ML20138G363

Forwards Staff Evaluation Re Westinghouse Provisions for Live Load in AP600 Seismic Model.Staff Concludes That Westinghouse Has Not Satisfactorily Included Live Loads in Seismic Model

ML20138G363
Person / Time
Site:	05200003
Issue date:	05/01/1997
From:	Slosson M NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9705060271
Download: ML20138G363 (3)

Text

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! -8 May 1, 1997 i I j  :

Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Activities  !

Nuclear and Advanced Technology Division  !

• Westinghouse Electric Corporation P.O. Box 355 j 'Pittsburgh, PA 15230

SUBJECT:

' WESTINGHOUSE PROVISIONS FOR LIVE LOAD IN AP600 SEISMIC MODEL j

Dear Mr. Liparulo:

a i In previous meetings, telephone conferences, and correspondence with the

{ Westinghouse staff, the Nuclear Regulatory Commission Civil Engineering and Geosciences Branch has-discussed the inclusion of live loads in the seismic

! model for the AP600 advanced reactor design. The staff has reviewed your-L recent letters on design changes implemented to address post 72-hour actions  !

i dated March 14, 1997,- and the response to seismic open items dated March 26,

1997. The staff concludes that Westinghouse has not satisfactorily included

! live loads in the seismic model. Enclosed is the staff's evaluation. l l 1 1 You are requested to address the issues concerning live loads in the seismic l j model as discussed in the attachment and previous communications in a time  !

frame sufficient to support the AP600 review schedule. If you have any  ;

3 questions regarding this matter, you can contact Diane Jackson at  ;

j (301) 415-8548.

i .

Sincerely, i

original signed by:

Marylee M. Slosson, Acting Director i

Division of Reactor Program Management

] Office of Nuclear Reactor Regulation j Docket No.52-003

Enclosure:

As stated cc W/ enclosure:

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1 f Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 3

i ~ cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director i Advanced Plant Safety & Licensing Advanced Reactor Programs Westinghouse Electric Corporation Nuclear Energy Institute

! Energy Systems Business Unit 1776 Eye Street, N.W.

t P.O. Box.355 Suite 300

! Pittsburgh, PA' 15230 Washington, DC 20006-3706 Ms. Cindy L. Haag Ms. Lynn Connor {

i Advanced Plant Safety & Licensing Doc-Search Associates

! Westinghouse Electric Corporation Post Office Box 34

Energy Systems Business Unit Cabin John, MD 20818 i Box 355 l Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs i Mr. M. D. Beaumont GE Nuclear Energy j Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 i Westinghouse Electric Corporation San Jose, CA 95125 j One Montrose Metro '

l 11921 Rockville Pike Mr. Robert H. Buchholz 1 Suite 350 GE Nuclear Energy  !

Rockville, MD 20852 175 Curtner Avenue, MC-781 j i

San Jose, CA 95125 '

l Mr. Sterling Franks U.S. Department of Energy Barton Z. Cowan, Esq.

I' NE-50 . Eckert Seamans Cherin & Mellott l 19901 Germantowh Road 600 Grant Street 42nd Floor l Germantown, MD 20874 Pittsburgh, PA 15219 4

l Mr. S. M. Modro Mr. Ed Rodwell, Manager Nuclear Systems Analysis Technologies PWR Design Certification  ;

! Lockheed Idaho Technologies Company Electric Power Research Institute  :

" Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303 i j Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engincer U.S. Department of Energy, NE-42 AP600 Certification

! Office of LWR Safety and Technology NE-50 4 l 19901 Germantown Road 19901 Germantown Road

Germantown, MD 20874 Germantown, MD 20874 a'

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i 4 a l-* Live Load Mass and Desian Chanaes of the Shield Buildina Roof Structure 1 l Due to the Post 72-Hours Actions i

[ The seismic design model for the complete nuclear island structures, systems, J

and components for the AP600 does not include acceptable provisions for live i loads. The staff raised the concern regarding the lack of consideration of

any live load masses in the seismic model of the nuclear island structures in the draft safety evaluation report issued in November 1994, in a letter dated

July 18, 1996, and in several seismic design review meetings that were

! conducted between NRC and Westinghouse. The staff is concerned about the lack i of live load masses in the seismic analyses, and that the change of mass properties due to the inclusion of 1-ive load masses could significantly affect j the seismic responses of the nuclear island. On March 26, 1997, Westinghouse {

submitted a draft of the standard safety analysis report, Revision 12, to  !

l present a live load mass consideration for the global seismic model. The '

I staff must review the criteria of live load mass considerations and its

! effects on the overall seismic model and response used to support the

, March 26, 1997, letter. To date, the staff has not reviewed this information i

in detail. However, the staff believes that the addition of live load masses i to the seismic model will significantly affect the overall seismic responses

of the nuclear island.

I In addition, as a result of the post 72-hour action concerns discussed in i SECY-96-128, Westinghouse recently revised the shield building roof structure i by (1) increasing the maximum water level from Elevation 298 feet to 303 feet,

(2) raising the top of the tank by one foot, (3) reducing the thickness of the tank roof from 24 inches to 15 inches, (4) decreasing the thickness of the j inner tank wall from 24 inches to 18 inches, and (5) adding a nine-inch-deep l l fire water tank comp 0 sed of two stainless steel plates underneath the passive l containment cooling system (PCS) tank roof. Based on its estimation that the affected structural mass decreases by 2-percent in the horizontal direction and increases by 5-percent in the vertical direction, Westinghouse concludes

that these changes are small enough to have only a negligible effect on the

global seismic analyses of the nuclear island structures, and will only have a i small effect on the structural design of the shield building roof. At this

time, the staff does not concur with the conclusion drawn by Westinghouse, because Westinghouse has not demonstrated that the global effect of the design change is insignificant through a comparison of in-structure response spectra I and design of critical sections.

l From the discussion above, Westinghouse should:

5 1. revise the existing 3-D lumped-mass stick seismic model to include the

! mass effects due to the live loads and the increase of water inventory in j the PCS tank at each mass degree of freedom, i 2. incorporate the changes of the PCS tank structure design and revise

! stiffness properties of the shield building roof structure stick model, and i 3. for each of the design site conditions, develop in-structure response

} spectrum envelopes, and determine the impact of the design changes and j live loads to the seismic responses and the design of the nuclear island.

i Enclosure l

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