ML20138B324

Forwards Draft Response to Question 1 Re NAPS USI A-46

ML20138B324
Person / Time
Site:	North Anna
Issue date:	08/23/1999
From:	Shaub T VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC
References
TASK-A-46, TASK-OR NUDOCS 9908250212
Download: ML20138B324 (3)

Text

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, iGordon Edison. Ax S:ng Kum}3uistions g4APS USl A 40 _

__ Page1 bb'.SE0f3fl From:

<Toin.Shaubo vapower.com>

To:-

OWFN DO.owf4_po(GEE) j' Date:

- Mon, Aug 23,1999 9:41 AM

Subject:

Re: Sang Kim's questions NAPS USl A 46 Attached is our draf t response to question 1. Pleae provide it to the appropriate reviewer.

- Thanks Tom-(See attached file; tanks naps ral. doc) l

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NORTil ANNA POWER STATION-l'SI A 46 Submittal Respome to additional NRC reauest dated Auemt 9.1999 August 19,1999

~ NRC Reauestt Data (preferably physical) to support two tank earthquake demand and capacity calculations (RAI S) particularly with regard to inclusion of water hold down force, sloshing and resulting stresses in tanks stability and anchor bolt adequacy of the tanks.

Mennomet in our response to RAI # 8 on April I,1999, the USl A 46 calculations for the two tanks, i.e., the Emergency Condemate Storage Tank (CST) and the Refueling Water Storage Tank (RWST) were provided to the NRC Staff.

Both of these tanks were initially classified as outliers, in addition, CST is unanchored and no guidelines for the base overturning moment of unanchored tanks are provided in the Generic implementation Procedure, Revision 2 (OlP 2). %erefore, other guidelines and criteria were used in specific portions of the analyses of these tanks. The

' details of the analyses, data and the references to support the criteria are contained in the cateulations provided to the NRC Staff earlier. A summary of the methodology used in the various aspects of the analysis is provided below for these two tanks, The analyses of both tanks are based on sound technical guidehnes and are systematically presented in the tank calculations. Criteria other than GIP 2 were used from well known references and only where required and/or not provided in GIP 2. The use of these additional criteria does not conflict with those portions of the tank cateulations where the GIP 2 methodology is used. The main references from which data and criteria were obtained for use in these calculations are also listed below.

Condensate Storane Tank For the various aspects of the analysis of this tank, the methodology is as follows:

Sliding shear capacity: The calculation is based on GIP-2.

Freeboard clearance: The calculation uses the GIP 2 method.

Convective (sloshing) mode response of the tank: This is calculated using the GIP 2 method.

Impulaive mode response (base shear and overturning moment): The calculation uses the GIP-2 method.

Oserturning Moment Capacity: Uplifting of the tank and the fluid hold down forces were used to calculate the moment capacity of the tank. For unanchored tanks, the small displacement theory is excessively conservative, and an upper bound theory is considered appropriate, in accordance with Reference 2. The equations in reference 2 are based primarily on Flugge (ref. 3) and also on references 4 and 5. Reference 2 recommends limiting uplift height to 0,ll, where L is the uplift length of the base. The uplift length was estimated as 16"(less than 5% of the diameter),

therefore,0.lb worked out as 1.6".

Ilowever, for additional conservatism, the uplift height was limited to 0.8" which is 50% of the value recommended in reference 2.

- Tank Stability: The criteria used for the tank buckling are primarily based on GlP-2. Elephant foot buckling follows the OlP-2 method, and the asial stress capacity is calculated from the equation provided in GIP 2 page 7 21, which is the same as EPRI NP-Sil (ref,6). The diamond shaped buckling capacity is based on NASA SP-8007 (ref 7) and guidance from GIP 2.

Refueline Water Storane Tank Tank respomes,i.e., base shear and overturning moment, including impulsive mode and comective (sloshing) mode: These calculations are primarily based on the GIP 2 methodology. Although in Attachment A of the

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calculation several equations, e.g. to calculate convectise mode frequency, base shear and moment responses, are listed as being taken from Reference 6, they will essentially provide the same result as the GIP 2 methodology.

- Top plate stress, tank shell stress, s ettleal stiffner plates and chair to lank w all u eldt The calculation uses GIP.

2 equations.

i Sloshing height and freeboard clearance: These calculations are based on GIP 2.

i A'nchor bolt tensile capaelty, overturning capaelty, and permissible uplift The initial anchor bolt tensile capacity was based on GIP 2 and ACI 349. Subsequently, the capacity was revised by studying the failure mechanism for overturning as follows. The calculation of the overturning moment capacity, initially based on the GIP 2 criterion, showed that the moment capacity was lower than the demand. A further evaluation was performed i

based on a yield line analysis of the top plate that utillied ref. 8. This analysis showed that the permissible load capacity of the anchorage v,s substantially hightr than the initially calculated value.11ased on this, the overturning i

moment capacity was reevalueted, as shown in Attachment D of the calculation. Note that the fluid hold.down forces were neglected, consistent with GIP 2.

The permissible uplift was based on Ref. 2 (smaller than that permitted by GIP 2).

Tank Stability: The criteria used for the tank buckling are primarily based on GIP 2. Elephant foot buckling follows the GIP 2 method, and the asial strrss capacity is calculated from the equation provided in GIP 2, page 7 21, which is the sans c.a EPRI NP 6041 (ref. 6). The diamond shaped buckling capacity is based on NASA SP-8007 (ref. 7) and guidance from GIP 2.

References

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Winston and Strawn et al.," Generic implementation Procedure, Revition 2 (GIP 2)" Seismic Oualification Utilities Litsp February 14,1992.

Bandyopadhyay, K., et al., " Seismic Design and Evaluation Guidelines for the Department of Energy liigh Level Waste Storage Tanks and Appurtenances", Brookhaven Nationall,aboratory, October 1995.

W Flugge, Stresses in Shells, Springer Verlag,1960.

G. C. Manos. " Earthquake Tank Wall Stability of Unanchored Tanks", fournal of Structural Encineerine, Vol.112, No. 8, ASCE, August 1986, pp 18631880.

M. A. Haroun and 11. S. Badawi, " Nonlinear Axisymmetric Uplift of Circular Plates", Dynamics of Structures, ASCE August 1987,pp77 89.

Jack R.- Benjamin Associates, et al., "A Methodology for Assessment of Nuclear Power Plant Seismic Margin (Rcvision 1)", EPRI NP.6041 SL, August 1991,

" Buckling of Thin Walled Circular Cylinders", National Aeronautics and Space Administration, [4ASA SP.8007, August 1986.

R. P. Kennedy, Notes on yield line analysis", Structural Mechanics Consulting, July 29,1986.

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