ML19276H631

Interim Deficiency Rept Re Use of Invalid Seismic Amplified Response Spectra in Design of safety-related Components. Contractor Is Redesigning Containment Annular Steel Frame. Contractor 791106 Ltr Re Deficiency Encl

ML19276H631
Person / Time
Site:	Seabrook
Issue date:	12/06/1979
From:	PUBLIC SERVICE CO. OF NEW HAMPSHIRE
To:
Shared Package
ML19276H630	List: ML19276H629 ML19276H631
References
NUDOCS 7912120466
Download: ML19276H631 (9)

Text

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O Public Service Company of New 11ampshire Scabrook Starion Interim Report en Use of Invalid Scismic A:aplified Response Spectra Date: Decc:abe r o , 1979 M

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i Scabrook Proicct Inticim Report on Use of Invalid Seismic Amnlified Resnense Snectra Introduction on Tuesday, November u, 1979, Mr. J. Devincentis, Seabreak Project Manager for Yankee Atomic Electric Company, . reported by teleritanc to Mr. J. Mattia, NRC Region I Inspection and Enforcement inspector for the Seabrook Project, two significant design deficiencies under 10 CFR50.55(c). YACC had that same day received written aotice of the two deficiencias from the Scabrook architect-enginecr-construction manager, United Enginects & Constructors Inc., under UESC letter numbers SBU-31426 and SCU-31428.

The purpose of this report is to provide in t e ria, infarination ca one of those reported deficiencies; namely, that identified ta SEL'-31426 (sce Attachment 1) involving the use of incorrect seismic amplified response spectra (ARS) in the 'ign of components supported by the containment building annular steel frame.

Structural Descriotion of Containment Bui. ld iut; For plans and clevation arrangements of the Seabrook containment building internals, refer to Seabrook PSAR Figures 1.2-2 through 1.2-6.

We following is a brief description of the Seabrook contaituaent building and tis internal structures:

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Structural Description of Containment I:n i Id i ne. (Co n t ' d )

The Containment Shell is a reinforced concrete cyllader eita an he:.:L-spherical dome, both lined with carbon steel plate. Se contain:nent con-crete internals consist of the pritaary and secondary shield vallu, support-ing columns for the gantry cranc, the refueling caaal and ficor :, labs at elevations 25 ft. and 0 ft. The Containment Sitell and Internala are connected to the foundation mat which is founded on rock. The working floor slab at the bottom of the containment is at El. (-) 26'.

The s tructural stec i frame involved in this detinn deficiency u., the annular steel frame located inside the contatnment building in tne annular space between the containment secondary shield wall and the contait= cat cuter shell.

The annular steel frame consists of steel columns and platf.:rm f ra :-

ings at elevations 25 ft. and 0 ft. It also has framings at various ic, ;e r clevations which are essentially utilized for pipe supports. Severai radial beams of the annular steel framing are rigidly connected to the F

containment secondary shield wall.

Desien Deficiencv

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In late September 1979, a UE&C employee assigned to perform the seismic response analysis of Safety Class 2 and 3 piping in the containment building (including piping running in the annulus, supported by the structural steci framing) was reviewing tiic file of Scabrook Amplified Response Spectra (.\RS) for the proper input to his particular analysis. lie came upon the document se 1

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Design De fici ency. (Cont 'd) i entitled "Sei.smic Analysis of the Annular *; teel", with toe unique Menti-fication nu:uber SCSAC-14CS, dated October 7, l977. in reviewing the

' contents of this document,*the analyst determined that certain af the A s for portions of the annular structural steci in that document had consid-erably higher "g" values that those used as input to previous analyses of Safety Class 2 and 3 piping supported by the saue annular structural steel.

Further investigation revealed that the seismic analyscs of Safety ,

Class 2 and 3 lines in the same area performed to that time used as input ARS extracted from a document, entitled "Scismi.e Analysis of Containment Structure", with the unique identification number S3 SAC-4CS4, dated 3/19/76.

This document presented the ARS for the reinforced s ancrete contair ent outer shell and the interior concrete structures including the secem!aq.

shield walls. The ARS values contained in this c.;ocument arc, in p neral, lower than the previously mentioned document since, by their nature, concrete structures in general are stiffer than structural steel structures.

fhe immediate design deficiency was, therefore, thac Safety Class 2 and 1 piping systems were scismically analyzed using incorrect, low values of ARS. The possibility exists, therefore, that had this deficiency not -

been revealed, one or more of the piping systems in question would be over-stressed under maximum scismic and operating loadings.

Corrective Action

l. UESC is conducting a short-term audit of selected setumic Category I systems and components to assure use of correct A::plified Response 2,

Spectra in their scismic design. ..

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s 4-Corrective Action (Cont'd)

2. Containment building annular .tect f ra:ue ia being redeaig.ed to increase its rigidity. The intent is to reduce the valuca of the ARS imposed on the piping systems and other componentu supported by the annular steci frame.

3. A "110LD" has been placed on the design and analysis of piping systems located in the containment annulus.

4. UE&C will conduct a longer term audit of all seismic Category I systems and components to assure use of currect ARS in their seismic destga.

5. When the redesign of the annular s teel f raming is comple te , a scismic analysis of it will be performed, generating ntw .iRd at significant individual points.

6. Existing analyses of Safety Class 2 and 3 pipint, running in the containment annulus will be reviewed against ARS generated in 5

1. 5 above. Where necessary, piping will be reanalyaed to assure conformance with applicable Code and regulatory requirements.

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7. UE&C is currently reviewing the seismic design requirements of all other components supported by the containment annular steel frame. They are the followtug:

a. Containment Recirculating Air Units : ,

These would be used for post-LOCA hydrogen mi::ing and are Safety Class 3.

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Corrective Action (Cont'd)

b. Containment Cooling Units:

Thrse are non-sdfety-related, non-sciumic Category *..  !!uwe v t. r ,

they util be seismically designed since they are located in a seismic Category I building,

c. Hydrogen Recombiners:

There are two thermal-type recombinces mounted on the annular secci frame. They are safety Class 3, seismic Category I.

d. Cable Trays and hcir Support Systems:

Tray supports are scismic Category I.

e. Heating, Ventilating and Air Conditioning Ductworx. Syste.ui:

These are a mixture of Category I and non-Categorj I qutem: . .

f. Air Compressors:

Two small non-Category I units for inutrumentation anl control supply.

8. Existing UE&C procedures involving scismic deui.gn, especially those treating Amplified Response Spectra, are under review to determine the need for revisions or additions which will upgrade them in areas of selection, use and review o f ARS.

9. Quality Assurance training sessions, in addition to thoue the regular schedule, are planned on the subject of ARS t rea ta:e n t for all UE&C personnel who interface with ARS.

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Construction Stntus

'the Seab rook cont ainment buildity,, linit 1. structor.il m.i t anti till mat have been poured. Ibe cylindrical shell liner plate h.is bu s, erected to El. 119'-0". Internal concrete, including primary and seconuary shield walls, are in various degrecs of forming, reinforcing bar installation and concrete pouring to approximately Clevation O'.

The contain: cent annular steel has not beca released for fabrication.

It is anticipated that the aforementioned annular steel redesign work and its scismic ar.alysis will be complete in a timely manner so that the prefab-ricated stccl can be d111vered and crected in accordance zith the prt.sent cons truction schedule - July 1980.

The piping systems analyced using incorrect .\RS have been releawd ;.cr fabrication. Engineering experience and judgement predict that en reanalysis, the geometry and wall thicknesses of these systems util not changu, peta ps only the nu:rber and location of seismic supports. In any case, v.cca.e t ry o f prefabricated piping could be modified in the Cicid. Pipe and other ccmpunent crection in the containment annulus is scheduled o con:nence approximate 1.

July 1,1980, and to continue for a period of about tuo years.

Final Reoort The final report on this subject, including a discussion of any safety implications, and the results of the corrective actions enumerated above, will be complete and issued by June 1, 1980.

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,. D f. ConstnsCtor c irc noe,?C'e L C-r;o'd 30 Soutn 17th Stre t . ..;, . . u c Post Office uox 8r3  %^ : Mm

• Philadelphia, PA 19101 VIA TELECOPIER

!iovember 6, 1979 .

SP.U-31426 file: 3.1.6 Catg:  : ICD

!!o Response Required tir. John DeVincenti s , Project Manager Yankee Atomic Electric Company Scabrook Station 20 Turnpike Road Westborough, Massachusetts 01581 .

Dear Mr. DeVincentis:

Public Service Company of !!cw Hampshire Scabrook Station Discrepancy in the Seismic Design in the Containment Annular Area he purpose of thi s 1ctter is to advise you o f a des t;,n discrepanc ,

in the anplified response spectra used in the scismic desir,n of na:ety

. related components supported by the containment annular steel frame.

It was recently discovered that the analyscs being donc for campo-ncnts supported by the containment annular steel f rame were based on incorrect scismic amplified response spectra. He a:r. ell fied response spectra used for this design was that for the contain.:ent interior con-crete and not the annular steel frame which should have been used.

An evaluation has shown that the amplified response spectra for the annular steel frame has "g" values greater than that used in the compo- ,

nent design. Some o f the peak values are such that it is unlikely a satisfactory component design could be achieved.

Action is currently undervay to redesign the containment annular stee'. frame by providing additional bracing in order to reduce the ";"

values. We desien of all components located in this area will then be checked against the redesigned containment annular steel frame and its resulting amplified response spectra.

The containment steel annular f rame has no yet been released for fabrication and will be held until the additional bracine in desi . ned, ne manufacture of a number of components in this area has been released, but it is not intended to place a hold on these items since it in believed that a satis factory design can be achicved without significant .

changes to the components.

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.S T r.<. . l A Revtbean Company

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if r . Jchn DeVincentis  ;;a./cu:> c r 6, 1979 Project Manager S3U-31426 In order to ensure that other discrepancies do not e:< i s t in tae seismic design, an audit will be performed to ensure that the preper ampli fied response spectra was used in the dest;n of all ite=s on the Scabrook project.

We will keep you advised of our progress in resolving this problen and completing the audit of the other items. -

It is our belief that this design discrepancy is a reportable . t e:::

in accordance with 10 CTR 50.55(c) and it is, t h e r e :~o re , r e c e:=e nd e. '

that it be reported to the fiuclear Regulatory Cent.ission.

Very truly yours,

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ji (.c'k G. F. Cole Project :anager GFC:hr cc: Messrs. John DeVincentis - YAEC - 4L B. B. Beckley - PS;al - 3L J. D. Haseltine - PStal - 1L T. ft. Sherry - YAEC - 1L J.11. Iterrin - PS!al - YAEC Field Of fice - IL O 2

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