ML20209G126
| ML20209G126 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/08/1986 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | Mckenna E Office of Nuclear Reactor Regulation |
| References | |
| DCC-86-133, FYR-86-083, FYR-86-83, NUDOCS 8609120374 | |
| Download: ML20209G126 (7) | |
Text
Telephorc (6 t ?) 8778100 TWX 710L380 7619 YANKEE ATOMIC ELECTRIC COMPANY 1[7' d
1671 Worcester Road, Framingham, Massachusett 01701 DCC 86-133
,YAN KEE 2.C2.1 September 8, 1986 FYR 86-083 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Ms. Eileen M. McKenna Project Manager, Project Directorate No. 1 Division of PWR Licensing - A
References:
(a) License No. DPR-3 (Docket No. 50-29)
(b) Letter, USNRC to YAEC, dated August 12, 1986 (c) Letter, USNRC to YAEC, dated June 6,1986
Subject:
Strain Dependent Soil Parameters and Ultimate Soil Bearing Capacity
Dear Sir:
In your letter of August 12, 1986 (Reference (b)), Yankee Atomic Electric Company (YAEC) was asked to review the strain dependent soil parameters to be used by the NRC in the confirmatory analysis of the Primary Auxiliary Building.
YAEC has reviewed the parameters. The use of the shell data for the shear modulus ratio is reasonable. The use of the D. J. Murphy et al. test data for damping is conservative, particularly for higher soil shear strains.
However, for the shear strains expected in the PAB confirmatory analysis, the use of the D. J. Murphy test data appears to be reasonable. to this letter is the response to Enclosure 2 of Reference (c). The responses should provide sufficient information to resolve the issue of ultimate bearing capacity.
Very truly yours, O
G m
G. Pap.
c, Jr.
Senior Project Engineer Licensing GP/dps Enclosure hY: 600lAd 001 Ald a & C A A B C 0609120374 060908 PDR ADOCK 05000029 P
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REVIEW OF YANKEE NUCLEAR POWER STATION REACTOR SUPPORT STRUCTURE (RSS) FOUNDATION:
SOIL MECHANICS INVESTIGATION J
Question f
1.
The bearing capacity evaluation is for seismic loading conditions for which momentary eccentric loads will be applied to the RSS foundation.
The reference material is only valid for symmetric foundation loads resulting in an overestimation of bearing capacity.
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Response
1 l
1.
Foundation dead and seismic loads for the Reactor Support Structure (RSS) are given in the RSS Structural Analysis Report (Reference 1),
i The soll bearing stress due to dead plus seismic loads, including any eccentricities, is less than the ultimate soil bearing capacity.
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r-Page 2 of 6 Question 2.
The material in reference uses 1956 Standard Penetration Test (SPT) data for the foundation soils to estimate bearing capacity.
SPT data for soils that'contain gravel, cobbles, and boulders is generally invalid unless carefully interpreted. Later, soll investigation data is available and should be used. Also, the staff's SEP Evaluation of Topic II-4.F made in 1982 indicates that an SPT value of 35 is appropriate for the finer grained portion of the lodgement till found at the Yankee Plant.
Response
2.
Information from the 1978 Weston Geophysical Corporation borings (Reference 2) was used to estimate the ultimate bearing capacity of the glacial (lodgement) till.
The NRC staff's evaluation of SEP Topic II-4.F (Reference 3) states that:
"The SPT data show that the lodgement till has consistently high SPT values of $5 blows /ft or more." This SPT value is based on a review of all (1956 and 1978) site boring logs and represents lower bound measurements of SPT values at some elevations in some borings. Measured SPT values are consistently higher than the lower bound value of 35 blows /ft.
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f Page 3 of 6 Question 3.
The dimensions and depth of the RSS foundation are not given in Reference 1.
The shape of the foundation is apparently circular, but the bearing capacity evaluation is for a strip (continuous) foundation, resulting in an overestimation of bearing capacity.
Response
3.
The dimensions and depths of the RSS foundations are given in the RSS Structural Analysis Report (Reference 1).
The bearing capacity evaluation (Reference 4) was performed to estimate the ultimnte bearing capacity of the glacial till irregardless of foundation geometry.
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1 Page 4 of 6 l
Question 4.
The Yankee Atomic letter gives the original seismic loading design value as 8 KSF under seismic conditions.
If the 8 KSF value is correct, staff believes it is unlikely that the lodgement till will be required to resist a seismic bearing load 20 KSF due to a new analysis. Thus, for our edification, the staff requests the computed values of RSS foundation dead loads, peak vertical and horizontal seismic loads, and peak seismic overturning moment. Foundation dimensions would also be helpful in concluding our review.
Response
4.
Foundation dead and seismic loads are presented in the RSS Analysis Report (Reference 1).
The 8 ksf is the original allowable soll bearing stress under dead plus live loads. This allowable bearing stress was incressed by 1/3 to 10.6 ksf for loading combinations which included wind loads. Original plant design loads did not include seismic loads.
The 20 ksf is not the seismic bearing stress, but is the minimum ultimate bearing capacity of the glacial till.
Foundation dimensions are given in Reference 1.
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Page 5 of 6 Question d
5.
Some consideration of the loose backfill material adjacent to the RSS and Vapor Containment (VC) foundations may be in order to sufficiently evaluate ultimate bearing capacity.
Response
5.
No credit is taken for the potential beneficial effect of the backfill in the bearing capacity evaluation.
The estimated bearing capacity of the glacial till (Reference 4) is representative of the material on which the RSS foundations rest.
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Enciczura 1 Page 6 of 6 REFERENCES 1.
" Reactor Support Structure, Yankee Nuclear Power Station, Structural Analysis Report," CYGNA Energy Services, Report No. EY-YR-80023-6, March 1983, Revision 3 2.
" Geology and Seismology, Yankao Rowe Nuclear Power Plant, Weston Geophysical Corporation," dated January 29, 1979 3.
Letter, Caruso (NRC) to Kay (YAEC), "SEP Topic II-4.F, Settlement of Structures and Buried Equipment - Yankee Nuclear Power Station," dated September 16, 1982 4.
Letter with Attachments, G. Papanic, Jr. (YAEC) to J. Clifford (NRC),
" Ultimate Soil Bearing Capacity at Yankee," dated May 5, 1981