic Category l' pipe supports for the Prairie Island Nuclear Generating. Station Units' 1 and 2 evaluated by TES meet.the requirements of the IE Bulletin No. 79-0 For the NSP Prairie Island Nuclear Generating Station Units 1 and .

2,.TES'has' completed the analysis and the redesign of all Seismic l Category 1 pipe supports. Both large and small bore supports were included in the evaluatio h. - Based on-the evaluation and analysis,. all those Seismic Category 1 pipe supports received.from NSP for the Prairie Island Nuclear Generating. Station Units 1 and 2 meet the requirements of the IE Bulletin No. 79-02. Further, it was documented in the TES Technical Report TR-3501-1, Rev.1, that:

.(1) Concrete expansion anchor bolts which are not preloaded )

do not deteriorate when subjected to cyclic loadin (2) . A linear assumption for shear-tension interaction loading on concrete expansion anchors is highly conservativ (3) Baseplate flexibility should be considered in determining the load on concrete expansion anchor ,

I (4) Testing performed under this program does not indicate a reason for applying different safety factors to different types of expansion anchor l

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. Conclusion Baseplate modifications have been completed. The' modifications

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were. accomplished in accordance'w'th licensee engineering and QA/QC'

requirements. The Region'III ins- ctor. reviewed paperwork and examined se'veral of the modified plates. , , a discrepancies between design drawing and. construction were discerne , Based on the aforementioned date, it is. concluded that IE Bulletin No. 79-02 has.been fully' implemented at' Prairie Island Nuclear Generating

.J ~ Station, Units 1 and . Exit Neeting The inspector met with' licensee representatives'(denoted under Person Contacted) on August 13, 1987. The inspector summarized the purpose ~and

. findings of the' inspection. The. licensee acknowledged the findings as reported herein. ; The inspector also discussed the likely informational

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content:of the' inspector's report with~ regard to documents or processes reviewed'by the inspector.during'the inspection. The. licensee did not

identify any such' documents / processes as proprietar ,

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