AP1000 Response to Request for Additional Information (TR ...

OWestinghouseU.S. Nuclear Regulatory CommissionATTENTION: Document Control DeskWashington, D.C. 20555

Westinghouse Electric CompanyNuclear Power PlantsP.O. Box 355Pittsburgh, Pennsylvania 15230-0355USA

Directtel: 412-374-6206

Direct fax: 724-940-8505e-mail: [email protected]

Your ref: Docket No. 52-006Our ref: DCPNRC_002651

October 8, 2009

Subject: AP 1000 Response to Request for Additional Information (TR 85)

Westinghouse is submitting responses to NRC requests for additional information (RAI) on TechnicalReport No. 85. This RAI response is submitted in support of the AP1000 Design CertificationAmendment Application (Docket No. 52-006). The information included in this response is generic andis expected to apply to all COL applications referencing the AP 1000 Design Certification and the AP 1000Design Certification Amendment Application.

Enclosure 1 provides the response for the following RAI(s):

RAI-TR85-SEB 1-40 R3

Questions or requests for additional information related to the content and preparation of this responseshould be directed to Westinghouse. Please send copies of such questions or requests to the prospectiveapplicants for combined licenses referencing the AP1000 Design Certification. A representative for eachapplicant is included on the cc: list of this letter.

Very truly yours,

Robert Sisk, ManagerLicensing and Customer InterfaceRegulatory Affairs and Standardization

/Enclosure

1. Response to Request for Additional Information on Technical Report No. 85

031 0jb.doc

DCPNRC_002651October 8, 2009

of 2

cc: D. JaffeE. McKennaB. GleavesP. BuckbergT. SpinkP. HastingsR. KitchenA. MonroeP. JacobsC. PierceE. SchmiechG. ZinkeR. GrumbirD. Lindgren

U.S. NRCU.S. NRCU.S. NRCU.S. NRCTVADuke PowerProgress EnergySCANAFlorida Power & LightSouthern CompanyWestinghouseNuStart/EntergyNuStartWestinghouse

1E1E1E1E1E1E1E1E1E1E1E1E1E1E

031OIjb.doc

DCPNRC_002651October 8, 2009

ENCLOSURE 1

Response to Request for Additional Information on Technical Report No. 85

031Oljb.doc

AP1000 TECHNICAL REPORT REVIEW

Response to Request For Additional Information (RAI)

RAI Response Number: RAI-TR85-SEBl-40Revision: 3

Question:

Regarding the dynamic stability of the NI structures, Westinghouse is requested to provideadditional information to demonstrate how the sliding criteria assumed during the API000 SSIanalyses (sliding friction value of 0.7) are in fact to be attained from the interface between thebasemat and mudmat and from the interface between the top portion of the mudmat and thelower portion of the mudmat through the waterproofing membrane.

Additional Request (Revision 1):

The staff reviewed the RAI response submitted in Westinghouse letter dated October 19, 2007,and notes that the outstanding issues raised by this RAI are considered to be very significant.Westinghouse has still not demonstrated that all sliding interfaces have been properlyconsidered. Therefore, Westinghouse is requested to demonstrate the technical adequacy ofthe approach being used in each of the sliding interfaces listed below.

1. Regarding the sliding interface between the bottom of the NI concrete basemat and the top ofthe upper concrete mudmat, Westinghouse is requested to provide the technical basis forassuming that the coefficient of friction between these two surfaces is at least equal to 0.7. Ifthis cannot be demonstrated then what special interface treatments (e.g., roughened concreteas defined in ACI) will be needed between the mass concrete basemat and the upper concretemudmat to achieve the 0.7 coefficient of friction, or will a testing program be needed toguarantee that a minimum friction factor of 0.7 can be achieved.

2. Regarding the sliding interface between the upper concrete mudmat and lower concretemudmat through the waterproofing membrane - issues related to ensuring that suchwaterproofing membrane is suitable and will have a minimum coefficient of friction of 0.7 areaddressed in RAI-TR85-SEB1-35.

3. Regarding the sliding interface between the bottom of the lower concrete mudmat and thesoil, Westinghouse is requested to provide the technical basis for assuming that the coefficientof friction between these two surfaces is at least equal to 0.7. The current formulation beingused for sliding resistance (i.e., Section 2.9 of TR85 and DCD Section 3.8.5.5.3) is applicable tosliding resistance/shear failure within the soil media not concrete on soil (see item 4 below).Since standard data indicates that effective ultimate friction between concrete and soil istypically less than 0.7 (e.g., Navy design manual DM-7.02), then Westinghouse needs to explainwhat coefficient of friction is assumed for this interface and the basis for this value.

4. Regarding the sliding interface within the soil media, and as described in Section 2.9 ofTR85, and in Section 3.8.5.5.3, "The governing friction value at the interface zone is a thin soillayer (soil on soil) under the mud mat assumed to have a friction angle of 35 degrees." Usingtan(phi) gives the coefficient of friction of 0.7 which was assumed by Westinghouse to begoverning coefficient of friction among the different sliding interfaces. It should be noted thatthis is the sliding resistance/shear failure capacity within the soil media, not concrete on soil.Also, the technical basis for assuming that the governing coefficient of friction among the

RAI-TR85-SEBn-40, Rev. 3

G Westinghouse Page 1 of 28



different sliding interfaces has not been provided (see Items 1 through 3 above). As noted inRAI-TR85-35, the RAI response did not address the requested information. In calculating thefactor of safety for the basemat against sliding during earthquakes, Westinghouse combines thefriction force at the bottom of the basemat and the maximum soil passive pressure resistance onthe foundation walls and basemat vertical edge as the total resisting force. Westinghouse isrequest to provide the technical basis for using this approach which utilizes the static coefficientof friction of 0.70 (which implies essentially no horizontal sliding of the basemat) at the sametime as the maximum soil passive resistance (which would require sufficient horizontaldisplacement of the foundation to mobilize the passive resisting forces at the foundation wallsand the side of the basemat). Further issues related to utilizing the soil passive pressure forboth sliding and overturning are discussed under RAI TR85-SEB1-35.

In addition to the above 4 items, Westinghouse is requested to identify what set or sets of soilparameters were utilized in (a) the seismic analyses for stability evaluations to develop themaximum shear and moments and (b) the sliding and overturning stability calculations(including passive soil pressure calculations). These would include the soil properties andcompaction requirements for the backfill material at the side of the embedded foundation wallsand the vertical edge of the basemat. Soil properties beneath the basemat which were used todevelop the subgrade modulus values should also be defined. These properties should beclearly presented in the DCD so that the Combined License applicants can reference the DCDdesign without performing additional site-specific stability analyses. Also, describe in the DCDhow each of these soil parameters should be obtained (i.e., tested and measured) and verifiedat the site.

5. Describe how the potential effect of saturated soils from groundwater or water infiltrationfrom the surface has been considered in: all seismic soil structure interaction (SSI) analyses,calculation of the subgrade modulus (used in all seismic analyses for bearing pressure, stabilityevaluations, and design of the basemat foundation), selecting the coefficient of friction, andcalculation of the passive soil pressures used in the stability evaluations and the design of thefoundation walls.


Based on the information provided for Item 5, in Revision 1 to this RAI response, Westinghouseindicates that the effects of saturated soil conditions are addressed in the seismic soil structureinteraction (SSI) analyses by setting the pressure wave velocity (Vp) equal to 5,000 ft/sec. It isnot clear to the staff if the conditions without saturated soil were considered as well. Therefore,Westinghouse is requested to explain whether unsaturated conditions were also considered inperforming any SSI analyses to determine the effects of unsaturated soils on the response ofthe NI in terms of member forces, deformations, and response spectra. If unsaturated soils werenot considered, provide the technical explanation for not evaluating the effects.


What are the differences in soil properties and input to SASSI for saturated and unsaturatedconditions? Include discussion in RAI response.

Westinghouse Response:

RAI-TR85-SEBl-40, Rev. 3Wetstinghouse Page 2 of 28



Alternate approaches for waterproofing systems are described in subsection 3.4.1.1.1.1. Foreach of the waterproofing system selected for a site a test to demonstrate that the interfacebetween the top portion of the mudmat and the lower portion of the mudmat has a slidingcoefficient of friction of at least 0.7 will be performed. The Combined License applicant willdescribe the excavation and backfill methods, along with the description of the waterproofingsystem selected, and reference the test report that documents that the minimum coefficient offriction of 0.7 is achieved. If there are site conditions that could affect the sliding coefficient offriction, separate from the waterproof membrane, a lower coefficient may be justified byperforming site specific analyses and demonstrating sliding stability.

DCD subsections 2.5.4.1, 2.5.4.6 and 3.4.1.1 are revised as shown below to clarify the

requirements for the waterproofing membrane and the mudmat.

Westinghouse Response (Revision 1):

1. A test program will be performed that is documented in a report that can be referencedby the COL applicant.

2. As stated in RAI-TR85-SEB1-10, Rev. 1, and RAI-TR85-SEB1-35, Rev. 1, the coefficientof friction has been reduced from 0.7 to 0.55, and a test program will be performed todemonstrate that this coefficient of friction.

3. The coefficient of friction of 0.55 is consistent with what is expected for soil; therefore,the coefficient of friction between the interface of the mudmat and concrete, and theconcrete and soil, will be equal to or greater than the coefficient of friction (0.55)between soil interfaces. In accordance with NAVFAC DM 7.02 (Sept. 1986), Table 1,page 7.2-63, the interface friction factor (or coefficient of friction, p) between massconcrete placed on clean gravel, gravel-sand mixtures or coarse sand subgradematerials ranges from 0.55 to 0.60. The lower coefficient of friction (0.55) thatWestinghouse is now using in the sliding stability calculation is consistent with the lowerbound coefficient of friction for the waterproofing membrane, and that of the granular,in-situ subgrade material.

4. As noted in RAI-TR85-SEB1-10, Rev. 1, Westinghouse is no longer using the fullpassive pressure for sliding stability, and has reduced the coefficient of friction to 0.55.In this RAI response lower coefficients of friction below 0.55 are discussed. It is shownthat the Nuclear Island remains stable and within the factor of safety of 1.1 withoutsignificant displacements. It is also noted, and discussed in RAI-TR85-SEB1-10, Rev.1, passive pressure is no longer used in the calculation of the overturning factors ofsafety.

In addition to the above 4 items, responses are given for the supplementary items:

a. To develop the maximum shear and moments for the seismic analyses for stability, sixsoil types were considered: hard rock, firm rock, soft rock, upperbound soft to mediumsoil, soft to medium soil, and soft soil. These are described in DCD Section 3.7.1.4,Revision 17.

RAI-TR85-SEB1-40, Rev. 3

Westinghouse Page 3 of 28


Response to Request For Additional Onforrmation (RAI)

b. For the sliding and overturning stability calculations the six site characteristics describedin item a above are used. The passive soil pressure calculation is described in RAI-TR85-SEB1 -35, Rev. 1. The Combined License applicants referencing the AP1 000design must address site specific information related to the geotechnical engineeringaspects of the sites. This is discussed in DCD Section 2.5.4.6, Revision 17.Excavation and backfill requirements are described in this section. Further, per DCDSubsection 2.5.4.6.7, Revision 17, "Earth Pressures - The Combined License applicantwill describe the design for static and dynamic lateral earth pressures and hydrostaticgroundwater pressures acting on plant safety-related facilities using soil parameters asevaluated in previous subsections." No further action is required for sites within thebounds of the AP1 000 site parameters as defined in the DCD. The testing programsand measurements is the responsibility of the COL applicants. The strain-dependentshear modulus curves for the foundation materials are shown in Figures 3.7.1-15 and3.7.1-16 of DCD Revision 17. The different curves for soil in Figure 3.7.1-16 apply tothe range of depth within a soil column below grade.

5. In the seismic soil structure interaction (SSI) analyses the effect of saturated soil fromgroundwater or water infiltration from the surface is considered by setting the pressurewave velocity (Vp) equal to 5,000 ft/sec. The strain-dependent properties used in theSSI analyses for the safe shutdown earthquake are shown in DCD, Revision 17, Table3.7.1-4 and Figure 3.7.1-17 for the firm rock, soft rock, upper bound soft-to-medium soil,soft-to-medium soil, and soft soil properties. As stated above, the coefficient of frictionhas been reduced from 0.7 to 0.55 to be consistent with the soil characteristicsassociated with design condtions. The calculation of the passive soil pressures used inthe stability evaluations and the design of the foundation walls are described in RAI-TR85-SEB1-02, Rev. 1,, RAI-TR85-SEB1-10, Rev. 1, and RAI-TR85-SEB1-35, Rev. 1.


The effect of the groundwater level has been studied extensively for the AP600. For theAP1000, Westinghouse has performed a time history analysis using a saturated andunsaturated soft-medium soil profile (Poisson's ratio = 0.35) and compared the FRS of the twoanalyses. Generic SSI analyses for the AP1 000 assume the water table to be at grade level withsaturated soil properties supporting the Nuclear Island. The unsaturated soil profile wasproduced from a SHAKE analysis where the water table was assumed to be well below theNuclear Island.

The results of this analysis were presented during an NRC audit during the week of May 4th -

May 8th, 2009 and have been provided in this RAI response. Based on this study, it can beconcluded that the depth of the water table used for SSI analyses has a negligible effect on thefloor response spectra at the key nodes. Since the FRS differences between the two models arenegligible, no additional analyses are required to compare member forces or deformations.

RAI-TR85-SEB1-40, Rev. 3s Westinghouse Page 4 of 28

AP1o00 TECHNICAL REPORT REVIEW

Response to Request For Additional Onformation (RAIl)

APo000AP1000 TR85 NRC Audit

SSI Analysis Effects of WaterTable

RAI-TR85-SEBl -40

Presented:Week of May 4th-May8th, 2009

)Westinghouse

(I)WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 5 of 28



Subject APl00

Need to explain whether unsaturatedconditions were also considered inperforming any SSI analyses to determinethe effects of unsaturated soils on theresponse of the NI in terms of memberforces, deformations, and responsespectra. If unsaturated soils were notconsidered, provide the technicalexplanation for not evaluating the effects.

O Westinghouse

(OWestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 6 of 28


Response to Request For Additional Gnformation (RAI)

SSI Analysis APIl00

* Generic SSI Analysis for the AP1000assumes Water Table Grade Level(Elevation 100')

* The FRS results from the generic soilprofile are compared to the soft to mediumsoil profile with the water table consideredwell below the foundation.

OWestinghouse


Page 7 of 28



API 000CIS at Reactor Vessel Support Elevation 100' - FRS X Direction

FRS Comparison X Direction

08 -

on•

0,2

0,0

Frequ,

ni20kSM - Generic Analysis(water table at elevation 100')

ni20kSM-nw - Soft to Medium Soil Profile(water table well below foundation)

[ oi,20kkS-57 0 S,--d5 1707

10

ency (Hz)

100

4

O Westinghouse

* WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 8 of 28



API o00CIS at Reactor Vessel Support Elevation 100' - FRS Y Direction

FRS Comparison Y Direction

1.4 r- -r--

12-

10-

0.8-

0.6

04-

02

-- ri2OkSM-00 1761-Oi20kSM-,1v~-45 1781


10Frequency iHz)

100

ni20kSM-nw - Soft to Medium Soil Profile(water table well below foundation) O Westinghouse

la WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 9 of 28



APIP100CIS at Reactor Vessel Support Elevation 100' - FRS Z Direction

FRS Comparison Z Direction

1.2

1.0

S0.8

-ý-t2kSM-d5 1761]

0.0

ni20kSM - Generic Analysis F,.o

(water table at elevation 100')

* ni20kSM-nw - Soft to Medium Soil Profile(water table well below foundation)

10

uency (Hz)

100

OWestinghouse

lo WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 10 of 28



APIOOO

CIS at Operating Deck - FRS X Direction


1.81.6

1.4

1.2

0.8

0.4

0.2

F



-n2NkMd028

10

Frquency (Hz)

100

7

()Westinghouse

( WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 11 of 28



APl1000

CIS at Operating Deck - FRS Y Direction


o=0.8

2 ,i OekSM-nu-d5 2199]

()Westfinghouse

ni20kSM - Generic Analysis Fmq



10 100

uency(Hz)

8

O WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 12 of 28



APl OOOCIS at Operating Deck - FRS Z Direction


1.8

1.6

14 .. ..

12

0.8

06

04

02

O0ý



- ý1,2OkSM-r,-452 219

r OFrequency (Hz)

100

9

9Westinghouse

OWestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 13 of 28



AIo00ASB NE Corner at Control Room Floor - FRS X Direction


0I i - ni2OkSM-d5 2078,2OkSM-nw-5 2078

10

Frequnc.y (Hz)

100



10A)9Westinghouse


Page 14 of 28



AP"lo0ASB NE Corner at Control Room Floor - FRS Y Direction


I -4-.N20kSM-d0 2078- i20kSM--~-d5 2078

10

Frequency (Hz)

100



I I

fWestinghouse


Page 15 of 28



API 000ASB NE Corner at Control Room Floor - FRS Z Direction


1.4 ' T

1.2 •

10•

0,6

0.4 2 •-_

0.2 0 -

--- ni20kSM-d5 2078-- ni20kSM-nw-d5 2078

10

Frequ.ecy (Hz)

100



12A -Westinghouse

( )WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 16 of 28



AP100ASB Corner of Fuel Building Roof at Shield Building - FRS X Direction


i< 1.

** ni2OkSM-d5 2675- ni2OkSM-n~-d5 2675

ni20kSM - Generic Analysis Frquency (Hz)



100

13

O Westinghouse

* WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 17 of 28



A"Plow0ASB Corner of Fuel Building Roof at Shield Building - FRS Y Direction


30

2.5 --

2.0

1 51.0

0.5 i _

0.0 1

Fmquei



-4 i2OkSM1-d5 20715- i2OkSM-nwd5 2675

0

.. y (H.)

100

14

)Westinghouse


Page 18 of 28



API000ASB Corner of Fuel Building Roof at Shield Building - FRS Z Direction


2.5

0.5

0.0

ni20kSM - Generic Analysis FreIq



1-0-Ok5NM-d5 26175- QM2OSM-,-d5 26751

10

-ncy (H.)

100

15

) Westinghouse

( WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 19 of 28



AP"lo00ASB Shield Building Roof Area - FRS X Direction


8,0

70

60

-40

30

20

10

0.0

ni20kSM - Generic Analysis Frq



~., q-.-4 4~ p.e 0

-0 i20S-5 332'- ,i20'kS'MZrn*-d5 3329

10

.-ncy (H.)

100

16

OWestinghouse

OWestinghouse RAI-TR85-SEB1-40, Rev. 3Page 20 of 28



A"PIo00ASB Shield Building Roof Area - FRS Y Direction


8.0

6,0

5.0

I

4.0

30

20

10

00

ni20kSM - Gen(water table at

* ni20kSM-nw -(water table we

~IIIIli I ____ [7~I7II

-4----- --.- - -

~ ~.pE liEu

-4-NiOSM-d5 3329ni20kSM-nw-5 3329

eric Analysis Frn

elevation 100')

Soft to Medium Soil Profile=11 below foundation)

10

quency (Hz)

I w

17

O Westinghouse


Page 21 of 28



APIo00ASB Shield Building Roof Area - FRS Z Direction


30

2.5

204

154

10

05

00

1 10Frequency



49Q20SM-d5 33290-i20kSM-n.1d5 33291

(Hz)

100

18

O Westinghouse

*oWestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 22 of 28



AP1000

SCV Near Polar Crane - FRS X Direction


0.5

~1

ni20kSM - Generic Analysis F'q



[-nn•:2kSM-d' 2788-n20kSM-n.-d5 2788

10

uency (Hz)

1(mr

19

O Westinghouse


Page 23 of 28



APIO0

SCV Near Polar Crane - FRS Y Direction


3.5

2.5

2.0

I 15

I'd

2--- rikS-dw 2788- r0i2OkSSM-rnw-d5 2788

Jm00

ni20kSM - Generic Analysis Freque



10

ncy (Hz)

100

20

)e9stinghouse

loWestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 24 of 28



AP11000

SCV Near Polar Crane - FRS Z Direction


2.5

2.0

1.5

ii1.0

0.5

00

ni20kSM - Generic Analysis Fmque



-@- j20k0M-d5 2788W.S.00-~-d5 2788

(1 W stinghouse

10

ency (Hz)

100

21


Page 25 of 28


Response to Request For Additional Gnformation (RAIl)

Conclusion APl00

" The effects of the water table at grade isnegligible from the results of the AP1 000SSI analysis.

" This was studied extensively in AP600.

22

)Westinghouse

I& WestinghouseRAI-TR85-SEB1-40, Rev. 3

Page 26 of 28




In Revision 2 responses, the comparison of two soil profiles was presented for the soft-to-medium soil cases. The saturated water level is at elevation 98 ft. The unsaturated water levelis below elevation -20 ft. The soil profile used for the unsaturated condition is in Table RAI-TR85-SEB1-040-1 and soil profile used for the saturated condition is in Table RAI-TR85-SEB1-040-2. The P-wave velocity varies from 2461 fps at surface down to 4365 fps at depth of 120 ftfor the unsaturated condition while P-wave velocities are constant at 5000 fps for the saturatedcondition.

Table RAI-TR85-SEBl-040-1: Soft to Medium Soil Profile with Unsaturated Condition

Thicknes Total Shear wave P- waveLayer of layer unit velocity velocity Damping

Number f ly weight(ft) (kcf) (ft/sec) (ftlsec)

1 17.5 0.11 1005 2461 0.039

2 22 0.11 1156 2833 0.043

3 5.5 0.11 1238 3034 0.051

4 7.5 0.11 1279 3132 0.053

5 7.5 0.11 1396 3420 0.041

6 6 0.11 1443 3534 0.042

7 7 0.11 1487 3642 0.042

8 7 0.11 1535 3759 0.043

9 10 0.11 1592 3899 0.043

10 10 0.11 1658 4060 0.042

11 10 0.11 1721 4216 0.042

12 10 0.11 1782 4365 0.041

Halfspace 0.15 8000 13856 0.020


Page 27 of 28



Table RAI-TR85-SEBl-040-2: Soft to Medium Soil Profile with Saturated Condition

Total unit Shear P- waveLaver Thickness wave velocity DampingNumber of layer (ft) weifh velocit (ft/sec)(kcf) (ft/sec)

1 17.5 0.11 897 5000 0.043

2 22 0.11 1023 5000 0.051

3 5.5 0.11 1209 5000 0.052

4 3.5 0.11 1248 5000 0.053

5 4 0.11 1337 5000 0.040

6 7.5 0.11 1360 5000 0.042

7 6 0.11 1416 5000 0.042

8 7 0.11 1459 5000 0.043

9 7 0.11 1509 5000 0.043

10 8 0.11 1558 5000 0.043

11 8 0.11 1614 5000 0.042

12 8 0.11 1669 5000 0.042

13 8 0.11 1722 5000 0.041

14 8 0.11 1773 5000 0.040

Halfspace 0.15 8000 13856 0.020

DCD Revision:

The revisions described in Revision 0 of this response are incorporated in DCD Rev 17.

PRA Revision: None

Technical Report (TR) Revision: None


Page 28 of 28

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