ML20199F476
| ML20199F476 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 12/18/1997 |
| From: | Joseph Sebrosky NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9802040017 | |
| Download: ML20199F476 (7) | |
Text
.
p
- December 18, 1997
, Mr. Nicholas J, Liparulo, Manager -
Nuclear. Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation.
P.O.~ Box 355 Pittsburgh, PA - 15230 -
SUBJECT:
OPEN ITEMS ASSOCIATED WITH CHAPTER 3.8.5 OF THE AP600 SAFETY EVALUATION REPORT (SER)
Dear Mr. Liparulo:
The Civil Engineering and Goosciences Branch of the Division of Engineering has provided an l
SER for Cha; ter 3.8.5. However, the SER contained some open items. These open_ items have i
been extracted from the SER and can be found in the er tsure to this letter..
- You have requested that portions of the information submitted in the-June 1992, application for s
design certification be exempt from mandatory public disclosure ;While the staff has r,ot completed its review of your request in accordance with the requirements of 10 CFR 2.7g0, that portion of the submitted information is being withheld from public disclosure pending the staffs final determination. The staff concludes that these follow on questions do not contain those portions of the information for which exemption is sought. However, the staff will withhold this :
letter from public disclosure for 30 calendar days irom the date of this letter to allow Westing-1-
house i,ne opportunity to verify the staff's conclusions, if, after that tinie, you do not request that all or portions of the information in the enclosures be withheld from public disclosure in accor-dance with 10 CFR 2.790, this letter will t.o placed in the Nuclear Regulatory Commission Public -
Document Room, if you have any questions regarding this matter, you may contact me at (301) 415-1132.
Sincerely, original s'igned by:
Joseph M. Sobrosky, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation
}
g Docket No.52-003 ;
il
Enclosure:
As stated h
cc wlencl: See next page g
DISTRIBUTION:
See next page.
- DOCUMENT NAME: A:ECGB_385.RAl-
-To receive a copy of this document, indicate in the box: "C" = Copy without attachment / enclosure "E" = Copy with attachment / enclosure "N"= No copy /
OFF;OE PM:PDST:DRPM l D ECQB:q$
l' D:PDST:DRPM l l
NAME JMSebrosky:sg M GBadcFi W TRQuay 'IFQ f
DATE 12/M/97
//
12/ \\197 12/ft/97
~
p ' OFFICIAL RECORD COPY 4 ld t-
. dd l l l l h, l,l l.
9902040017 971218 PDR ADOCK 05200003 4
1 E
4 l
plSTRIBUTION: Letter to Mr. Nicholas J. Lloarulo. dated: nocomhor iR. 1997 f
- Docket File
- Enclosure to be held for 30 days
- PUBLIC PDST R/F
. TQuay TKenyon WHuffman
- JSebrosky
- DScaletti i
JNWilcon ACRS (11)
. WDean,0-5 E23 JMoore,0-15 B18 TCheng,0-7 H15 JBrammer,0-7 HIS GBagchi,0-7 H15 i
l
9 Mr. Nicholas J. Liparuto Docket No.52-003 Westinghouse Electric Corporation AP600
{
cc:
Mr. B. A. McIntyre Ms. Cindy L. Haag l
Advanced Plant Safety & Licensing Advanced Plant Safety & Licensing i
Westinghouse Electric Corporation Westinghouse Electric Corporation Energy Systems Business Unit Energy Systems Business Unit P.O. Box 355 Box 355 Pittsburgh, PA 15230 Pitteburgh, PA 15230 Enclosure to be distributed to the following addressees after the result of the proprietary evaluation is i
received from Westinghouse:
Mr. Russ Bell Ms. Lynn Connor Senior Project Manager, Programs DOG Search Associates Nuclear Energy institute Post Office Box 34 17761 Street, NW Cabin John, MD 20818 i
Suite 300 i
Washington, DC 20006-3706 Mr. Robert H. Buchholz GE Nuclear Energy Dr. Craig D. Sawyer, Manager 175 Curtner Avenue, MC-781 Advanced Reactor Programs San Jose, CA 95125 GE Nuclear Energy 175 Curtner Avenue, MC-754 Mr. Sterling Franks San Jose, CA 95125 U.S. Department of Energy i
NE 50 i
Barton 2. Cowan, Esq.
19901 Germantown Road Eckert Seamans Cherin & Mellott Germantown, MD 20874 i
600 Grant Street 42nd Floor Pittsburgh, PA 15219 Mr. Charles Thompson, Nuclear Engineer AP600 Certification Mr. Frank A. Ross
. NE-50 U.S. Department of Energy, NE-42 19901 Germantown Road Office of LWR Safety and Technology Germantown, MD 20874 19901 Germantown Road Germantown, MD 20874 Mr. Robert Maiers, P.E.
Pennsylvania Department of Mr. Ed Rodwell, Manager Environmental Protection PWR Design Certification Bureau of Radiation Protection Electric Power Research Institute Rachel Carson State Office Building 3412 Hillview Avenue P.O. Box 8469 Palo Alto, CA 94303 Harrisburg, PA 17105-8469 e
\\)
s' j'
Open items Associated with Chapters 3.8.5 -
Open item 220.129F ( The following concerna DSER open item 3.8.5-9)
Westinghouse should demonstrate the adequacy of using a 6-foot thick foundation mat, especially the foundation met undemeath the containment vessel. ?n its position letter dated
.{
November 4,1994, the staff offered two options for Westinghouse to consider in resolving this issue: (1) demonstrating that the final foundation mat design can accommodate the effects of soll stiffness variations of hard and soft spots undemeath the foundation mat, and (2) using different foundation mat thicknesses for a foundation mat with uniform soil foundation stiffness (such as -
rock sites) and for a foundation mat with non-uniform soil foundation stiffness (such as soil sites with hard and soft spots) and submitting the completed design of each foundation mat thickness for the staff review and approval.
During the meeting conducted on August 4 through 15,1997, the staff reviewed the final design of the 6-foot thick foundation mat. As a result, based on the commitment made by Westinghouse in SAR Section 3.8.4 (Revision 15) that (1) the design and analysis procedures for SC-l structures are in accordance with ACl-349 Code for reinforced concrete structures, and (2) the ductility criteria of ACI 318 Code, Chapters 12 and 21, are considered in detailing, placing, anchoring and splicing of the reinforcing steel, three design concoms were identified by the staff:
1, According to Chapter 21 (Section 21.3.3.4) of ACI 318-95 Code, stirrups used as shear reinforcement have to be provided with a 135 degree hook at both the top and bottom faces of the foundation mat. However, only stirrups, with 90 degree hook at the bottom face and 135 degree hook at the top face of the mat, were provided by Westinghouse for resisting shear force. The flexural steel is spaced at 6 inch on centers top and bottom.
Therefore, the provision of 135 degrec, hooks is not practical.- The 6 ft thick foundation n at
- does not appear to be constructible with such heavy reinforcements.
2.
According to the ratio of span to depth, the Nl foundation mat should be classified as deep flexural members and be designed for the requirements for deep flexural members (Section 11.8.1 of ACl 349-90). However, based on some test results, the ACI 318 Code -
i Committee determined that errors were identified in the 1983 code (same errors were in the ACI 349 code, because the 349 code is based on the 318 code) and these errors could result in an unconservative design for deep flexural members. As a result, ACI 318-95 was revised to correct these errors. For the case of AP600 foundation mat with exterior and interior stiffening walls, the foundation mat should be classified as a continuous deep _
flexural members (Sections 11.8.1 and 11.8.3 of ACl 318-95). ACl-318-95 Code (Section 11.8.5) requires that the critical section for shear is to be located at 0.15 times the span length from the support edge with reinforcing steal uver the full span and the design should be based on Section 11.8.3. However, Westinghouse did not treat the foundation mat as a deep flexural member. The shear reinforcement used in the design es based on a much reduced shear force at a section which is further away from the edge at a distance of the effective depth of the mat. The correct amount of shear reinforcement would require the use of larger reinforcing bars which would be spaced at a distance not more than 'd/2" throughout the length of the member.
Enclosure
2-3.
The foundation met calculation was performed using soll stiffness variation in a".emate span;; :Vhile this design approach will maximize bending moments in the mid span, it will not indicate increases in shear force due to soil variation. If the soit variation is such that the soil stiffness is constant over two adjacent spans, and spans on either side are with
{
i lower or higher stiffness, the maximum shear force will occur at the wall between the two spans with the greatest stiffness. This gecmetry was not considered in the Westinghouse design.
On the basis of the discussion above, thf staff concluded that Westinghouse failed to demonstrate that the proposed foundation mal design is adequate with respect to the pieviously issued staff position. The final design of the foundation mat did not meet certain code requirements committed to in the SAR.
For the concem of seismic books used for the shear reinforcement (Item 1 above),
Westinghouse proposed the use of ht aded anchors (instead of 135 degree bends) at both ends of the shear reinforcement (stirrups) during the meeting on August 4 through 8,1997, Westinghouse also provided, in the meeting, test results published by the manufacturer for the staff review. As a result, the staff found that the shear rc'nforcement with headed anchors is equivalent to the use of 135 degree bends at both ends of the shear reinforcement and concluded that this issue is technically resolved. However, Westinghouse should document this commitment in a future revision of the SAR.
With regard to the concems of the use of design code and soil stiffness variation (items 2 and 3 above), Westinghouse's response and the staff's evaluation are summarized below:
i 1,
in the submittal dated November 24,1997, Westinghouse provided a draft of SAR t
Section 3.8.5.5 to commit that the foundation mat below the auxiliary building is designed for shear in accordance with the requirements for continuous deep flexural members in ACI 318-95 (Section 11.8.3). Specifically, Westinghouse committed:
(1)
The design for shear is based on Sections 11.1 through 11.5 of ACI 349-90 except that the critical section measured from the face of the support is taken at a distance of 0.151,.
(2)
Shear strength, V, is not taken greater than 8(f,')'#b,d when 1/d is less than 2.
n When IJd is between 2 and 5, V,=2/3(10+1/d)(f,')'8b.d (3)
Area of vertical shear reinforcement, A., is not less than 0.0015b s and the spacing of shear reinforcement, s, does not exceed d/2 nor 24 inches.
(4)
Shear reinforcement required at the critical section is used throughout the span.
Westinghcuse's commitments in the draft SAR meet the requirement of ACl 318-95 and, therefore, are acceptable.
3.
In Revision 17 of SAR Section 3.8.5.4.4, Westinghouse stated that the design moments and shetrs are increased by 20 percent above the required for uniform sites to
3 accommodate the nonuniform sites defined in SAft Section 2.5.4.5. According to the common engineering practice and the stars review experience, to increase the design moments and shears by 20 percent will accommodate the effects due to nonuniform sites.
This issue is considerad resolved.
On the bases discussed above, the staff concluded that the concem regarding the design of shear reinforcement for the foundation mat is technically resolved. However, Open item 3.8.5 9 will not be closed until Westinghouse formally revises the SAR to document its commitments concoming the use of hooded anchors for shear reinforcement and the commitments contained in the submitta! dated November 24,1997.
Open item 220.130F (The following concerns DSER Open item 3.8.5-10)
Based on the staff's past licensing review experience, the unevenly distributed construction loads on the foundation mat, especially for the foundation mat with large dimensions and irregular shape, can be very significant and may cause severe foundation cracks. Westinghouse should provide the basis for demonstrating the design adequacy in coping with the unevenly distributed construction loads, in the meeting on August 4 through 8,1997, Westinghouse presented its design approach and results for considering the effects of construction settlements in the design of the foundation mat.
During this meeting, the effects of construction settlements ca developed moments and shears in the Ni structures were reviewed and discussed. As a result of the discussion regarding the staff's review findings, the following design procedures for considering loads due to construction sequence and settlements in the foundation mat design are acceptable to the staff:
(1)
Obtain stress resultants at critical locations on the Nl from the following load ceses: (a)
Case 1 of PCRA analysis for the deep clay site, (b) Case 2 of PCRA analysis for the sand / clay site, (c) the analyses based on the simptilied INITEC's Winkler spring models.
(2)- Obtain the maximum valves of stress resultants at each of the criticallocation from the cases in item 1 above. This list of maximum stress resultant values is then to be considered as the resultant dead load stress resultant solution.
(3)
Tho stress resultants due to dead load from item 2 above are then to be combined with all other stress resultants to obtain stress resultants in satisfying the various load combinatior requirements. For each load case, the list of maximum stress resultant values represents the elastic demand on the N!.
(4)
The elastic demand is then to be compared with the section capecities of the concrete
- structural elements of the Ni to judge the adequacy of the design.
(5)
Because soil bearing pressures calculated from the PCRA and INITEC analyses are not sensitive to the size of finite elements used in ine model, they can be used in the localized analysis with more finely discretized finite elements to calculate final design moments and shears.
W F
/
~
l I
4 Westinghouse should follow this procedure to design the Ni structures for resisting the loads induced by construction sequence and settlements. In addition, Westinghouse should document this procedure in the SAR. On the basis discussed above, Open item 3.8.5-10 remains unresolved, l
l
-