ML13324A864
| ML13324A864 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/31/1986 |
| From: | Andrew Ward ABB IMPELL CORP. (FORMERLY IMPELL CORP.) |
| To: | |
| Shared Package | |
| ML13324A863 | List: |
| References | |
| 01-0310-1458, 01-0310-1458-R02, 1-310-1458, 1-310-1458-R2, NUDOCS 8605210247 | |
| Download: ML13324A864 (12) | |
Text
Se SEISMIC EVALUATION OF THE SONGS-1 CONDENSATE STORAGE TANK PREPARED FOR:
SOUTHERN CALIFORNIA EDISON COMPANY PREPARED BY:
IMPELL CORPORATION 350 LENNON LANE WALNUT CREEK, CALIFORNIA 94598 REPORT NO. 01-0310-1458 REVISION 2 MAY, 1986 D6R210247 860519 PD ADOCK 05000206 PDR
Contents Coversheet 1
Contents 2
1.0 Introduction 3
2.0 Tank Description 3
3.0 Site Inspection 4
4.0 Tank Evaluation 5
5.0 Conclusions 6
6.0 References 7
Figure 3.0-1 Walkdown Sketch, Equipment Adjacent to CST 8
Figure 3.0-2 Walkdown Sketch, Attachments to CST at Ground Level 9
Figure 3.0-3 General Arrangement Around CST 10 Figure 3.0-4 General Arrangement Around CST 11 Impell Report 01-0310-1458 Revision 2
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A
- 0.
IMPELL CORPORATION REPORT APPROVAL COVER SHEET Client: Southern California Edison Project: SONGS-1 Job Number: 0310-079 Report
Title:
Seismic Evaluation of the SONGS-1 Condensate Storage Tank Report Number: 01-0310-1458 Rev.
2 The work described in this Report was performed in accordance with the Impell Quality Assurance Program. The signatures below verify the accuracy of this Report and its compliance with applicable quality assurance requirements.
REVISION RECORD Rev.
Approval No.
Prepared Reviewed Approved Date Revision A
L I 1 61.
For Comment o
Vb Eo or I
Incorporated 1_______
SCE Comments
- 2.
j
1.0 Introduction Seismic reevaluation of the Condensate Storage Tank (CST) was not required as part of the SONGS-1 Return to Service (RTS) effort. The safety function of the CST was eliminated by construction of the new Auxiliary Feedwater Tank (Tag No. AFW-D-2A). However, an evaluation of the CST was performed to determine any adverse effect on safety related (SR) systems or structures in the vicinity of the tank This report discusses the results of Impells evaluation of the CST.
The CST was analyzed in its present, unanchored, condition to determine the effects of the postulated.67g Modified Housner event.
A walkdown of the area immediately adjacent to the tank was performed to identify components that might be affected by failure of the tank.
2.0 Tank Description The CST is a 34 ft. diameter by 37 ft. tall water storage tank. The tank is constructed of A283 Grade C steel plate. The shell plates are 0.26 inch thick with a Plasite liner. The bottom plates are 5/16 inch thick.
The CST is located at the southwest corner of the turbine generator pedestal, immediately north of the 138 kV take-off towers. The tank sits on a 6 inch thick layer of gravel which extends approximately two feet beyond the boundary of the tank shell [5].
From section 3.2.2 of
[23, the northern two-thirds of the tank is founded on category B backfill; the remainder of the tank is founded on undisturbed San Mateo sand.
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3.0 Site Inspection The area immediately adjacent to the CST was inspected to locate equipment in the vicinity of the tank which could be affected by a tank failure. Figures 3.0-1 and 3.0-2 of this report are based on the data gathered during the walkdown.
These figures show the area around the CST. Additional information regarding the equipment around the tank is available on [4) and [6].
The appropriate portions of [4) and [6) are reproduced as figures 3.0-3 and 3.0-4. Review of the figures show that the following equipment is in the immediate vicinity of the tank:
North of the Tank Air Receivers, C-4A, B, C Acid Storage Tanks, G-58A, B West of the Tank H Cylinder Storage Oil Separator Electric Reactors and Circuit Breakers (Tag Nos. RX1, RY1, Z01, Z02)
South of the Tank Station Auxiliary Transformer 'C' 138kV Takeoff Towers None of the equipment listed above is shown as safety related on 14],
15], or [6].
The CST is surrounded on the east side by the west wall of the turbine building (which is located approximately 10 from the tank) and, on the south side, by a 16-1/2 inch high 'fire wall' (between the tank and the aux. transformer). There is a concrete retaining wall on the west side and part of the north side of the tank. The retaining wall elevates the tank approximately six feet above grade.
A four inch drain line is shown at the north end of the piping trench on the northeast corner of the CST [61 (the trench is for line no.
CND-721-14" (NSR)).
An additional drain is located in the drain pit on the southwest side of the tank. This drain was observed to have an inside pipe diameter of approximately 6 inches.
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If the CST was to suffer damage due to a seismic event or soil settlement such that the tank was to leak, the drains described in the preceding paragraph may not have the capacity to drain the entire contents of the tank. Much of the water would flow to the west in the direction of the oil separators, the hydrogen cylinders, and the electrical equipment located immediately west of the tank (see Fig.
3.0-1). If the leakage was at a large rate, it is possible that the water could surge over the firewall and affect the aux. transformer.
However, since none of the equipment is safety related, damage to the equipment will not affect the ability of the plant to shut down after a seismic event. After leaving the immediate vicinity of the tank, the leakage in excess of the drain capacity will flow west towards the yard sump which empties into the intake structure. From the intake structure the water will drain into the ocean. The masonry wall of the turbine building (located east of the CST) blocks the flow path of water from the CST. The failure of the CST would result in leakage of water from the tank and not a water surge so that the masonry walls will be able to withstand the fluid loads and successfully provide a barrier to prevent leakage to safety related areas in the turbine building.
4.0 Tank Evaluation The potential for tank overturning was evaluated using the energy method desribed in Section 4.4 of Reference E7].
The energy method compares the maximum kinetic energy of the structure during seismic excitation with the energy required to overturn the tank. Kinetic energy was calculated using velocities from the free field velocity time history.
The velocity time history corresponds to the acceleration time history used to generate the LTS Response Spectra for the Reactor and Turbine Buildings. The evaluation, performed in Ell, showed that the CST has a factor of safety against overturning of approximately 18. Values greater than 1.5 are considered acceptable.
Therefore, the CST will not overturn during the postulated 0.67g Modified Housner Event.
Information is available in technical literature regarding the behavior of unanchored tanks under seismic loading. Reference E33 reports that during an earthquake in Livermore, California, unanchored tanks with aspect ratios similar to the CST suffered 'elephants foot' type buckling. Of the approximately 100 tanks which buckled during the earthquake it is reported that one tank, in which the elephant foot buckles were stamped flat during the main shock, leaked as a result of aftershocks but that "most of the damaged tanks did not rupture."
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0I 5.0 Conclusions A review has been performed to determine the effects of a seismic event on the SONGS-1 Condensate Storage Tank and the adjacent components. The high factor of safety against overturning, the historical performance of tanks leaking instead of failing catastrophically under seismic loading, and the absence of safety related equipment adjacent to the tank and in the flow path of any leakage from the tank, show that failure of the tank due to seismic loading will have no impact on the ability of the plant to shut down.
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6.0 References
- 1.
"Evaluation of the Existing Condensate Storage Tank," Impell Calculation No.: CST-1, Rev. 0, dated 4/25/86, Impell Job Number 0310-079.
- 2.
"Addendum 2 to Report on Soil Backfill Conditions -
San Onofre Nuclear Generating Station, Unit 1," September 14, 1983.
3 Niwa, A.,
and Clough, Ray W.,
"Buckling of Cylindrical Liquid-Storage Tanks Under Earthquake Loading," from Earthquake Engineering and Structural Dynamics, Volume 10, Number 1, January/February 1982, pp. 107-122. John Wiley and Sons, New York.
- 4.
"General Arrangement Plan Of Elev. 14'-0" ", Southern California Edison Company Drawing No. 568701-7, 7/11/83.
- 5.
"Utilities Details, Sheet 1", Southern California Edison Company Drawing No. 567776-2, 7/14/66.
- 6. "Foundation Plan and Details, Area 12", Southern California Edison Company Drawing No. 567782-9, 7/27/81.
- 7.
"Topical Report:
Seismic Analysis of Structures and Equipment for Nuclear Power Plants," Report No. BC-TOP-4-A, Revision 3, November 1974, Bechtel Power Corporation, San Francisco.
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approx. 161" high Cableta North Coudensate Storage Teak (CAD-D-2)
Rscomy Support
- 5.
35 Electrical Reactors Circuit Breakers Figure 3.0-1 Walkdown Sketch, Equipment Adjacent to CST Impel l Report 01-0310-1458 Revision 2
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.CND-37 (4
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0"aoegaeuigFag 2 MPS Uil OD at 120 above grede) r,d4esate Stoage Tank 356 (CST hose connection Isolation header)
Drain Pit, Drain size approx.
Figure 3.0-2 Walkdown Sketch, Attachments to CST at Ground Level Impel1 Report 01-0310-1458 Revision
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