ML20113A835

Manual Ultrasonic Exam of RCP Flywheel

ML20113A835
Person / Time
Site:	Beaver Valley
Issue date:	11/22/1994
From:	DUQUESNE LIGHT CO.
To:
Shared Package
ML20113A839	List: ML20113A835
References
UT-304, NUDOCS 9606260015
Download: ML20113A835 (28)

Text

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O ATTACHMENT A INFORMATION ON QUALIFICATION OF RCP FLYWHEEL EXAMINATIONS AT BEAVER VALLEY l

9606260015 960614 PDR ADOCK 05000334 P

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i DUQUESNE LIGfr CIMPANY Nuclear Power Division j

Quality Services Unit Quality Services Inspection & Examination Department 1

TITLE:

NDE PROCEDURE 1REBER UT-304 l

Manual Ultrasonic Examination of Reactor Coolant Pump (RCP) Flywheel REVISION 7

PAGE 1 OF 11 l

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01 az~ //-ty4 f PREPARED BY DATE LEVEL TII APPROVAL DATE n-asy (2/r D d - a u,

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QSIE 6IRECIOR T

DATE ANII REVIEW

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OSC REVIER DATE QS MANAGER APPROVAL

' [ FATE h

II W GENERAL MANAGEllt NUCIEAR OPS.

DATE

.EXE E8GE REVISION EFFECI'IVE DATE Entire Procedure 4

January 3, 1991 Entire Procedure 5

November 27, 1992 I

Entire Prrvwhire 6

April 6, 1993 Entire Prrvwhire 7

December 9, 1994

" * ~ ' ' '

,3 e4 J

l 5

Ur-304 Revision 7 1.0 RJRPOSE AND SOX'E 1.1 To provide minim m requirenants for the manual ult M.c straight beam examination of RCP flywheels.

1.2

'1his procedure is intended to meet the ultrasonic requirements of NRC Regulatory Guide 1.14 Revision 1 (Reference 6.1).

1.3

'1his procedure is applicable to BVPS Units 1 and 2.

2.0 EXAMINATION REQUIRDENTS NOTE: When using Ultragel II muplant, safety gla m or goggles are required.

Individuals that are sensitive to detergents should wear gloves.

2.1 Ensure contact surfaces are clean and free frun all foreign matter, pits, nicks, or dents, etc., that would adversely affect or limit the examination.

If such mnditions are noted, correct than prior to conducting the examination.

2.2 Examine the entire volume of the RCP flywheel to the mavi=wn extent possible. Attach a drawiry of any limitations encountered to the Flywheel UT Examination Report (Attachment 7.1).

2.3 Prior to beginnirq examinations, calibrate the ultrasonic instrument sweep to represent a linear 40 inch longitudinal wave sourd path.

'Ihis may be acocmplished using a carbon steel IIW block and the straight beam search unit specified in Para. 5.2.2.

2.4 Feyway Corner Examination.

2.4.1 Calibration A.

Apply muplant to one of the 1 inch diameter gage holes (A,

B, C or D for Unit 1; A, B, C, D, E, or F for Unit 2).

B.

Insert the gage hole probe into the hole and direct the beam t w ard the flywheel center bore hole.

1 C.

Maamns the distance fran the gage hole to the center bore hole.

Adjust the delay control SDly to position the.

response at the proper sweep position correspciding to the physical maastu.eient.

D.

Obtain the maximum response fran the center bore hole and adjust the gain to bring the respcraie to 80%

( 5%) FSH.

2

l i

h Ur-304 Revision 7 E.

Record the instrument gain setting and reflector sweep l

position on the Flywheel Ur Examination Report.

j

)

2.4.2 Examination i

f A.

Increase the instrument gain a mininum of 6 dB.

B.

Starting at the top of the gage hole, rotata the probe j

from the

=v4== bore signal area to obtain the

]

=v4 = = response fran the keyway corner, then back to the bore response.

Continue to examine the full length of the keyway by inserting the probe in 1/2" j

ir m.ats.

C.

Examine the keyway cornars for indications propagating

{

sound path.

~

90 degrees to the i

fran the keyway at approximately l

D.

Repeat the entire calibration and examination cycle j

from endt of the remaining gage holes, confirming calibration after ag;b examination.

1 t

3 2.4.3 Recortiing j

j A.

Recorti all indications that exhibit a deviation fran i

the normal keyway gecanatry response observed fran each j

gage hole examination.

2.5 Radial Gage Hole Examination.

J 2.5.1 Calibration (Unit 1 Attad -it 7.2) s A.

Apply couplant to gage hole D.

B.

Insert the gage hole probe into gage hole D and obtain the =vi== response frun ream bolt hole 5.

C.

Adjust the instrument gain to bring the response to 804 ( 5%) MiH.

D.

Rotate the probe to obtain the maxirum response from roam bolt hole 2.

E.

Construct a distance-anplitude correction (DAC) at.'s by w..ecting the =vi== response points with a line.

F.

Record the instrument gain setting, sweep positions and anpli+' h on the Flywheel Ur Examination Report.

2.5.2 Calibration (Unit 2 Attadiment 7.3)

A.

Apply couplant to gage hole F.

3

Ur-304 Revision 7 B.

Insert the gage hole probe into gage hole F and obtain the mav4== response fran ream bolt hole 4.

c.

Adjust the instrument gain to bring the' response to j

80% ( 5%) FSH.

D.

Rotate the probe to obtain the maxinum response frm ream bolt hole 1.

j E.

Construct a distance-anplitude correction (DAC) curve by wMing the mavi== response points with a line.

F.

Record the instrument gain setting, sweep positions, and anplitudes on the Flywheel Ur Examination Report.

2.5.3 Examination A.

Increase the instrument gain a minimum of 6 dB.

B.

Starting at the top of the gage hole, slowly rotate the probe 360 degrees to examine the volume of the flywheel.

Observe reflectors fra flywheel cpc==tific.

features as the probe is rotated, identifying each reflector source as it appears. Continue to examine the volume by inserting the probe in 1/2" iru==:.Tus.

C.

Repeat the examination frcan the remaining gage holes ushry the initial calibration settings.

D.

Confirm instrument calibratics when radial gage hole examinations are otmpleted using the steps outlined in para. 2.5.1 or 2.5.2.

2.5.4 Recording A.

Record all unidentified reflectors equal to or greater than 50% LV.

2.6 Periphery Examination (Attachment 7.2 and 7.3) l 2.6.1 Calibration A.

Couple the straight beam search unit to the outside edge of the lower flywheel plate and obtain the mav4== response fra ream bolt hole 5.

B.

Adjust the gain to bring the response to 80% (IS%) ESH and mark the point on the screen.

4 i

i

Ur-304 Revision 7 e

C.

Couple the straight beam search unit to the outside edge of the upper flywheel plate and obtain the mavi= = response frcan ream bolt hole 5.

Mark this point on the screen.

D.

Construct a DAC curve by cuiu scting the response points with a line.

E.

Record the instrument gain setting, sweep positions xd anplitudes on the Flywheel Ur Examination Report.

2.6.2 Examination A.

Increase the instrument gain a mininum of 6 dB.

B.

Scan the flywheel periphery face to include the area frun the edge up to and includity the ream bolt holes.

Conduct this exam on both the upper and lower i

plates, 360 di.:g s, around tha periphery.

C.

Where possible, progressively move the probe across i

and along the flywheel edge so as to scan the entiru edge overlapping each previous scan by at least 25% of the tra M a r diameter.

2.6.3 Recording A.

Record all unidentified reflectors equal to or greater than 50% DAC.

2.7 Calibration confirmation 2.7.1 Confirm calibration at the fatervals specified within each examination category.

2.7.2 Evaluate calibration confirmation ip accordance with the following criteria:

A.

A IECREASE in sensitivity of more than 2dB requires recalibration and reexamination of all items examLned since the previous acceptable calibration or calibration confirmation.

B.

An INCREASE in sensitivity of more than 2dB requires recalibration and reinvestigation of all indications recorded since the previous acceptable calibration or calibraticm confirmation.

5

4 17f-304 l

Frvisim 7 c.

If any point on the DAC curve has moved more than 10%

of the sweep division reading, correct the sweep range calibration and note the correction on the flywheel examination report.

If reflectors were recorded, recalibrate and raav=ine all items examined since the previous acceptable calibration or calibration confirmation.

2.8 Post-Examination cleaning 2.8.1 Dry-wipe the area to remove any tenporary markings and couplant.

- 3.0 RECORDING REQUIRDENTS 3.1 Record data specified within each examination category on the Reactor Coolant Pung Flywheel Ultrasonic Examination Report.

3.2 Reports are to be numbered in accordance with @P 9.4.

3.3 Documentation is considered as lifetime and treated as su d in accordance with QSP 17.1.

4.0 NDCEPDWCE STANDARDS 4.1 Due to the techniques enployed and the unique nature of this examination, all recorded reflectors will be evaluated by a Ur Inval III to determine their origin, size, location and orientation.

'Ihis evaluation process will be performed and h-qted in accordance with GP-105.

5.0 PERSONNEL AND EQUIPMENT GUA M ICATIONS 5.1 Porscrinal Qualifications 5.1.1 Personnel performing examinations shall only perform tasks oceaneneurate with their experience and level of certification.

A.

DM w Light personnel are certified in accordance with QSP 2.3.

B.

All individuals performirq examinations to DI.C 17f prMwe(s) shall receive sufficient training and orientation to ensure understanding of prrmtwal requirements.

6

j 4

s Ur-304 Revision 7 i

C.

Ultrasonic examination personnel who determine which indications are to be recorded shall have s - = fully ecmpleted a qualification program administered by the Quality Services Inspection & Examination Department which demonstrates proficiency in discriminating between flaw indications ard indications of gecnetric or metallurgical origin.

5.2 Equipnant Qualifications Use a pulse-echo instrument capable of 5.2.1 Ur Instrument establishing a minimum 40 inch metal path in the flywheel material.

Additionally the instrument must meet the linearity requirements of Ur-201.

5.2.2 Scarch Unit (s) ~

Use a

'0 inch diameter, 2.25 MHz straight beam searth unit for initial metal path' calibration and for the periphery scans. For the gage hole examinat!.cna.

.n a

.5" x

.1", 2.25 NHz gage hole inspection ward. (!vertics C1281 1" bore probe).

'Jse Ultragel II, Sonotrace 40 or equivalent as 5.2.3 Couplant permitted by the Pre-Engineered Material List.

6.0 REFERENCES

6.1 USNRC Regulatory Guide 1.14, Revision 1, dated AtxJust 1975 6.2 D n _= =1e Light canpany Quality Services Inspection Examination NIE Procedures 6.3 ASME Boiler and Pressure Vesal Code,Section V, 1983 Edition, Sunmar 1983 Addenda 6.4 DIco. Nuclear Engineering Memorandum 90104, dated 4-19-85 6.5 ISI Istter ND3ISI:0106, dated 11-8-85 6.6 Westinghouse response # DIN-86-512, dated 2-19-86 6.7 NPDhP 9.6 Experdable Products Cbntrol 6.8 D M = =1e Light Capany Quality. Services Procedures 9.4, "Nordestructive Examinations"/ 17.1 " Control of the Quality Services Unit QA Records";

2.3

'Hritten Practica For Qualification and Certification of Nondestructive Examination and Testing Perscrinel" 6.9 DICo Quality Ctrittel Report #638, dated 3-9-93.

7

UI-304 Revision 7 7.0 ATTACHMEffrS 7.1 RCP Flywheel Ur Examination Report 7.2 Unit 1 Flywheel Hole Identification Drawing 7.3 Unit P. F3yvheel Hole Identification Drawing 8.0 GiRONOIDGY OF ODNGES 8.1 Revision 7 Inwrporate safety requirements with the ure of Ultragel II couplant, add Quonology of Changes Section, made administrative changes, and perform two year review.

I 1

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Ur-304 Pavision 7 Attactmuunt 7.1 Illustrative only RCP Flywheel UT Examination Recort l1 l'

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ATTACHMENT B INFORMATION ON REQUALIFICATION OF PERSONNEL AND EVALUATION OF MEGASONICS PROBE FOR RCP FLYWHEEL EXAMINATIONS AT BEAVER VALLEY

Record of ICE Procedure Oualificaticn Page 1 of 7

Procedure t/ 7~- 3 0 't' Pevision lo cate 3 -I to c: 3 initial qualification requalification*

requalification not g.

Tzsr carecr DEscaIPrIoN:

Um r i nuecon cooun r na mw ), a L

• QUALIFICATION LIMITATIONS /029ElfIS: PR.ELtmi w Aay* Qua LJie a rieu d o c u m r-wT6d ON Ari n e.u s:d ocR *6aB.

A c.Tu s t c2u Atici c ar ie w ro be ceudocnci I w cc w.r u s cr i e w wITh Ewam,undou ATIACHMDirs:

calibration record test object drawing examination record other OCA #$3 8'

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I 3-/6-M 42d zrt.

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Performed By Invel Data Perforfbed By

' Invel Date w/S

-4 94 9/A 9/S 9/A Witness Inval Data Witness Invel Date 1

Procedure qualificatien results are acceptable and procedure is qualified within the prMnw scope and subject to the limitations notad above.

dhd 3 16-93 C ~__ O

_7.AP-93

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DIro Bevel III Data

~- ANII Date

• If requalification is not required, the DIro. Inval III should write a brief explanation in the er=wnts section.

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A4.606A7 i

FDlh D37-122153 QCR NUMBER DUQUESNE LIGfr CutPANY Quality Services Unit QUALITY CarISOL REPORT 638 SIATION BVPS Units 1 & 2 EQUIEMENT/SYSTIM Pawt.or coolant Pw'n Flwbaal UP Pv===

i REPCEP TITIE Trio P-vt44estinohr=== Elm uv. +eir al Division. @ mawick. PA l

Evaluaticm of Mannarmirm HCP Flwbaal Ur Pv=mination Probe I

On March 8,

1993, the author and George Brk, Serlier N3C Rwaminar traveled to the Westinghouse El Lv !"danical Division in Chamwick, PA. 'Iha purpose of the trip was to perform an evaluatim of the recently piu.dd reactor coolant pung flywheel Ur avaminatico probe.

'Iha trip was arranged as a mtually beneficial evaluation of the Megasanics RCP flywheel proba en an ac+n=1 EP flywheel. Mr. M 1== Iseman, Westinghouse NDE Inval III, assisted in setting up a time d en the G aswick Plant would have a 75" diamater RCP fly @ eal available. 'Ihm flyseal being memfactured had 6 gage holes in a circle 29" frca the flywheel cantarline. '!his design is similar to the RCP flywheels at BVPS Unit 2.

('Iha Unit 1 flywheel has caly 4 gage holes.),

I

'Iha Megasmim flywheel probe differs in design from previously used sdiss in that the saart:h unit element is curved to ocopensate for the ocnvex entry surface required to make contact in the 1" diamatar gage holes. '!he dammstrated net effect of this curvature is that the ulL-.c.i-dc beam spread is greatly rarh=d due to the acoustic focusing effect.

'Ihis focused been allows easier identification of reflectors encountered as 'well as reduced signal to noise ratio frt:sn material characteristics.

'Iha been probe is used to perfona two separata types of Ur examinations on a RCP flywheel.

'Ihm first type 'm the examinaticn of the area surrounding the center bore hole and keyway corners frca the gage holes. 'Ihm Megamenics bore probe performed this task readily, exhibiting far less been spread than the previously used probe, which was used for &dson.

'Ihm seccmd type of examination is a 360* scan of the flyesel volume frtun each of the gage holes.

In this examination, the 1 F c.Edes bore probe performed exomptimally well, providing awullant resolutics of closely spooed holes at significant metal paths.

'!he attached pages show =nar ific calibration scenarios regrementative of Ur-304 r w bral requirements. As a result of observaticms made, several procedure revisions have been requested to fully take advantage of the probe capabilities.

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QCR 638 Page 2 While the ocnfiguraticrt of the flywheel examined is similar to the BVPS Unit 2 i

flywheel design, differences in actual flywheel configuraticn will r*,aaaitate i

prmachive qualificaticn en the actual flywheel (s).

'Ihis qualification of the j

revised tJP-304 will take place on the BVPS Unit 1 flywheel at G aswick during April, 1993 in conjunction with the IJr examinations. Unit 2 flywheel configuration will i

also be qualified in ocnjunction with 17r examinations. This report will serve as a j

preliminary

g.. - bm qualification to validata the technique and to @=at the i

inproved avam%ation capabilities of the Marymmertics few,iaari bore probe.

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cc: M. A. Purger J. J. Gicculdi G. L. Buck Factory Mztual ANII QSIE File

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l ATTACHMENT C ASME TECHNICAL PUBLICATION PAPER NO. 74 PVP 25 REACTOR COOLANT PUMP FLYWH',EL OVERSPEED EVALUATION e

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Reactor Coolant Pump Flywheel Overspeed Evaluation P. C. RICCARDELLA' The owrspeed capability of the large steelJywheels used on light water reactor primary oenerse Atomsc ca.'

san oiego. canst.

cwlant pumps has been escaluated through a combinui analytical and experimental efort. Limiting speeds of the prototype fywheel design were calculated for the ductile W. H. BAMFDRD

/*il"" **d' "'ing the Principles of Secdon M of the ASME Boiler and Pressure Vessel Code, and for the brittle fracture mode using a fractwo mechanics approach westenanouse Nuesear in which stnss intensity factors utre determinedfrom fnite elsment computer analysis.

'Mu*,','h*R The accuracy of the analytical approach was wriped by a scale model test program which demonstrates excellent agreement between experiment and analysis. The results of the epaluation are presented in this paper, and they illustrate the kinds of things which can be accomplished through application of modern fracture mechanics tech-nology, including plasticity considerations, to the solution of hardware problems of real engineering interest.

Introductl0n ASME Boiler and Pressure Wesel Code for ductile failure con.

siderations, and utilising the principles of linear elastic fracture In the event of a postulated loss of coolant accident in a pres-mechanics (LEFM) for brittle fracture considerations. Due to surized water reactor plant, it is possible for the reactor primary plastidtn W LEFM appmsch is not strictly apgesle to this coolant pump to achieve speeds on the order of two to three times its norrW design Speed. At speeds of this magnitude, con-cern arises as to the likelihood of componente of the pump-motor assembly fracturing and producing high energy missiles within the containment. Of utmost concern in this regard is the reactor coolant pump flywheel, since it possesses the most ro-tational inertia in the pump motor assernbly, and thus the g

highest amount of energy at a given speed.

The Westinghouse coolant pump flywheel design consiste of 0

O two large steel disks, 75 in. and 65 is. in diameter, which are

. o i s o. f-' '

bolted together in order to provide the necessary rotational inertia to maintain Sow and thus prevent core overheating in I

• O g pl the event of loss of power to the pumps. A sketch of the flywheel pl i!l assembly, showing the significant details and dimensions is l

lI,6 given in Fig.1. The two plates are 7.5 in thick and 6.5 in thick, o

ll il respectively, and contain numerous holes and keyways as shown.

g The flywheel is fabricated frorn A-533, Grade B, Class I steel l'

plate.

ll I

t The purpose of this evaluation is to determine the speed at which this flywheel design becomes critical from the str.adpoint I; p,'

I, of fracture and subsequent missile production. An analytical l

"S"'

lg lj approach is taken, utillaing the methods of Section III of the i

ni H- "-

IFonserty, of Westingh Nuclear Emersy Bressous.

T l

rg,s

' Numbers la breakasa densmane Refereness at and of paper.

Coetnbuted by the Premmare Vessels and Pipias THetmoe for presentauoe l

l N'

at the Preneure Vesseis and Pspens Confereses eth Nue6sar Easineertas and

_l Matanals Dmasona. Miami D.sach. Fla.. June 26-2s.1974. of Tas AasenP"AW 7 se sia eW modt +1[*

,,,,ag Socrsry ca Macia&EXA1. ENGmesse Maausenpt recieved at ABME Head.

'6 quarters. March 23.1974. Paper No. 74 PYP 33.

'M

" "'" 8 Y Copsee m3 be avadable unki Mareb.1974 Fle.1 A*ect*' ***8 eat pump flywheel seemetre 1

I

w w

a w "

n-g(Tr$ '

I.

,.1 'a.7

.r g F5ui

'O 3gm..

e d,,,

-pw4g f",-

e. ~. -

2M..,,

..# -88;88 M C S 18Js m aast f

i

.M

. M&sd Reactor Cao ant Pump flywheel (verspeed Evaluation P. C. RICCARDELLA' Th* otersyed capabsti!v ol the large stel.*!yu keis used on light uvuer reactor pn mary

"*ln o e*g]c$r' coolant pumps has Mn otalua'ed through a comb 1n'd analytval and expersmen:al eprt. Lsmuing speeds of 'he prototype 4ytcheel dresgn twre calcula:ed for the ducti e g y' gggg failt.re mode ussrig the pnnc1ples of Netton til of the ASME Bat ler and l'ressure Vessel Code, and for the bru!lt fracture mode ussng a fracture mechanscs approach

• estenanouse nuciear sn tchsch s:ress sntenatty l actors were determtned from finue e'smen computer analyess.

'"p*,'N,','Q The accuracy of the analytncal approach teas ienfied by a scale mairl test program tchich demonstra:es excellera agreemen beturen expersmera and analgess. The resuits of the evaluatwn are presen:ed sn this paper, and they s'lustrate 'he kinds of thsngs tchsch can be accompisshed through applica: son of modern fracture mechanses tech-nology, including plas:sesty consruiera:wns. :o the solutwn of hardtcare problems of real engsneenng traerest.

Introduction ASME Boder and Pressure Ve.inel Code for ductile failure con.

siderauor.s. and utilizing the pnnciples c4 linear elutic fracture In the event of a pmtulated loan of coolant accident in a pren.

mecharuna (LEFM) for bnttle fracture conmderationa Due to sunzed water reactor plant, it is pmaible for the reactor primary pianucity, the LEFM appmach is not stnetly appi ca de to this coolant pump to achieve speeds on the order of two to three

~

~

times its normal demgn apeed At speeds of this magnitude, enn.

cern an3es u to the likelihood of component 4 of the pump-motor ueembly fractunng and producing high energy rnstlen w,ttan the contamment. I)f utmoet concern in this regard ts the

+

reactor coolant pump dywheel, unee it pouemen the mont ro-K tational icertia in the pump-motor asembly, and thus the N

highest amount of energy at a given speed

/

O The Westingbouse coolant pump dywbrel design ennaista of

/

0 two large steel lisu 75 in and G5 in. in diameter, which are

.-f*

bolted together in order to proviae the necenary mtauonal

{

inertia to maintain dow snd thus prevent core overheaung in o a

• O j

the event of i+vi of power to the pumpg A sketch of the Sywheel i

\\

/

unem bl y, showmg the significant details and dimensions is l

given in Fig 1. The two plates are 7 5 in thick and 6 5 in. truck, s

o o

repectively, and mntain numerous bolen and keyways sa shown l

3 The dywbeel ta fabncated from A '33. Grade B. Claas I steel I

plate The purpone of than evaluston ts to determine the speed at which ttus dy wheel demgn hemmam entical from the atsadpoint of fracture and subacquent mmde prMirtion An anaivtical approach is taken. aubring the methods of

• tion !!! of t he T ormordr. '>f Wakaanouse Ne a.i Ene,g.y dymem g

)

l i

~ - c.,. u

.u n t..<

.,.u,e m.,

t

< cate wM

• y it.e Pr = mea. V% su Ppas : w,e he pr e tnuno I

L 1

a--

J f

..t..

rs s..

.uew.s,mo.

.,,,.2 s,., t,.s. c, s.m M a er s.s wa Mam,kone f's

., ne 4 6 4A. :' t.iTae*eeer.

• ~

• w s rv r. a M s m.a

< a s, t.w a s s en M an..r e p

.r

..t a t eMi H onei w &/'ers M aie r, 43.474 P a per '. ' 6-P N P J 1 C vt,4eb Cd *4 4 'b.ar; we 4 3 ka M 6,e f

,g?q r bg. j RggCLOfCe@44RtOWfMSrY Wh4Gi$eOffteiff T

1 t

w as shown in Fig. 3. Note that the circumferential strees (ae) is 4

essentially linear over about 90 percent of the Bywheel radius, with a sharp peaking effect due to the stress concentration at the bore. Although the magnitude of the stresses wi'l vary with angular velocity, the shape of the stress distribution shown in Fig. 3 will be the same at any speed. The shape of the stress distribution has an important effect upon the behavior of the flywheel and must be considered explicitly when applying stress e,

limits to the calculated stresses.

Faufted Conditten Stress Limits. The capacity of a structure to resist ductile failure with sufficient margin of safety during faulted conditions can be dernonstrated by meeting the faulted condition criteria of Section III of the ASME Boiler and Pres-

%c sure Vessel Code [3] (Appendix F). The faulted condition limits for elastic analysis are as follows

• *f P. < 0.7 S.

P. + P. < 1.05 S.,

(2) where S. is the minimum specified ultimate tensile strmgth of the material, P. is the primary membrane stress intensity under faulted condition loading, and P. is the primary bending stress intensity. (The term stress intensity is defined here as twice the Tresca maximum shear strees in accordance with the Section III definition of the term, and should not be confused with.the l

linear elastic fracture mechanics strees intensity factor which is used later in this paper.)

Fis'.

• Netstlea used la flyweieel evolustsen Since the thicknees direction stress (a.) in the flywheel is assumed to be negligible, and the radial stress (a,) always falls problem, and thus a scale model test program was implemented maximum 8 trees intens."ty at any point in the to verify the analysis. A summary of the flywheel evaluation stress (as),

i and h supporting test program is given in this paper. A more flywheelis equal to b careumferential streu. In order to apply detailed report on this work can be found in [1].8 the strees limits of equation (2) to a nonlinear strees distribution such as that shown for a,in Fig. 3, the actual stress distribution

""'"**I'*

' " ' " " ***

• d Ductile Failure Analysis 1

N Flywteselstresees. The stresses in the reactor coolant pump P. = (b-a)

Sywheel, neglecting local stress concentrations such as holes and keyways, can be calculated by the following equations (2),

6 P. =

a,(r. - r)dr, (3)

1. ' ~

+ ~

~

8 where r. is the flywheel mean r us defined as (a + 6)/2. Sub.

stituting the cricumferential strees term from equation (1) and a, - f 3,,,t,y

.-- -- f t + 3r r8 carrytog out b integrals in (3) yields pw8 68 + at +

\\

/

\\3+r/

- (1)

P. =

@ - a) (68 - o8) 13 3+r a

1 1 + 3r 3+y sw 8

where the notation is defined in Fig. 2. Bubstituting the ap.

propriate geometric data for the reactor coolant pump flywheel

- [ 3 + y } 6pw 68 [ 1 + 3r (Fig.1) into equation (1), and noting that h material density P..

( 8 / (b - a)8 I2(3+r (p) le given by 0.238 lbm/in8, the stresses at various radial depths can be described as a fuaetion of angular velocity u (rad /sec) bao" l_3[\\3+r/~1 + 3r j ~

~ a b81n(6/a)

}

n 2

l 8

lo 1 [ t + 3, } "

a4 [ 1 + 3r j '

s

~

l

'2

+ 3 ( 3 + r /-

12(3+r/;

~'

-ee ser il

[

Finally, substitution of the appropriate geometrie data from l

li Fig.1 into equation (4) yields 1

ig 8

.i e.

.d, b,

P. - o.* a' (pai) h P. - 0.22 w (pei)

(5) s..

it 8

l**

I i'

je:

i

~

i Equations (2) and (5) will now be compared in order to evaluate e

& opeed at which the flywheel stresses eseeed the Section III l

isulted condition criteria.

~

i ee me sets. Values of P. and (P. + P.) have been calculated

. [.E.i from equation (5) and compared to the faulted condition stress Fg,3 sens,e ee ssy,e,ses se,eee deen,ensene.

limits of equation (2) to determine the limiting flywheel speed 2

Transactions of the ASME 4

under ductile failura consid:ritions. An ultimite tensila strIngth s.o of 80,000 pai, was used in computing the faulted condition limits which is the minimurn specified value for A-533 Grade B, Class r steel given in (3). The limiting speed based on the membrane 3:

+ bending stress limit is 365 rad /see or 3485 rpm, and the limit- }

ing speed based on the membrane stress limit is 372 rad /see or 1-3 5550 rpm. Therefore, the membrane + bending limit is govern.

ing.

E t In summary, the results of the analysis performed in this sec.

I, tion demonstrate that the reactor coolant pump flywheel can Q

f withstand a rotational speed of 3485 rpm, which corresponds to i!

approximately a 290 percent overspeed condition (Fig. 10)

=

/

without exceeding the faulted condition criteria (Appendix F) 5

/

us"*

of Section III of the ASME Boiler and Pressure Vessel Code.

E o- - --- 4 j"!'," <"'" "

Compliance with these limits assures that the flywheel can i

withstand this overspeed condition with sufficient margin from y 'o -/

o-- -o *ha"g ggya g

the standpoint of ductile failure, g

/

i

?

ll Brittle Fracture Evaluation j

fj Closed Form Stress intensity Facter Seduties. An approximate E

b l

solution for the stress intensity factor for a radial crack emanat.

ing from the bore of a rotating disk has been reported by Williams

,j i

i 1

l and Isherwood [41, and is given by the following expression o.o no to 3.o

..o s.o s.o 7.o conce oteta Foe FLas Diasaties peou strway (incuts) r Fig. 4 Stress lassasaty f acter camputatlees for reacter coelent pump 6

6 ftywn e K, - pw868*D (6)

(1 - 9 )

8 where the flywheel, including half of one keyway,is required to model the complete flywheel. A number of diNerent crack depths and

~

locations were studied by placing the special cracktip model at o

6 various locations within the fine grid region. Elastle solutions

<D-(3+y 3

1 + o8

+3 g

g g

were obtained for all cases assuming the loadmg to be due only to centrifugal forces resulting from flywheel spinnina. The ef.

a fects of contact loadmg at the inner bore and keyways were

+Es))(3_oY assumed to be negligible, and the flywheel was assumed to be in (I+6 o8 6/

- [ 1 + 3r j a state of plane strain. Values of stress intensity factor were a

+

1,-

( 32 /

estimated from the numerical stress resulta in the vicinity of the cracktip by fitting the data to the first two terms of the series 0

expansion for the crack tip stress 6 eld along the plane of the s-crack given by

, e

~E

\\6/

\\6/ +1g

/

(7)

(e,, o }

3 [,, e, }

o i n.

6 6/

g 6/

and where the geometrie quantities a, 6, and e are defined in Fig. 2. The quantities p and w refer to the material density and angular velocity as before. Substituting and appropriate geo-metrie data from Fig.1 into equations (6) and (7) leads to stress intensity factor as a function of angular velocity for various nasumed cracked depths as shown by the solid curve in Fig. 4.

Note that for the case of a crack emanating from a keyway, the keyway depth is included as part of the total crack depth for conservatism.

Inspection of Fig. 4 indicates that the closed form solution technique erroneously gives a nonzero value of stress intensity factor for zero crack depth. Thus it becomes obvious that the t

assumptior, of adding keyway depth to crack depth is overly

?FT conservative for very short crack depths. In order to eliminate

...... / - --

iai this undue conservatism, and to consider the eNect of the keyway more accurately, a detailed finite element model of the f!ywheel 4

with a crack emanating from the keyway was set up and analysed.

mciainmie m

/

\\

rentte Element Anstysis. Approximately 500 constant strain triangular fird'e elements were used to model the reactor coolant

\\

pump flywhee for analysis using the computer program PPCNT

[5]. A detailec. illustration of the models used in the analyses is shown in Fig. 5.

Due to symmetry, only a 6%Jeg segment of Fig. s Finite element model of re <ter coetent pump flywheel Journal of Pressure Vessel Technology 3

K, Tabio a reywnses plastic asne sense e, =._ + C.

(8)

V2rr Flaw site (d)

I'lastic zone size (r,)

Itatio (r,id)

I where r is the radial distance from the crack tip, C is an arbitrary dg",

@ij hy cortstant, and Ki is the cracktip stress intensity factor. This

2. 0 in 0.52 in 0.25 procedure is described in detail elsewhere [6), and leads to the finite element stress intensity factor data shown by the dashed The plastic zone sizes listed in Table 1 are far too large to curves in Fig. 4.

satisfy b plasticity limitationa of linear elastic fracture me-The agreement between the closed form and numerical resulta chania. Nonetheless, the critical speed calculations of the pre.

in Fig. 4 is excellent for crack depths of 1.0 in. and greater, thus vious section are expected to be accurate.

providing an independent check of one technique against the in the pump flywheel problem, the plasticity is completely other for those crack depths. For crack depths less than 1.0 contained. Nt is, due to the large stress gradients (Fig. 3), the in., however, the closed form solution with its ultraconserva-outer periphery of the flywheel remains elastic even at the cal-tive keyway assumption gives unrealistically high stress in-culated critical speed levels. Contained plasticity such as this tensity predictions. It is also noteworthy that, contrary to creates, in effect, a strain controlled loading situation for which what one would expect, the strees intensity factor for a 0.5 in.

experience has shown [12,13) that elastically calculated strain crack emanating from b keyway corner is smaller than that distributions are accurate well beyond the limits of strict ap-for the same crack emanating from the center of the keyway. plicability of the theory of elasticity. This concept of " strain This phenomenon can be explained by the fact that the strees equivalence" is well secepted in low cycle fatigue applications, concentrating effect of b keyway corner is extremely localised, and its extension to fracture problems is straightforward, and thus has no effect at a distance 0.5 in, from the corner. The Accepting this strain equivalence argument allows one to stress intensity factor for cracks of this size is governed by the justify the use of linear elastic fracture mechanics for the fly-overall flywheel stress distribution rather than by local stress wheel evaluation using Rice's J-integral Concept [14). It has concentrations.

been shown experimentally (15,16] that the J integral is a pa-The streme intensity factor data of Fig. 4 will now be com-rameter which takes on a critical value (Jic) at fracture over the pared to the material fracture toughness to determine critical complete range from linear elastic to fully plastic behavior, it is speeds for b Sywheel as a function of assumed crack depth. well estabbshed that in b elastic range b J-integral approach Based on the above discussion, the most meaningful stress in-is identical to linear elastic fracture mechania. However, due tensity factor data of Fig. 4 is the finito element curve for a to & principle of strain equivalence discussed above, the identi-ersek emanating from the eer.ter of the keyway, and this curve ty betwena J and LEFM can be extended well into & eluso-will therefore be used in b remainder of the evaluation.

plastic range in strain contro:iad loading situations (171. Hence, b reactor coolant pump flywheel evaluation presented herein Freetere Teogheses. The fracture toughness and obr me-a Al Musen, d a such is valid re m

.chanical properties of A-533 Grade B, Class I steel have been gardless of the excessive plastic sone eises developed.

studied extensively under the AEC Heavy Section Steel Tech.

In su==ary, the methods used to predict brittle fracture in b nology Program (7,8,9,101 Lower bound fracture toughness reactor coolant pump Sywheel are not strictly applicable be.

versus tempersture data for both the longitudinal (RW) and of ye platicity. Howerw, it is argW ht b transverse (WR) directions were obtained in % program using Sywheel is a strain controlled loading situation for which the

& equivalent energy concept for lower bound fracture tough-methods used correspond to an elastoplastic J-integral approach ness testing. The data were obtained from several heats of steel, which is applicable. In order to confirm these arguments, a all of which had drop weight nil ductility transition temperatures scale model test program was icsplemented and is discussed in the range of 0 des F to +10 des F. Therefore % data should g,g g;, paper, be applicable to renesor coolant pump Sywheel rnatorial with th* "m' t'"*iha $"sPwatum.

FlyWheelinSp0Ction and Quality ASSuranCG neestes. The Sywheel operation temperature is +120 des assenrees go mnatsee Teses. Westinghouse reactor coolant F, and b minimum material fracture toughness at % tem-pump flywheels are fabricated from A-533 Grade B Clas I steel perature froma [9l is 230,000 psi /ts. This value is for the weak plate which is produced by a process that minimizes 8aws in the or transverse direetman, the longitudinal direction toughness material and improves its fracture toushness properties (vacuum being much higher. '1%us, the analysis assumes the worst poo-degnesang, neuum melting, or electroslag remelting). Supplier sible location and orisatation of any Saws which may exist, cairti6estion reports are available for all plates and by demon.

Using % toughmens value, and b 6 nite element data for a strate the acceptability of the sywheel materint on the basis of center keyway eraak (Fig. 4), critical Sywheel speeds have been the following requinmente (181:

determined as a fuaselon of crack depth, and are shown along with the ductile faites limit in Fig.10.

(a) The nil-ductility transition temperature (ND'IT) is ob-tained by two drop weight tests which must whibit "no-pteennesty caessessansee. Strict applicability of linear elastic break" performance at 20 des F in accordance with the fracture mechanics is limited to situations in whleh the extent rules of ASTM Testing Procedure F 208 (19). These of plastic dow in the vicinity of the cracktip is small in compari-drop weight testa assure that the ND'IT of b Bywheel son to the crack depth and other pertinent geometrie quantities materialis no higher than +10 des F, of the problent. Irwin (111 has suggested the following approxi-(6) A minimum of three Charpy V-notch impact specimens mation for plastic some sine in a plane strain crack problem are tested at ambient (+70 des F) temperature in so.

eerdance with ASTM speci8estion E-23 (20). The or[\\ a, /K'Y' (9)

Charpy V notch energy in both b parallel and normal 1

orientation with respect to b rolling dinetion of the Sywheel material must be at least 50 f 6-lb.

where K,is the apphed stress intensity factor and a,,is b ma-terial yield stangtk. Values of plastic sone size have been enl-Compliance with b foregoing criteria insures that all ructor culated according to % expression for the reactor coolant pump coolant pump flywheel material has a low enough NDT tem-flywheel at incipient fracture (Kr - Kic), and b ruults are perature and a high enough upper shelf toughness so ht the summarised in Tahis 1.

lower bound fractun toughness data o. [9] are applicable.

4 Transactions of the ASME

.i Ptai new uns a.a gram was implemented. Three sette model Sywheels (quarttr.

see '

n scale in. plane dimensions, full thickness) were fabriented with F.

I f-fC '.',

Saws present in the most critical location and orientation.

/~. n.....

l l y= w Analytical falluru predictions were made using the same methode Eh

. / /a

.p se wue used for b prototype flywheel evaluation. The models

~'" "

}

Oj f

,,9 were then tested to failure and the actual fracture speeds com.

]

pared favorably with the analytical predictions, thus lending a f*' "

high degree of credibility to the pump Sywheel analysis i

i I

asedes Febrseatsen. Fabrication of scale model Sywheels with sharp cracks nquine a relatively mmplex multistep procedure srte 1 - mriat weninise (see Fig. 6) which has been developed at & Westinghouse Re.

gQc,n.,,,,,

L;*y'a esare and Development Laboratorice [221. In the initial ma-W chinies phase (Step I), three 21 in square blanks with thick.

l

, _,,,,, %'n'?. g j/

,,u,,,

nesses of 9.5 in. were machined from a 12-in-thick piste of A533 "m

i

/ """"

Grade B Class 1 steel. One quarter in. holes were then bored at J g, I

.T.

p.

, 's distances (D) from b centerpoint af & blanks.

I l

The beles were also counterbored at the top and ha**mn surfsee d

as absen in Fig. 6 to accommodate the pressure eychng device l

d used for precracking. Finally, an electrie are tEscharge ma-i MN @MD *M"

• M 2 pMm a UM4g M site a - sariai,e retenacai e emaanting from the 1/4 in. hole. Step II in the model fabrica.

g'3

/'""["'.,s....

tion procedure was fatigue procracking A pressure cycling de-vice was used to pulsate pressure in the holes at a frequency of a ' ""

- a.=e w 60 cyss, and an ultrasonic flaw detection =h=== was used to

/

jI

/)

Me contisuously monitor and control crack growth during the pres-7,,,

sure eyeling operation. Maximum pressure during fatigue pre.

r g

l$p

'do cracking was limited as a function of crack heath in order to 4'

d

% ru avoid b problems associated with excessive creektip plasticity UZE /

l {'"'

during procracking [221. In b final phase of fabrietion (Step III), the models were =~h6 d_ to their 6nal du==wa=, by re-w site m - rint mcainine movies & excess peripheral and surface material as shown.8n Fig. 6. The inner boro, keyway and a slot from the keyway to the Fig. 6 Scale model flywheet febricetlea precedure I/4-in. hole were also machined in this step.

The anal models thus contained composite erecks of pre.

Mendestreetive gaemeneteen. Each dywheel plate is subjected speciged lengths consisting of a machined slot, a 1/4-in, bole, an to 100 percent volumetric ultrasonic examination in accordance EDM slot, and a fatigue procrack, all emanating from the key-with paragraphs NB-2532.1 and NB-2532.2 of Section III of the ways in the flywheel bores. The irregularity of b crack surface AS.%IE Boiler and Pressure Vessel Code [3] for acceptance. After does not afect b validity of & experiment since the magnitude fabrication, the finished machined bore and keyways are sub-of strum intensity factor is only adected by crack shaps in the jected to magnetic particle or liquid penetrant surface examine very near cracktip region. Note also that the anal crack is tions. The finished flywheela are also subjected to a 100 percent oriented in the transverse or weak direction with respect to the ultrasonie examination according to & above referenced pars-rolling direction (WR), The creek sise parameter D was chosen graphs of [3].

so as to yield nominal final crack depths of 1 in.,3 in., and 5 in.

In addition to the aforementioned shop inspections, the fly. The emnet value of crack depth could not be determ ned until wheels receive extensive further examination as part of the re-after the tests, however, due to variability in the leash of &

quired inservice inrpection program for reactor coolant pump fatises procracks.

flywheels (18). A surface examination and full 100 percent ultra.

sonie exsmination are performed at approximate ten-year inter.

P'emminary Frosture Toedeme Tests. In order to character.

vals. Westinghouse is also introducing a new inpnection procedure ise the fracture toughness of the specific heat of material used to (21), in which the critical regions of b dywheel (bore, keyway, fabricate the scale model flywheels, six standard compact ten-and bolt hole regions) can be examined ultrasonically by paesing sion specimens [23] were fabricated from the same plate. The a transducer through each of b four sage holes in & Sywheel

• P""=aaa were taken in & transverse (WR) orientation and (see Fig.1). This new procedure provides a more thorough ex.

were 2.0 in. in thickness (2TCT) Tests were performed at 0 des amination of these critical regions, and can be used at more F, +50 des F, and +70 des F, and values of fracture toughness frequent intervals since it does not require removal of & fly. were determined from the specimen load.de8ectaon curves using wheel.

Witt's equivalent energy concept for lower bound fracture tough.

All of the ultrasonic teste discussed in the foregoing are cali-ness testing (10], since the specimens were not large enough to brated to provide detectability of Saws as small as 0.25 in. in be interpreted according to & ASTM recommended testing radial penetration. Thus flaws on the order of 0.5 in, are a factor proendure (23l. Fig. 7 shows the fracture toughness data ob.

of two greater than the inpsection capability of the techniques tained in this manner. For comparison, the lower bound fracture being used. Furthermore, inspections of the flywheel are both tousbase cum used in & Sywheel analysis (9l has been in-extensive and frequent. It can, therefore, be concluded that flaw, dezed to & model material drop weight NDTT and is shown of this size wdl not esespe detection in flywheels and that fly, in this 6gure. Note that & experimental data are significantly wheels containing such Saws will not be accepted for service.

higher than the lower bound curve, which is an indication of the conservatism nosociated with that curve for this beat of steel.

Scale Model Test Program Th' *"perimatal data rahr than the town bmd cum wdl be used in making h fracture predictions for the scale model In order to verify the analytical procedures used in the present flywbsels in order to provide a meaningful evaluation of the ac-dywheel overspeed evaluation, a scale model flywheel test pro-curacy of the analytical techniques used.

Journal of Pressure Vessel Technology 5

m :e

/

rio wo o/

,m n.

26e coc

/

.W

(

/O l

o

.o xo O,/

. ~= q '~

O: M;

$ 4mW

- m.n "u...

,e g,

[

2 o aco ua

l. (

[ 200 coo

/Y a

x

]> iso coo

/

j

'm h iso coo j/

~ ' *

'N

/

-o N

0 "iTd so

.o ao 3e 4

g aa n..

,:.w g ice oco gs, mparte.a et analyss and.speri..

,,,,,,,,,,,,,,i,,

so coo w is the critical speed based on the membrane + bending stress.

ao ooo Values of e and w have been calculated as a function of crack 40#

depth. As in the case of the prototype flywheel, the two' limiting speeds are very close; however, the mernbrane + bending limit

(%) is governing. This limit is shown as a dashed line in Fig. 8.

I I

o

/

The method for brittle fracture analysis of the scale models also o

onor rewsmus t.q foll ws that of the prototype evaluation, however, the experi.

mentally measured material fracture toughness data of Fig. 7

.t i m are used in place of the lower bound fracture toughness curve.

Fig. 7 Fracture toughness data for scale medel flywheel materte Substituting the scale model Bywheel parameters into equations (6) and' (7) yields model flywheel stress intensity factor data Analytical Fracture Prodlettene. As in the prototype flywheel which have been compared to the average value of measured overspeed evaluation, the scale model Bywheels were evaluated fracture toughnens of the model material at the test temperature on the basis of both ductile failure and brittle fracture con.

(+75 deg) to predict critical speeds for brittle fracture of the siderations.

scale model flywheels. These limiting speeds are shown as the The method for ductile failure analysis follows the foregoing solid line in Fig. 8.

description for the prototype flywheel, except the ultimate A third set of limiting speeds is shown in Fig. 8, which is tensile strength of the material (S. = 80,000) is used in place of rep teentative of critical speeds as determined in the prototype the Section III faulted condition limit (0.7 S.) since no safety flywheel evaluation. The critical speeds for the pump Bywheel margin is desired when making the failure prediction. Sub-calculated in the sections, entitled " Ductile Failure Analysis" stituting the scale model flywheel dimensions into equations (4) and " Brittle Fracture Evaluation" are not failure speeds since yields they are based upon 0.7 S. for ductile failure and a lower bound fracture toughnese curve for brittle fracture. The safety margins P. - 0.025 w8 (pei) assodated with these methods of critical speed determination are ustrated in & 6gure.

P. - 0.014 w8 (pei)

(10)

For the scale model flywheels, the prefabricated cracks represent g

a significant reduction in load bearing area of the cracked plane.

Referring to Fig. 2, the effect of reduesi bearing area can be

.'T incorporated into equations (10) by the following approxirnation j

y g

P. - 0.025 w8R (psi)

P. - 0.014 w8R (pel)

(11) where 23 - o)

R 2(b - o) - d (12) k.

Assuming that failure occurs when F. exeoeds S. or when (P. + P.) exceeds 1.5 S. leads to the following expressions for ductile failure speed as a function of crack aise

.g-

.W w

B.

g=

a 0.025 R

/

(13)

)

, jl.5 B.

,h r~

s r.

10.039 R

~

where % is the critical speed based on the membrane streme and Fig.s Types : treetere # es ne eneses rey.h.es 6

Transactions of the ASME

w L. R. Singer, G. O. Sankey, and L. J. Cawluni in carryms out I

the esperunental portion of this program.

References 1 Riccardella, P. C., and Bamford, W. A., "Resetor Coolant Pump Overspeed Evaluation" Westinghouse Nuclear Energy

[

e Systems WCAT.8145, Dec.1973.

E 2 Timoehenko, S., and Goodier, J. N., " Theory of Elastle.

~ - h,U i

ity," 3rd edition, McGraw-Hill, New York 1970.

g 3 ASME Boiler and Pressum Vesel Code,Section III,

" Rules for Construction of Nuclear Power Plant Components,"

i h

m.

American Society of Mechanical Enginaars, New York,1971

T?"

Edition & Addenda.

4 Williams, J. O., and Isherwood, D. P., " Calculation of the Strain-Energy Release Rates of Creded Plates by an A proximate Method," Journal of Sdrain Analyeis, Vol. 3, No. p.

200 1,

1968, pp.17-22.

5 Gabrielse. S. E., " User's Manual for Westin seard General Purpose Finite Element Programs,ghouse Re.

Wuting.

i i

i i

"oe house Research Report 70-1E7-POPSC.R1, April 23,1970.

i'o eo n.o

.e ie e,

6 Oglesby, J. J., and Lomacky, 0., "An Evaluation of asma cua enn o.oul Fin to Element Methods for the Computation of Elastic Stress Fle,18 Hesults.of reacter seelant punip flywteeet everspeed oveie.

Intensity Factors," TRANs. ASME, Vol. 95, Series B,1973, even pp.177-185.

7 Mager, T. R., and Thomas, F. O., " Evaluation b Linear Test mesuite. The three scale model Sywheels, fabricated as Elastic Fract,m Mechanics d Radiation Darnage to gnosm

~

described above, were tested to failure in the his speed turbine rotor testing machine at Westinghouse Research Laboratories.

Study of A533, Grade B. Class 1 Steel,p Characterisation 8 Mager. T. R., " Fracture Tou Westinghouse Nuclear The tests were performed at room temperature (+75 deg) and test temperature and rotational speed were monitored con.

% [ yste 8,

19 mantal Veda.

l tinuously throughout the test.

cation d wer Bound Kic V31ues Utilisms the Equivalent l

The specimens fractured in the manner shown in Fig. 9. The Energy Concept," H88T Progracu 6th Annual Information fracture data from these experiments are plotted on Fig. 8, in Mestagi$ Paper No. 23 A 972 terms of fracture sped versus actual crack depth for comparison 10 y,3 m he al tu

~

with analysis. The agreement between the fracture predictions Ridge National Laboratory, ORNL TM 3b04, 972.

and the experimental data is excel'ent, thus lending a high de-11 Irwin, G. R., " Fracture," Kw' Y,1958,- $_ of Physics, Vol. 6, edited g$"N ' Y k 1966 gree of credibility to the analytical procedures used in the S. Flu

.S erlag, N p.551-590.,

8 Stress and I4w cle Fatigue, prototype 8ywheel evaluation, even in the presence of eseessive M

ew w, '.

plastic sone asses.

13 Lanaer, B. F., " Design of Pressure vessels for Low-Cycle Fatigue," TmANs. ASME, Vol. 84, Series D,1973, pp. 389-402.

ConcluSlonS 14 Rice, J. R., "A Path In and the Approximate Analysis of Strain Conantration Notches and Cracks,"

A detailed evaluation has been performed to determine the

. ASME, o 90 Se 1

pp.

critical speed for the Westinghouse reactor coolant pump By*

Fracture dIterion," Fradurs Tougenses, ASTA P 514,

'i wheel design from the standpoint of fracture and subsequent American Society for Testing and Materials, Philadelphia,1972, ile production.' The resulte of this study are summarized in ppg-23I ndes, J. D., and

, J. A., "The Effect of Specimen j

t 8-Geometry on Jeo" Fracture nas, ASTM.STP.514 Amer.

Ductile falle and brittle fracture of the Sywheel were con.

ican Society for Testing and M terials, Philadelphia,1972, pp.

sidered separs.tely and limiting speeds were established for 24-39.

each. The limiting speed curve of Fig.10 shows that the ductile 17 Riccardella, P. C., and Swedlow, J. L., "A Combined failure limit of 3485 rpm (290 percent overspeed) is governing (en Es ted at SeY-l n

rse m Sti y

2 for ernck sizes less than 1.15 in., and that the brittle fractum 1973, University of Maryland, American Societ Testing l

and Materials, Philadelphia, Pa. (to be published)y limit becomes governing for larger crack sizes. Since this crack 18 AEC wbsolIg,Safetg Guide 14 "Resetor Coolant Purnp Fl size is very large in comparison to that which is detectable under ty C, Oc 1971 current inspection and quality assurance procedures for the Sy.

wheel design, it can be concluded that 3485 rpm is the limiting ducting Drop Weight Test to Determine Nil-Ductility Transi.

speed for the design.

tion Temperature of Ferritie Steels," ASTM Standards (1973).

Finally, a scale model Sywheel test program was carried out to Part 31, Annerican Socie for Testing and Materials, Philadel.

verify the analytical procedures used in this evaluation. Three P P

3g.

y6 tests were performed, and the resulte of all three were highly con-Bar Impact Testing of Metallie Materials " ASTM Standards firmatory. On the basis of this scale model test program, it can (1973), Port 31, American Society for Testing and Materials, be concluded that the methods used to predict aywheel fracture Philadelnhia, Pa.,1973, pp.,277-293.

21 dark, G., "Ultranonic Procedum for the Examination of in this report are highly accurate and, in conjunction with the 1

6 cation 94351 RU, Rev,ywheels," Westinghouse Process Speci.

Main Coolant Pump Fl conservative materials property data used, should serve to pre-

1. Apr.1972.

elude Bywheel fracture under overspeed loading conditions pree.

22 Clark, W. O., and Ceschini. L. J., " Fatigue Precracking viding the calcuWed limiting speeds are not exceeded of Spin-Burst Toughness Specimens," K perintendal Mechanics, Vol. 9,1969, pp.123-128.

23 ASTM Btandard E.399, " Standard Method of Test for Acknowledgment Plane.8 train Fractu e Toughness of Metallic Materials ", ASTM Siendards (1973) Part 31, American Society for Testing and The authors gratefully acknowledge the assitance of Messrs. Materiale, Philadelphia, Pa.,1973, pp. 960.-979.

Prinied La (LS.A.

1 Journal of Pressure Vessel Technology 7

j

)