ML20235P612

Forwards Response to Request for Addl Info Re Integrated Design Insp,Including Util Position on 14 of 19 Concerns Raised by Integrated Design Insp.Results of Insp in Civil Area Do Not Bring Into Doubt Overall Structural Adequacy

ML20235P612
Person / Time
Site:	Sequoyah
Issue date:	10/02/1987
From:	White S TENNESSEE VALLEY AUTHORITY
To:	James Keppler NRC OFFICE OF SPECIAL PROJECTS
References
NUDOCS 8710070325
Download: ML20235P612 (27)

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e** * . s TENNESSEE VALLEY AUTHORITY CH ATTANOOGA, TENNESSEE 37401 6N 38A Lookout Place October 2, 1987 Mr. James G. Keppler, Director Office of Special Projects l U.S. Nuclear Regulatory Commission 4350 East-West Highway EWW 322' Bethesda, Maryland 20814

Dear Mr. Keppler:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 Your letter of September 29, 1987, requested additional information which may be relevant to the Integrated Design Inspection (IDI). Your letter implies that TVA has been reluctant to provide this information or to meet with your staff on this matter. This latter issue needs to be clarified.

As,I explained to you in our discussion on September 29, the TVA IDI Response Te'am was ready to provide additional information prior to the September 11 exit meeting to assist the NRC IDI Team in resolving concerns in several areas of the inspection, particularly the civil / structural area. It is my understanding that your constraints did not allow time for a post-inspection review with your staff and my Response Team prior to the exit meeting on September 11. Subsequent to the exit meeting, my Response Team attempted unsuccessfully on a number of occasions to meet with the NRC IDI team to discuss information considered essential to the preparation of the final NRC report.

With respect to the additional information considered necessary to mitigate the staff's concern in the civil / structural area, I am enclosing herewith our position on fourteen of the nineteen concerns raised by the IDI. Of the remaining five issues, four are related to equipment loads on the structures and design of their supports. Information from equipment vendors needs to be received in order to resolve the specific items that have been raised. Design deficiencies, if any, in these items are expected to be relatively minor. The fifth remaining issue is related to the design of tornado missile protection barriers. The NRC has raised some questions which require additional analytical work. We believe that the barriers will be shown to be adequate.

0 W 6 P G

An Equal Opportunity Emptoyer

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Mr. James G. KepplerL October 2, 1987 i In' addition to TVA's effort to resolve your staff's concerns, I. formed a team i of four technical. experts from two architect / engineer firms to perform an independent assessment of the need to review the adequacy of Sequoyah.

structures and to' provide.a plan to accomplish this review, if'such were lnecessary. As part of their scope, this team of experts was also to assess the IDI structural' findings and the associated TVA responses.

As a result of'TVA's extensive review of the IDI civil structural findings, we do not believe.that the resolution of the overall structural issues raised by.

the.IDI are prerestart conditions or that an additional independent review of -l the Sequoyah-civil / structural design is warranted. TVA's consultants, referred to above, came to the same conclusions independently while reviewing these issues and TVA's proposed responses. In summary, it is our position, as

' well as our consultants, that the results of the NRC's IDI in the civil / structural area do not bring into doubt the overall structural adequacy at'Sequoyah.

Let me reiterate. My staff and I have been and are ready on a moment's notice to go over the detailed calculations and pertinent backup material to get this

issue' resolved as soon as possible.

Very truly yours, TENNESSEE VALLEY AUTHORITY .

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_R . d'L-A.' White Manager of Nuclear. Power Enclosure cc (Enclosure): .

Mr. G. G. Zech, Assistant Director  !

for Inspection. Programs Office of Special Projects U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 )

Atlanta, Georgia 30323 Mr. J. A. Zwolinski, Assistant Director for Projects Division of TVA Projects 3 Office of Special Projects U. S. Nuclear Regulatory Commission 4350 East West Highway EWW 322 Bethesda, Maryland 20814 I Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 ,

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P ' ITEM NO.:- D4.01 ,

. TITLE: Seismic Analysis of Shield Building o

SUMMARY

OF ITEM:

u-Thisl item addresses the fact-that some. sheets in the seismic' analysis J.1 < Lealculation' package had not been. initialed as checked. The concern was that a

. mistake.in the calculation of Amplified Response Spectra (ARS) may have gone undetected.

CLASSIFICATION: Documentation

RESPONSE

- TVA performed an audit in January 1987. During.this audit, it was~ identified

that-TVA's civil calculations for the seismic analysis of the Shield Building

'did not conform to the: requirements of SQW-QAP-III-1.3 in that every sheet did

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not show a checker.- TVA therefore initiated a review of all seismic' calculations (reference 3). 'TVA has generated alternate calculations (B41-870917 008) to verify the adequacy of the' original seismic' analysis of i the. Shield Building.

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.In addition, eight'(8)'other calculation packages associated with controlled reports.have also been checked and reviewed using either alternate calculations or rigorous verification of original calculations. This verification reconfirmed the adequacy of these calculations..

i No further. action is required to resolve this item because 100 percent of the I

-civil seismic calculations were reviewed. .!

J This finding ~has nol impact on.the safety of the plant, and nol hardware'or. l design changes.are required. ,

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REFERENCES:

,1. Quality Assurance Procedure SQN-QAP-III-1.3, " Preparation,  !

Review, and Records of Design Computations," March 8, 1970.

2. Calculation (B41 870917008).

3. Significant Condition Report SCR SQNCEB8714.

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! ITEM NO.:g D4.03- '

l L< 1 TITLE:.. Hydrostatic Uplift Loads li ~

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SUMMARY

OF ITEM:.

For design of the Auxiliary Building anchor rods, the hydrostatic uplift pressure was reduced by.1.4 k/ft 2 to. account for the weight of the building. ~ The' hydrostatic pressure should be reduced by only 0.6 k/ft 2, the combined dead weight of the structural slab and fill slab.- ,  ;

CLASSIFICATION::' Minor Calculation Error

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RESPONSE

The reduction'in hydro' static' uplift pressure'for the base slab design was

-incorrect. Problem Identification Report;(PIR) SQNCEB8781 was' written to document!the. discrepancy.  ;

> Additional calculations (references 2 and 3) have.been completed which

indicate that even with the correct dead' load the stresses in the anchor rods and'the base slab design are acceptable and meet ACI 316-63 code

. requirements. Additionally..these calculations.also confirm that the anchor rods are not required for overall building flotation or' seismic overturning; i stability.

A review of: the. calculations. for other Category I. buildings with anchor rods - j (Reactor and Control Buildings) has been completed (reference 2). "It was-determined-from this review that the' dead weight considerations were properly.

accounted for_in the design of the anchor rods for these buildings.

LThereLis no impact- on safety and no structural modifications are required.

REFERENCES:

1. Problem Identification Report PIR SQNCEB8781 (B25 870902 006).

2. DNE Calculations SCGlS163 (B25 870916 451). ,

3. DNE' Calculations SCG1S164 (B25 870916 452). l l

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.t H LITEN.NO.:' -D4.04 TITLE: Development' Length of Ancho'r Rods j i:

SUMMARY

OF ITEM:

The length'of embedment of the' anchor rods in the Auxiliary Building base slab does'not fully develop the anchor rods in accordance with ACI'318-63.:

, CLASSIFICATION: No Deficiency RESPONSE: i cl W F. -

Theembedment'of.theanchorrodsintheAuxiliaryBuildhgbase'slabwas .

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' ' 3' obtained using'the ACI 318-63 code bond stress allowables./ The total.requiredr embedment was determined and this length was bent to keep the reinforcement within the confines of the: concrete,as shown.in Figure 1. This application was not precluded by the ACI 318-63 code, and the resulting design was

, consistent with the industry practice. <

Additionalcalculationswereperformedusingthereq}tirementsofACI318-83.

.The embedment requirements for. reinforcing were significantly reduced by ACI 318-83 based upon more recent tests.. (The tests are referenced in the <

Commentary.to ACI 318-83.) Figure 2 shows that the embedment offthe hook intoc

..the slab to develop the full strength of the anchor rod would be 21.6: inches.

using the. provisions of the 1983 code'for 3000 lb/in 2 concrete (actual '

strength of!the concrete will be greater due.to aging).-'The actual length provided is.21 inches. 'For the actual load the, required embedment would be f 12.8 inches, c r i/ s .I

. Calculations.using tha code of record and the current code have shown that'ther embedment of the anchor rods in the slab is adequate and'that no structural 4 ,[

modifications are required.. ,

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REFERENCE:

Calculation-(B25 870916.450)'. f

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ITEM NO.: D4.05

. TITLE: Shear Stress Calculations for Concrete

SUMMARY

OF ITEM:

No calculations of shear stress were includet la the calculations for the Auxiliary Building EL 778.0 roof slab and Al-line and A15-line walls.

CLASSIFICATION: Documentation RESP 0NSE:

Shear stresses were normally checked for critical areas of concrete walls and slabs such as exterior walls at lower elevations and larger span, heavily loaded slabs. Shear calculations were not documented for areas where it was judged, based on a review of the shear forces and corresponding member thicknesses, that the shear stresses were not critical. However, to document this judgment, new calculations were generated which demonstrated that the shear stress for the most highly loaded areas of the Auxiliary Building EL 778.0 roof slab and the Al line and A15 line walls are significantly below the allowable stress.

Approximately 294 critical sections / elements which may be subject to significant shear stresses were identified in the various Category I buildings. These critical sections / elements included walls, floor and roof slabs, base slabs, beams, and coluuns. A review of the calculations associated with these sections / elements identified that shear calculations existed for approximately 274 cases. In response to this itere, calculations were made for the remaining 20 critical sections / elements to document the acceptability of the shear stresses. In every case for all slabs, walls, beams, and columns in the reviewed structures, the shear stresses were less than the allowables. This review is documented in calculation package (B25 870917 450).

There is no impact on safety, and no structural modifications are required, i

REFERENCE:

Calculation B25 870917 450. i i

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,1- .o j ITEM NO.: D4.06 j TITLE: Negative Moment Reinforcement in Base Slab

SUMMARY

OF ITEM:

Negative moment reinforcement was not provided in the Auxiliary Building base ]

slab placed against rock.

CLASSIFICATION: No Deficiency

RESPONSE

The base stab for the auxiliary building has reinforcement in the top face of the slab only. The use of only top face steel is not in violation of ACI code requirements. The slab is structure 11y adequate for all design conditions.

The design of the base slab is entirely based on resisting hydrostatic uplift for the various design basis flood elevations. Interior loads on the slab are transmitted directly into the underlying fill concrete and rock.

'To resist the hydrostatic pressures, the span of the slab was reduced by.

installing a grid of anchor rods into rock. This reduced the span of the 2-foot thick slab to a maximum of approximately 5 feet. The resulting moments in the slab were therefore relatively small. The reinforcement quantities in the slab were determined for top face only.

Additional calculations (reference 1) have been performed on the slab which show that the top face reinforcement is adequate. The quantity is significantly greater than needed for the positive moment that would develop in the slab if all negative moment capability of the slab were lost due to cracking at support point (anchor rod locations). The calculations also indicate negative moment in the slab is not sufficient to crack the slab. The tensile stress in the concrete was 59 lb/in2 versus the allowable of 119 lb/in2 for an unreinforced footing (allowable for maximum probable flood). ,

Cracking of the slab could occur due to thermal effects. The calculations indicate that were this to occur the opening of the crack would be very small and would not adversely affect the anchorage of the anchor rod. If a thermal crack occurred at an anchor rod, the crack width which would result from free rotation of the slab at the anchor rod has been very conservatively calculated as 0.0016 inches (assuming a one way span). This conservative crack width is about 16 percent of the normal ACI 316-63 crack width for exterior exposure, and 2 percent of the minimum height of the anchor rod deformations.

There is no impact on safety and no modifications are required.

REFERENCES:

1. Calculations (B25 870916 452).

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ITEM NO.: -D4.07 TITLE: Seismic Analysis of Steel containment

SUMMARY

OF. ITEM:

This item addresses the fact that most sheets in the original horizontal analysis had not been initialed as checked. The. concern was that'a mistake in

-the calculation of Amplified Response Spectra (ARS) may have gone undetected.

CLASSIFICATION: Documentation

RESPONSE

TVA performed an audit in January 1987. During this audit, it was identified that TVA's civil calculations for the seismic analysis of the SCV did not conform to the requirements of SQN-QAP-III-1.3 in that every sheet did not show a checker. TVA therefore initiated a review of all seismic calculations i (reference 3). TVA has checked calculations (B41 870918 006) to verify the  !

adequacy of the original seismic analysis of the SCV.

In addition, eight (8) other calculation packages associated with controlled reports have also been checked and ceviewed using either alternate calculations or rigorous verification of original calculations. This verification reconfirmed the adequacy of these calculations.

No further action is required to resolve this item because 100 percent of the civil seismic calculations were reviewed and verified.

This finding has no impact on the safety of the plant, and no hardware or design changes are required.

REFERENCES:

1. Quality Assurance Procedure SQN-QAP-III-1.3, " Preparation, Review, and Records of Design Computations," March 8, 1970. I

2. Calculation (B41 870918 006). (

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3. Significant Condition Report SCR SQNCEB8714.

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-ITEM NO.: D4.08 TITLE: Slab Loading.

SUMMARY

OF ITEM:

The," worst case" load condition was not used for design of the Auxiliary Building floor slab at elevation 669.0. The construction load case with increased allowable stress used in the calculations is not the controlling loading condition.

CLASSIFICATION: Minor Calculation Error

RESPONSE

TVA agrees this was.a valid concern. A Problem Identification Report (PIR SQNCEB8780) was issued to document'and track the resolution of this issue.

However, TVA's ongoing live load reconciliation program (initiated in 1985) would have resolved. the issue.

Based'on the reviewer's comments'in the original calculations for the elevation 669.0 floor, the construction live load condition, 400 lb/f t 2, was-considered the controlling load case. The normal design live load considered in the calculation was 200 lb/ft2 instead of-the 300 lb/ft2 load shown on I drawing 41N704-1R6forgortionsofthefloor. The calculation should have i

considered the 300 lb/ft live load.

Work scheduled for postrestart as part of a comprehensive program initiated in 1985 for the review and evaluation of loads estimated or assumed during design and construction for all Category I buildings would have identified the discrepancy between the calculations for the elevation 669.0 floor and the live load drawing 41N704-1 R6. This comprehensive program requires live load reconciliation in accordance with sequoyah Design Criteria SQN-DC-V-1.3.3.1, and the corrective action required for Employee Concern Program Elements 215.02 (Rebar Cutting) and 215.06 (Cumulative Effects of Attachment Loads).

The prerestart phase of this program required that representative " worst case" walls and/or slabs be evaluated for each Category I building required for safe shutdown to compare the load carrying capacity of these concrete features to the final in-place loads. The calculations for these evaluations are complete and are identified ~by references 1 through 8. The " worst case" features were selected by a drawing review. The major considerations for selection of the

" worst cases" were span to depth ratios of the concrete elements and the concentration of attachment and equipment loads.

Since no structural modifications were required for the " worst case" evaluations, the remaining features are to be reviewed postrestart.

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ITEM NO.: D4.08 (Continued)

The." worst case" evaluations are also documented under Employee Concern Program Elements 215.02 and 215.06 (B25 870612 028). The postrestart work is outlined under "Long-Term Work Plans for ECTG Elements 215.02 and 215.06" (B25 870318 007).

To fully resolve this issue before the scheduled postrestart work, all live l loads shown on drawing 41N704-1 R6 not previously evaluated were compared to I the live loads used in the original calculations. Discrepancies between the drawing and original calculations have been resolved by preparing additional calculations Which have been issued (calculation package B25 870918 450). The floor design data drawing will be revised by November 2, 1987, to reflect the correct floor loading as shown in the calculations.

There is no impact on safety, and no modifications are required.

REFERENCES:

1. Concrete Calculations, Auxiliary Building El 714.0 12" Slabs (B25 870622 803).

2. Concrete Calculations, Auxiliary Building El 734.0 12" Slabs (B41 870130 011).

3. Concrete Calculations, Auxiliary Building El 749.0 12" Slabs (B25 870622 805).

4. Concrete calculations Control Building El 685, 706, and 732 Slabs (B41 870130 007).

5. Concrete Calculations, Diesel Generator Building, ERCW Pumping Station, Additional Equipment Buildings East Steam Valve Room, EDWE Building, CNDS Pumping Station, Reactor Building, and Waste Packaging Building " Worst Case" Slab (B41 870130 009).

6. Concreto Calculations, Reactor Building Shield Wall (B41 870130 005).

7. Concrete Calculations, Auxiliary Building Shield Walls (B41 870130 006).

8. Concrete Calculations, Auxiliary Building U-Line Wall (B41 870130 008).

9. Problem Identification Report PIR SQNCEB8780 (B25 870902 005).

10. Concrete Calculations, Live Load Review for Drawing 41N704-1 R6 and Reevaluation of El. 669 Floor of Auxiliary Building for Live Load (B25 870918 450).

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b 1 TEM NO.: -U4.09 1'

TITLEi LERCW Access Cell. Design

SUMMARY

OF ITEM:

ERCW access cells were analyzed as a monolithic structure. However, the .

I concrete shrinks away resulting in its behavior as individual cells.

.This item documents-the concern that the original analysis of the ERCW accesc-cells may be based upon an unconservative assumption.- The seismic analysis may.needsto consider each cell.as acting independently.

1 l CLASSIFICATION: No Deficiency

' RESPONSE:

Based upon the following design features, the analyst established that.the l- monolithic assumption represents a reasonable engineering simplification to a more complex structure and the structural responses that were calculated represent conservative approximations of actual behavior.

o. A steel member was designed and placed in the concrete of the cells to ensure horizontal interaction.

l o The individual' circular cells are separated by a filler cell that partially surrounds them on either side.(much like a ball and socket joint).

.o The cells are embedded to varying depths in rock fill (100 percent to a minimum of.35 percent). Credit for the rock fill damping effect was not taken in the original analysis.

o We do not agree with the assertion that the concrete has shrunk away from the interlocking sheet piling sufficiently to cause the cells to act independently. Considerable force is needed to remove steel forms from circular poured-in-place concrete columns. .If the concrete shrinks away from its forms as asserted, the forms would readily separate from the columns.

.To further respond to the NRC concern,'TVA has analyzed one individual cell (

acting independently to. calculate dynamic movements and to show that the j structure 'is' stable (reference 1) . .This is a. bounding calculation that further demonstrates the adequacy of the structure.  !

This is a unique structure and no generic issue is identified. This issue has no impact on the' safety of the plant and no hardware or design changes are required.

REFERENCES:

1. Calculation (R0 B41 870925 003). I l

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.3 A ITEM NO.: U4.10 TITLE: Dike Stability

SUMMARY

OF. ITEM:

During a review of the ERCW piping support slab a question was raised j regarding the stability of the rock fill ERCW access dike in which the slab i and piping are buried and the consequences to the piles supporting the slab should a slope failure occur in the dike. Subsequent questions related to the issue include:

1. Why are factors of safety less than the minimum required safety factor apparently accepted for some sections?

2. What is the justification for the higher material property (0 = 45*)

used?

3. Was a vertical earthquake coefficient used in the stability analysis?

4. Was the probable maximum flood (PMF) used in the analysis?

5. FSAR should be revised to show that a friction angle (0) of 45* was used for the rockfill.

CLASSIFICATION: Documentation

RESPONSE

The original ERCW access dike calculations were done using a conservatively assumed value of internal friction angle (0) = 35' for the rockfill l material. Using this asnumption, there were two instances out of the more than 45 combinations of toading cases and cross sections analyzed that had factors of safety (FS) less than required (Criteria Requirement 1.05; calculated 0.97 and 1.02). Additional analyses performed at that time for those two cross sections indicated that a 0 of 39.5* would be necessary to i meet the minimum required FS. Concurrent with the analysis, the actual rock fill material to be used for constructing the dike was being tested by the Corps of Engineers South Atlantic Division Laboratory. The test results indicated that 0 = 45' (B41 870312 004). These test results were included in the original calculations but no definitive statements were made to clearly document what was done or the decisions made.

A recent revision of the calculation has been made (Bel 870910 006) which includes statements to correct the documentation deficiency described above.

The critical case for each cross section was also recomputed using 0 = 45*

for the rock fill. The minimum FS obtained was 1.12. Therefore, the design of the dike is acceptable, i

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U4.10 (Continued)

The FSAR will be revised to reflect 0 = 45* for the rock fill material at the next annual update.

The original calculations did not consider vertical earthquake accelerations.

The pseudo-static analysis procedure was used with only the earthquake peak horizontal acceleration values. This approach is considered to be adequately

' conservative and a standard industry practice. Justification for the use of only the peak horizontal acceleration is provided in the revised calculation.

This justification consists of standard Corps of Engineers practice, literature by professionally recognized individuals and A-E firms, and data derived from 40 actual earthquakes (see references 1 through 4). A CAQR (SQN 871410IDI) has been issued to reflect the discrepancy between the FSAR (FSAR states vertical component was used) and the calculation package. The FSAR will be revised at the next annual update to reflect the calculation method actually used.

The effect of thb pMF was not addressed in the original calculation. The revised calculation evaluated the effect of the PMF upon the stability of the dike. (It should be noted that considering the PMF to act simultaneously with the SSE is not a required design case.) The revised calculation shows that the water levels associated with the PMF will not affect the structural l integrity of the dike because: (1) the dike is constructed of highly permeable material which prevents the development of differential water pressures and (2) the reduction in effective material weight (buoyancy) as a result of submergence affects both the driving and resisting forces such that there is essentially no net effect. For the seismic load cases, the horizontal seismic coefficient was applied to the total weight (rock and entrapped water) when computing horizontal forces resulting from SSE.

This issue has no impact on the safety of the plant and no hardware or design changes are required.

This is a unique structure and.therefore, has no generic implications.

REFERENCES:

1. Corps of Engineers, " Engineering and Design Stability of ,

Earth and Rock-Fill Dams," Manual No. EM 1110-2-1902, Office  !

of the Chief of Engineers, Dept. of the Army (1970).

2. Seed, H. B., and Martin, G. R. (1966) "The Seismic I Coefficient in Earth Dam Design," JSMFD, ASCE, Vol. 92, No. l SM3, May, pp 25-58.

3. Sarma, S. K. (1975) " Seismic Stability of Earth Dams and Embankments," Geotechnique 25 No. 4, pgs. 743-761. j l

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U4.10 (Continued)

4. Calculation (B41 870910 006).

5. TVA Condition Adverse to Quality Report (CAQR) No.

SQP871410IDI.

6. Calculation (B41 870312 004).

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ITEM NO.: U4.11 TITLE: Seismic Model Versus Drawings

SUMMARY

OF ITEM:

The seismic model of the Auxiliary Control Building does not match the concrete outline drawings. Some walls are not included, and columns have been neglected. The concern is that this may underpredict amplified response spectra ( ARS) and structural loads.

CLASSIFICATION: No Deficiency l

RESPONSE

TVA procedures in the generation of seismic models are compatible with standard industry practice. In constructing the seismic model of the Auxiliary Control Building, some minor partition walls and columns were not included. These columns and walls add very little shear strength and any additional structural stiffness, and mass would be insignificant. Review of outline drawings for this building has shown that structural walls and slabs have been included in the model.

A comparison of the checked hand calculations (RO) with the properties (Rl) computed by the TVA computer code INERTIA indicated differences of less than 2 percent for area and moment of inertia. A noted difference in the cross sectional area of ele. ment 12 was resolved after it was determined that the checker had indeed considered the effect of two U-line walls in the RO calculation. Calculations (reference 1) document this comparison.

The calculations generated to resolve this concern have been included in the original seismic analysis calculations. No further action is required to resolve this issue.

This finding has no impact on the safety of the plant, and no hardware or design changes are required.

REFERENCES:

1. Calculations (R4 B41 870917 004).

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' ITEM NO.: D4.12-1

' TITLE: Minimum Horizontal Reinforcement in Walls

SUMMARY

'0F ITEM:

1. .TVA did not provide minimum horizontal steel in walls in accordance with ,'

'ACI 318-63.

2. For the calculations for the A5 line wall the area of minimum steel was i based on the effective depth of the member instead of the total thickness. ']

l CLASSIFICATION: 1. Minimum Horizontal Steel - No Deficiency

2. Implementation - Minor Calculational Error d i

RESPONSE

.1. Requirement for Minimum Horizontal Steel TVA is in compliance with the ACI 318-63 requirements for minimum horizontal steel in walls. Sequoyah wall designs were. performed in accordance with Section 2201 Paragraph A of ACI 318-63. This section states that "The limits of thickness and quantity shall be waived Where structural analysis shows adequate strength and stability." Calculations show the walls to be structurally adequate.

In addition, the'ACI 318.63 Code commentary Chapter 22, second paragraph stateo, "(3). The empirical limits of Section 2202 on wall thickness and

. reinforcement do not apply where a structural analysis is made." All structural walls including A1, AS, All, and A15 have been designed based

-on structural analyses.

2. Use of Effective Depth for Determination of Minimum Area of Steel The minimum area of steel reinforcement is normally calculated using the TVA temperature and shrinkage design standard. Using the effective depth (d) of the member instead of its total thickness slightly underestimates the amount of reinforcement. A Condition Adverse to Quality Report (CAQR) (SQP 8713711DI) has been prepared to address this deviation.

Calculations for structural slabs and walls in the Auxiliary Building, Reactor Building, ERCW Pumping Station, and Control Building have been reviewed (B25 870916 453). Occurrences of the use of "d" for calculation of minimum steel were reexamined. It is concluded that adequate  ;

reinforcement has been provided in these structures.

There is no impact on safety and no hardware and design changes are required.

REFERENCES:

1. CAQR SQP 871371IDI.

l 2. Calculations B25 870916 453.

ITEM NO.: U4.14 1

TITLE: Vertical Seismic Analysis for the Steel Containment Vessel (SCV)

SUMMARY

OF ITEM:

The amplified response spectra (ARS) for the SCV were regenerated as part of the corrective action for PIR SQNCEB8652. Comparison of the revised spectra to the old spectra indicated significant increases in the peak accelerations.

Additionally, there was a concern that the TVA design basis computer programs (DYNANAL, et al) used in the generation of scismic loads and ARS underpredicted the peak spectra values.

CLASSIFICATION: Documentation RESPONSE: 1 A discrepancy in the vertical ARS between digitized computer files and published data was discovered in August 1986 and led to the filing of PIR SQNCEB8652. The following is a chronology of events in the resolution of PIR SQNCEB8652.

DATE EVENT

1. 1971/1972 A seismic analysis of the SCV was performed. The original (Sept-July) ARS in the vertical direction were obtained by taking 2/3 of the horizontal spectra. This analysis is documented in report CEB-75-3 RO.

2. 1979-1980 Task initiated to update the seismic analysis with generation of vertical response spectra. Objective was to reduce conservatism in original vertical spectra. New digitized spectra for the vertical direction were generated. The data was loaded into the GETSPEC non-QA piping database and inter into the FRAMS QA piping database when it became operational. This data was used in subsequent design work.

3. Aug 1986 When the discrepancy between the spectra data in FRAMS and CEB-75-3 was identified, PIR SQNCEB8652 was prepared and i issued, and corrective action was initiated.

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' ITEM NO.: U4.14 (Continued)

L4. '1986-1987, The spectra available in FRAMS were' examined for (Sept-Mar) consistency with available documentation and the existing,-

unverifled : vertical spectra calculations were . reviewed in -

detail.. A new analysis.to generate the vertical response spectra was performed. :The FRAMS~ database was updated to include the revised vertical spectra in March 1987 and' report CEB-75-3 R1 was' issued.

5.: March 1987 Since the vertical spectra showed. increased responae over a to date limited frequency range due to a shift in peak frequency, 11 " worst case" piping analysis problems were analyzed for the new vertical seismic spectra. Evaluation.of other attachments'to the SCV (i.e.,lHVAC,' electrical-penetrations, cable trays, etc.) have/are being performed

'for the' revised vertical spectra. -All activities associated with this work are scheduled for completion by November 15, 1987.

In parallel with the regeneration of vertical seismic ARS for the SCV, all other response spectra contained in.the FRAMS QA' database have been verified and compared against current CEB reports and corresponding calculation-packages. No deficiencies were identified during'this comparison. This review is documented by calculation package B41 870918 007.

Based on work performed to date, there is'no impact on the safety of the plant.

Issue 2.- DYNANAL versus STARDYNE To resolve the question =on the adequacy of the design basis computer programs (DYNANAL,:et al) versus present day computer codes, the seismic analyses of the Shield Building and the Auxiliary Control Building have been rerun using

.present day programs. . The frequencies, dynamic participation factors, mode shapes and responses.are consistent and within the normal range of accuracy for this type of analysis...Any nominal differences are attributable to

' differences in the algorithm used to calculate the responses. Calculations (B41 870918 008'and B41 870925 006) documenting this comparison are complete.  !

There is.no impact on safety and no hardware and design changes are required.

No..further action is required to resolve this issue.

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? ITEM NO.: U4.14 (Continued)

REFERENCES:

.1. PIR SQNCEB8652.

2. "Sequoyah' Nuclear Plant - Dynamic Earthquake' Analysis of the-

Steel Containment Vessel and Response Spectra for Attached

!. Equipment," Report CEB-75-03 (R0 B41 801107 001).

3. DNE Calculations, " Seismic Analysis of the Steel Containment Vessel and Generation of Response Spectra":(R0 B41 870310 007).

4. -DNE Calculations, "TPIPE Data File Storage and Verification for Category I Structures" (R0 B41,870918 007).

5. 'DNE Calculations, " Shield Building - Seismic Analysis -

,' Comparison of.-Response Spectra":(R0 B41 870918 008).

6. DNE Calculations, " Auxiliary Control Building - Seismic Analysis : Comparison of Response Spectra" (R0 Bel 870925 006).

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i ITEM No.: D4.15 TITLE: Use of Rawl Anchors  !

SUMMARY

OF ITEM:

Discuss reduction in strength for Rawl versus Phillips. Discuss apparent discrepancy in 79-02 report if Rawl anchors were used. What allowed construction to use Rawl anchors as substitute for Phillips?

CLASSIFICATION: Documentation

RESPONSE

CAQR SQ870101 issued on June 16, 1987, identified discrepancies in the i documentation relating to the use of Rawl brand self-drilling expansion anchors at SQN. The discrepancy was identified by the NRC during an audit of ,

the employee concern program. TVA's response to NRC OIE Bulletin No. 79-02 states that "to the best of our knowledge no Rawl anchors were used at SQN." '

However, Rawl anchors are called for on drawings for pipe supports that were prepared for TVA by Basic Engineers. Also, a memorandum prepared by the construction division indicates that Rawl anchors were used. i Based on the investigation and tests discussed in the following text TVA has concluded that the use of Rawl and Phillips anchors interchangeably was  !

authorized by General Construction Specification G-32 and TVA Civil Design Standard DS-C6.1 and that the Rawl anchors are effectively equivalent to the Phillips anchors.

Use of Rawl Anchors in Lieu of Phillips

.TVA General Construction Specification No. G-32 covered the installation of expansion anchors. It was issued in 1972 and was therefore applied to I virtually all anchor installations at SQN. The specification required the use 8 of Phillips Self-drilling anchors or equal. It was found during our review that Phillips self-drilling anchors were substituted for Rawl anchors where Rawl-anchors had been specified on design drawings.

No formal documentation has been located that specifically instructed the use ,

of Phillips in lieu of the Rawl anchors called for on the Basic Engineers drawings. However, TVA Civil Design Standard DS-C6.1 for Anchorage to Concrete' listed " approved" self-drilling anchors. Phillips and Rawl anchors )

were both on the list. This list and the requirements of G-32 were the j probable basis for the use of Phillips anchors.

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D4.15 (Continued) l Manufacturer's Test Data The manufacturer's d ta for the Rawl anchors indicates that some sizes of the Rawl self-drilling anchors have capacities less than Phillips self-drilling anchors. However, the tests performed for the manufacturer on the Rawl anchors exhibited failure by splitting of the test blocks. This mechanism for failure would not occur in anchors installed in slabs or other members with adequnte edge distance. Therefore, the manufacturer's tests are not directly applicable to.the conditions.that exist at SQN and the Rawl anchors at SQN would be expected (see attachment) to develop greater strength than those obtained in manufacturer's tests.

Usage of Rawl Anchors at SON

'Although the Basic Engineers drawings call for Rawl self-drilling anchors, 1 Phillips anchors were probably used for most of the installations. The consensus of personnel knowledgeable in anchor usage is that Phillips anchors were generally used although some Rawl anchors may have been used during the early stages of construction.

No evidence was found in TVA's procurement records to indicate purchase of the Rawl anchors. However, this is not considered to be conclusive evidence.

Anchor proof load records are available. However, TVA inspection procedures did not require the brand of anchor to be recorded on the report until 1979.

Proof load reports after 1979 indicato use of only Phillips anchors.

A support which was installed in 1975 was inspected to determine the brand of anchor installed. The support (lAPBH-425) was designed by Basic Engineers and called for Rawl anchors. The inspection of the anchors showed that the anchors were Phillips (as indicated by the distinctive red cone expander).

TVA Testing of Rawl Anchors  !

Since it is not possible to determine conclusively that the Rawl anchors were or were not used, testing was performed by TVA to determine if the Rawl anchors meet the G-32 requirements. The tests compared the capacities of the Rawl anchors to the Phillips anchors.  ;

Basic Engineers performed the original design for pipe supports outside containment. Basic Engineers drawings called for Rawl anchors for about one-half of the supports and phillips for the other half. Approximately 5 percent of the drawings call for 7/8" anchors, 25 percent 3/4", 20 percent 5/8", 50 percent 1/2", and less than 1 percent 3/8". During the on-going regeneration effort for pipe supports, no 1/4" anchors have been identified.

D4.15 (Continued)

The tests were performed in a test slab at Bellefonte Nuclear Plant since an existing slab was available and the concrete properties are similar to SQN.

The concrete was made with a similar coarse and fine aggregate (dolomitic limestone). The actual properties of the concrete are not of particular significance since the tests are intended only for comparison of the two anchor brands. The concrete at BLN would also be more representative of SQN concrete than concrete used for testing by a manufacturer in another part of the country.

Parallel tests were performed on Phillips and Rawl self-drilling anchors.

Three anchors of each size and brand were loaded to failure to determine the ultimate tensile capacity. The ratio of the average results of the Rawl and Phillips anchors are given in the attached table for the Rawl sizes called for by Basic Engineers. The ratios vary from 0.94 to 1.05. One-quarter inch anchors were tested prior to determination that they were not used. For the 1/4" anchors the Rawls had lower capacity (Ratio = 0.89).

The range of results is similar to the ratios that are obtained by comparing the manufacturer's 'results to the G-32 requirements. However, the sizes above and below the G-32 requirements are almost reversed. For the manufacturer's tests, the 5/8-inch and 7/8-inch were greater than 1.0 and the 1/2-inch and 3/4-inch were less than 1.0. This indicates that deviations in results in the order of 5% would be expected. Therefore, deviations of this magnitude are not significant.

In order to provide evidence that the Rawl anchors meet the engineering requirements, the attached table also pc '4 des the ratio of the Phillips anchor capacities to the G-32 requirements. *hese ratios are based on the qualification test results obtained for the Phillips anchors at Watts Bar Nuclear Plant. Again, this concrete is similar to the concrete at SQN and would be more representative of the concrete than a manufacturer's tests.

The attached table shows that the Phillips anchors exceed the ultimate tensile capacity requirements of G-32 by about 10%. The table further shows that the calculated ratio of the Rawl anchor capacities to the G-32 requirements based on the two sets of tests exceeds the requirements.

Conclusion The Rawl and Phillips self-drilling anchors are effectively equivalent.

Deviations in capacity for some sizes of approximately 5% are compensated for by the fact that Phillips anchors have been shown to exceed the minimum required capacities by approximately 10%.

There is no impact on safety and no modifications nor design changes are required.

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. s) ** Q D4.15 (Continued)'

REFERENCES:

I: 1. Test Report!- Comparison of'Rawl to Phillips Anchors SME-CON-87-065 (B46 870821 003) - Tests performed at Bellefonte.

2'. ' Watts Bar Bulletin 79-02' Report - Appendix G - Ultimate

' Anchor Capacity (CEB 841210 002)

Watts Bar qualification results.

3... TVA General Construction Specification No.'G-32

'(B41-870701 040).

4. ~ TVA' Civil Design Standard DS-C6.1 (See Appendix'A-of.

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D4.15 (Continued)

SEQUOYAH NUCLEAR PLANT COMPARISON OF TESTS ON RAWL AND PHILLIPS ANCHORS Size Ratio #1 Ratio #2 Ratio #3 Rawl/Phillips Phillips/G-32 Rawl/G-32 3/8 1.05 not tested -

1/2 0.95 1.09 1.04 5/8 0.95 1.15 1.09 3/4 1.04 1.08 1.12 7/8 0.94 1.09 1.02

1. 1 - Based on comparison tests at BLN.

1. 2 - Based on qualification on tests at WBN.

1. 3 - Product of #1 and #2.

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-t' ITEM NO.: U4.16 1

TITLE: tRoof Flexibility

SUMMARY

OF ITEM:

l The seismic design of the Auxiliary Building roof systems assumed the roof to be rigid'and used the corresponding vertical acceleration from'the response

.)

I spectra. However, it is not a rigid structure and should not be analyzed that way.

CLASSIFICATION: Minor Calculation Error

RESPONSE

'TVA agrees that the roof of the Auxiliary Building is not rigid. However, the original design'was consistent with industry practices which was to utilize the roof ZPA. The increase in vertical loading due to the increased vertical response is equivalent to 17 psf which is 6 percent of the original roof design load. Due to the long. span of this structure resulting in lower frequency and the increased magnitude of the floor response at this elevation, the percent increase due to flexibility for-this roof system is potentially the highest that will be seen for any floor or roof structures.

A preliminary calculation has determined that the roof design has adequate margins to meet design requirements considering this additional load except in the areas of roof-mounted tanks which are being addressed in issue U4.17.

Final calculations will be issued by October 15, 1987.

This condition has been identified and will be dispositioned by CAQR SQP871386.

REFERENCES:

1. CAQR SQP871386.

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