ML20086U166

Affidavit of W Walsh Re Thin Wall Pipe.Pipe Fittings Larger than Nominal Wall Thickness Assumed by Piping Designers Will Increase Thermal Expansion Loads on Piping Supports & Nozzles

ML20086U166
Person / Time
Site:	Comanche Peak
Issue date:	02/28/1984
From:	Mary Walsh Citizens Association for Sound Energy
To:
Shared Package
ML20086U151	List: ML20086U147 ML20086U166 ML20086U170
References
NUDOCS 8403070181
Download: ML20086U166 (4)

Text

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AFFIDAVIT 01P MARK WALSH On Sunday morning, February 26, while going through the mail n,

which 'had accumulated while I was preparing for the February 20-24, 1984, hearings, I came across an item which applies to the Lygna Report which we need to call to Cygna's, the Board's, and the parties' attention. The item is attached hereto.

The applicable . portion is contained in the Observation Record in the Cygna Report No. PI-01-01. Under 4.0 Potential Design Impact, it states, in part: "For thermal expansion, stress levels will remain basically unchaged (sic), since the loads are directly'related to the thicknesses, while stresses are inversely related."

The informationL I have just received is contained in a letter (and attachment) from George W. Knighton, Chief, Licensing Branch No. 3,' Division of Licensing,'NRC, Washington, to Earl J.

Woolever, Vice. President, Nuclear Construction, Duquesne Light Company, Pittsburgh, Pennsylvania, under subject of " Evaluation oof the.Effect of Overthickness an Pipe Fittings." It indicates that pipe fittings (that is, elbows and tees) that are larger

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than the nominal wall thickness assumed by piping designers will significantly. increase thermal expansion loads on the piping 9

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n supports and nozzles. The NRC Staff stated "The most significant impact of oversized fittings was found in its effect on anchor loads. The effect on anchor loads is important because the equipdent nozzles to which the piping is attached tend to be the limiting component with respect to stress (i.e. the equipment nozzles tend to reach their allowable values prior to the piping reaching its allowable value)." (Attachment to letter, page 10.)

The- Staff further stated: "The thermal expansion loads on the 1 :- piping ' supports tend to increase significantly with oversize fittings.. 'Yhe . average load increased 36%. However, the individual load increases ranged from 8% to 82%. This indicates that. the restraint loads are impacted significantly but is dependent on the piping systee configuration.'? (Attachment to letter, page 11.)

I do not want to change what I had stated in my previous testimony; this is additive 'to what is written in my 2/7/84 testimony on' page 8, lines 12 through 21. I believe that at Comanche Peak, Applicants have used what is commonly referred to as " thin wall" pipe in many instances, and that there are also many instances of minimum pipe wall violations at Comanche Peak.

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In addition, it states in the attached report on page 6 that "The results appear. to indicate that overthickness of elbows is prevalent . throughout the Beaver Valley-2 f acility and is likely to-Lexist in most nuclear facilities today." This is not a new

- issue. However, I believe that Cygna should address it in light 2

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of this new and signficant information, since this was not specifically included in the summary of our cross-examination areas stipplied to Cygna on February 22.

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I have read the foregoing affidavit, which was prepared under my prrsonal direction, and it is true and correct to the best of my knowledge and belief.

(Signed) y /W Date: NN

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STATE OF TEXAS COUNTY OF MLMM On this, the 28th day of February, 1984,= personally appeared before me Mark Walsh, known to me to be the person whose name is subscribed to the foregoing instrument, and acknowledged to me

-that he executed the same for the purposes therein expressed.

Subscribed and sworn before me on the 28th day of February, s

1984'. *

/ a n o g:G? /m ar m Notary Public in and for the State of Texas My Commission Expires: .c 0_-sd W &#

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/jgcarg UNITED STATES

! I g[o,o, NUCLEAR REGULATORY COMMISSION e ,1 WASHINGTO N, D. C. 20555

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Docket No.: 50-412

& 27 W Mr. Earl J. Woolever Vice President, Nuclear Construction Duquesne Light Company -

Robinson Plaza Building No. 2, Suite 210 PA Route 60 Pittsburgh, Pennsylvania 15205

Subject:

Evaluation of the.Effect of Overthickness in Pipe Fittings In a letter dated July 26, 1983, the Director of the Division of Project and Resident Programs, Recion I USNRC requested thatuthe Office of Nuclear Reactor Regulation (NRR) review and evaluate the significance of using heavier walled pipe fittings in safety-related systems at BeQa ar Valley-2,

_ Hope Creek, and Limerick. In addition, NPR was requested to review 707- -

Duquesns Light, Beaver Valley-2's resolution to the oversized fittings and t

evaluate its acceptability.

On October 25, 1983, you provided your resolution of the issue. The staff has reviewed the resolution and finds that the data presented in your report provides a suff

. fittings _on seismictresses s.icient basa_is_to is not sa_fetyconclude concern. that the ef.fect_of_

However, the staff oversized believes that'foTfr~Yeport has not suff'1clentry demonstrated the acceptability of the effect of. oversized _f.ittings on equipment nozzle loads, piping i

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restraints, and,_JL_pi_ng

~ other than tees and elbows foFthermal expansion load ~iligs. -"- -=

Attached for review and resolution is the staff's evaluation of your sub-mittal and the actions required to resolve the issue. A meeting is currently being arranged.to discuss the staff's draft Safety Evaluation Report on Mechanical Systems. At this meeting the staff would also like to discuss the issue of overthickness of pipe fittings. The Licensing Project Manager will make the arrangements for this meeting with your staff.

C// /

h George W. Knighton, Chief gW */ '.]/

@ l--- Licensing Branch No. 3

~ts / Division of Licensing

Attachment:

As stated cc: See next page - -

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Beaver Valley Mr. Earl J. Woolever -

Vice President, Nuclear Construction Duquesne Light Company ' " '

Robinson Plaza Building, No. 2, Suite 210 -1 .

PA Route 60 P1ttsburgh, Pennsylvania 15205 Gerald Charnoff, Esq. Mr. H. M. Siegel, Manager Engineering Jay E. Silberg, Esq. Beaver Valley Two Project Shaw, Pittman, Potts & Trowbridge Duouesne Light Company "

1800 M Street,-N.W. Robinson Plaza Building No. 2 Washington, DC 20036 Suite 120 i PA Route 60 Pittsburgh, Pennsylvania 15205 Mr. C. W. Ewing, Quality Assurance Zori Ferkin Manager .

Assistant Counsel Quality Assurance Department Governor Energy Council

. Duquense Light Comoany 1625 N. Front Street

- P. O. Box 186 Harrisburg, PA 15105

. Shippingport, Pennsylvania 15077 Mr. R. J. Washabaugh BV-2 Project Manacer Duquense Light Comoany Director, Pennsylvania Emergency Robinson' Plaza Building No.'2 Management Agency Suite 210 Room B-151 Pittsburgh, Pennsylvania 15205. Transportation & Safety Building

. Harrisburg, Pennsylvania 17120 Mr. T. J. Lex Mr. Thomas Gerusky Westinghouse Electric Corporation Bureau of Radiation Protection Power Systems PA Department of Environmental P. O. Box 355 Resources Pittsb'urgh, Pennsylvania 15230 'P 'O. Box 2063 Harrisburgh, Pennsylvania 17120 Mr. P. RaySircar -

Stone & Webster Engineering Corporation BVPS-2 Records Management Supervisor

-P. O. Box 2325 , Duquesne Light Company Boston, Massachusetts 02107 Post Office Box 4 Shippingport, Pennsylvania 15077 Mr. Glenn Waltnn -

' U. S. NRC John A. Lee, Esq.

P. 0.zl81 Duouesne Light Company

-Shippingport, Pennsylvania 15077 1 0xford Sentre 301 Grant Street Mr. . Thomas E. Murley, Regional Admin. .Pittsburgh, Pennsylvania 15229

.. U. S. MRC, Region I 631 Park Avenue. -Ms. Susan L. Hiatt King of Prussia, Pennsylvania 15229 OCRE Representative 8275 Munson Road Mentor, Ohio 44060 g G S l . .

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s Mr. E. F. Kurtz, Jr. , Manager ' '

• Regulatory Affairs . !. .

Beaver Valley Two Proiect Duquense Light Company Robinson Plaza Buidling No. ?

Suite #210 PA. Route 60 Pittsburgh, Pennsylvania 15205 ,, -

Dr. Judith H. Johnsrud Co-Director and Legal Representative

= Environmental Coalition on Nuclear Power 433 Orlando Avenue

State College, Pennsylvania .15066

^ Mr. Ralph F. Walker 1518 Fifth Street New Brighton, Pennslyvania 15066 Mr. George S. White Box 58.

Shippingport, PA 15077 5

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. STAFF EVALUATION OF THE EFFECT OF OVERTHICKNESS IN PIPE FITTINGS f-r I INTRODUCTION ,, -

Wrought steel butt welding fittings made according to the requirements of the

ANSI B16.9 or ANSI B16.28 standards have been used for many years in piping systems, including nuclear power p ats, and have generally given satisfactory service. It has recently become apparent to the staff that the actual wall

, thickness of elbows'and tees made to these standards is consjderably larger than the nominal' wall thickness assumed by piping designers in their design Lanalyses. The purpose of this report is to address the significance of over-

thickness in pipe fittings when used in safety-related piping systems and

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- their effect on the calculational results of the piping design analyses.

II . BACKGROUND

- In May 1983,'during a routine safety inspection of.the Beaver Valley Power A . Station Unit 2 conducted by the NRC Region I staff, a potential concern was

identified regarding the overthickness of elbows and teos in the etergency diesel generator exhaust piping system. The actual wall thickness and we g ,

of cibows' and tees used in the installatico were about %the_astminal values used in the procurement specifications and design analyses.

' Subsequently, NRR was requested to review and evaluate the significance of using overthickness pipe fittings in the safety-related systems at Beaver

, Valley-2 and to address the generic significance of this issue.

e On. July 27,,1983 the NRC staff (NRR.and Region I) and its consultants from Oak

Ridge National, Laboratory met with representatives from Duquesne Light Company co add Stone' & Webster Engineering Corporation to discuss the applicant's response to the: inspection finding. A summary of the meeting is discussed in Reference 1.

At the: conclusion of the meeting, the applicant proposed to provide a report to '

the staff' addressing the influences of overthickness pipe fittings on the diesel s

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7y generator exhaust system and the generic influences of these fittings on the -

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p In a letter from E.J. Woolever (DLC) to R.W. Starostecki (USNRC) dated Octooer 25, yk y

1983, the applicant transmitted its final report to the staff addressing the @

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... issue of overthickness fittings. The staff has reviewed the October 25, 1983

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G N. report and has based our evaluation on the results presentec in that report. --

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Our evaluation is discussed in detail in Section V of this report. Y w.

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?;].. Bef. ore addressing the significance of the overthickness pipe fitting, it would [;<.

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be beneficial to discuss some of the underlying factors which might have contrib- T[

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13.1 uted to the as-manufactured condition of the overthickness fittings. We will $; -

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?>K briefly discuss the dimensional controls established by current standards and 3,;

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. .j* . i some common manufacturing practices that are used by several pipe fitting '.4.f.e y .pr manufacturers. m!;.

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Ze7^ III DIMENSIONAL CONTROLS D.

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The ANSI B16.9 standard covers long radius elbows, tees, crosses', lap joint j-

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stub ends, caps, and reducers. ANSI B16.28 <. overs short radius elbows. Fittings jy..

fJ. made to these standards are usually accepted without additional requirements. f.'

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.f' Design requirements including the rules for the design and analysis of ASME Code

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p. {..y Class 1, 2, and 3 piping systems are contained in Subarticles NB/NC/ND-3600 of Pg e.

. Ud . the ASME Code (Reference 3). The ASME Code accepts the use of B16.9 fittings and Y, v ..s .

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.s B15.28 short radius elbows provided the wall thickness of short radius elbows  :.4 g

6. ' w g} meet the additional requirements of NB-3642.2 for ciass 1 piping systems. For

.4. t. " .-: Class 2 and 3 piping systems, the Code considers butt welding elbows to be

j .. j suitable for use with pipe of the same nominal wall thickness and of the same rg.

I; * $ . material. Design analysis formulae, stress indices, stress intensification W e.

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). i factors, and flexibility facters are based en the assumption that the dimensional j

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characteristics of the fittings are within reasonably close tolerance to those j,.

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fe [.$ specified in the ANSI standards. Neither of the standards, however, give '.[

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characteristics that are important for_an accurate design stress analysis.

- Thus,;the piping designer does not have complete assurance that fittings purchased under the standards will be compatible with the metho'd'of analysis specified in NB/NC/ND-3600 of the ASME Code.

Prior to 1977, the dimensional controls contained in the butt welding fitting standards consisted of: -

a) center-to-ends or _ overall length, with tolerance, b) outside and inside diameters'at the an*dt, with tolerance,

-c). angularity tolerances for the end plan'es., and d) minimum wall thickness requirements. (Ref. 4)

For" design stress analysis purposes, an important dimensional characteristic not controlled was the maximum wall _ thickness (except at the ends by diameter

-control). .Until 1977,-none of the butt' welding fittings standards contained an over-tolerance on wall. thickness-or weight. In the 1977 Edition of Manufac-

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1turing Standardization Society (MSS) standard practice SP-87 a requirement was added to control' the actual thickness of pipe elbows and tees. The MSS-SP-87 standard in Chapter 8 states:

- 8.1.3 The actual thickness of the elbows may not exceed 1.25 times the nominal ' wall, except as follows:

a). For short ' radius elbows', since the nominal wall must be increased by 20%.to compensate for shape, the actual thickness of this~ elbow may not exceed 1.5 times the nominal wall. -

b)- _For elbows with a counterbore or other close tolerance internal machining, the thickness-must be increased to provide mater _ial for these additional machining operations.

'For these elbows, thickness up to the next higher schedule than the nominal wall may be used. Where there is no next_ higher schedule the wall may not be thicker than

, _ 1.33 times the nominal wall. For short radius U bows,

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. 'the'next higher schedule above the adjusted -

nominal wall may'be used, or where there is no ,, , ,

next higher schedule the wall may not b1 thick'er' than 1.33. times the adjusted nominal-wall.

Furthermore, for tees the MSS-SP-87 standards states:

8.2.4 The actual thickness throughout the body except in the crotch may not exceed 2 times the nominal wall thickness of the matching run pipe.

The-MSS-SP-87 standard-was subsequently adopted by the ASME Code in the Winter 1978 Addenda (issued December 31, 1978) in its reference to the MSS-SP-87

-. standard oer Table NB-3132-1. However, prior to the MSS-SP-87 standard, there

[ were no standards which controlled overthickness in pipe fittings.

- As a' result, a schedule 80 elbow taper-bored on the ends to schedule 40

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dimensions could have fully met the fitting-standards. However, from a piping.

system analysis standpoint, the wall thickness value which was used to calcu-

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late .the flexibility factor (k), the ' stress index (C ),2 and, the stress inten-Jsification factor (i)'would have been incorrect. The significance of using nominal values versus actual dimensions is discusse'd in Section V of this report.

- I MANUFACTURING PRACTICES Subsequent to the July 27, 1983 meeting.with Duquesne Light Company and Stone

& Webster (SWEC), the staff consultants surveyed several manufacturers of pipe fittings and,briefly discussed our concern with overthickness of pipe elboss.

LThe. manufacturers were asked if they knew of any reasons why elbows for nuclear Lpowerf plant piping would tend to be thicker than the nominal wall thickness.

-The following manufacturers were contacted (Reference 5).

' 1) - . Tube-Turns 2)' Taylor Forge

13) Crane' ,

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4) Ladish -

5) -Flowline . __ ,

The answers provided were as follows:

(1) If elbows are ordered to be counterbored, it is common practice to

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use the next available heavier wall thickness to assure minimum --

wall ~. All except Taylor Forge cited this cause; Tube Turns had some maybe's.

(2) Depending upon the manufacturing practice, the wall thickness of elbows may be thin in the back region, thick in the crotch region.

-The starting material must be increased to compensate for the

. thinning. In elbows for nuclear power plants, the manufacturers are very aware of " quality control" and they may go heavier to make absolutely sure they will not have under-thickness. All except Tube Turns mentioned this.

(3) Raw material availability is an increasing problem. Let us suppose an'd elbow manufacturer wishes to start with a raw material that is

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10% thicker:than nominal'. Let us suppose that nominal is 0.375" so the. manufacturer wants to get pipe or plate with wall thickness of 1.1 x 0.375 =-0.412 in. Can the elbow manufacturer get that thickness in pipe or plate? Pipe and plate manufacturers, in streamling their

' operations, are becoming less willing to supply small quantities of.

" odd ball" wall thickness. Accordingly, tha elbow manufacturer may

-be forced to use 0.500-in. wall pipe or plate. All five manufacturers mentioned this aspect.

4 (4) Buckling of large D/t elbows. Taylor Forge mentioned this although

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Ladish perhaps should have since it may be particularly relevant to the 38x0.375" nominal wall elbow at Beaver Valley-2. In making

. elbows with large D/t, it may be necessary to increase the wall thickness to prevent buckling (wrinkling) of the elbow.

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From~ the, informal discussions described above, the staff has fcund that: .

(a) Ifelbowsareorderedwithacounterbore(ANSIB16.2h' standard C-dimension), the chances are high that the wall thickness will be significantly (30% or more) greater than nominal.

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(b) Elbows for nuclear power plants are a' bit more likely to be over- -

thickness because of more concern about having under-thickness.

(d) Decrease in raw material availability of various sizes tends to lead

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toward increased elbow wall thickness. This applies to non-nuclear as well as nuclear piping.

- Thus, it appears that in recent years pipe elbows have become progressively thicker. .The staff took a few actual measurements of randomly selected pipe

- elbows and tees at the Beaver Valley-2 facility. The measurements were taken with a portable ultrasonic testing device (NORTEC NDT-131 Ultrascope).

- Attachment A to this report'_ summarizes the wall thickness measurements obtained

~at Beaver Valley-2. The results appear to indicate that overthickness of elbows is prevalent throughout the Beaver Valley-2 facility and _is likely to exist in most nuclear facilities today.

V SIGNIFICANCE OF OVERSIZED PIPE FITTINGS

.The applicant for the Beaver Valley-2 facility has provided the staff with a report entitled, " Structural Review of Piping Analysis Including Effect on

. Heavy Elbows," dated October 1983 (Reference 6). The report presents the cany

.conservatisms inherent in the analysis of piping systems. The report also presents the results of a generic study performed on four sample pipirg models.

. The. conclusion of the report is that the data presented in the study "provides a sufficient basis to conclude that the current design methods, which use SSE

. ARS having 1 percent-of critical equipment damping and nominal standard weight

. fittings, will yield conservative pipe stress results and conservative pipe s

. support 11oads. "

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The staff has raviewed-the applicant's report and has found that the report -

.contains a considerable amount of detailed results comparing M e loads and ,

' stresses for three different cases;.1) standard fittings, 2) heavy fittings, and 3) extra heavy fittings.

The " standard fittings" models used the nominal wall thickness of elbows and

' tees that would,normally be used.in piping design analyses. The "neavy fittings" -

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models used a value for the fittings equal to twice the nominal wall thickness.

The " extra-heavy" fittings" used a value for the fittings equal to three times the nominal wall-thickness. The staff believes that the models for ." heavy _

, fittings" (2 x nominal-wall thickness) are likely to be bounding for the fittings installed in the Besver Valley-2 facility.

D l ' The applicant's ' report contains the results.for i

[ '. 1) pipe stresses,

2) anchor. loads, and

3) support loads.

?The.results include the loads resulting from thermal, weight, and seismic loadings. However, the staff finds the report.to be , inadequate because the .

• -results have not been aporopriately evaluateo by the applica_nt (neither-

quantitatively ~nor_ qualitatively)...The report draws its conclusions-based on

the many conservative assumptions used in piping dynamic analysis. However, the report does not explicitly address the' significance of the tabulated

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results. -Furthermore, the conservatisms/used in static (weight and thermal) analysis, methods are not suf.ficie.ntly discussed.

~ 1 Consequently, the staff has interpreted the " raw data" provided in the'appli-M- cant'sfreport. Using'.the tabulated. values provided in the report (Figures 7.9

through.7.38 of. Reference G),.the staff has calculated the average increase or l decrease in' piping stresses, . anchor loads, and restraint loads that could result from using oversized fittings. The evaluation was performed for thermal,

weight,1and seismic loadings.

The results are summarized in Attachment B to Ethis report.' .

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LThe average load change was cal.culated as fcllows: (e.g. for " heavy fittings") _

heavy fittir.os value - standard fit.ings vilue -

load change'= standard fittings value

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Thus, a positive load change indicates that the heavy fitting results in a load increase. A negative load change indicates that the heavy fitting results .,.,

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in a load decrease. The load change'is defined as the " percent change divided

. by 100." The' load change was calculated for all the node points provided in the applicant's report. tables. The " average load change" was calculated as follows and is simply the arithmetical mean of the load changes:

Average-Load change. = -I x n

where n = total number of node data points provided for the particular evaluation x = load change for a specific 2, a node point A detailed:avaluation of each' of the selected components and their loadings is discussed in the following sections with regards to.the significance of using

. oversized fittings. We 'will discuss only the effect of " heavy" fittings.

Pipe' Stresses'(Thermal)

The effect of " heavy" elbows and tees on piping system stresses subjected to

. thermal loadings tend to decrease such stresses-in the fittings when the piping system is modelled with oversized fittings. The average decrease was 35%. The: decrease:can be attributed to the larger _ moment of inertia of the elbow and tee' cross-sectional area due'to the increased thickness.

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For straight pipe and anchors, the thermal stresses-i_ncreased significantly_. -

For: straight pipe, the average stress' increase was 43% whereas,,_for piping ,

. connected to anchors, the average thermal stress increased 40%.-' For the straight pipe the individual stress- change values were either very high or very low'which resulted in a large . standard deviation valte of 0.63. This would indicate that the effect of the eversized fittinas on__s.traight_ pip _e_is_a

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.Pioe Stresses (Weicht) ti ~

!For. elbow and tees, the pipe stresses due to the weight loading tend to decrease approximately:33%. The load change was very similar to the thermal load change (35%) and is .also likely to be attributed to the increased moment

. of' inertia.

For straight pipe and anchors, there was a small increace in the pipe stresses.

J Individual load-changes were either very large or very'small which resulted in a large standard deviation .value of 0.32. However, the actual stress magnitude n

vasl generally-found to be a small:value when.the percent stress-increase was large-(i.e. a 50' psi stress increasing to a 100 psi stress would be shown as a i100% increase although the 50 and 100 psi values are relatively low stresses). .

The staff" concludes-that the effect of the increased weight of the oversized (fittings could be~ significant_when an equipment nozzle, to which the piping is attached. .has ai very low allowable value. Otherwise, the effect is considered

minimal.

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' ' Pipe Stresses (Seismic) q

-For seismic loadingss the staff reviewed only the results where a flat amp,li-

fied reponse -spectrum (ARS) was used. The BVPS-2 ARS results were not evaluated

' lbecause the' steep slopeslof'the ARS peaks would tend to cause large-differences

.in the results. Thus, if the_ staff.had used the BVPS-2 ARS, the staff would

_ not have been able'to. determine whether the. increase or decrease in the load change were caused by--the modal frequency shift on or off the spectrum peaks py .

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.. or were caused by the difference in the oversized fittings. By using the . s results from a flat ARS, the load changes can be attributed only to the use of oversized fittings. - -- -

The seismic results indicate that for all piping stresses, the effect of over-sized fittings is not significant and.will decrease in elbows and tees. The small increase in straight pipe stresses is likely attributed to the small f~

increase in the weight of the oversized fittings. However, the staff does not believe the small increase is significant.

Anchor Loads (Thermal)

The most significant impact of oy_q.rsized fittinos was found in its effect on anchor loads The effect on anchor loads is important because the equipment nozzles tc which the piping is attached tend to be the limiting component with respect to stress (i.e. the equipment nozzles tend to reach their allowable l values prior to the piping reaching its allowable value). The staff found that the average thermal expansion load on the anchors tends to increase 40 to 50%. This;1arge increase is attributed primarily to the intrgased stiffness (or conversely, a decreased flexibility) in the pipe elbows. The staff considers tne effect to be s.ignificant.

Anchor Loads (Weicht)

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For anchor loads, the increase in the force due to the added weight of over-sized fittings was found to be insignificant. The moment load was found to increase very.slightly. As in the piping stress at anchors described above, the moment load percent increase was. either very large or very small. However, when the percent. increase was found to be very large, the actual magnitude of the moment load was found to be a small value. Thus, the overall effect of

~ the increased weight on anchors is not significant unless the anchor (equip- _ __

ment nozzle) allowable load value is very low.

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' Anchor Loads (Seismic) -

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'The effect of oversized fitting for st .; 's on archors waY found to be insignificant. The sverage load increastd approximately 10%. The increase is likely to be attributed to the increase in elbow mass.

Restrah t Loads (Thermal) ."

The thermal expansion loads on the piping supports tend to increase significantly with oversize fittings. The average load increased 36%. However, the individual load increases ranged from 8% to 82%. This indicates that the restraint loads are impacted significantly but is depend,ent on the piping system configuration.

, The results appear to be similar to the effect of oversized fit ings on the stress in straight pipe.

. Restraint Loads (Weight)

-The staff found that the effect of the increased weight of oversized fittings is-insignificant for the pipe support loads. The average load increase was found to be 3%.

r Restraint loads (Seismic)

The effect of oversized f.ittings on the seismic support loads was found to be insignificant. Using the results for " flat ARS" the staff found an average load increase of A%.

VI CONCLUSIONS AND REQUIRED ACTIONS The staff has reviewed and evaluated the results of the analyses performed by

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the applicant which was provided to the staff in its October 25, 1983 letter.

The staff r6 cognizes that many conservative assumptions are used in. dynamic piping analysis methods. However, based on our review of the analysis results, the staff has found that the effect of oversized fittings on seismic loadings is-insignificant. Thus, the staff does not believe that there is a safety concern with respect to the effect of oversized fittings on seismic loadings. _~

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g + ._ _...

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l?: JForithermel expansion loadings, the static analys'is methods do not employ .

-large; uncertainties; typically found in seismic' analysis methods. The values L  :

used to-calculate thermal expansion are reasonably accurate ( 10%) and the analysis is relatively straight-forward (Reference 7). However, the staff b  : recognizes that the modelling of anchors (equipment nozzles) with an infinite stiffness value is conservative. - For those cases where equipment nozzle loads are near their allowable value, the applicant should verify with the vendor that the potential increase in thermal losds will not result in an unacceptable overloading of the equipment nozzle.

~ Action:

The staff requires that the applicant address the impact of thermal ex-pansion-loads on'the equipment nozzles and provide the basis for assuring ~

that any signifirant increase will not impair the ability of the equipment to perform its safety-related function.

-For restraints and piping other.than. tees and elbows, the staff believes that the effect of secondary (self-limiting) stresses due to restraint of thermal

' expansion can be shown to~be acceptable because of local yielding or redistri-bution of stresses.

A_ction:

The staff requires that the applicant address the impact of the effect of

" heavy" fittings on thermal expansion stresses for restraints and piping other than' tees and elbows.

f o Therefore, based on an acceptable resolution of the above identified concerns,

"" the staff believes that the issue-regarding the use of oversized pipe fittings can be acceptably-resolved.

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REFERENCES _

1) MemorandumfromD.TeraotoR.BosnakdatedAugust18,19h3. '

2) NUREG/CR-1677, " Piping Benchmark Problems," (Volume 1) dated August 1980.

3) ASME Boiler and Pressure Vessel Code,Section III, Division 1, " Nuclear ...

Power Plant Components," 1977 Edition.

4) _ .Rodabaugh, E.C. , Moore, S.E. , and Robinson, J.N. , " Dimensional Control of Buttwelding Pipe Fittings for Nuclear Power Plant Class 1 Piping Systems,"

ORNL/Sub/2913-5, Oak Ridge National Laboratory, December 1976.

5) Letter from E.C. Rodabaugh to S.E. Moore (0RNL) dated August 10, 1983.

6) Letter from E.J. Woolever (DLC) to R.W. Starostecki dated October 25, 1983 6 ~w ith attachments.

7) .Rodabaugh, E.C., " Sources of Uncertainty in the Calculation of Loads on Supports of Piping Systems," (DRAFT) (Work funded by the USNRC).

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_ - _ _ - _ _ _ _ _ _ - - - _ . _ _ _ - _ _ _ _ _ _ _ _ - - _ _ _ - - _ - - - - , , - - _ - - - - - - - - - - = _ - - - - _ - - - - - - - - - - - - - - - - - -

i _

- :- ATTACHMENT A _

WALL THICKNESS MEASUREMENTS l

BEAVER VALLEY-2, JULY 27, 1983 Component- Manu- Mat- NPS Nom. Measured Wall (a) , in. t avg /t nom

! facturer erial Wall , n. 1 2 3 (a) 90* El Ladish C 6 0.280 0.501 0.453 0.422 1.64 90* El B&W C 6 0.280 0.565 0.530 0.437 1.82 90* El Flowline S 6_ 0.718 0.881 0.720 0.711 1.07

- CO* El'S.R. Flowline'

, S 6 0.718 0.884 0.785 0.695 1.10 90* E1 Ladish C 16 0.843 1.136 1.150 1.043 1.32

' 90* E1 Ladish C? 4 0.337 0.503 0.484 0.444 1.42 90* El Flowline S 12 0.375 0.639 0.585 0.512 1.54 90* El Flowline S 10 0.365 0.568 0.499 0.437 1.37

~ Tee Flowline S 12 0.375 0.467 0.514 0.596 1.44

. Tee (D)' 'S 14 0.a38 1.12C 2.56 90* El(b) S 14 0.438 0.607 0.496 0.485 1.18

-(a)

J \

euw: .@ Tee t @ ,O.e 3)- -.a nu

= 0. 319 '

D

'(b) ' Dimensions previously measured and cbtained from Glen Walton, Sen. Res. Insp. (NRC), Beaver Valley-2.

a i.--...g ., ..

y- .

'~* .6*'

..f.

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ATTACHMENT B _

COMPARATIVE RESULTS FOR OVERSIZED FITTINGS . ,[

Average Load Change System Component Trend (% + 100)

Pipe Stresses Thermal Heavy X-Heavy elbows / tees decrease -0.35 -0.50 ,.

straight large increase (1) 0.43 0.75,

,' 0.55 anchors (pipe) large increase 0.40 Weicht -

elbows / tees- decrease -0.33 -0.44 straight. small increase (2) 0.33 0.56 anchors -small increase (2) 0.53 0.89 Seismi.: (flat ARS) elbows / tees. decrease -0.62 -0.75 straight -

small increase 0.16 0.27 anch9rs insignificant -0.002 0.06 Anchor l'oads f7" Thermaf'~

gl ~3I~c'e large increase 0.50 0.70

. Moment large increase 0.42 0.56 Weicht- )

Force . insignificant ((2) 0.04 0.09 Moment small increase ~0.38 0.53 Seismic (flat ARS)

Force insignificant 0.10 0.18 Moment' insignificant 0.08 0.17 Restraint Loads .

Thermal large increase 0.36 0.51 Weight insignificant 0.03 0.06

-Seismic (flat'ARS) . insignificant 0.04 0.06 Notes: .

(1) Individual values are typically either very large or very small.

.(2) Individual % change values are typically very large or very small, however, the actual stress (or moment) is usually a small value when the % is large.

(3) One data point was not consistent with other results and is neglected.

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