ML20206S749

Evaluation of Structural Aspects Re Point Beach Plant

ML20206S749
Person / Time
Site:	Point Beach
Issue date:	05/31/1986
From:	Liu Q, Chris Miller, Philippacopoulo BROOKHAVEN NATIONAL LABORATORY
To:	NRC
Shared Package
ML20206S689	List: ML20206S686 ML20206S709 ML20206S749
References
CON-FIN-A-3826 TAC-43669, TAC-43670, NUDOCS 8609220363
Download: ML20206S749 (15)

Text

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2 Evaluation of Structural Aspects Related i to the Point Beach Nuclear Plant by

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C.A. Miller, Q. Liu, A.J. Philippacopoulos and C.J. Costantino 1

Structural Analysis Division Department of Nuclear Energy Brookhaven National Laboratory Upton, NY 11973 May 1986 l

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ABSTRACT This report describes an investigation which was c'arried out for the Point Beach Nuclear Plant. The purpose of this investigation was to evaluate structural aspects related to the condensate storge tanks and the facade strucure. This work was performed by the Structural Analysis i- Division of the Brookhaven National Laboratory for the Nuclear Regulatory Comission under FIN A-3826: " Indian Point Unit 2 and Point Beach Wind

! - Vulnerability Analysis".

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TABLE OF CONTENTS Page

~ ABSTRACT ...................................................... 11 LIST OF FIGURES

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1.0 INTRODUCTION

. . . . . ................................... 1 2.0 CONDENSATE STORAGE TANKS . . . . . . . . . . . . . . . . . . . . .. . . . . . . 1 3.0 : FACADE STRUCTURE . ................................... 2

4.0 CONCLUSION

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LIST OF FIGURES Figure Page 1 Condensate Storage Tanks .............................. 5 2 P1 ant Layout .......................................... 6 3 Finite Element Model of Facade Structure .............. 7 4 Deformed Shape of Facade Structure. Case 1 ........... 8 5 Deformed Shape of Facade Structure. Case 2 ........... 9 6- Deformed Shape of Facade Structure. Case 3 ........... 10 7 Deformed Shape of Facade Structure. Case 4 ........... 11 e

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s-y POINT BEACH REVIEW .

1.0 INTRODUCTION

'Several questions were raised regarding' the safety of. the Point Beach

. Nuclear Power Plant in Generic Lettr 81-14 " Seismic- Qualification of Auxiliary Feedwater System Point Beach Nuclear Plant, Units 1 and 2".-

Wisconsin Electric responsed to these; questions in a letter to NRC dated April 26,-1985.- This report describes the work perfonned by Brookhaven

. National Laboratory (BNL) to audit Wisconsin Electric's ' response to two of the questions. The first question dealt with the potential hazard of -

failure of the condensate storage tanks due to seismic loads. The second

. question concerns! the consequences of failure of the facade structure due

, to seismic loading. Neither of these . structures- are safety _ related. The

. concern.therefore is whether failure of these structures would cause damage to nearby safety related equipment. .

BNL first reviewed documents describing the concerns. An audit of the pertinent calculations was performed during a visit to the Wisconsin Electric offices on November 20, 1985. The plant was inspected at the same time. BNL staff participating in this visit were: C.J._ Costantino, C. A.  !

Miller and A.J. Philippacopoulos. H. Polk of NRC was also on the audit team. Additional calculations were perfonned at BNL after the audit. The results for each of the concerns are discussed in the following two -

. sections of the report.

2.0 CONDENSATE STORAGE TANKS The concern was stated as follows:

"The licensee stated that each condensate storage tank with approximately 180 tons of water was mounted to the diesel generator building roof with 4 eight 3/4-inch diameter anchor bolts. Since these tanks are non-seismic,

- the consequence of these tanks breaking loose from their mounts and

, impacting the control building roof should be analyzed, including the

. effects of flooding".

The applicant responsded that the steel = and concrete structure surrounding the tanks precludes the possibility of their impacting the control room

'_ roof if they should fail during a seismic event. An inspection of the area  :

{ during the site visit confirmed this.

l The second part of the concern is related to flooding of safety related

, areas or equipment if the tanks ruptured during a seismic event. The tanks >

, are mounted on the reinforced concrete roof of the diesel generator i building (see Fig. 1). Concrete walls surround three sides of the area in '

! which the tanks could be contained on the roof. The water would flow from i

the fourth side of the roof to Elev 8' and into a sump. The site inspec-

tion confirmed that there is no safety related equipent located in areas which would be exposed to the water.

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One area of concern, howeve. , is the air intake to the diesel generator building. Louvered air intakes to the diesel generator building are located on the roof of the diesel generator building close to the condensate tanks. The. louvers are mounted vertically into a concrete >

structure. There is adequate' freeboard below the louvers so that the water would not enter. However, it may be possible for the tanks to collapse.

onto the. louver structure so that water from a rupture higher up in the tank could spill into the louvers. A . failure in the tank could also result 1 in a stream of water directed at the louvers. The control panels for the diesel generators are located directly below the louvers and would be exposed to any water coming through the louvers. The applicant should be directed to consider the consequences of this event.

. 3.0 FACADE STRUCTURE The concern was stated as follows:

"In order for the design of the structures housing the AFWS to be acceptable, the licensee should demonstrate that all of these structures are capable of withstanding a safe shutdown experience".

One AFW pump steam supply line for each unit branches off a main ~ steam line at the containment structure exterior and is routed through the facade into the auxiliary building. The other steam supply line is routed from the facade through the north or south wing before entering the auxiliary.

building (see Fig. -2). The facade is not a Category I structure and the concern is whether failure of the facade during'a seismic event might cause failure of the safty.related steam lines.

The facade is a steel frame structure which encloses the containment. It is vertically supported on columns which are part of the facade structure with horizontal support provided by attachments to either the containment or the auxiliary building. Metal siding forms the skin of the facade  ;

structure.

The facade structure was originally designed for a 360 mph wind loading assuming that one third of the siding remained intact. A study was performed to show that the SSE loading resulted in smaller shears than would occur for the design wind loading. The licensee therefore concluded that the structure could withstand the SSE loading. These calculations were reviewed during the audit and were judged to be acceptable.

. The facade structure is supported horizontally from both the containment and the auxiliary buildings. The licensee's analysis loaded the facade structure with inertial loadings consistent with the design response

, spectra, and then performed a static analysis. No consideration was given i to the stresses which could develop in the facade if the containment and i

auxiliary buildings moved out of phase during a seismic event.

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l BNL performed a study with the objective of establishing the consequences of such relative motion. A three dimensional model of the facade structure was developed for solution with the SAP V computer program. Beam and truss elements were used to model the structure. A sketch of the computer model is shown on Figure 3. The structure was then loaded by imposing the seismic displacements of the containment and auxiliary structure at the points of attachment to the facade. The displacements which were used are listed in.-Table 1 and were determined from the licensee's seismic analyses.

Table 1 SEISMIC DISPLACEMENT IMPOSED ON FACADE Structure Elevation Displacement (inches)

Containment 67 0.533 108 0.629 142 0.750 Auxiliary 85 0.27 108 0.54 Four computer solutions were found for the following cases:

Run 1 Only Containment Displacements Run 2 Only Auxiliary Displacements Run 3 Containment and Auxiliary Displacements in Phase Run 4 Containment and Auxiliary Displacements out of Phase o The deformation patterns for these four load cases are shown on Figures 4 through 7.

The resultant peak stresses in the bracing members are:

Run 1 10.0 ksi Run 2 17.3 ksi Run 3 17.3 ksi Run 4 17.3 ksi o

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l The resultant . peak stresses in the beam members (beams and columns) are:

Run 1 4.0 ksi Run 2 7.4 ksi Run 3 7.4 ksi Run 4 7.4~ksi It is concluded that these stresses are sufficiently small so that the facade structure will not collapse during the SSE event and damage the piping.

4.0 CONCLUSION

'wo concerns regarding the potential of non Category I equipment failing

'aring an earthquake and damaging safety related equipment are investi-jated. The first investigation concerned failure of the condensate tanks.

It is concluded that failure of these tanks will not effect safety related equipment unless they fail in such a manner that water from the tanks will spill through the diesel exhaust structures onto the diesel control panels. It is recommended that the licensee be asked to address this issue.

The seismic response of the facade structure was investigated in detail.

It is concluded that the facade structure will not collapse during the SSE event and therefore presents no safeaty hazard to equipment located near the facade.

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