ML20063P059

Nonproprietary Version of Interim Power Operation Evaluation Rept

ML20063P059
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Site:	Summer
Issue date:	09/30/1982
From:	WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
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WESTINGIIOUSE PROPRIETARY CLASS 3

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INTERIM POWER OPERATION EVALUATION REPORT i

V. C. SUlFIR i

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Septoriber 1982 I

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5 Westinghouse Electric Corporation P. O. Dox 355 Pittsburgh, PA 15230 83_10120250 8210o4 PM ADOCK 05000395 PDR O!.'Vic / 75c: 5 093032 1

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t WESTINGil0VSE PROPRIETARY CLASS 3 li INTERitt POWER OPERATI0tl EVALUAT10fl REPORT 8I 1

V. C. SUMMER TABLE OF C0!1 TENTS l.

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.. Section Title 1.0 Introduction 2.0 Engineering Evaluation 3.0 Power Operation Program Evaluation

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4.0 Sumary I

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WESTINGil00SE PROPRIETARY CLASS 3

1.0 INTRODUCTION

Westinghouse Model D3 steam generators with significant periods of operation at high power levels have experienced tube wear at baffle plate locations in the outer tube rows of the preheater. To define and resolve the issue, Westinghouse has established a multif aceted program which makes use of diagnostic data from operating units, air and water model test data and from analytical studies.

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4-This report presents an evaluatico of the relationship between main feed flow rate and tube wear, based on operating plant and model hest data currenti,y available.

It is used in conjunction with operating plant experience to provide a conservative estimate of tube wear for a suggested interim operating pregram at Virgil C. Summer Station.

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WESTINGl10VSE PROPRIETARY CLASS 3 2.0 ENGINEERIllG EVALUATION li 1

Tube motion accelerometers have been installed inside steam generator tubes in two operating plants with 03 steam generators and one operating plant with D2 steam generators.

These accelerometers are installed in tubes adjacent to the feedwater inlet, where tube wear has been observed.

This instrumentation has been utilized to characterize the tube motion in Model D2 and D3 steam genera tors. Tube motion and interaction with the tube structural supports i.

have been indicated previously to produce tube wear in other shell and tube i'

heat exchangers.

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Based 3'

-on this data, 50 percent main feed flow rate to the main nozzle is b2ieved to g.

be a prudent interim operating conditicn for plants with D3 steam generators.

h' Similar observations have been inade from motion data from instrumentation f

installed in Model D2 steam generator tubes.

The data from the D2 and D3 instrumentation is comparable when correlated on the casis of aquivalent local h

conditi~ons at each instrumented tube.

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l a.c,c A pertinent comparison of operating data which follows shows the operating histo'ry of three plants with similar steam generators in terms of hours and li-power levels. Cumulative hours of operation are tabulated in Table 2-1, 2.1 Plant Operatino_ Data

.m Plant A started up in the f all of 1980 and, up to shutdown in October 1981, had operated at power levels at or greater than 50 percent for more than 3000 i

hours (see Table 2.1).

Plant A was shut down in October 1981 with a i

primary-to-secondary leakage.

Subsequent inspection revealed that one tube I

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i WESTING 1100SE PROPRIETARY CLASS 3 was leaking on the cold leg side in the pre-heat 'section of one steam generator. Eddy current test (ECT) inspection of'all three steam generators revealed wear indications in general on tubes in the first three rows of seach steam generator.

l Plant A returned to power in April 1982. Although Westinghouse reconmended operation at 47 percent of main feed flow, the unit was operated at 40 percent of main feed flow (with short intervals at higher power levels to obtain 1,nstrumentation data) for an approximate 1500 hour0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> operating period.

This period ended in June 1982.

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An eddy current inspection was performed in June and those results compared with the flarch inspection. The June data resulted in a decrease in the total number of indications but a slight incresse in the size of the larger

(>30 percent) indications (Table 2.2).

, Plant A returned to power in August 1982, operating at 40 percent of main feed flow.

Plant B Plant B started up in the spring of 1981 and, up to shutdown in tiovember 1981, had operated at power level at or greater than 50 percent for more than 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> ((see Tabic 2.1).

Plant B was shut down in early flovember 1981, to perf6rm ECT inspections of steam generator tubes. A pattern of indications similar to, but less pronounced than, that at Plant A was found.

Plant B returned to power in Decenber 1981, for an approximate 1500 hour0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> 7 ' operating period at 50 percent of main feed flow (with short i' tervals at n

higher power icvels to obtain instrumentation data).

This period ended in March 1981. ECT inspection of the steam generators was performed, and it was concluded that little, if any, ucar had occurred. A comparison of ECT indications before and af ter this operating period is shown in Table 2-3.

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WESTIfGit0VSE PROPRIETARY CLASS 5 i

The most recent experience at Plant B was a 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> operating period (which

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ended in July 1982) at 50 percent main feed firsw. A photographic evaluation k

of the ECT data comparing March and July has been completed by Westinghouse.

The conclusion is that there has been no significant change in tube wear due y

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to this operating period.

A comparison of ECT readings taken before and af ter this operating period is shown in Table 2-4.

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I Plant C:

g Plant C perfomed startup testing in late 1981 and operated at various power

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1evels up to 100 percent through February 1982, accumulating 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> of f

operation at and above 50 percent power, including 324 hours0.00375 days <br />0.09 hours <br />5.357143e-4 weeks <br />1.23282e-4 months <br /> at and above l

75 percent power.

ECT inspection following shutdown in February 1982 revealed e

only minor degradation ( < 20 percent throughwall penetration by differential ECT) on four tubes af ter this first period of opert. tion.

.The most recent experience at Plant C was a 1500 hour0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> operating period at 50 percent main feed flow, followed by a 710 hour0.00822 days <br />0.197 hours <br />0.00117 weeks <br />2.70155e-4 months <br /> peried at 75 percent, which ended in June 1982. An eddy current inspection was performed in June and 6S indications were located. The inspection was performed using mostly differential eddy current which tends to overestimate the depth of defects.

Table 2-5 lists those tubes with indications greater than or equal to 20 percent, ihe absolute value is given when available.

An additional eighteen indications 'were present with values of less than 20 percent, as dete nined by the differential method. All of the remaining indications were not related to wear (distorted signals, dents, perm 2 ability variations).

The conclusion to the eddy current inspection was that some wear has occurred but it is difficult to quantify due to the varying inspection techniques.

Plant C returned to power in July 1982, and has been operating at 50 percent main feed flow, with some operation at 75 percent.

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c WESTINGil00SE PROPRIETARY CLASS 3

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I TABLE 2.1 POWER llISTORIES CUFULATIVE Il00RS OF OPERATION

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l Plant A 1

(D3 Steam Generators) i e

Percent Full Power Through Through Feed Flow 10/81 6/82 l

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>90 to 100 1640 1670 5

>75 to 90 540 600 li

>50 to 75 1580 1665 i'

>20 to 50 1390 4350 li' ll Plant B k

(D3 Steam Generators) 1; I:

Percent Full Power Through Through Through Teed Flow 11/81 3/82 7/82

>90 to Id3 1455 1480 1480

>75 to 90 95 120 120

>50 to 75 535 585 585

>20 to 50 790 2585 4240 Plant C

'N (D2 Steam Generators) 1

-30 Per-

-40 Per-

-50 Per-

-7 5 Pe r-

-100 Per-cent cent cent cent cent Through 3/81 360 1330 295 50 Through 6/82 365 2865 1005 50 054Sc/75c:5 093082 7

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WESTINGIOUSE PROPRIETARY CLASS J TABLE 2-2 PLANT A j

ABSOLUTE ECT C0ifAR150N OF INDICATIONS >30 PERCENT Row /Coluinn Baffle Plate March 1982 June 1982 Chance S/G 1 R49/C49 2

37 38

+1 6

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R49/C61 5

33 33 0

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t-S/G 2 R49/C47 6

37 41 4

y R49]C53 5

32 30

-2 R49/C54 5

33 35

+2

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R49/C54 8

27 34

+7 l-R49/C55 5

37 40

+3 R49/C57 6

37 43

+6

.f R49/C58 5-37 37 0

ll 149/C61 6

'32 33

+1 R49/C63 6

38 45

+7 R49/C71 5

32 30

-2 S/G 3 R49/C47 5

36 39

+3 R49/C59 8

28 33

+5 i

R49/C67 6

33 32

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E WESTINGIOUSE PROPRIETARY CLASS 3 TABLE 2-3 PLANT ~ B 1981-1982 INDICATI0fl DEPTH COMPARIS0N DIFFERErlTIAL MODE Absolute Differential S/G No.

Row No.

Col. No.

Depth, Percent Depth, Percent 81 82 82-81 2

3 49 53 31 45 46

+1 3

49 57 24 49 49 0

3 49 65

.25 47 47 0

1 48 50 22 49 44

-5 1

48 53 22 48 43

-5 1

48 54 23 48 48 0

Note:

For the particular type of degradation in the preheater area, a correlation of laboratory masurements of pulled tube wall thickness 2.nd eddy current indications using the absolute method indicates that this eddy current raethod prov' ides a best estimate of the arrount of tube wall penetration. For comparison purposes, however, the differential method indications are used because the absolute method was not employed in the 1981 eddy current testing at Plant B.

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WESTINGil00SE - R0PRIETARY CLASS J

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TABLE 2-4 PLANT B R0W 47-49 CD.D LEG MARCil 1982 - JULY 1982 ECT COMPARIS0fl 0F IftDICAT10flS > 10 PERCEftT ABSOLUTE M00E S/G Row Column / Plate March 1982 July 1982 Reading Ntaber Ntabe r Nttnber Abs Depth Percent Abs Depth Percent Chance 1

49 54/6

< 10 10 a

-1 48 50/6 17 17 0

53/6 54/6 18 15

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20 17

-3 60/6 12

<10 a

2 49 68/7

< 10

<10' a

t 3

49 47/6 11

<10 a

50/6 13 11

-2 57/6 21 23

+2 3

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61/6 15 15 0

1-63/6 14 13

-1 65/5 12 11

-1 65/6 23 25

+2 i

68/6 15 15 0

Notes:

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'Cannot compute a reading change t

b)

For the particular t3pe of degradation in the preheater area, a correlation of laboratory measurements of pulled tube wall thickness and

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eddy current indications using the absolute method indicates that this I

eddy current method provides a best estimate of the amount of tube wall

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penetration. For comparison purposes, however, the differential method l

indications are used because the absolute method was not employed in the 4

1981 eddy current testing at Plant 8.

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WESTINGIOUSE PROPRIETARY CLASS 3 TABLE 2-5 PLANT C ECT INDICATIONS >20 PERCENT JUNE, 1982 DIFFERENTI AL TUBE ECT INDICATION S/G Row / Column Baf fle Plate (Percent)

COMMENTS a

A R49/C55 3

32

< 5 percent by Absolute 6

76

<10 percent by Absolute

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R49/C63 5

37

< 5 percent by Absolute 6

61

< 5 percent by Absolute

• 8 25

< 5 percent by Absolute C

R49/C41 6

34 No Absolute Data Available R49/C40 6

27 No Absolute Data Available R49/C75 6

20 Ho Absolute Data Available D

R49/C75 6

85

<20 percent by Absolute

• This tube w'as plugged due to the 61 percent indication.

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WESTINGl!0USE PROPRIETARY CLASS 3 l

3.0 POWER OPERATI0il PROGRN4 EVALUATI0ft l

The f ollowing represent Westinghouse's current engineering judgment for the first interim period of operation prior to steam generator modification at the l

Virgil C. Summer Station.

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The unit should be started up and perform power ascension tests, through the J

50 percent power level tests, per standard startup procedures.

(Prior to l

startup", a multi-frequency eddy current inspection of the three outboard rows of steam generator tubes (Row 47, 48, 49) should be performed to provide a I

good baseline for comparison with future inspections of this region of the I

tube bundle. This inspection should include differential and absolute mode h

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eddy current techniques reconmended by Westinghouse.)

Following the.50 percent tests, the unit should continue to operate at the approximate 50 percent power level, not exceeding 50 percent of full power feedwater flow _

I to the main feedwater nozzle, for a period of up to 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> of operation, h

in'cluding the time at or above 50 percent power during power ascension f

testing. Eddy current inspections of selected tubes at the end of this period should fe' planned.

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A prediction of steam generator tube wear has been made for the Virgil C.

Sumner Station, based on correlations and methods developed at Westinghouse.

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WESTIt0ll00SE PROPRIETARY CLASS 3 Steam Generator Tube Wear Evaluation "M

additional assessment can be made by comparing the V. C. Summer operating program to the operating experience at Plant B identified in Section 2.0.

Prior to Deconber 1981, Plant B had operated at levels significantly higher

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than 50 percent of main feed flow for a significant time period (see Table 2-1) and tube wear was indicated by eddy current testing for this period.

Plant B's power history from December 1981 through July 1982 represents 3500 hours0.0405 days <br />0.972 hours <br />0.00579 weeks <br />0.00133 months <br /> of operation at 50 percent of fu1~1 power main feed flow, for which

' period ECT data is available from before the period, af ter 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, and at the end of the period. No significant wear due to this 50 percent of main feed flo'w operation has been indicated by the data.

(A corrparison of ECT indications of Novenber 1981, March 1982, and July 1982 is shown in T6ble 3-1.)

The results of Plant B's operating history of 3500 hours0.0405 days <br />0.972 hours <br />0.00579 weeks <br />0.00133 months <br /> at 50 percent c,f full power main feed flow indicates that wear consistent with the best estimate above would be expected for the V. C. Summer program of 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> at the sane hours at the same flow level; however, because V.

C'. Summer has not yet accumulated operating experience, the upperbound value above has been included

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^ further assessment of the V. C. Summer operating program can be obtained by considering the experience at Plant C.

This plant has been operated at 50 percent power and at higher powers, as summarized on Tabic 2.1.

This operating experience of Plant B substantially exceeds the initial power c3cle porposed in this report for Virgil C. Sumer station.

Furthermore[ ' Plant B has obtained further approval to operate fran July to Novenber 1982, including operation at 75 percent power for a maximum of 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />; the plant is now operating accordingly.

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TABLE 3-1 PLANT B I

ASME DIFFERENTIAL ECT DEPTil COMPARIS0N

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Nov. 1982 March 1982 July 1982 Depth Depth Depth 8affle Indication Indication Indic ati on S/G Row Column Plate Percent Percent Percent

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48 50 6

49 44 49 48 53 6

48 43 47 t-48 54 6

49 48 49 i

3 49 53 6

45

' 46 a

49 57' 6

49 49

, 45 49 65 6

47 47 44 l

1 Notes:

a)

Tube pulled af ter March 1982, Eddy Current Inspection.

'b)

For the particular type of degradation in the preheater area, a ss I

correlation of laboratory measurements of pulled tube wall thickness and I

I eddy current indications using the absolute method indicates that this cddy current method provides a best estimate of the amount of tube wall i

I penetration. For comparison purposes, however, the differential method indications are used because the absolute method was not employed in the 1981 eddy current testing at Plant B.

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1 WESTIfGIOUSE PROPRIETARY CLASS 5 4.0

SUMMARY

Until a modification to the steam generators can be performed, an interim operation program for the V. C. Summer station has been suggested on the basis of precluding significant steam generator tube wear.

The interim operation program consists of low power testing followed by power escalation testing to approximately 50 percent power and 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> of o,peration at 50 percent of full flow through the main nozzle.

The evaluation of this program is based on a combination of tube motion instrumentation data from three operating plants, experience in operation of a Model D3 at similar operating conditions and hydraulic and mechanical test model results.

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