ML20058G666

Summary of 930909 Meeting W/Licensee in Rockville,Md Re Results of Util Analysis of CR-3 SG Tubes Pulled During Last Outage.Attendees Listed in Encl 1

ML20058G666
Person / Time
Site:	Crystal River
Issue date:	11/24/1993
From:	Silver H Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9312100039
Download: ML20058G666 (60)

Text

__ _ . _ - _ - _ -

Novcaber 24, 1993 Docket No. 50-302 I

l LICENSEE: Florida Power Corporation l

FACILITY: Crystal River Unit 3 (CR-3)

SUMMARY

OF MEETING ON SEPTEMBER 9, 1993, REGARDING CR-3 STEAM GENERATOR TUBE EXAMINATION Representatives of the licensee met with members of the staff on September 9, 1993 in Rockville, Maryland, to discuss the results of the Florida Power Corporation (FPC) analysis of the CR-3 steam generator tubes pulled during the last outage.

Enclosure 1 is a list of attendees. Enclosure 2 consists of the licensee's handouts distributed at the meeting.

Six tube sections were pulled to permit examination of an increasing number of small amplitude indic-tions during eddy current examination. The degradation was determined to be pit-like intergranular attack (IGA), caused by a now-inactive sulfur intrusion into the steam generator. Burst pressure tests exceeded the requirements of Regulatory Guide 1.121 and the degradation was not deemed to be safety significant. Further inspection of tubes with similar indications will be performed ;c the next outage and additional tubes will be pulled for examination.

A number of questions were raised by the staff which were later addressed by the licensee in its letter of September 30, 1993 (Enclosure 3). Review of this letter will be addressed in separate correspondence.

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(Original Signed By)  !

Harley Silver, Senior Project Manager '

Project Directorate 11-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation i

Enclosures:

As stated cc w/ enclosures:

See next page 60 1 CHICE LA:PDII-2 PM:PDI]4 D: PD1J_-2.~ EAc3k[ \:PDII[

NAME ETana /ff HSilM HB[rhb ML[.bf RC u mt 11/ 8 93

/ 11/ 6 /93 II/N /93 ///21/O ['I k 0FFICIAL RECORD COPY - DOCUMENT NAME: C:\ AUTOS \WPDOCS\ CRYSTAL \

9312100039 931124 .

A h h (

T Crystal River Unit No.3 Florida Power Corporation Generating Plant cc:

Mr. Gerald A. Williams Mr. Joe Myers, Director Corporate Counsel Div. of Emergency Preparedness Florida Power Corporation Department of Community Affairs KAC-A5A 2740 Centerview Drive P. O. Box 14042 Tallahassee, Florida 32399-2100 St. Petersburg, Florida 33733 Mr. Bruce J. Hickle, Director Chairman Nuclear Plant Operations Board of County Comissioners Florida Power Corporation Citrus County Crystal River Energy Complex 110 North Apopka Avenue 15760 W. Power Line Street Inverness, Florida 32650 Crystal River, Florida 34428-6708 Mr. Robert B. Borsum Mr. Rolf C. Widell, Director B&W Nuclear Technologies Nuclear Operations Site Support 1700 Rockville Pike, Suite 525 Florida Power Corporation Rockville, Maryland 20852 Crystal River Energy Complex 4 l 15760 W Power Line Street Crystal Rive:, Florida 34428-6708 Regional Administrator, Region II y U. S. Nuclear Regulatory Comission Senior Resident Inspector 101 Marietta Street N.W., Suite 2900 Crystal River Unit 3 Atlanta, Georgia 30323 U.S. Nuclear Regulatory Commission Mr. Bill Passetti 6745 N. Tallahassee Road Office of Radiation Control Crystal River, Florida 34428 Department of Health and Rehabilitative Services Mr. Gary Boldt 1317 Winewood Blvd. Vice President - Nuclear Tallahassee, Florida 32399-0700 Production Florida Power Corporation Attorney General Crystal River Energy Complex Department of Legal Affairs 15760 W Power Line Street The Capitol Crystal River, Florida 34428-6708 Tallahaseee, Florida 32304 Mr. Percy M. Beard, Jr.

Sr. Vice President Nuclear Operations-Florida Power Corporation ATTN: Manager, Nuclear Licensing (NA2I)

Crystal River Energy Complex 15760 W Power Line Street Crystal River, Florida 34428-6708

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November 24, 1993  ;

DATE:  ;

Distribution

DocketJ11e

• NRC & Lccal PDRs PDII-2 RF <

T. Murley/F. Miraglia 12-G-18 L. Callan  !

S. Varga G. Lainas H. Berkow H. Silver E. Tana 0GC E. Jordan, MNBB 3701 T. Reed K. Karwoski l R. Coe -

P. Sherburne L. Connor E. Murphy W. Lyon J. Donoghue J. Strosnider H. Conrad J. Wiggins -

R. Jones R. Luken X. Karwoski l ACRS (10)

M. Sinkule, RII R. Croteau

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,,a Encionuro 1 '

y Crystal River Unit 3 Steam Generator Tube Examination Meeting on September 9,1993 Attendees Hast Office Harley Silver NRR/PDII-2 Herb Berkow NRR/PDII-2 Phyllis Dixon FPC Ken Wilson FPC Rolf Widell FPC Gerry Cowles FPC -

Loretta Cecilia FPC f Kenji Kreywosk EPRI f L. Raghavan NRR/PDII-2 $

Sterling Weems MPR Rocky Thompson FPC Ray Luken BWNT Robert Jones NRR/SRXB James Wiggins NRR/DE H. F. Conrad NRR/EMCB Jack Strosnider NRR/EMCB Joe Donoghue NRR/SRXB Warren Lyon NRR/SRXB Kevin Redmond B&W/NESI Emmett Murphy NRR/EMCB Lynn Connor STS Paul Sherburne BWNT Robert DePriest NRR/PDII-2 Richard Coe BWNS Ken Karwoski NRR/EMCB Tim Reed NRR

1 Enclosura 2

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1 ONCE THROUGH STEAM GENERATOR REFUEL 8 1 TUBE PULL ANALYSIS l .

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FLORIDA POWER CORPORATION CRYSTAL RIVER UNIT 3 i f

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SUMMARY

• DECISION TO PULL TUBES WAS BASED ON  ;

L AN INCREASING NUMBER OF SMALL .

AMPLITUDE INDICATIONS

• SIX TUBE SECTIONS WERE REMOVED FOR

.: ANALYSIS

• . DEGRADATION IN THE FORM OF PIT-LIKE  :

' IGA DUE TO ATTACK BY SULFUR OXYANIONS i WAS IDENTIFIED  !

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• SOURCE OF SULFUR WAS BELIEVED T0 BE  !

RESIN FROM CONDENSATE DEMINERALIZERS j l l

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• DAMAGE MECHANISM ORIGINATED IN EARLY  !

! 1980s AND IS NOT ACTIVE l 1

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• BURST PRESSURE TESTS DEMONSTRATE i- TUBES EXCEED RG 1.121 LIMITS i i  !

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.* TUBES WITH PIT-LIKE IGA WILL BE l

! REINSPECTED DURING REFUEL 9 AND WILL  ;

I BE LEFT IN SERVICE  !

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SU41ARY OF EDDY CURRENT INSPECTION PRIOR TO REFUEL 8 (1992)

"A" AND "B" STEAM GENERATORS "A" STEAM GENERATOR 1987 REFUEL 6 1989 HIDCYCLE 1990 REFUEL 7 NO. OF TUBES 3370 (22%) 2831 (18.2%) 3795 (24.4%)

INSPECTED PLUGGED 3 1 10 (<1%)

TOTAL No. PLUGGED 20 (<1%)

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1987 Re.:JEL 6 1989 HIDCYCLE 1990 REFUEL 7 NO. OF TUBES 0 2097 (13.5%) 4155 (26.8%)

INSPECTED PLUGGED 0 0 24 (<1%)

T",TAL No. PLUGGED 51 (<1%)

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SAMPLE 1 SAMPLE 2 SAMPLE 3 MINIMUM 466 TUBES MINIMUM 932 TUBES MINIMUM 1864 TUBES (ACTUAL 1122 "A" (ACTUAL 2243 "A" (ACTUAL 4596 "A" 891 "B") 1782 "B") 3752 "B")

MINIMUM 3% MINIMUM 6% MINIMUM 12%

l MRPC INSPECTION MRPC INSPECTION [ MRPC INSPECTION i

100% or ALL INDICATIONS SELECTED INDICATIONS SELECTED INDICATIONS

I ULTRASONIC EXAMINATION SELECTED INDICATIONS l

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GOOD GENERAL CONFORMANCE TO EPRI PWR STEAM GENERATOR EXAMINATION GUIDELINES

• CHOSE AN EXPERIENCED ISI VENDOR

• ESTABLISHED PLANT SPECIFIC WRITTEN EDDY CURRENT DATA ANALYSIS GUIDELINES '

• EXAMINED BOTH STEAM GENERATORS

• EXAMINATION CONSISTED OF A RANDOM AND EXPANDED SAMPLE, INCLUDING KNOWN AREAS OF CONCERN AND PREVIOUSLY DEGRADED TUBES

• USED APPROPRIATE NDE DIAGNOSTIC METHODS

• USED DIGITAL MULTIFREQUENCY EDDY CURRENT INSTRUMENT.\ TION AND '

APPROPRIATE FREQUENCIES FOR PRODUCTION BOBBIN COIL TESTING ,

• PRIMARY AND SECONDARY DATA ANALYSIS

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• EPRI GUIDELINES RECOMf1END THAT TUBES WITH DISTORTED OR UNDEFINED SIGNALS  :

BE RECOMMENDED FOR PLUGGING UNLESS  !

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TUBE PULLS OR PREVIOUS NDE DIAGNOSTIC  !

DATA) OR IS DEVELOPED DURING THE  !

COURSE OF THE OUTAGE, WHICH JUSTIFIES l THEIR RETENTION AS ACTIVE TUBES  !

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TUBE PULL PLAN G0ALS

• PHYSICALLY CHARACTERIZE ANY TUBE .

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• IDENTIFY THE DAMAGE MECHANISM, IF ANY EVALUATE THE STRUCTURAL INTEGRITY OF THE TUBING QUANTIFY THE ACCURACY OF EDDY CURRENT TECHNIQUES l

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I TASK 1: NONDESTRUCTIVE PHASE  !

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• RECEIPT INSPECTION

• VISUAL INSPECTION & PHOTOGRAPHY  !

• EDDY CURRENT TESTING

• ULTRASONIC TESTING ,

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4 TASK 2:- DESTRUCTIVE PHASE Tube Sections Description 97-91-2 52-51-2 52-51-4 133-33-3 of Task 106-32-2 90-28-2 109-30-2 41-44-2 90-28-5 133-33-9 133-33-2 Hand-Pull ECT X X X X*

00 Descaling X Post-Clean ECT X ,

Liquid Penetrant X Tube Sectioning X X X Tube Swelling X X X X Burst Testing X Deposit Sampling X X X X Stereovisual X X X X X X Tube Sectioning X X X X X SEM/EOS X X X .~.

Hetallography X X X '

-X X SAM /XPS X

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52-51 133-33-3 Deposit Analyses: 106-32-2 90-28-2 109-30-2,41-44-2 90-28-5 133-33-9 133-33-2 SEM/EDS (F1akes) X X X X

' SAM /XPS (?lches) X X X fCP X X X X XRD X X X X Total Carbon X X X X Tota'i Sul fur X X X X FTIR X X X l.aser Raman X X X XRF (LTSF dep.) X Mossbauer Spec. X(ID)

X X X Hg Porosimetry. X X X y Spectroscopy ' X X(IO) f 1

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NON-DESTRUCTIVE EXAMINATIONS. l

• FIELD AND LABORATORY EDDY CURRENT .

RESULTS WERE IN GENERAL' AGREEMENT  :,

MRPC INDICATED EDDY CURRENT SIGNALS FROM FIRST SPAN WERE' TYPICAL OF PITS  !

INDICATIONS LOCATED 5 TO 18 INCHES'ABOVE i THE LOWER TUBE SHEET SECONDARY FACE  !

• INDICATIONS i

ON PULLED TUBES WERE j

" REPRESENTATIVE OF THE TOTAL POPULATION l

OF INDICATIONS IN FIRST SPAN  :

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k$

u c ^20"2s" .

. .i . , , ,

o.s s.io io-is 1s 20 as.ao soas as.40 40 4s a

ELEVATION ABOVE LTSF, INCHES

"?

l 8 '

1

.--.-,_.-,.m~.

--ww. . - - . , , - . - -.-.r,--. . . , - - - . . . , - - - - ~ - - - . . ~ ~ _ , - . . - . . - . - , 2 ..,_.- . _ _ _ __=_m---. - -_ _ ~ _ _

0

0 _

1

" ,0 0 G "

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PIN _

HIA S M -

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NE u@ g OR o .

T I

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a 2 p

,1 E S at t

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RE D EB uM p E

SU a 0G L

AT o ,0 1 N H A P D n

'F.

w E S

SU A Ew H NU ,80P EP "e DG "

c OS l

T -r uO P -

y ,0 0

MB o A3 -

R + 0 C

4 0

5 5 4 5 3 5

2 2 5 $ 5 C -

4 3 2 0 h >itO i

aka i

j 1

DESTRUCTIVE EXAMINATIONS l l

• HYDRAULIC EXPANSION OF TUBE SECTIONS ]

REVEALED TINY PATCHES OF INTERGRANULAR'  :

ATTACK (IGA) i

• MORPHOLOGY OF DEFECTS WAS PIT-LIKE IGA j WITH GRAINS INTACT '

t

• DISTRIBUTION OF THROUGH WALL DEPTHS- l CLOSELY RESEMBLED A NORMAL DISTRIBUTION l WITH AN AVERAGE THROUGH WALL DEPTH OF-  !

28%  !

l i

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f

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/

3 a

J l

a 1

J j

i j

J i

a y -T

c. r a..' .. . 4 .M:3 g,

.. e 4 .(

e c 1

, f. ' 6 e., .

ec ,'T',.

s

, ,,,Q - m ,. . . , g. . -

o. . . s -

, -w . - 1 g- +

r,,;, e g ur .e, 3 i . . . . . , , . . , . s e 3  ?.

,.6.

5 v c ,

, q -

. 4*  %

1

. g s l -

1 i . .

i 1 ..

e .. . . _ _ . .._.. . . _-

i I

) 100X Cross Section Through IGA - Tube Section ,

109-30-2B i

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l . .,  !

1 . . _ . . _ . . _ . _ . ____ _ _. - -

__ _A h.A_ _%.i

_ X + - #r . __ _ m; t 4- 6 u.

n. - 4 DISTRIBUTION OF IGA PATCH DEPTHS ALL TUBE SECTIONS PERCENTAGE OF TOTAL IGA PATCHES 30%

25%

4 4 20% l .

l .

15% / \,

a ..

l 10%

5% -

N.

4

.g i- .. .,

• • . . I 0% ~ "'"-'---- '

0% 20% 40% 60% 80% 100 %

DEPTH (%TW) .

D i

I

.-. 2v4 a A + w -- - t.-e &

O k e-a 0.04" ->

15' I 19 J, 28% TW if AVERAGE PIT-LIKE IGA 1

4

. -w _ nu w-- . ----..m.---.- ,- w-ww ,....,,e - . . , . . . . , , , . --w r,.- ,, - -... w,*w.-..w.. . ~ . , - . < , . . - *~,,,-,,.<ww., -

.,4%..- ,.,.w. -- , , -, - . v... we *,m-, ,, e-- --,-w'ee<=*- ,-.ww.--

i I

I i

i i

CHEMICAL ANALYSIS 1

• SIGNIFICANT LEVELS OF SULFUR ON GRAIN  !

FACETS OF DEFECT SURFACES  !

t

• SLIGHT NICKEL DEPLETION AT THE GRAIN  !

BOUNDARY I

• PRESENCE OF SULFUR AND NICKEL DEPLETION INDICATES INTERGRANULAR !

ATTACK BY SULFUR OXYANIONS i P

i f

i

)

)

4

• 4 3f0793-02 FIGURE 6 Dt-1 ECTION RATE, BOBBIN EC TUBES 52-51, 90-28, 97-91, & 106-32

,gg S/92 FIRST SPAN INDICATIONS ONI,Y 90 2

5 80 cn 87 [ 7, E* / /

O 50 e* / d -

8*

W

//

//

0*' f2 C

O

-_JJ. . -

20 40 60 80 100

%TW FROM DESTRUCTIVE EXAM NOTE: VALUE FOR 60 70% TWIS BASED g$ ON ONE DATA PO4NT.

$d ..

%: -e- FIELD DATA -M- FIELD AND LAB DATA d

l 3F0793-02 f!GURE 7 DETECTION RATE, MRPC TUBES 52-51, 90-28, 97-91, & 106-32 5/92 FIRST SPAN INDICATIONS Oyt,Y 90 --

O 80 ~ - - -

EM /

70 cco 60 / r.

o

• W / /

O 40 W //

8 //

10 --

-s A

0 9

= .

=g- . .

9 g9

. c .

g .

%TW FROM DESTRUCTIVE EXAM yy NOTE: VALUE FOR 90 70%1WIS BASED D

7 ON ONE DATA POefT.

• --e- FIELD DATA --*- FIELD AND LAB DATA nt as

FPRE  :

f I

i D E~~ECT O N 3 lO 3AB _ TY  !

100

=! 90 7 I-  ;

O 1 O 80 - i z

55 70 /

/ i l

i 1 co O - / l m 60 7 =  :

m 50

/ .

1 2

O 40 ,

r  !

O 30 -t w

b  !

20 o

• 10 -

/ - 1 i

0, .

1, 0 10 20 30 40 50 60 70 80 l

% WALL LOSS BY DESTRUCTIVE ANALYSIS  !

-=- BOBBIN COIL RESULTS  :

I t

i Figure 2 - IGA percent detection at various ' depths by bobbin coils i.

I f

t

3F0793-02 FIGURE 8 BOBBIN EDDY CURRENT ACCURACY TUBES 52-51, 90-28, 97-91, & 106-32 ,

100_ INCLUDES BOTH FIELD AND LAB DATA 90 z -

80_ WEND BY B088W EC "

$

• r, 8 '0 6 a ~ ._ . /

g a e v 8:..

E /O @%

/- - .

• ~

6 20 fo O UNDERSIZED BY BO99tN EC 10 / d o

2'O o a 4'o do do 100

%TW FROM DESTRUCTIVE EXAM o v.

&. 7 uw a* =

Om FIELD DATA. O LAB DATA MM NO

+

- - . . . . , . . . . - , -,. .._ -,, . , , . . , _ . . . - - - - . . . - . , . ~ . . -

. . - ~ . . . . . . . .--...-,<.._......~_---...._J_.,, . - - . _ . - . . .---~,..-_,_.__..-_.._m,_ _ _

. EPRI~

L CO V 3A t .VE A\ ALYS S 5/14/92 g 100 s i x g 90 + "

• x-' '

EC DATA F 80 - -

x .*

W n 70 , BEST FIT i N /,

O w

Q-50- *x - [/'/

• CORR. COEF. 25%

{w 40 RMSE 27%

w n . x

[ 30 # '

2'

$ x I SLOPE .65 0 20 l

>- x

• x .x 10- / -

rx -

X/Y-MEAN 36/30% ,

0 "

. i x ix x . i . .

0 10 20 30 40 50 60 70 80 90 100 MET PERCENT WALL LOSS Figure 3 - Linear regression analysis of eddy current bobbin coil estimates versus metallurgical test results

i i

BURST TESTS i

• MULTIPLE INDICATIONS WERE SUBJECTED TO RAPID PRESSURIZATION AS PART '0F BURST TESTS  :

• TUBES WHICH WERE BURST WERE  !

REPRESENTATIVE OF INSERVICE TUBES i

• BURST PRESSURES EXCEEDED REGULATORY  !

GUIDE 1.121 LIMITS  !

i

~

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f t

t

BURST TEST RESULTS t T-  !

NUMBER OF L TUBE INDICATIONS BURST ON TUBE l SECTION PRESSURE 1 97-91 (PSIG) I 17 12,400 106-32 62 _ i 11,400== -

a i

l I

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[

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l 3F0793-02 FIGURE 10 l

A;',""';,%" BURST PRESSURE PARAMETER CURVES EDM SLOT MODEL, SGTIP m 1=

O g r it.soo est. 40% IV als rit.tthe IGA E

o.9-E o.e- nn .25 3

m o.7-l m -

M = .4 0.6-l 1

o-m o.s-x '

U h/t = .00 m 0.4-O "*e 0"'s. .izi tien p x op>

us 0.3-u n

i! o.2- m .so 2

E o.1 -

k o , ,

m - 1.0 I

O 2 4 6 j ,, g a 1o 32- 14 16 18 20 P!? cn41ues:s NORMALIZED LENGTH (tJsqrt(Rt)) 'd's.3 t - ei o g3 uaxtenem

^

"I .

A SURRY DATA g$

• I "8

1 I

CONCLUSION c

PRESENCE OF PIT-LIKE IGA DOES NOT AFFECT  ;

TUBES' STRUCTURAL INTEGRITY. 1 TUBES WITH PIT-LIKE IGA CONTINUE T0 l PROVIDE ADEQUATE REACTOR COOLANT SYSTEM  :

PRESSURE B0UNDARY  :

i i

4

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't

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4 1

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i REVIEW 0F ECT HISTORICAL DATA 1 1

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+

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BWNS REVIEW i

INDICATIONS FIRST OBSERVED ON FOUR  !

TUBES IN 1980 INSPECTION  !

• i THESE IN 1985, FOUR 1989, TUBES WERE ALSO INSPL AND 1990  ;

• BWNS REVIEW OF INDICATION-i SIGNAL --

CHARACTERISTICS INDICATES NO EVIDENC  !

OF GROWTH BETWEEN EACH INSPECTION ,

-[

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~

i

_ _____ _ ___________- - __j

~

i EPRI INDEPENDENT REVIEW l

• EPRI INDEPENDENT REVIEW OF ECT  !

HISTORICAL DATA FOR PULLED TUBES l WHICH WERE INSPECTED IN 1989, 1990,

'AND 1992

• DETERMINED NO NEW INDICATIONS APPEARED ON TUBES BETWEEN EACH -!

INSPECTION L

• DETERMINED INDICATIONS APPEARED STABLE AND HAVE NOT GROWN BETWEEN INSPECTIONS l

1 l

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I

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CONDITIONS FOR ORIGINATION OF IGA  !

• REDUCED SULFUR ,

i

\

• 0XYGEN (OXIDIZING CONDITIONS)  !

• Low TEMPERATURES (<170 F)  !

• SENSITIZED MATERIAL j

l l

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i 5

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l

RATIONALE FOR ORIGIN OF PITLIKE IGA }

l

• FIRST SPAN INDICATIONS ARE _WITHIN l TODAY'S KIDNEY-SHAPED FLAKE PILE  !

REGION -j

• RESIN LEAKAGE TESTS PERFORMED AS PART  !

OF EPRI STUDY IN 1982 INDICATED HIGH LEVELS OF RESIN IN CONDENSATE i DEMINERALIZER EFFLUENT; HIGH NUMBER l OF MAINTENANCE ACTIVITIES ON RESIN l TRAPS IN SAME TIME FRAME .j

• SEVERAL TRIPS WHERE OTSG LEVEL WAS VERY LON OR TRANSIENT ANALYSIS NOTED l

" BOIL DRY"  !

i

• EMERGENCY FEEDWATER WAS MANUALLY I' INITIATED AFTER SEVERAL EQUIPMENT  ;

CHECKS i

• EMERGENCY FF.EDWATER PIFING RUN IS  !

CONSIDERABLY LONGER TO "B" STEAM  !

GENERATOR THAN "A"  !

I t

i j

i l

9 ALL IUBES X11H ist SPAN S/N INDICA 110HS 9

M7; GYSTR GUI 3 -

GDGWR 8 e nt rmc:m f:50 10TAL R8ES . 15531 10TR IIIS ASSMG: f5f SJPORT RESI J  : 48 s man w w

s. . . . . .. .

u- .

3 n.

s..... .v .

n. . .

m- ....... ... ...

r E.

. s. .

S.

.. .s .s... . . .

a.

. . . ... .....s. . . . .. . . . . . . ... . . . .. ....

m. . .. .. .. . s.

. ..ss ...... s .ss

s. .. ...

m. . .

..s.s...

....s

. .v.....

. s. ... .

. .s . .. ......

. ..... ....s... ........ ... . .. .. .... ...... .. .........s...

.s...........s. .s. . . . . .

N. .

. . . . . .s..... ... . . . ... ..

.s.i .

m.. . . ... . ... ... .. .. ... . ... ........... .......... ..

.... . .s.. . .s..p. . .. . .. . ... ... . ... . ..

t w.... .

... s.... . . .............

. . .. . . . ...i._...

. . . . . . .s. .. . . . .. . . . . . .. .. . .. . ... .

. .. .... ..... . .......ss n..... . .. .. .. .

es . .

O. ... . . ... ..

. . . .s. .... . . .... .. . . . .. . . . . .

.s. . .

m. ..

1

. .. . . ....n. ........ . . . . . . .. .. . . .. .. . .... .. ..

m.. ... . s. . . . . . .

. . . . s. . . ...... .....

.. . ..s..... ... .... ..............

S. .. .. .. . . .. . . . ... .w.vs.. .. .. .... . .... ..........s . .

. .. . . . ... . .. ..s.s..

..s... .. .

w..

. . . .. . s ... .. . ... . .. ....... . . . . . . .

.s. .. .. ....

s. . . s. . . . . . ... .. .. .... . . ..... ........

s.

. . .. .. . s... .

c. m.

.s. ...

....ss.s.... . . ..

. . ....... .....s..

m.... ... .

. .s. . .

...m....

o.s

.......i. . .... .... .. . . . .. ....

m. . . . . . . . . . . .

. .... ..... ..... ... ....... .s s

g_. ...

us . .... .. . . .... . . . ..

. . v s. . .

. . . . . . . ... .. . . .. ...... e

m. ... ..... .... ................ ....... .. ... .... . . .... .. . .. .

d ..

m.. ... .... .. .... ....

m.

4 . .. .

se . .. . . .... .. . .

. .. ... . .. .............. . . . .. . .. ... r y.

. .. . . . . ... . . . . . . . . . . . . . l

p. q M .. . .. ..

H , . , . -

s ,.

a 7

.i i

i DAMAGE MECHANISM IS NOT ACTIVE l

• - ECT HISTORICAL DATA DOES NOT INDICATE .  !

GROWTH  !

l

• LESS- REPAIR ACTIVITIES ON j DEMINERALIZER RESIN TRAPS  !

• AUTOMATIC EMERGENCY FEEDWATER  !

^

INITIATION CONTROL (EFIC) INSTALLED IN 1985 q

l I

9 l

r l

i

._ _ . _ _ .__.-_i

P i

i CONCLUSIONS .i i

• DAMAGE IS PIT LIKE IGA DUE TO SULFUR OXYANIONS i

• TUBES WITH PIT-LIKE IGA MEET l'G 1.121 l LIMITS  ;

i i

• NO EVIDENCE OF GROWTH BETWEEN .

INSPECTIONS OR OF NEW INDICATIONS  :

. . . _ y i

i i

I i

I l

\

a REFUEL 9 PLANS  !

i t

• REINSPECT FIRST SPAN OF AFFECTED i TUBES TO CONFIRM N0 GROWTH AND LEAVE i TUBES IN SERVICE

• TUBE PULLS FROM 7TH TSP  !

i k

t

-f N

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. . - . .~ ... . . ,- - .n - - .n a .a >

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5 AREAS TO BE ADDRESSED IN R9 1 REVISED ANALYST GUIDELINES ,

I

• ESTABC_ISH CRITERIA FOR REINSPECTION OF EXISTING INDICATIONS TO FURTHER i

VERIFY NO GROWTH CONCLUSION i I

• DETE'RMINE HOW

' TO DIFFERENTIATE  !

BETWEEN PIT-LIKE IGA AND ANY NEW  !

DAMAGE MECHANISM WHICH MIGHT OCCUR IN i SAME REGION I I

• ESTABLISH CRITERIA i TO DISPOSITON  !

"NEW" PIT-LIKE IGA INDICATIONS t i

.i l

1 4

t

SUMMARY

FIRST FOUND IN EARLY/MID-1980'S I

SUBSEQUENTLY CONCLUDED CAUSE WAS SULFUR, TRACED BACK TO RESIN INTRUSION DUE TO DEMINERALIZER TRAPS / SCREENS FAILURES IN EARLY 1980's (SUBSEQUENTLY REPAIRED)

PULLED TUBES AND CONFIRMED ESSENTIALLY NO STRUCTURAL DEGRADATION (BURST PRESSURE ABOUT 87% OF VIRGIN TUBE)

ATTACK IS SMALL, LOCALIZED IGA PITS (ABOUT 1/16 INCH DIAMETER MAXIMUM) MOSTLY IN BOTTOM SPAN (APPARENTLY ASSOCIATED WITH SLUDGE) .

N0 INDICATION OF DEGRADATION GROWING WILL CONTINUE TO MONITOR / CONFIRM .

INDICATIONS TO BE LEFT IN SERVICE SINCE T00 SMALL TO ANALYZE, T00 SMALL TO BE OF STRUCTURAL SIGNIFICANCE, AND NOT GROWING

e Enclosuro 3 1

I

=

l e e

i eye

! :lorida l Dower Cowcmon aw 5eptember 30, 1993 3f0993 22 U. S. Nuclear Regulatory Commission f

Attention: Document Control Ossk Washington, DC 20555 l I

Reference A: FPC to NRC letter, 3f0793 02, dated July 29, 1993 l

Subject:

Once Through 5 team Generator inspections and Analyses

Dear Str:

}

i Florida Power Corporation met with the NRC staf f on September 9.1993, to discuss our letter, Reference A. That Letter presented the results of analyses done on tubes removed from Crystal River Unit 3's Once Through Steam Generator (OISG). '

We agree with the NRC staf f that the meeting was very beneficial, and appreciate ths resources devoted to the review of our work. A number of items warranting clarification were lcentified and are sddressed in Attachment 1.

l l

We understand that final resolution of this and like situations at other facilities will be resolved through rulemaking activilles currently underway.

In the meantime, florida Power Corporation would propose Attachment 2 which includes a statement to be added to the Crystal River improved Technical Specifications recognizing that the Indications similar to those on tubes removed during the last refueling outage need not be repatr6d. Thethe definition of Technical "similar" is intentionally left to be resolved outside Specifications so that advances in methodologies can be readily implemented following review by the NRC, We would appreciate feedback on the acceptability of this proposal as soon as possible, l

0 40 f' n -

$U\ ; '

noel T9S 6464 CRYSTAL NVER cNERoY CouPLEX: 16760 W. Power Lh.e 9L e CryeW Ner, Florida M4264700 e A two rmgress compey

'. ='

9310060032 930930 PDR O

ADOCK 0$000302 PDM It- s

4:

, 'j: .

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~

. U. 5. Nuclear Regulatory Comission 3F0993 22 Page 2 of 5 Florida Power Corporation will subalt the relevant aspects of the analyst planned 015G inspections.

guidelines to the (RC no later than 90 days prior to No substantial changes to these guidelines would be implemented without providing the NRC staff further opportunity to review and coment, i

Sine rely,

\

?

G. L. oldt I

Vice President l Nuclear Production L Attachment .

l xc: Regional Administrator, Region !! e  !

Senior Resident inspector

' NRR Project Manager j j f

i i,

l

?

i.t

f

> U. 5. Nuclear Regulatory Comission s i 3f0993 22 Page 3 of 5 ATTACHMENT 1 Several issues requiring additional explanation were identified in the Once '

Through 5 team Generator meeting held 5sptember 9, 1993. The following information is provided for clarification.

1. TheAupust 31,1993. Draf t final Report ICE 93160 titled " Examination of Crysta l River Unit 3 Steam Generstor Tube Sections," which was provided to the NRC in preparation for the so.tember

9,1993 meeting contained several errors. These errors wl11 be corrected prior to the issuance of the final  ;

report. The info *mation presented during the September 9th meeting reflects information which is more current than that provided in the draf t l

report.  !

2. Analyst guidelines us'ed during 0T50 tube inspections allow the analyst to deterstne when a signal is sufficiently clear to determine a through wall l percentage even if the signal to noise ratto is less than the cutoff value. This guidance allows a "best effort" by the analyst to assign a through wall value to the indication. A designated code for futbre  !

reference is recorded when the signal amp 11tude cannot be effectivMy sized.

3. The significance of clusters or groupings of indications on 015G tubes as It relates to the burst test can be evaluated from the actual test data provided in the August 31, 1993, Draft final Report. #CC 93 160. figure 2 38. " Sectioning Otagram for 106 32 2." on page 2 68 of this report is an example of a' tubd where the failure or burst occurred at a single indication, AG2 (40% through wall burst at 11,400 psig), as opposed to t where clusters of indications were present on the tube, most notably at X2 and AMI.

4. The July 29, 1993, letter submitting the OT5G tube pull results contained  ;

a table of the signal to noise indication information for both steam generators. There were three indications in the 'A' OT5G and one Indication in the 'B' OT5G which had location references that spanned a distance as opposed to a single location. These indications have been identified as manufacturer burnish marks as identified by MRPC inspection in the 'B' 015G.

5. Primary to Secondary leak detection' 15 continuously monitored by the condenser air ejector exhaust radiation monitor, RM Al2. This monitor ,

samples the condenser for radioactive nnble gases that would be  ;

transported from the 015G's to the condenser should the steam generators This monitor has a range of ,

develop a tube leak.

(2X10' utt/cc) to 1,000,000 counts per minute (lX10',10 counts uCl/cc) and per normally minute reads approximately 60 counts per minute (-5X10 uC1/cc). RM Al2 is equipped with remote readout anc chart recording in the Control Room and i

i

T ,

9 2

U. 5. Nuclear Regulatory Comission 3f0993 22 Page 4 of 5 .

ATTACllMENT 1 (Continued) annunciated warning and high alarm functions. The monitor alarm functions presently provide annunciation when the concfntration of noble gases in the condenser off gas is approximately IX10' uCl/cc. A one gallon per minute lyk with normal reactor coolant system radioactivity would result in a 10' uC1/cc concentration at RM Al2. Past experience with this monitor has shown that small 0150 tube leaks can be detected Operating and the procedure Control Room quickly alerted to the condition.

guidance provides for consideration of plant shutdown when the primary to secondary leak rate exceeds 0.3 gpm. ,

Crystal Alvar Unit 3 (CR 3) also has main steam line radiation monitors whose primary function is for off site dose assessment. These monitors are equipped with a lock out function on the rad'ation level alarm to aid in the determination of which OT5G has the tube leak.

In addition, daily monitoring of primary to secondary leakage is '

accomplished using the comparison of Tritium concentrations between this reactor coolant and the condensate systems. This is done to estabitsh h long ters trend for minor leak detection. The procedure which govertis i this activity also provides for the use of Na 24 to determine leakage 4 rates based on plant conditions.

A

< 6. Typical reactor coolant systen (RCS) radioactive lodine levels are 3.5X10*8 1 131. The secondary system  ;

utt/ gram Dose Equivalent are routinely less than the l (DE)ower limit of detection,110',0E uCl/ gram.I The 131 values Technical Specification ilmit on secondary coolant system DE l 131 ;

10.10 utt/ gram, and an administrative limit has been established at 10.01 uCt/ gram.

7. Florida Power Corporation bases the Steam Generator Tube Rupture strategy on ths Emergency Operating Procedures (EOP) Technical Basis Document (TBD) l Revision 6 with one notable exception. While steaming to atmosphere with both OTSG's expertencing tube leaks, the TBD directs the operator to not isolate the OTSG with the smaller Isakrate even if the estabitshed i steaming time to atmosphere based on the existing RCS Dose Equivalent I-131 is exceeded. Off site dose limits may -be exceeded under these circumstances. The TBD chose to manage the associated risk through continued steaming to atmosphere to avoid the potential of a stuck open i

)

main steam safety valve (HS$V) should RCS and OTSG pressure control fall

• to maintain conditions at less than 1000 psig. FPC has chosen to take  ;

exception to this guidance and requires the operators, via the plant F

E0P's, to isolate the OTSG's once the limits are exceeded. CR 3's operators have demonstrated the ability to control RCS inventory to preclude the lifting of M55V's. The applicable E0P on Steam Generator

! Tube Rupture directs the operator to establish conditions that will not j i challenge the MSSV's by dsmonstrating inventory control prior to isolation  !

J and providing a contingent method of controlling OTSG pressure (i.e., OTSG t drains) should isolation be required prior to establishing RCS pressure l control.

• ya 1,, -

g x U. 5. Nuclear Regulatory Commisifon 3f0993 22

.Page 5 of 5

.[

I ATTACHMENT 2 SAMPLE IMPROVED TECHNICAL SPECIFICATION  ;

ON STEAM GENERATOR TUBE INTEGRITY I

l Add the following sentence to Section 5.6.2.13 under subsection 4, " Acceptance ,

Criteria," item a.7, " Plugging /51eeving Limit." l

' Pit ilke indications consistent with those evaluated in Refuel 9 are l excluded from the Plugging /5lesving limit and are assessed against analyst guidance provided for inspection of the Once Through Steam Generators. 1 I

1 1

s I

4 i

1 i

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5 l

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$I\Id . s.~ . s. d. ,

I