RBG-21199, Forwards Supplemental Info Re Clarification to Section 6A.10 Re Methodology Used to Calculate Bulk Suppression Pool Swell Impact Loads for Structures Less than 6 Ft Above Suppression Pool to Close Out SER Outstanding Issue 7

Forwards Supplemental Info Re Clarification to Section 6A.10 Re Methodology Used to Calculate Bulk Suppression Pool Swell Impact Loads for Structures Less than 6 Ft Above Suppression Pool to Close Out SER Outstanding Issue 7

ML20129H306
Person / Time
Site:	River Bend
Issue date:	06/03/1985
From:	Booker J GULF STATES UTILITIES CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
RBG-21199, NUDOCS 8506070543
Download: ML20129H306 (9)

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- .i GULF STATES ' UTILITIES COMPANY POSTOFFICEBOX 2951

• BEAUMONT. TEXAS 77704 ewe AREA CODE 409 838 6631 June 3, 1985 RBG- 21199 File No. G9.5, G9.8.6.2 Mr. Harold R. Denton, Director

.0ffice of Nuclear Reactor Regulation:

U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Dear Mr. Denton:

River Bend Station-Unit 1 Docket No. 50-458 Enclosed for your review is a Gulf States Utilities Company (GSU) supplement to the letter ' rom J. E. Booker (GSU) to H. R. -Denton (Nuclear Regulatory Commission-NRC) dated March 1, 1985 (GSU Letter No.

RBC-20270).! The information herein is provided to close-out Safety Evaluation Report (SER) Outstanding Issue No. 7. Enclosure 1 provides a Final Safety Analysis Report (FSAR) clarification to Section 6A.10 concerning the River Bend Station (RBS) methodology used to calculate bulk suppression pool swell impact loads for structures less than six feet above the suppression pool. The RBS approach addresses pool swell phenomena and predicts pressures on those structures which are not addressed in NUREG-0978. This approach is technically justified by comparison to alternate methods previously approved by the NRC Staff in NUREG-0487 and NUREG-0661. Attachment i summarizes such an alternate method (referred to as the Bedrosian methodology) which also predicts pressures on structures within six feet of the suppression pool.

Attachment 2-compares the results from the RBS methodology with the Bedrosian methodology and demonstrates the RBS methodology is at least as conservative as that of this previously' approved method. The FSAR revisions contained in Enclosure 1 will be incorporated into a future FSAR amendment.

Sincerely,

. f.

J. E. Booker

-Manager-Engineering, Nuclear Fuels & Licensing River Bend Nuclear Group Attachment'(2)

Enclosure (1) 8506070543 850603 PDR ADOCK 05000458 L , A0

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p' - 4 g J cs-J ATTACHMENT 1 The-following steps describe the Bcdrosian methodology for calculating impact loads . for structures within six feet of the suppression pool. .

This methodology is comprised of various procedural secps which have

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been previously approved by the NRC Staff in NUREG-0487 and NUREG-0661. -St.e Attachment 2'for a tabular summary of the results.

1. Determine properties of small structure under consideration:

_ Orientation (radial or circumferential)

- Width: W in inches

-- Height of structure's bottom above suppression pool: H in feet Length: L in feet 2.- Determine hydrodynamic mass of impact per unit area from - GE Report No. NEDE-13426P (Reference 2, Figures (6-8) and (6-9)) (

corresponding to structure's orientation and width:

.(MH /A) in Ib ,/ft

3. Determine the impact velocity of water slug, V,. corresponding to height, H:

V-= H/10 x (2.6 - 1.6$/10) x V,,x , in fps, for 05H J10 ft V -. V x = 50 fps, for 10 s H r 18

4. Determine design impulse:

1 I =

(MH /A)x(V)32.2 x 144 e in Psi x sec

5. Determine impulse duration according to G. Maise (Reference

'1, Equations (5)- or (9)) corresponding to structure's orientation, height above pool, and. length:

T, in seconds (see FSAR Section 6A.10.1, Subsections la-d and 2a-c for a detailed precedure) 6.. Determine the peak dynamic pressure design value:

=

P max. tp , in psi

7. Apply the impact load as a triangular impulse with the peak pressure and pulse duration determined in Step 6 and Step 5, respectively (see attached Figure 1).

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REFERENCES

1. G. 'etaise, " Suggested Acceptance Crit. ria for Impact Loads on Short Stark III Structures Close to the Pool," Department of Nuclear Energy, Brookhaven National Laboratory, Up:ca, NY 11973, February 15, 1934.

2. General Electric Co., ".'t.trk III Contirmitory Test Pregram. One-Third Scale Pool Swell Impact Tests, Te.st Series 5305," GE Report No. NEDE-13426P, August 1973.

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g i-l Target- t Elevation i flidth I Velocity I tm/A - 1 Structure i Ful'st - se i FST,R 1 Eadrosian i FSAR' I i ft I in i ft/see i Ibs/sqfti Racial 'f Circum i H.cial I Circum 1 I

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-1 I Becrosian -1 1 Equip Natch Platform framing E. 95' BEM B1 94.27 6.5 33.2 15.5 I .236 115- 36.96 3.11 BEM B2 93.6 6 29.5 15 I .WES 4.10

~115 28. C .

BE M B3 93.6 6 29.5 15 I . N57 115 33.47 3.44 -

BEM B4 91.94 8 18.4 21.5 I .0068 9.30 115 25. 25 BEM B5 92.94 8 25.5 21.5 I .9254 2.63 115 43.73 t

Cantitiver Beas at Et.95' L=4' 94.58 4 34.73 11 I .9961 4.26 115 27 Cantiliver Beas at .

E. 95' L=6' 94.58 4 34.73 11 I .N51 4.26 115 27 Control Rod Drive (CRD)

Platform L > 4' 93.6 9 29.5 23.5 I .0057 2.19 115 52.45 N

IMPACT ASSESSMENT OF P00L SWELL LDADINi - Conduit .

! Equipment I Phot. ShMkl. Iran.S E osi 1 i Elevation i Dia:eter i Velocity I m/4 i Structure i Pulse see i Ff/It i Bearestan i FSAR I L or Conduit i ft I in i ft/see i its/sqfti Radial 1 Circus i Racial i Circum i I I Eecrosian i Conduit to RTDs - 244,B C 8 H 8 483 95 1.25 36.7 .5 -I .N2 121 5 24.Et Conduit to HTDs - 24E 8 6 8 48A 8 C 95 1.95 36.7 .5 I . 042 _121 5 24.28 h]

tl TTDs are Supression Pool temperature monitoring instruments t3 A, C, and D are required post-accident '5

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.e IWACT ASSESDENT OF P0il S ELL !.DADING - Pior Stress ~

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i Strue:ure i Pulse see i F5M - l Beerosian lFSAR I I I I ft I in 4 - ft/see i Ine/sqfti Radial i Circus i Radial I. Circ m i i J edrosian i E

'7184 DER 92.5 8.625 22.5 6. 9 I .M25 31.8 25.4 1.25 DER 92.5 8.625 22.5 3. 7 I .2215 55.1 24 2.38 71 3 DER 92.5 8.625 22.5 6. 9 I .9826 31.8 25.4 1.25

• DER 92.5 8.625 22.5 3.7 .N15 55.1 I 2- 2.38 710C DER 92.5 8.625 22.5 6.9 I .3326 31.8 25.4 1.25 DER 92.5 8.625 22.5 3.7 I .9215 55.1 24 2.38 71 3 DER 32.5 8.625 22.5 6.9 .9826 I 31.8 25.4 1.25 DER 92.5 8.625 22.5 3. 7 - t .3215 $5.1 24 2.30 DER 92.5 6.625 22.5 2. 8 1 .0J15 55.1 18.1 3.04 IMPACT ASSESSST OF POOL S6 ELL LIMDI2 - Large Bore Pipe Sucwts 1 Poot St48u IMPULSE psi I i Pipe Suppcrtl Target i Elevation 1 Diameter i Velocity 1 Mh/A I Structure i Pulse see i FSM Eedrosian i FSAR

• l Number I i ft i in i f:/see i lba/sqfti Radial i Circum i Radial i Circun I i

• SeceasW l IChS-PSR- 6" SCH168 91 6.625 18.47 5. 4 I .0324 27.2 10.2 2.67 39t!A4 6' SCH168 31 6.625 12.47 5. 4 I .N24 27.2 13.2 2.67 I.WACT ASSESST NT OF POOL SWELL LCADING - Small Bore Pipe Supports I Pool. 34stL I.WULSE psi i i Pipe Supportl Target i Elmvation i Diameter i Velccity i Mn/A I Structure i Pulse se: ! F5M Becrosian i FSAR I I humber i I ft i , in i ft/see i los/sefti Radial I Circum i Radial i Circus ! I i beeg I t

1ICS-54e 6' SCH 44 92.5 6.625 22.5 5. 4 1 .0237 32.6 19.4 1.58 PSR3 I

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TN(sed.-1 LINES.WITHIN 6 FEET OF THE SUPPRESSION POOL AFFECTED BY' POOL SWELL IMPACT AXRNo. = 710 Line No. 1-DER-008-286-2, & Class 4 L 11ne (Penetration Z40A) -

I L These' lines are fed from Control Rod Drive Hydraulic System scram i accumulator vent &' drain headers -'l-DER-003-313-4 & DER-003-317-4 It is assumed that all-rods are inserted upon initial scram and

-there is no drain required post LOCA.

AX ? . 710B Line.No. 1-DFR-008-403-2, & Class 4 Line (Penetration Z37A)'

AX 710C _ Line No. 'l-DFR-008-400-2, & Class 4 line (Penetration Z37B)

Inese lines convey drywell floor drains from the drywell through containment. They do not perform a safety function and are not required post-accident.

AX No. = 710D Line No. = 1-DER-008-450-2, & Class 4 line (Penetration 240B)

A. These lines are fed from local instrument panel drains in containment including Class 4 lines (1-DER-750-899-4) - 3 CRD hydraulic scram accumulator vent and drain ~ headers and 1 reactor water cleanup holding pump line.

B. These lines are fed from CRD Hydraulic System scram discharge volume P ii P ng.

It is assumed that all rode are inserted upon initial scram and

, there is no drain required post-LOCA.

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L . E c a5ute 1 ke 1 d- A RBS FSAR 6A.10 LOADS ON STRUCTURES BETWEEN THE POOL SURFACE AND THE HCU FLOORS As described in Reference 1 (Section 3B.10).

6A.10.1 Impact Loads 15 All structures (e.g., beams and pipes) in the annulus above the suppression pool within 18 ft above the pool have widths less than 20 in. Impact loads due to bulk pool swell on these structures are as shown in Fig. 6A.10-2. For structures leos than 10 ft above the pool surface, the impact pressure can be reduced by:

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V'1 Sulfs VGDCfTV sN Feer- Rut MD where/HFis the "icts.ne: c'c c c e th; p::1 curface.

All beams and pipes experiencing these impact loads fall within the conservative range as defined in GESSAR is Fig. 3B.33-1 through Fig. 3B.33-4, with the pulse duration T and pressure amplitude adjusted as follows:

1. Radial-oriented structures

a. For structures within 6 ft of the pool surface, the pulse duration T 3 is given in Fig. 6A.10-7.

b. For structures less than 4 ft in length, the pulse duration T2 is given in Fig. 6A.10-8.

17

c. For structures both less than 4 ft in length and within 6 ft of the pool surface, the pulse duration is given by:

T =

(Tt x T2 ) /0. 007

d. The value of T need not be less than that calculated by:

Cylindrical targets T = 0.0463 D/V Amendment 17 6A.10-1 March 1985

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.RBS FSAR Impact loads on structures attached to the containment wall are described in'section 6A.6.

Impact loads acting on structures are based on.a pool swell velocity which varies with height above the pool surface.

This variation is given by:

V = 5H (2.6 - 0.506 di) for H < 10 ft h6eNoE.1)

V = 50 ft/sec for 20 2 H 2 10 ft V = (3788 - 64.4 H for 30 2 H > 20 ft

=

6A.10.2 Drag Loads The drag load on grating is based on Fig. 6A.10-4. The drag load found from this figure is multiplied by (V/40)2 if V is greater than 40 ft/sec.

For drag loads on flat plates, Fig. 6A.10-5 is used. If the velocity is greater than 40 ft/sec, the drag load is

.: s multiplied' by (V/40)2 If the shorter side (b) is attached to the containment or drywell wall, the abscissa in Fig. 6A.10-5 becomes 2(a/b) instead of a/b.

For other shapes, Fig. 6A.10-6 is used to calculate the pressure for 40 ft/sec. If the pool swell velocity is y greater than 40 ft/sec, the pressure is multiplied by (V/40)2

>For all drag loads, the duration is 0.5 sec.

6A.10.3 Fallback Loads As described in Reference 1 (Section 3B.10.3).

Whew H is 7w usmus AEow The 7;ool.

SdFACE Mxe .1 : V was TMM x rr/sec sMu.

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t Amendment 15 6A.10-2 November 1984 d