View source for 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

{{Adams
| number = ML20129H306
| issue date = 06/03/1985
| title = 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
| author name = Booker J
| author affiliation = GULF STATES UTILITIES CO.
| addressee name = Denton H
| addressee affiliation = NRC OFFICE OF NUCLEAR REACTOR REGULATION (NRR)
| docket = 05000458
| license number = 
| contact person = 
| document report number = RBG-21199, NUDOCS 8506070543
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 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
                                                                                    ~
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                                    ~
                                                                                                           '                                                                        )
l AI         I Systes ! Elevation i Diameter i Velocity I mi/A I ibot suHiu I*;tLSE                     psi   'l'            '
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:
17 P'
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                                          ^**
P           -MS-   (" "           1.g./
(50)
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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   . 1                                                                  P A c- s a cr 62.
                                     .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.
M     BE %.
t Amendment 15                 6A.10-2               November 1984 d}}