ML19289F542

Submits Addl Info Re Base Mat,In Reponse to 790529 Telcon Between Util,Consultants,Bechtel & NRC

ML19289F542
Person / Time
Site:	Wolf Creek
Issue date:	06/06/1979
From:	Koester G KANSAS GAS & ELECTRIC CO.
To:	Parr O Office of Nuclear Reactor Regulation
References
NUDOCS 7906110159
Download: ML19289F542 (9)

Text

KANSAS GAS AND ELECTRIC COMPANY r- =,cr..e c-w GLENN L

• O E S T E 88 m c c ... . c c ~ , . c .c .. . n ,

June 6, 1979 Mr Olan D Parr, Chief Light Water Reactors Branch No 3 Division of Project Management Nuclear Regulatory Cornission Washington, DC 20555

Dear Mr Parr:

During a telecon on May 29, 1979 between the applicant, thcir consultants, NRC staff members and Bechtel Power Corporation, several questions were raised by the staff to clarify the information that was presented at the public meeting held in Burlington, Kansas on May 15.

Attached for your information are the answers to all of those questions raised.

Sincerely, y/f GLK/ ash Attach cc-Mr Karl V Seyfrit, Director Office of Inspection and Enforcement U S Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 cc-w/ attach 2230 352 7906110/Sy [

201 N. Market - Wichita Kansas a Mail Address P. O. Box 208 ! Wichita, Kansas 67201 - Telechone Area Code (316) 264-1111

6/6/79 Additional Information for Wolf Creek Base Mat

1. Selection of the eleven remnants to be petrographically/ chemically tested during the second phase of 90 days remnant testing was based on the following considerations:

a. The remnants which had already been tested in phase one.

b. Remants were selected which had indicated strengths less than 5,000 psi (8 of the 11 were below 5,000 psi).

c. Remnants were selected from sets which had 90-day average strengths less than the 28-day average strengths (9 of the 11 were from sets with strength reversal).

d. All available remnants were not tested so that material would be available for testing by other organizations or for differ-ent tests which might be proposed. (Subsequent to the second phase testing, three pairs of retnants were turned over to the NRC.)

2. Windsor probe testing, considered separately, does not provide data which absolutely establishes concrete compressive strength. Many factors including proximity of rebars, concrete preload, aggregate size and hardness, etc. may affect the test results. However, when Windsor probe testing is supplemented with other tests, a high de-gree of assurance of concrete quality is obtainable. This much is for certain regarding the Windsor probe testing of the Wolf Creek Reactor Building base mat; it gave positive indication that concrete around the periphery is unifctm, no " soft" spots or areas of significantly different strength are present; it gave positive indication that the strength of the concrete around the periphery is high, probably above 5,500 psi.

3. The attached table provides the base mat seismic loads obtained from a seismic analysis based on a fixed base approach. This analysis, which considers a lumped mass model utilizing modal response and response spectrum techniques, was performed in accordance with BC-TOP-4A. Fixed base analyses were performed to provide upper bound results. Based on the shear moduli shown in Appendix F of the base mat reanalysis report all subsurface material greater than 35.5 feet below grade has a shear wave velocity greater than 3,500 fps, and may therefore be considered rock. The effect of this rock on the soil-structure-interaction is negligible, as implied by Section 3.7.2 of the SRP. Accounting for the tendon gallery, reactor cavity and lean concrete fill that occupies the annular space between the two, less than 10 ft. of soil (which has a soil 2230 353 modulus of 15,000 ksf at a 10-4% strain level) separates the base mat and rock. The fundamental frequency of this soil column is above 33 h:. The foundation medium for the base mat can therefore be considered as rigid, resulting in a building response which simulates that obtained on a fixed base. This approach is further justified by the fact that studies (12,13) have shown that the fixed base analysis provides an upper bound response for the soil-structure-interaction system.

Since the horizontal response in the two orthogonal directions are nearly identical, the higher east-west direction results are shewn.

Loads at Top of Base Mat (Elevation 2000'-0")

.12g (SSE) .06g (OPE)

Horizontal Vertical Horizontal Vertical (Ort r.ogona l (Orthogonal

_ Directions) Directions)

Shear (kips x 10 )

3 14.11 --- 9.46 ---

Moment (kip-ft x 106) 1.78 --- 1.21 ---

Vertical Force (kips x 10 ) --- 10.27 --- 6.05 Base hbt Acceleration (g's) 0.12 0.12 0.06 0.06 These results may be compared with the 0.2g SSE/0.12g OBE seismic loads used in the base mat reanalysis and reported in Appendix H of the reanalysis report.

In general, the SSE results are approximately 60% of the corresponding values presented in Appendix H. Similarly the OBE results are approximately 50%

of those values presented in Appendix H.

2230 254 4 The load carrying capacity of the base mat has not been appreciably reduced by using the 4460 psi as the design concrete strength instead of using the 5000 psi as specified.

In performing the Wolf Creek reactor building base mat reanalysis, the stress levels in the reinforcing and the concrete were deternined due to combined flexural and axial loads at each design section in the mat in accordance with BC-TOP-5A. The method used quantified the stress levels in the cat for comparison with allowables (as opposed to using load interaction tables). By inspection of these stress levels, it is evident that concrete compressive stresses did not control design. Concrete compressive strength also influ-ences the load carrying capacity of the section by virtue of the bond between reinforcing steel and concrete. Since no lap splicing of reinforcing steel is used in the base cat, only end anchorage of bars is influenced. As defined in BC-TOP-5A, the anchorage criteria is a function of the square root of f'c, as well as other parameters (such as section loads, section properties, and anchorage methods).

Therefore, since the reduction in f'c is 10.8%, an upper bound limit for the reduction in load carrying capacity to resist combined flexural and axial loads of the base cat is 3.3%.

The load carrying capacity of the base mat for shear loads at any given section is dependent upon the cross-sectional concrete dimensions and properties as well as the reinforcing ties provided and the particular load combination to which the cat is subjected. The shear stress that can be resisted by the concrete is a function of the square root of f'c (and it may be equal to 0 under certain conditions). Therefore, since the reduction in f'c is 10.8%, an upper bound limit for the reduction in shear load carrying capacity of the base cat is 3.31.

5. The site specific soil properties for each site were used in the original soil structure interaction analysis (FLUSH analysis) to develop the seismic loads. The upper bound results of the site specific seistic analyses were used as the SNUPPS envelope. The use of Wolf Creek site soil properties resulted in seismic loads which were within the SNUPPS design envelope. Presented below is a quantitative comparison, in terms of percent reduction of the loads at the Wolf Creek site versus the SNUPPS design envelope loads (utilizing the same ground motion) .

SSE OBE N-S E-W Vert N-S E-K Vert Moment at top of mat 14% 10% --- 25% 2 3'$ ---

Shear at top of mat 9% 4% --- 26% 17% ---

Vertical force at top of mat --- --- 18% --- --- 0 '.

Base mat acceleration 15't 7% 5 *. 10% 6 '. 4%

2230 .555

6. Uplift of the base mat due to load combinations identified in Appendix D of the reanalysis report is considered. The nonaxisymmetric

. finite element model utilizes a " bed" of linear vertical and hori-

ontal springs at each nodal point below the base mat. The stiff-ness values used for these springs are representative of the foundation media soil characteristics. The initial analytical run is made utilizing the applied load on the structure with all springs intact for a conpletely elastic solution. The initial run is th n reviewed to determine which vertical springs are in tension. All vertical springs in tension are then released (by assigning an insignificant 1y small stiffness) and the analysis rerun. This review and adjustment is performed manually for each cycle and the analysis is iterated until equilibrium is reached with no soil springs in tension. The results of this converged run are utili:ed in the determination of resultant section loads on the base mat.

7. Consideration of the heavy equipment anchored to the base mat (not shown in the BSAP nonaxisymmetric model) was not limited solely to the inclusion of dead loads. The heavy equipment was incorporated in the seismic analysis model together with the other internals (e.g. , primary shield wall, secondary shield wall) . The results of the seismic analysis indicate that seismic loads due to all internal structures and equipment contribute approximately Si to the total building load. This load was incorporated in the static application of the seismic loads and conservatively applied at the shell to provide maximum uplift patterns. Incorporation of the internals in the BSAP model was conservatively omitted since no appreciable stiffness is added to the base cat by their inclusion.

In addition, equipment anchorage in the base mat was checked in detail (see Section 4.2.1 of the reanalysis report) for reaction loads, LOCA loads, and seismic loads to insure that the base mat could adequately sustain the resulting forces and moments locally.

S. The stress definitions provided in BC-TOP-5A are in terms of section stresses, not principal stresses, and the associated acceptance criteria are consistent with these definitions.

The maximum stress levels provided in the report are due to combined membrane plus bending effects and the corresponding acceptance criteria of paragraphs CC-3410 and CC-3420 of BC-TOP-5A are utilized.

BC-TOP-5A, Appendix C, paragraph CC-3136 provides the following definitions:

2230 a56 "CC-3136.1 Membrane Stress (")

o embrane stress is the component of normal stress, hoop or meridi-unal, which is uniformly distributed and equal to the average of stress across the thickness of the section under consideration.

CC-3136.2 Bending Stress Bending stress is the variable component of normal stress. The variation may or may not be linear across the thickness.

(a)As applied in this appendix not to be substituted for principal stress or stress intensity,"

The " sections under consideration" for the reanalysis are oriented in radial and hoop directions.

Principal stresses and their orientations are not utilized directly in the analysis of a cracked reinforced concrete section. No allowable stress limits are specified with respect to principal stresses. The same criteria and definitions are also specified in ASSI Section III, Division 2, Section CC-3000 for Concrete Containments.

The normal stresses utilized in the computation of section forces and moments are those that are resolved in radial and hoop directions.

The resultant reinforcing steel and concrete stresses are determined by cracking the reinforced concrete section due to the applied loads.

Since principal stresses are not used as the design basis, the shear stresses associated with the normal stress orientation are utilized in determining shear loads for which the section is designed.

9. Maximum stresses resulting from the inclusion of thermal loads in both service and factored load combinations are provided in the attached tables (Appendices N 6 P). Corresponding allowable stress levels have been increased in accordance with the criteria provided in Bechtel Topical Report BC-TOP-5A. All stresses are within the allowable limits.

10. The following computer programs used in the reanalysis effort which are not referenced in the SNUPPS PSAR submitted for the Wolf Creek Construction Permit (CP) or referenced topical reports are:

a. FLUSH

b. BSAP

c. Miscellaneous project developed programs Revisions of the PSAR, prepared subsequent to the CP, reference the FLUSH program. Verification of the FLUSH program is through the "public domain" acceptance alternative, i.e. , it is a recognized program in the public domain and has had a sufficient history of use to justify its applicability and validity without further demonstration (Ref: SRP 3.8.1.4).

2230 357

-S-

The computer program verification information requested for items b and c will be forwarded under separate cover directly

j from Bechtel Power Corporation. It is requested that this material be handled as proprietary to Bechtel Power Corporation.

References to Response #3

12) Hadjian, A. H., " Soil-Structure-Interaction - an Engineering Evaluation", Nuclear Engineering and Design, 1976

13) Parmelee, R. A. , Perelman, D. S. , Lee, S. L. , and Keer, L. M. ,

" Seismic Response of Structure - Foundation Systems", Journal of the Engineering Mechanics Division, ASCE, Vol. 94, No. EM6, December, 1968.

2230 358 APPENDIX N

SUMMARY

OF MAXIMUM PRI!!ARY + SEC0!!DARY (TilERfML)

STRESSES AND SIIEAR TIE REQUIREMENTS DUE TO SERVICE LOADS Concrete Stress Shear Tie Reinforcing Steel Stress (Tension) l (Compression Requirements

. (Allowable Stress = 40.0 ksi) l (Allowable Stressksi) = 25) (See Note Below)

' M.iximum Stress (ksi t Minimum Stress (ksi) i

• 9"'

(

lloop Radial lloop Radial From To Radial l Radius 'l op Provided Zone Radius '

Bottom Top Bottom 16'-6" 25'-0" 3.8 3.2 7.8 7.8 0.95 0.55 0.23 B1 a d di d c c c l

5.8 7.3 6.8 6.2 1.01 0.67 0.37 B2 25'-0" 35'-0" d c c a a d.

a L' 0.37 35'-0" 45'-0" 30.6 13.5 14.2 7.1 1.59 0.99 B3 a a d a d a e B4 45'-0" 55'-0" 31.3 13.2 18.4 4.7 1,49 1.12 0.37 a d a c u a a n l

55'-0" 65'-0" 24.0 8.0 20.6 3.8 l 0.99 1.10 0.92 B5 a d a d a a a 1

B6 65'-0" 77'-0" 11.0 18.1 16.1 0.0 _ 0.92 g 0.89 a 0.99 a d

A Edge of Reactor Cavity

• • Outside Edge of Base Mat l N

Note on Shear Tie Requirements CD The values listed are the ratios of the maximum shear tie area required to the shear tie area provided.

u Ratios less than or equal to 1.00 indicate that shear stresses are within allowable stress limits for (Ji the reduced concrete strength.

APPENDIX P

SUMMARY

OF MAXIMUM PRIMARY + SECONDARY (TIIERMAL)

STRESSES ANft SilEAR TIE Rl;QilIRf;f frNTS fille '10 FACTORF.D LOADS Concrete Stress Shear Tic (Compression) Requirement _s_

Reinforcing Steel Stress (Tension)

(Allowable Stress = 60.0 ksi) *** (Allowable Stress = 3.79 ksi)l (See Note Below)

Maximum Stress (ksi) Maximum Stress (ksi) lloop Radial lloop Radial From To Radial Provided Zone Radius Radius Bottom Top Bottom Top i 16'-6" 25'-0" 41.7 0.0 39.2 2.7 3.00 1.50 0.23 g B1 g g g 8 -- 8 12.6 47.2 2.3 3.51 1.94 0.68 B2 25'-0" 35'-0" 56.8 " E E 8 g g '

21.5 51.1 0.9 3.37 2.18 0.72 B3 35'-0" 45'-0" 59.2 g e E 8 8 g h 55'-0" 51.6 23.2 56.4 1.3 2.59 2.13 0.87 B4 45'-0" g h g e g c e i

55'-0" 65'-0" 30.5 26.5 55.4 2.8 1.30 g

1.81 0.68 c BS g g g e e 10.7 33.9 49.9 4.3 0.93 1.26 0.66 l B6 65'-0" 77'-0" , 7 g h e g y

• Edge of Reactor Cavity *** Per BC-TOP-5A, strain may exceed yield N ** Outside Edge of Base Mat N i I

Note on Shear Tie Requirements u The values listed are the ratios of the maximum shear tie area required to the shear tie area provided.

Ch Ratios less than or equal to 1.00 indicate that shear stresses aro within allowable stress limits for CD the reduced concrete strength.