ML20062E858

Seismic Evaluation of Wolf Creek Generating Station Structures Using Livermore Spectrum,Evaluation of Piping Sys & Supports

ML20062E858
Person / Time
Site:	Wolf Creek
Issue date:	07/23/1982
From:	BECHTEL GROUP, INC.
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ML20062E853	List: ML20062E850 ML20062E858
References
NUDOCS 8208100343
Download: ML20062E858 (5)

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SEISMIC EVALUATION OF WOLF CREEK GENERATING STATION STRUCTURES USING LIVERMORE SPECTRUM EVALUATION OF PIPING SYSTEMS AND SUPPORTS DECIITEL POWER CORPORATION GAITHERSBURG, MARYLAND JULY 23, 1982 8208100343 820805 PDR ADOCK 05000482 A ppg

TABLE OF cot 1TEf1TS I. Introduction II. Stress Evaluation of Piping Systems III. Stress Evaluation Results IV. Conclusion

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l I. Introduction i

This report is intended to outline the methodology and re-t sults of a stress evaluation performed for all site specific l Essential Service Water System Nuclear Class 3 piping at i Wolf Creek Generating Station, to determine the ef fects of increasing the current SSE ground motion design spectra g level linearly from 0.12g (zero period acceleration) to 0.15 g. The basis for the selection of a 0.15g SSE design

! spectrum, as well as its effects on the various plant build-i ings, buried piping, electrical duct banks and appurtenant structures have been discussed in a previous' report dated April 2, 1982. This report is therefore limited to the evaluation of ESWS piping and associated supports within the pumphouse and in the valvehouse adjacent to the control

building.

i II. Stress Evaluation of Piping Systems i

The Essential Service Water System site piping servicing the Wolf Creek plant power block extends from the pumphouse located adjacent to the ultimate heat sink through the

valvehouse and into the west wall of the control building, where it enters the power block.- The piping is buried below grade at all locations with the exception of the pumphouse l and the valvehouse. Buried ESWS piping, although not a part

of the standard power plant, was designed for seismic loads obtained from several SNUPPS sites and is not affected by l the increased design spectra. Therefore, only the piping

within the aforementioned structures has been considered in

! the stress evaluation.

l For analytical purposes, all piping is divided into piping i

runs individually modeled and identified with a stress problem number. Each stress problen. is modeled to include support and boundary conditions and analyzed using the applicable floor response accelerations. -All piping stress problems within the pumphouse - and valvehouse were investi-gated fo r possible stress increases resulting from higher floor response accelerations associated with a 0.15g SSE design spectrum.

SSE design accelerations used in the original dynamic analy-l sis of each piping stress problem were compared to floor i response spectral accelerations associated with the 0.15g

! design spectrum. Floor response accelerations resulting l from the original "FLUSII" analysis, as well as the fixed base analysis (see April 2, 1982 report as transmitted via KMLNRC 32-192, G. L. Koester to H. R. Denton, dated May 3, 1982) were utilized as a basis for comparison. As per pre--

vious commitments, spectral accelerations for the original

! "FLUSil" curves used in the comparison were conservatively adjusted upward by 25% to reflect the rise of 0.12g to 0.15g.

i , -

1 Where the original SSE design accelerations were not greater than the scaled " FLUSH" curves - or the fixed base analysis curves, the stress problem was reanalyzed utilizing original analysis methods as defined in the FSAR to evaluate the increased stress levels. Stress levels in the piping sup-ports and their attachments, as well as the stress levels

.t in the piping system were evaluated. The following stress problems were affected:

4 STRESS j PROBLEM NO. DESCRIPTION LOCATION 4

317 30" Supply Lines. Pumps ESWS Pumphouse A&B to pumphouse wall.

318 3" Traveling Water Screen ESWS Pumphouse i

Spray Piping. Train A 318A 3"' Traveling Water Screen ESWS Pumphouse

.l Spray Piping. Train B

319 3" Vent Line. Pump A ESWS Pumphouse 319A 3" Vent Line. Pump B ESWS Pumphouse 320 4" Backwash Line. ESWS Pumphouse Strainer A ,

i 320A 4" Backwash Line. ESWS Pumphouse Strainer B 322 30" Warming Line in ESWS Pumphouse Pipe Pit. Train A 322A 30" Warming Line in ESWS Pumphouse

Pipe Pit. Train B

166 30" Supply Line. Train A Valvehouse 166A 30" Supply Line. Train B Valvehouse III. Stress Evaluation Results Of the eleven stress problems affected by the increased i

' floor response accelerations, four problems, (317, 318, 322 and 166) required reanalysis. Problems 319 and 320 did not

require reanalysis since the design accelerations used in

the original analysis exceed or are reasonably close to the l comparison basis curves. The evaluation showed that safety i

margins above those required for design, and outlined in the FSAR, exist in all. stress levels for these problems to

ensure their integrity even with the increased spectral accelerations.

A

Problems 319A and 320A are symmetrical to problems 319 and 320. Their evaluation is therefore identical.

The reanalysis of problems 317, 318, 322 and 166 indicated all pipe stresses, although greater than the original design stresses, are within ASME code allowables. The magnitude of load increase found at all piping supports for these prob-lems, with the exception of hanger No. K-EF11-C009/011(Q),

is not significant. Hanger No. K-EP11-C009/011(Q) will be

, subjected to a significant load increase, but will not re-quire redesign, since this hanger is common to both the Callaway and Wolf Creek pumphouses and was originally de-signed for the higher Callaway loads associated with a 0.20g SSE design spectra. Problems 318A, 322A and 166A are sym-  !

metrical to problems 318, 322 and 166 and are evaluated '

similarly.

IV. Conclusions All Essential Service Water System Nuclear Class 3 piping, including supports, have been reevaluated to spectral accol-erations which, when compared to those resulting from the suggested design spectra for 0.15g as per previous commit-monts, yield conservative results.

The evaluation also considered the available stress margins in the piping and support systems and indicates that no modfications would be.regoired for the piping or supports as a result of the suggested design spectra.

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