ML19207B910

Submits Response to IE Bulletins 79-02 & 79-02,Revision 1. Detailed Analyses & Insp of Expansion Anchor Bolts Considered Unnecessary

ML19207B910
Person / Time
Site:	Crane
Issue date:	07/09/1979
From:	Herbein J METROPOLITAN EDISON CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
GQL-0882, GQL-882, NUDOCS 7909060061
Download: ML19207B910 (20)

Text

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Metropolitan Edison Company (j Q 7T f (

Post Office Box 542 Reading Pennsylvania 19640 215 929-3601 Writer's Direct Dial Number July 9, 1979 GQL 0882 Mr. B, H.

Orier, Director Office of Inspection & Enforcement 4

Region I U.S. Nuclear Regulatory Con =ission 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Sir:

Three Mile Island Nuclear Station, Unit 1 (TMI-1)

Operating License No. DPR-50 Docket No. 50-289 I&E Bulletin 79-02/79-02 Rev.1 Enclosed please find Met-Ed's response to the subject bulletin.

Sincerely, J. G. Herbein Vice President Generation JGH:RJS:=r:

Enclosure cc: U.S. Nuclear Regulatory Cct=issicn Office of Inspection and Enforcement Division of Reactor Operations Inspection Washington, D.C.

20555 7000 0 60 d6l

,,r Metrocohtsn Ed son Ccmoany is a fMmcer cf :he Genera Puc'.c Uta t:es System f.) 1, ]i 5 '; 1;

July 9, 1979 THREE MILE ISLAND NUCLEAR STATION UNIT 1 RESPONSE TO NRC IE BULLETIN 79-02/79-02 REV. I

1.0 INTRODUCTION

A design review was performed in response to IE Bulletin No. 79-02/79-02 Rev. I " Pipe Support Base Plate Design using Concrete Expansion Anchor Bolts," dated March 8, 1979/ June 21, 1979 for Three Mile Island Nuclear Station, Unit 1.

The review was performed on a representative sample of safety-related supports (Seismic Category I). Possible effects of base plate flexibility on base plate anchors were considered.

This report presents the methods and results of the design review.

Also a program was developed to inspect the in place anchor bolts.

2.0

SUMMARY

2.1 Summary of Design Review 1.

Most plates were determined to be flexible as defined by the NRC 2:1 ratio criteria.

There fo re, plates were reanalyzed using a method in which the ef fects of plate flexibility and shear-tension interaction were considered.

The results of the reanalysis confirmed the adequacy of the original design.

2.

A representative sample totaling 40 support base plates for pipe of a diameter 2-1/2" and larger, all anchored with Red Head self-drilling expansion anchors, were reanalyzed.

With one exception, the minimum factor of safety against failure was found to be grea'.er than the factor of safety of five (5) required by the Bulletin for shell type anchors.

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. 3.

All Seismic Category I supports are potentially subject to a relatively low number of seismic loading cycles which can be accommodated by the design.

Operational loads which could, during the lifetime of the plant, undergo a high number of load cycles, were identified during startup testing, and modifications to the pipe support system were made as required to assure that such loads are minimized.

2.2 Summary of In-Place Inspection On March 14, 1979, a preliminary inspection of 46 anchor bolts on 35 hangers within the Reactor Building was conducted, and no deficiencies were found.

This inspection established bolt size and bolt length.

As of this date, the testing of anchors has not been completed, and it is expected that the additional inspection results will be available by October 15, 1979.

3.0 REVIEW RESULTS In consideration of the requested action, a representative sampling of base plates for large bore (2-1/2" and larger) Safety Category I pipes were reanalyzed.

There are approximately 1,475 base plates in the plant which fit this category and 40 have been investigated.

Small bore (2" and smaller diameter) pipe was designed using a seismic support spacing criteria.

The criteria was developed based cm a conservative pipe stress and a multi-span model for each pipe size and schedule.

The analysis provides pipe stresses and support loads for a given span.

This approach has been verified by sample computer analyses to be conservative relative to applicable code requirements.

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. A series of typical support designs were generated and load rated by analytical techniques.

The supports were analyzed for structural adequacy for all members, welds and the expansion anchor bolts.

In generating the load rating, the most conservative geometry combination of the maximum distance from the pipe to the structure was used.

This resulted in the worst load case.

As a result of this conservative approach, detailed analyses and inspection of these expansion anchor bolts is considered unnecessary.

i 4.0 MET-ED RESFONSES 4.1 Response to Item 1 Base plates were considered rigid in the original design.

For reexamination of the base plates considering plate flexibility, procedures were developed for the analysis of the plates and anchorages for moment and axial load applied to the plate surfaces (Figure 1 and 2).

The expansion bolt stiffness (i.e. K, in Figure 1 and 2) was derived from force-displacement curves provided by the manufacturer.

For both loadings, equations were derived from statics and deflection compatibility which allows calculation of the prying force on the plate and, subsequently, determination of forces in the anchors and stresses in the plates.

For both cases, criteria have been formulated to determine whether or not prying exists based upon the geometry of the detail and material properties of the plate and anchor.

Prying was found to be negligible.

In all base plates, shear and tension effects were combined directly to evaluate the anchors with the resultant shear force being distributed equally to all anchors in the connection.

The method for combining these effects is described below in Section 4.2.

4.2 Response to Item 2 The concrete expansion anchor bolts used at TMI-1 are the Red Head self-drilling expansion anchors as manufactured by ITT Phillips Drill Division.

This is a shell type anchor, and therefore requires a minimum factor of safety of five.

The results of the reanalysis are summarized in attached Table 1.

The minimum f actor of safety is 6.8, except for one anchor on one support which has a factor of safety of 4.2.

This one case is being evaluated further using a more cefined analysis.

Approximately 83% have a factor of safety greater than 10.

The factor of safety against failure (F.S.) is determined using the following shear-tension interaction equation:

(F.S.)

(T )

(F.S.)

(S )

1 o

+

o

=

(T,)

(S )

where:

F. C = factor of safety against failure T = Tension Force induced into an anchor (considering plate flexibility)

T = ultimate tension capacity of an anchor

• a S = Shear Force induced into an anchor 9

S, = ultimate shear capacity of an anchor *

• From manufaccurers static load tests The minimum edge distance between the bolt centerline and the edge of a concrete member is equal to 5d or 4 inches, whichever is greater.

In accordance with the manufacturer's instructions, bolt spacings greater than 7 shell diameters develop 100% of the published ultimate scrength, and spacings of 3-1/2 shell diameters develop 80%.

Therefore, in those cases where the spacing is less than 7 and greater thaa 3-1/2 shell diameters, the anchor capacity has been reduced 20%.

The minimum spacing is 4.7 shell diameters.

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4.3 Response to Item 3 Pipe support reactions are generated as an output of a dynamic analysis and are utilized for the design of the individual pipe supports.

Therefore, theoretically, a dynamic amplification factor was not required.

The governing load combination is:

Deadweight + Thermal + OBE Seismic + Occasional Mechanical Loads

< Allowable Anchor Bolt Load A correctly installed shell type anchor develops its tensile capacity by radial expansion of the bottom portioa as expanded by a conical plug when the shell is driven into the concrete.

In e f fect, this gives an internally threaded insert rigidly anchored in'the concrete.

The base plate is bolted to the shell and the shell may or may not be in contact with the back of the base plate.

4.4 Responsexto Item 4 Sufficient QC documentation does not exist to satisfactorily respond to this item.

Therefore a test program has been developed to inspect a random sample, by system, of the expansion anchor bolts.

The test procedure is given in the attached Appendix 1.

It is expected that the test results will be available by October 15, 1979.

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TABl.E 1 RESULTS OF BASE PLATE ANCIIOR REANALYSIS Anchor Min. Spacing Factor of Mark Size O Shell Dia.

Safety Remarks DCll-15 5/8" 8.3 13.6 DCH-27 3/4" 6.0*

10.3*

Rigid Plate Analysis Compressive Load only DCH-52 3/4" 9.5 cc DCH-53' 3/4" 9.5 7.0 DCH-62 3/4" 7.5 61.3 MS-228 5/8" 11.5 17.0 MS-241 3/4" 8.0 92.7 MS-271 5/8" 9.5 38.7 MS-277A 1/2" 8.7 33.6 FW-121 3/4" 9.5 13.6 i

FN-122 3/4" 9.5 12.8 EF-11 5/8" 5.9*

102.8*

EF-22 3/4" 7.5 70.9 Rigid Plate Analysis EF-110 1/2" 9.0 7.5 MUH-5 1/2" 9.0 15.6 MUH-ll 1/2" 8.7 97.7 c

MUH-21 5/8" 7.1 123.2 MUH-42 1/2" 8.7 6.8 MUH-75 1/2" 9.0 9.2 MUH-118 1/2" 5.0*

21.0*

MUH-221 1/2" 7.2 86.2 Rigid Plate Analysis DHH-187 1/2" 11.6 40.6 RC-5 1/2" 5.8*

9.1*

NSE-2 3/4" 7.5 176.1 NSE-31 "5/8" 8.0 58.5 Rigid Plate Analysis SFH-20 5/8" 8.0 35.1 SFH-165 5/8" 9.1 107.5 SFE-28 5/8" 4.7*

47.8*

Rigid Plate Analysis PR-3A 7/8" 8.0 22.3 PR-6 3/4" 6.0*

281.8*

NSH-11 7/8" 11.4 12.0 NSH-55 5/8" 19.8 15.8 SSH-90 5/8" 8.0 8.0 NSH-91 3/4" 7.5 33.8 MSE-26 7/8" 8.0 26.6 NSE-93 5/8" 11.5 18.8 SPSE-2 5/8" 8.1 212.8 SPSE-3 3/4" 11.5 4.2 SPSE-4 1/2" 8.7 373.3 DCH-68 3/4" 4.7*

24.6*

• Dera ted 20% due to spacing less than 7 shell diameters but more than 3's shell diameters.

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APPENDIX 1 PROCEDURE FOR INSPECTION OF CONCRETE EXPANSION BOLTS 1.0 PURPOSE To set forth requirements for inspecting pipe support plates and concrete anchors.

Inspection is required by Nuclear Regulatory Commission (NRC) IE Bulletin 79-02 Rev. I dated 21 June 1979.

2.0 ACCEPTANCE CRITERIA Ensure Item 4 of IE Bulletin 79-02 (verification of anchor bolt design requirements) has been met.

Maintain documentation of anchor bolt inspection.

3.0 REFERENCES

NRC,{ulletin 79-02 Rev. 1 dated 21 June 19 79.

4.0 EQUIPMENT REQUIRED 1.

Ultrasonic test equipment to measure bolt / stud embedment depth (wedge type only).

2.

Hand tools.

3.

Machinist scale or depth gauge.

4.

Hanger inspection package - data sheets.

5.

Test fixture if required.

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2 5.0 INSPECTION REQUIREMENTS 5.1 Inspect all the concrete anchors used in the base plate of a selected '

support for the items found on data sheets.

5.2 Record all findings on the data sheets.

5.3 Determine anchor belt type as defined in section 6.0.

5.4 Inspect bolt for compliance with ' size specified on support drawing.

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5.5 Visually inspect the plate for loose anchors and any gap between the plate and the concrete.

5.5.1 If gap between plate and concrete exists, estimate the percentage of contact area.

5.5.2 Measure gap in the area of the bolts and record.

5.6 Check grouted base plates using the following:

5.6.1 Remo'Ye nuts and washers.

5.6.2 Inspect to ensure there are no leveling nuts behind the plate.

5.6.3 If leveling nuts exist, refer to A/E for direction.

5.7 Inspect each type anchor as specified in section 7.0; if anchor inspected does not meet req uirements specified, then inspect remaining anchors of support.

5.8 Measure and record the distance f rom the edges of the plate to the edge of the bolt hole.

Measure bolt hole diameter.

5.9 If anchor bolt spins, renove bolt.

Check hole diameter, if in tole rance, replace with a like kind and reattempt torquing.

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3 6.0 DETEP11INATION OF ANCIIOR TYPE 6.1 If threaded portion of anchor bolt protrudes through the plate and nut, the anchor is one of the following:

6.1.1 Hilti Kwik Bolt:

Check embedment depth to distinguish from Phillips F.edhead.

6.1. 2 Wej-it:

6.1.2.1 Wej-it is further identified by two square grooves cut 180 apart on bolt.

6.1.2.2 Washer will have two corresponding tabs which may not be visible.

6.1. 3 Shell-type anchor such as Phillips Redhead self-drilling anchor:

6.1.3.1 A s tud or ' all-thread' may be inserted into this type.

6.1. 3. 2 If a conventional machine bolt or cap screw is used, a shell-type anchor is the likely candidate for the connection in the concrete.

Record all findings on the data sheet.

7.0 INSPECTION AND TESTING OF ANCHOR 7.1 Inspect bolt for compliance with size specified on support drawing.

7.1.1 Wedge-type anchor:

Measure diamete r of bolt.

7.1. 2 Shell-type using standard hexagonal or square head machine bolt.

Check bolt head and compare with the follouing:

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4 TABLE 7.1.2.1 Bolt Regular Hexagonal Heavy Di ame t e r

& Square Head H_e xa gonal 3/8 9/16 7/16 5/8 11/16 1/2 3/4 7/8 9/16 7/8 15/16 5/8 15/16 1-1/16 3/4 1-1/8 1-1/4 7/8 1-5/16 1-7/16 I

1-1/2 1-3/8 7.2 Inspection of shell-type anchor.

7.2.1 Remove one bolt and ir.spect and record the following:

7.2.1.1 Expansion device installed (e.g. Redhead plug for Phillips, none for cin cTi-type). For Redhead ',ith expansion plug measure depth of plug f rom edge of shell to top of plug.

Record dimension and compare with sample for proper expansion.

7.2.1.2 Shell installed in concrete is flush or slightly recessed into concrete.

Record value.

7. 2.1. 3 Measure cleararce between shell insert and plate surf ace (concrete side).

7.2.1.4 Minimum thread engagement (bolt length minus plate thickness minus washer minus gap ninus recess).

7.2.1.5 Shell length (hole depth minus plate thickness minus washer minus gap minus recess; measured through plate).

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5 7.2.1.6 Measure clearance between plate and shell of anchor.

If clearance less than 1/16." looser remaining bolts on plate and install 1/8 in.

minimum shim but not to interfer with shell and plate.

7.2.1.7 Tighten test bolt to load in Table 7.2.1. 7.

Remove bolt.

Inspect to assure shell has not slipped.

If less than 1/16 in. slippage occurs, ir. stall plate to its original configuration.

TABLE 7.2.1.7 TORQUE VALUE TABLE Bolt Size To rq ue, in.-lbs*

F lbs 1/4 60 240 5/16 128 410 3/8 228 610 1/2 565 1130 5/8 737 1810 3/4 2032 2710 7/8 3300 3770

• Correlation between torque value and tension load must be verified through actual tests for each size bolt used in the plant.

Repeated three times for each size.

Tests should simulate conditions as found in the field with regard to plate, bolt head, and bolt threads conditions.

Results from this testing may require modification to the values in Table 7.2.1.7.

7.2.1.8 Repeat 7.2.1 for each bolt to be inspected.

7.2.1.9 If more than 1/16 in slippage occurs, repair will be made in accordance with replacement anchor manuf acturer's installation procedure and verified by QC in accordance with QC procedures.

7.2.2 Install all tested bolts to tight condition but not to exceed values in Table 7.2.1. 7 for shell type anchor.

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6 7.3 Inspection of wedge-type anchor.

7.3.1 Determine following:

7.3.1.1 Bolt length using ultrasonic test equipment calibrated to type, brand, and diameter of bolt being tested.

7.3.1.2 Nut and washer thickness.

7.3.1.3 Plate thickness.

7.3.1.4 Stud protrusion.

7.3.1.5 Assure nut is not bottomed on threads.

7.3.1.6 Thickness of grout, if used.

7.3.1.7 Apply torque to value in the Acceptable As-Found column in Table 7.3.1.7.

7.3.1.8 If nut rotates before the value is achieved; record value at which rotcAion begins to occur.

7.3.1.9 Continue to torque nut until table values are achieved.

7.3.1.10 If torque value cannot be achieved record value achieved.

7 TABLE 7.3.1.7 HILTI Design Acceptable Bolt Torque As-Found Torque Dia., in.

Embe dmen t ft-lbs*

F lbs Ft 1bs 1/4 1-1/ 8 10 max 1225 7

1-1/2 2050 1-3/4 2487 2

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2825 2-1/4 2895 2-1/2 3075 3/8 1-5/8 20-30 2300 15 2

2875 2-1/2 3487 3

3800 3-1/2 4012 4

4135 4-1/2 4190 1/2 2-1/4 35-50 5027 28 2-3/4 6500 3-1/2 8225 aw 4-1/2 9250 5-1/2 10150 6

10650 5/8 2-3/ 4 80-100 6005 60 3-1/2 7675 4-1/2 9500 5-1/2 10925 6-1/2 12012 7-1/2 13000.

3/4 3-1/4 150-175 9152 110 4

11550 5

14100 6

15900 7

18400 8

19500 9

19750 9{b b3

8 Table 7. 3.1. 7 (Con t' d)

HILTI (Cont'd)

Design Acceptable Bolt Torque As-Found Torque Dia., in.

Emb e dmen t fc-lbs*

F lbs Ft lbs 1

4-1/2 225-275 15000 160 5

17200 c.

6 21125 7

22850 8

22850 9

22850 10 22850 1-1/4 5-1/2 375-425 21000 300 6-1/2 24350 7-1/2 27350 8-1/2 29850 9-1/2 32000 10-1/2 33850 WEJ-1r 1/4 1

4-5 1305 3

1-1/8 1584 1-1/4 2097 1-1/2 2225 3/8 1-1/8 15-20 2878 12 1-1/4 3222 1-1/2 3450 2

3619 3-1/2 3959 4

4185 1/2 1-1/2 30-35 5080 22 2

5145 2-1/4 5210 3-1/2 5769 4

6491 5

7213 5/8 2

50-75 7455 38 3

10066 3-1/2 11372 3-3/4 12503 4

12934 4-3/4 13769 9 j ij 3 ;' :

9 Table 7. 3.1. 7 (Cont'd) t/EJ-IT (Cont'd)

Design Accep table

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Bolt Torque As-Found Torque Dia., in.

Embedment ft-lbs*

F lbs Ft lbs 3/4 3

75-100 17369 56 3-1/2 18373 4

19377 5

20324 7

23166 1

5-1/2 150-260 24526 112 6

25641 7

26755 1-1/4 5-1/2 260-330 36392 195 6

37239 7

38085 1-1/2 5-1/2 330-650 48555 248 6-1/2 50128 8

51699 PHILLIPS - Wedge type Acceptable Bolt Minimum Torque As-Found Torque Dia., in.

Embedment ft-lbs*

F lbs Ft lbs 1/4 1-1/8 10 max 2400 8

3/8 1-1/2 25-35 4000 19 1/2 2-1/4 45-65 5400 34 5/8 2-3/4 80-90 7680 60 3/4 3-1/4 125-175 10,000 94 i

7/8 4

200-250 13,700 150 1

4-1/2 250-300 15,000 187 1-1/4 5-1/2 400-500 19,200 300 91U

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DATA SHEET INSPECTION OF PIPE SUPPORT PLATES AND ANCIIOR BOLTS Plante Identification & Tag No.

Plate Size:

in. x in.

Type Anchor System:

Wedge Type Shell Type Bolt Size:

Specified Me asured Bolt Length:

Specified Me as ured Nut & Washer Thickness Plate Thickness Grout Thickness Calculated Embedment (Wedge Type)

(#$h or Engagement (Shell Type)

Mvv Plate to Concrete Gap:

Yes r

Percentage Contact Area y

Record Gaps:

, Check Torque: (Wedge Type)

As Fo und As Left Shell type:

Expansion Device Installed Shell Flush or Recessed 1/S" max Measured clearance between shell & back of plate If clearance exis ts, reinstall bolt, torque If no clearance exis ts, complete steps 7.2.1.6 and 7.2.1.7:

Step 7.2.1.7 Complete Step 7.2.1.8 Complete Step 7.2.1.8 Not required S tep 7.2.2 Comple te G,!

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DATA SHEET INSPECTION OF PIPE SUPPORT PLATES AND ANCHOR BOLTS (Cont'd)

Measure Edge Distances:

Repair Performed 9

b.

Signed

/ Date Engineering Evaluation Signed

/ Date

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