ML19309B265

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Slide Presentation Entitled, Core Spray Sparger Indications
ML19309B265
Person / Time
Site: Pilgrim
Issue date: 03/13/1980
From:
Office of Nuclear Reactor Regulation
To:
Shared Package
ML19309B251 List:
References
NUDOCS 8004030348
Download: ML19309B265 (45)
v • d • e


Text

.

O PILGRIM CORE SPRAY SPARGER INDICATIONS 5*

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o FABRICATION HISTORY BEND PIPE

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FIT UP IN SHROUD (CHECK FIT)

WELD HEADERS TO T-BOX (SHOP OPERATION)

DRILL N0ZZLE HOLES WELD HALF COUPLINGS TO HEADERS INSTALL ELBOWS MOUNT SPARGER IN SHROUD (COLD SPRINGIf!G ASSUMED)

AIM AND TACK WELD ELBOWS AND N0ZZLES i

1 1

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... ~.-.

I PERFORMANCE HISTORY FIRST CRITICAL - JUNE 1972 NO INADVERTANT CORE SPRAY INJECTIONS CORE SPRAY MAINTENANCE FLOW DURING EACH REFUELING MAX. AT = 130 F

FOUND INDICATIONS ON INNER BEND RADIUS - FEB. 1980 M*

l l

l 1

STRESSES - NORMAL OPERhTION ALL IDENTIFIED STRESSES DURING NORMAL OPERATIONS FOUND TO BE NEGLIGIBLE CONSIDERED i

IMPINGEMENT - FLOW PAST SPARGERS SEISMIC - PROPERLY MOUNTED IS RIGID STRUCTURE PRESSURE -AP

=0 THERMAL MISMATCH - AT 2

0 STAGNANT LINE TOP TO BOTTOM aT < 8 F

THRU WALL AT < 8 F

WEIGHT - NEGLIGIBLE PIPE 9.11 LB/FT f

WATER 4.2 LB/FT N0ZZLES 3 LB/FT l

r l

STRESSES - NORMAL OPERATION - CONTINUED B.0W INDUCED VIBRATION 6

^

PINNED FN 2 21 Hz 7

ct t f

SUPPORTED FN 2 Hz fg CASE 2 fj

3. i 3-to RESTRAINT IGNORED FN

~$ 19 Hz CASE 3 h-[

SUPPORTED NO TOUCH VORTEXSHEDDINGFREQUENCY=.2p F

= 2.64 Hz-y LONCLUSION - UNLESS UNSUPPORTED THERE WILL DE NO CONCERN FOR FLOW INDUCED VIBRATION,

POSTULATED INSTALLATION STRESSES INSTALLATION-RADIAL MISMALCH kR. h Ah -B X R1 CASE 1 R1 = R2 2

FORCE FOR SHRINK = 1/8 INCH o AT T-BOX 2 24 KSI (ELASTIC)

R1 4. R2 CASE 2 g--

  • i ASSUME R1 = 93.25 R2 = 94,25 l

l UNIFORM FORMING c 2 1,1%

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o 2 38.3 KSI (FROM c-e CURVE)

I CONCLUSION - RADIAL MISMATCH f

RADIAL MISMATCH CAN RESULT IN TENSILE STRESSES AT INNER BEND RADIUS STRESSES WILL RELAX TO ELEVATED TEMPERATURE YIELD STRESS DURING OPERATION STRESSES ARE DEFLECTION LIMITED SECONDARY STRESSES I

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STRESSES DURING CORE SPRAY INJECTION f

CONSIDERED j

IMPINGEMENT - FLOW PAST SPARGER = LESS THAN NORMAL OPERAT PRESSURE AP 2 16 PSI, STRESS NEGLIGIBl.E j

=

o 2 160 PSI THERMAL HIGH CIRCUMFERENTIAL AND LONGITUDINAL STRESSES DUE TO THRU WALL GRADIENT, CSECONDARY STRESSES)

SECONDARY BENDING DUE TO CHANGE IN BEND RADIUS I-l a 2 3KSI l-AXIAL STRESS DUE T0 AP AND BRACKET FRICTION o < 300 PSI

[

SEISMIC DUE TO THERMALAR ALL SUPPORTS ACTING THEREFORE = RIDGID STRUCTURE TORSION DUE TO N0ZZLE FLOW o < 200 PSI WEIGHT STRESS NEGLIGIBLE

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. STRUCTURAL INTEGRITY OF A SPARGER WITH CRACKS CONSIDERED IMPINGEMENT BENDING - INCREASE PROPORTIONAL TO DECREASED SECTION MODULUS -

STRESSES INSIGNIFICANT PRESSURE HOOP STRESS - NO CHANGE AXIAL STRESS - PROPORTIONAL TO CROSS SECTinNAl ARFA THERMAL (THRU WALL)

NO CHANGE IN MAX, STRESS CHANGE IN BEND RADIUS l

INCREASED STRESS PROPORTIONAL TO DECREASE IN SECTION MODULUS (DEFLECTION LIMITED)

(

NOTE:-

THIS LOADING WILL CAUSE A THRU WALL CRACK TO OPEN UP, WORST CASE ESTIMATED TO INCREASE GAP BY.005 INCH.

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STRUCTURAL INTEGRITY OP A SPARGER WITH CRACKS-CONTINUED

- AXIAL STRESS DUE TO AP AND BRACKET FRICTION WILL INCREASE PROPORTIONAL TO REDUCTION IN CROSS SECTIONAL AREA BOUNDING #1

=%NNAMM og CRACK OVER 90% OF THE CIRCUMFERENCE (PRESSURE AXIAL LOAD INCLUDED)

BOUNDING #2 ASSUME VESSEL WALL BRACKET HOLDS PIPE UNTIL BRACKET BENDS AS A PLASTIC HINGE HINGE AXIS

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0 = 15000 LBS p

30 KSI FU? A THRU WALL CRACK o

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CONCLUSIONS i

WITH THRU WALL CRACKS, SPARGER FLOW DISTRIBUTION MAY BE AFFECTED BUI CORE SPRAY WATER WILL BE DELIVERED TO SHROUD INTERIOR 5

SPARGER WILL RETAIN STRUCTURAL CONTINUITY

'l l

9 l

=:

STRESS EVALUATION OF THE CORE SPRAY SPARGER 0

OBJECTIVE IS TO EVALUATE DIFFERENT SOURCES OF STRESS IN THE SPARGER AND CONSIDER THEIR EFFECT ON THE OBSERVED CRACKING.

i j-t SR 3/13/80

t INITIAL CONFIGilRATION

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LOAD APPLICATION DURING FABRICATION e

9,

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r FINAL DEFORMED SHAPE AFTER LOAD REMOVAL SR 3/13/80

GENERAL ELECTRIC CO.

Nuclear En rgy Divisbn ENGINEERING CALCULADON SHEET ho..

DATE SUB. LECT 8Y SHEET op P '.

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TRANSIENT STRESSES 8

THERMAL AND PRESSURE STRESSES IN THE PIPE ARE SMALL 9

FLOW INDUCED VIBRATION IS UNLIKELY 8

FATIGUE USAGE DUE TO THE OPERATING TRANSIENTS IS THEREFORE NEGLIGIBLE P

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SR 3/13/80

STEADY STATE STRESSES 9

STRESSES DUE TO FABRICATION COULD BE SIGNIFICANT AND WOULD EXIST THROUGHOUT PLANT OPERATION.

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STRESSES DUE TO INSTALLATION AND RESULTING BRACKET CONSTRAINT ARE IMPORTANT.

9 THE RESTRAINT STRESSES WOULD BE FURTHER INTENSIFIED NEAR DISCONTINUITIES AND WELD REGIONS.

THE WELD RESIDUAL STRESSES TOGETHER WITH THE CONSTRAINT STRESSES COULD BE SUFFICIENT TO CAUSE CRACK INITIATION.

8 UNDER WORST CASE ASSUMPTIONS FOR STRESS CORROSION CRACKING, CRACK GROWTH COULD OCCUR WITH FLAWS OF 0.025 INCH DEPTH.

l SR 3/13/80

CRACK-ARQESTCONSIDERATIONS f

8 SINCE MOST OF THE APPLIED LOADING IS SECONDAR (DISPLACEMENT CONTROLLED), AS THE CRACKS GROW THE APPLIED STRESSES RELAX AND LEAD TO CRACK 8 THE RESIDUAL STRESSES DUE TO FABRICATION TENSION TO COMPRESSION.AS THE CRACKS PROPAGATE INTO REGIONS OF COMPRESSIVE STRESS THE APPLIE DROPS AND CRACK ARREST IS LIKELY.

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SR 3/13/80

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POTENTIAL LOOSE PIECES t

I.

SAFETY ANALYSIS II.

POTENTIAL CONCERNS A.

CHEMICAL OR CORROSION B.

FLOW BLOCKAGE C.

CONTROL ROD INTERFERENCE III.

LOOSE PIECES UNLIKELY IV.

REACTOR INTERNALS A.

SPARGER LOCATION B.

DIFFICULT PATH TO FUEL ORIFICE C.

DIFFICULT PATH TO CONTROL ROD 9

JEC-1 3/11/80

V.

POTENTIAL SHAPES A.

PIPE 1.

2 THROUGH WALL 360 CRACKS 2.

WEIGH LESS THAN 100 LBS.

3.

WILL SINK 4.

CANNOT CAUSE FLOW BLOCKAGE 5.

CANNOT INTERFERE WITH CONTROL ROD B.

N0ZZLES 1.

THROUGH WALL 360 CRACK 2.

WEIGH APPROXIMATELY l 3/4 LBS.

3.

WILL SINK 4.

CANNOT CAUSE FLOW BLOCKAGE 5.

CANNOT INTERFERE WITH CONTROL ROD C.

SMALL PIECES 1.

LONGITUDINAL AND CIRCUMFERENTIAL CRACKS 2.

WILL PROBABLY SINK 3.

FLOW BLOCKAGE A.

EXTREMELY UNLIKELY TO PASS THROUGH SEPARATOR B.'

DIFFICULT PATH TO FUEL ORIFICE C.

SINGLE PIECE CANNOT CAUSE UNACCEPTABLE FLOW BLOCKAGE

~

JEC-2 3/11/80

O 4.

CONTROL ROD INTERFERENCE A.

DIFFICULT PATH TO CONTROL ROD B.

REQUIRES PRECISELY SIZED PIECE C.

MAY BE DETECTED D.

IN WORST CASE, ROD WILL PROBABLY INSERT E.

ONE FULLY STUCK OUT ROD IS ACCEPTABLE F.

UNACCEPTABLE INTERFERENCE REQUIRES MULTIPLE PRECISELY SIZED PIECES VI.

CONCLUSIONS A.

NO POTENTIAL FOR UNACCEPTABLE CORROSION B.

POTENTIAL FOR UNACCEPTABLE FLOW BLOCKAGE IS ESSENTIALLY ZERO C.

POTENTIAL FOR UNACCEPTABLE CONTROL ROD INTERFERENCE IS ESSENTIALLY ZERO l

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b MATERIALS ASPECTS OF PILGRIM CORE SPRAY SPARGER CRACKING I

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LISTING OF POSSIBLE CAUSES OF CRACKING 4

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e MATERIALS DISCUSSION OF COLD WORK AND IGSCC i

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e

SUMMARY

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POSSIBLE CAUSES OF CRACKING LOCATION POSSIBLE CAUSE EVIDENCE 1.

SPARGER ARMS NEAR T-B0X e

SENSITIZATION BY LOCATION OF CRACKS WELDING e

COLD WORK FOLLOWED BY ESTIMATED 5% COLD WORK WELD SENSITIZATION NEAR T-B0X e

FATIGUE (THERMALLY UNDER EVALUATIONzST's INDUCED)

ARE LOH e

FATIGUE (FLOW-INDUCED UNDER EVALUATION VIBRATION)

AMPLITUDES ARE LIMITED 2.

SPARGER ARMS AWAY FROM T-BOX e

SENSITIZATION FROM NONE-FABRICATION e

COLD WORK FOLLOWED PIPE BEND FORMING

  • BY SENSITIZATION NO EVIDENCE OF SENSITIZATION e

LOCAL HEAVY COLD NONE WORK e

FATIGUE SAME AS AB0VE

  • SENSITIZATION AND COLD WORK STATE OF SPARGERS NOT YET KNOWN l

b

EFFECTS OF COLD WORK ON IGSCC 0F TYPE 304 STAINLESS STEEL m

INCREASES DECREASES SUSCEPTIBILITY SUSCEPTIBILITY TO CRACKING TO CRACKING IMPOSED STRAIN IMPOSED LOADS INCREASES YIELD STRENGTH o

COLD WORK INCREASES

_ PROMOTES _,

o CHROMIUM ACTIVITY CHROMIUM RECOVERY PRODUCES MARTENSITE AIDS RECRYSTALLIZATION IF CW > 15% AND HEAT TREATED

(

Y AT HIGH TEMP, x s

IGSCC IF SENSITIZED INCREASES i

  • -AFTER MODERATE COLD-CARBIDE WORK (STRESS REQ'D)

PRECIPITATION

/

TGSCC AFTER HEAVY COLD WORK (STRESS

/

RE0'D) s

EFFECTS OF COLD WORK ON IGSCC 70 Yield, 1/4 Hard A

@E 79 Ksi TYPE 304 0.2 ppm 0 1/4 Hard, Irradiated 8% Cold Work &

A b.

9 No Cold Work Furnace Sens.

g 5% Cold Work Furnace &

50 Yield, 8% CW k Sensit.

G A 8% Cold Work x

5% Cold Work & Furnace E

Sens.

A g-1/4Hard j

E!

+ Yield, 5% CW M 40

[] 5%ColdWork}

8% Cold Work l No Sensitiz.

A Furnace Sens.

30 9

Yield, Furnace Sens.

p 20 e--

APPR0XI. SAf1E TIME TO FAILURE i

IN SENSITIZED VS. CW & SENS.

1 Year 10 Years s

,L 10 I

I 100 1000 10000 100000 Time to Failure - Hrs.

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j 170 Ksi EFFECTS OF COLD WORK ON IGSCC (elastic) l 120 g

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. Yield 5% CW 40 of c,p_

Furnace Sens.

, Yield, Furnace Sensit.

CRACKING IN C.W. f1ATERIAL ONLY AT VERY HIGH STRESS WilEN NOT SENSITIZED 0

i 100 1000 10000 100000 Time to Failure (Hours)

I

EFFECTS OF COLD WORK ON IGSCC 3

I TYPE 304 O.2 ppm 0, 550 F 2

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Cold Work 9 No Cold Work Furnace T

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.4 CONDITION ONLY

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I 100 1000 10000 100000 Time to Failure - Hours j

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80

,0 70 Yield Stress vs.

% Cold Work 60 ys**

g gg 50 -

W ys&

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COLD WORK - STRESS / STRAIN 5

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v-EQUIVALENCE e

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10 3

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10 15 20 25 30 35

% Cold Work or Strain l

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COLD WORK AND-IGSCC e

MECHANISM OF ENHANCED IGSCC SUSCEPTIBILITY IS COMPLEX; NUMEROUS FACTORS ARE INVOLVED.

e MODERATE AMOUNTS OF COLD WORK REDUCE STRESS THRESHOLD TO 0.8 COLD WORKED YIELD IF MATERIAL IS SENTITIZED AFTERWARDS, e

TGSCC HAS BEEN OBSERVED IN HIGHLY COLD WORKED MATERIAL BUT AT STRESSES AB0VE YIELD.

e LOCAL (SURFACE) COLD WORK, IF SEVERE, CAN INITIATE CRACKS WHICH MAY GROW BENEATH THE HARDENED REGION.

- PIPE CPACKING EXPERIENCE ROLE IN CORE SPRAY SPARGER MAYBESIGNIFICANT L

SCENARIO ON CAUSE OF CORE SPRAY SPARGER CRACKING

. VARIABLE..

EVENT FROM PLANT TO PLANT 1.

SOME SENSITIZATI0ll FROM PIPE

/

VENDOR FABRICATION

+

2.

COLD WORK DURING PIPE BENDING

/

+

3.

WELD SENSITIZATION DURING T-SOME PLANTS ARE 304L B0X OR ELBOW WELDING

+

4.

INSTALLATION & RESIDUAL

/

STRESSES

+

COLD WORK / SENSITIZATION (IGSCC) e KEY CONTRIBUTORS TO CRACKING VARIABLE e

21 PLANTS INSPECTED TO DATE e

19 PLANTS REPOP.TED NO CRACKING l

PILGRIM SPARGER CONCLUSIONS e

CONFIDENCE THAT CRACKING NEAR T-BOX CAN BE EXPLAINED BY DATA AND SPARGER CONDITION 4

e LESS CONFIDENT IN EXPLANATION OF CRACKING MECHANISM AWAY FROM T-B0X 4

i 1

PILGRIM ECCS ANALYSIS o

REQUESTED BY BECO o

NO CREDIT FOR CORE SPRAY TRANSFER o

RUNS DONE WITH APPROVED MODELS CONSERVATIVE ASSUMPTIONS, NO MODEL IMPROVEMENTS CURRENTLY UNDER REVIEW o

PRELIMINARY RESULTS~

MAPLHGR REDUCED 5 - 10 %

o GE CONSIDERS BECO APPROACH EXCESSIVELY l

CONSERVATIVE l

4 JAA -1 i

3/13/80

NO CORE HEAT TRANSFER CREDIT 2

o LIMIT BREAK - 4.34 FT SUCTION BREAK o

EFFECT ON BLOWDOWN & REFILL CALCULATION

- NO CCFL PREDICTED

- NO REFLOOD DELAY

- NO CHANGE IN DEPRESSURIZATION RATE, UNC0VERY TIME, OR REFLOOD TIME o

EFFECT ON HEATUP CALCULATION

- NO SPRAY-TRANSFER ON FUEL RODS

- NO CREDIT FOR CHANNEL WETTING l

_ HIGHER PEAK CLADDING TEMPERATURES o

FIVE FUEL TYPES CONSIDERED

- 0 TO 30,000 MWD / ST EXPOSURE RANGE JAA -2 3/13/80

CONSERVATI SM,IN BECO APPROACH o

BUNDLE HEAT TRANSFER DURING CORE SPRAY PERIOD

- CORE SPRAY DISTRIBUTION

- POOL OF WATER

- CHANNEL COOLING

- STEAM COOLING o

REFLOOD TIME

- CCFL CORRELATION

- BYPASS LEAKAGE FLOW

- CCFL BREAKDOWN

- VAPORIZATION CORRELATION o

OTHER MODEL CONSERVATISMS

- DEPARTURE FROM NUCLEATE BOILING

_ FILM BOILING CORRELATION (BROMLEY)

- DECAY HEAT ( OLD ANS + 20%)

JAA - 3 3/13/80

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