ML20138B718

Forwards Staff SG 90-day Rept Review of Util 960905 Submittal of Unit 1 SG Tube voltage-based Repair Criteria & Informs That Util Results Consistent W/Those Obtained by Staff

ML20138B718
Person / Time
Site:	South Texas
Issue date:	04/23/1997
From:	Alexion T NRC (Affiliation Not Assigned)
To:	Cottle W HOUSTON LIGHTING & POWER CO.
References
TAC-M97305, NUDOCS 9704290253
Download: ML20138B718 (20)

Text

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. c April 23,1997 Mr. William T. Cottle Executive Vice-President & I General Manager, Nuclear Houston Lighting & Power Company South Texas Project Electric Generating Station P. O. Box 289 Wadsworth, TX 77483

SUBJECT:

STEAM GENERATOR TUBE VOLTAGE-BASED REPAIR CRITERIA 90-DAY REPORT, SOUTH TEXAS PROJECT, UNIT 1 (TAC N0. M97305)

Dear Mr. Cottle:

i The Nuclear Regulatory Commission (NRC) staff has reviewed the subject report, I dated September 5, 1996, as supplemented by letter dated March 4, 1997. The March 4, 1997, supplement was is response to NRC questions transmitted by letter dated January 22, 1997.

Based on its review and independent assessment, the staff concludes that  !

HL&P's results were consistent with those obtained by the staff. A copy of the staff's Steam Generator 90-Day Report Review is enclosed. The staff also concludes that HL&P should consider several items when implementing Generic l Letter 95-05 voltage-based tube repair criteria, as discussed throughout the l report.

Sincerely, Orig. signed by T. Alexion Thomas W. Alexion, Project Manager I Project Directorate IV-1 Division of Reactor Projects III/IV ,

Office of Nuclear Reactor Regulation  !

Docket No. 50-498 i Enclosure. 90-Day Report Review cc w/ encl: See next page DISTRIBUTION:

Docket File PUBLIC PD4-1 r/f )h JRoe EAdensam (EGA1) WBeckner CHawes TAlexion KKarwoski ACRS TGwynn, RIV OGC

)

I Document Name: STP97305.LTR 0FC PM/ d LA/PD4-1 NAME TAlexi h CHawes(h1N g g{ h DATE h/N/97 Y/S/97 COPY DES)N0 YES/NO OFFICIAL RECORD COPY 29000g 9704290253 970423 PDR ADOCK 05000498 ,

, P PDR l i

__1

SP UQu 4, e' Ju UNITED STATES

1. E NUCLEAR REGULATORY COMMISSION 1 f WASHINGTON. D.C. 20666 4 001

\...../ 1 April 23,1997 Mr. William T. Cottle Executive Vice-President &

General Manager, Nuclear Houston Lighting & Power Company South Texas Project Electric Generating Station P. O. Box 289 i

Wadsworth, TX 77483 j

1 1

SUBJECT:

STEAM GENERATOR TUBE VOLTAGE-BASED REPAIR CRITERIA 90-DAY REPORT, l SOUTH TEXAS PROJECT, UNIT I (TAC NO. M97305) '

Dear Mr. Cottle:

The Nuclear Regulatory Commission (NRC) staff has reviewed the subject report, dated September 5, 1996, as supplemented by letter dated March 4, 1997. The March 4, 1997, supplement was is response to NRC questions transmitted by letter dated January 22, 1997.

Based on its review and independent assessment, the staff concludes that  !

HL&P's results were consistent with those obtained by the staff. A copy of the staff's Steam Generator 90-Day Report Review is enclosed. The staff also concludes that HL&P should consider several items when implementing Generic Letter 95-05 voltage-based tube repair criteria, as discussed throughout the report.

Sincerely, g , bO Thomas W. Alexion, Project Manager Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket No. 50-498

Enclosure:

90-Day Report Rev'iew cc w/ encl: See next page

Mr. William T. Cottle Houston Lighting & Power Company South Texas, Units 1 & 2 cc:

Mr. David P. Loveless Jack R. Newman, Esq.

Senior Resident Inspector Morgan, Lewis & Bockius U.S. Nuclear Regulatory Commission 1800 M Street, N.W.

P. O. Box 910 Washington, DC 20036-5869 i Bay City, TX 77414 Mr. Lawrence E. Martin i Mr. J. C. Lanier/M. B. Lee General Manager, Nuclear Assurance Licensing )

City of Austin Houston Lighting and Power Company I Electric Utility Department P. O. Box 289 721 Barton Springs Road Wadsworth, TX 77483 l

Austin, TX 78704 l l Rufus S. Scott i Mr. M. T. Hardt Associate General Counsel 1 Mr. W. C. Gunst Houston Lighting and Power Company '

City Public Service Board P. O. Box 61867 P. O. Box 1771 Houston, TX 77208 San Antonio, TX 78296 l Joseph R. Egan, Esq.

Mr. G. E. Vaughn/C. A. Johnson Egan & Associates, P.C.

J Central Power and Light Co.npany 2300 N Street, N.W.

P. O. Box 289 Washington, DC 20037 Mail Code: N5012

Wadsworth, TX 74483 Office of the Governor 4

ATTN: Andy Barrett, Director i INPO Environmental Policy Records Center P. O. Box 12428 700 Galleria Parkway Austin, TX 78711 Atlanta, GA 30339-3064 Arthur C. Tate, Director  !

Regional Administrator, Region IV Division of Compliance & Inspection  !

, U.S. Nuclear Regulatory Commission Bureau of Radiation Control '

611 Ryan Plaza Drive, Suite 400 Texas Departn.ent of Health ,

Arlington, TX 76011 1100 West 49th Street

! Austin, TX 78756 Dr. Bertram Wolfe 15453 Via Vaquero Texas Public Utility Commission Monte Sereno, CA 95030 ATTN: Mr. Glenn W. Dishong 7800 Shoal Creek Blvd.

Judge, Matagorda County Suite 400N Matagorda County Courthouse Austin, TX 78757-1024 1700 Seventh Street Bay City, TX 77414

Steam Generator 90-Day Report Review 4

By. letter dated, September 5,1996, the licensee for South Texas Project Electric Generating Station, Unit I submitted a report titled, " Steam Generator Tube Voltage Based Repair Criteria 90-Day Report." By letter dated March 4,1997, the licensee provided additional information related to the September 5, 1996, 90-day report. The staff's review of the 90-day report is provided below.

1.0 Database l

In Section 2.0 of tha 90-day report, the regression parameters for the burst pressure, probability of leakage, and conditional leak rate correlations were provided. The para 4eters reported for the probability of leakage and

, conditional leak rate equations were consistent with those documented in the Electric Power Research Institute (EPRI) Report NP-7480-L, Addendum 1, titled,

" Steam Generator Tubing Outside Diameter Stress Corrosion Cracking at Tube

Support Plates Database for Alternate Repair Limits - 1996 Database Update" and dated November 1996. The parameters for the burst pressure equation, however, differed from those in the EPRI report. The difference appears to have resulted from normalizing the burst pressure data to a different flow )

stress. The EPRI report normalized the burst pressure data to a flow stress '

of 71565 pounds per square inch (psi). Based on evaluation of the regression '

parameters provided by the licensee, it appears that the licensee normalized I the burst pressure data to a flow stress of 75000 psi. Since the flow stress to which the burst pressure data is normalized to will not effect the

evaluation (provided it is properly accounted for in the calculations (i.e., the probability of burst and the structural limit calculation)), this difference was considered negligible. A flow stress of 75000 psi had been used previously by the industry to normalize the data.

For performing the evaluations discussed below, the staff utilized the correlations and data provided in the EPRI report. Although the review of the l EPRI report is not complete, the staff concluded that using the EPRI recommended databases (versus a slightly modified database) would not alter the conclusions of this evaluation regarding the structural and leakage integrity of the steam generator tubes.

2.0 Determination of the Tube Repair Limit i The tube repair limit is determined by adjusting the structural limit by allowances for flaw growth and non-destructive examination uncertainty as discussed in Generic Letter (Gi) 95-05. On page 7 of 65 of the licensee's 90-day report, the licensee inoicated the average growth rate of all steam generators combined was only 12.8 percent per effective full power year (EFPY)

, which is well below the 30 percent per EFPY criterion. The licensee further indicated that GL 95-05 specifies the " plant-specific" average growth rate be considered when determining the upper voltage repair limit (in lieu of a

" generator-specific" growth rate); and, as a result, the 30 percent per EFPY growth rate should be used to calculate the upper voltage repair limit for the i

next inspection. The staff doer not agree with this interpretation of GL 95-05. Specifically, the st af believes that generator-specific conditions should always be considered in evaluating the data and that the most limiting growth rate should be used regardhn of whether this process results in different repair limits for differeqt steam generators at a given plant.

ENCLOSURE

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3.0 ' Pro.iectina tSe End-of-Cycle (EOC) Voltaae Distribution

Based on a review of the 90-day report, the staff confirmed that the general ,

j methodology used by the licensee for projecting the EOC voltage distribution

was consistent with the methodology outlined in GL 95-05, " Voltage-Based i Repair Criteria fo.* W9stinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corresion Cracking." However, since the E0C voltage  ;

distribution projectlons may vary based on assumptions regarding how to i combine the various input parameters, the staff requested additional information from the licensee regarding these assumptions. By letter dated l March 4,1997, the licensee provided the requested information.

) Using the assumptions provided by the licensee, the staff duplicated the

! analysis performed by the licensee. A comparison of the staff's and

! licensee's projection of the E0C voliage distribucion for steam generators j "A', "B", "C", and "D" are provided in Figures 1, 2, 3, and 4, respectively. -

i The data supporting these figures is provided in tabular format in Tables 1, 2, 3, and 4, for steam generators "A", "B", "C", and "D", respectively.

Evaluation of these data indicate excellent agreement between the results

! obtained by the staff and the licensee. Although different assumptions could  !

, be used in the determination of the EOC voltage distribution, the staff 1 j concludes that the results obtained by the licensee are acceptable.

The staff evaluated the licensee's assumptions for determining the E0C voltage l

i distributions and concluded that they were acceptable. In general, the )

1 licensee made conservative assumptions except for the equation for determining 4 the true beginning-of-cycle (B0C) voltage. For determining the true BOC

voltage, the licensee used equation 3-6 of WCAP-14277, "SLB Leak Rate and Tube 4 Burst Probability Analysis Methods for 00 SCC at TSP Intersections," dated 4 January 1995, versus equation 3-5. However, given the other conservative

! assumptions in the methodology (i.e., no intsrpolation between the intervals (bins) used for the B0C voltage distribution), the staff concludes that the licensee results are acceptable. In future evaluations, however, to be i consistent with the guidance contained in the recent revision to WCAP-14277, (i.e., WCAP-14277, Revision 1, "SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP _ Intersections, dated December 1996), the licensee should determine the true beginning-of-cycle voltage using equation 3.5 of WCAP-14277. This equation is more accurate than the one used by the licensee.

The staff concludes that interpolating between voltage bins is acceptable since the data provided by the licensee in Table 3-4 indicate that the voltage i values fall within the bin rather than just near the endpoints of the bin (i.e., a qualitative review of the data indicate the indications have voltages which are scattered throughout the bins). In some cases (although this was .

not the case for the licensee's current data), interpolation of a bin may not i be acceptable such as when the bin width is large and contains relatively few l indications. Interpolation, in this case, may not be acceptable since it may  ;

underestimate the voltage of the indication. For example, suppose a voltage  !

bin was from 3.0 to 3.3 volts and one 3.29 volt indication was associated with this bin. If interpolation was allowed for this bin, the likelihood of the .

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3 i ,

?

indication being 3.01 volts would be as great as the indication being 3.29 )

volts. In this case, the voltage would be greatly reduced (i.e., by more than l

0.2 volts) which is non-conservative.

. In summary, the licensee's methodology for projecting the end-of-cycle voltage distribution is consistent with the methodology outlined in GL 95-05, i " Voltage-Based Repair Criteria for Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking" and should provide conservative estimates of the E0C voltage distribution.

i 4.0 Determination of the Probability of Ruoture i

j In Table 5-1 of the licensee's 90-day report and in response to Question 4 in j the licensee's March 4,1997, submittal, estimates of the mean and the 95%

i upper confidence limits on the probability of burst were provided. To verify i the licensee's estimates for the probability of burst, the staff performed j independent calculations using the E0C voltage distributions listed in Tables

I through 4 (i.e., the staff E0C voltage distributions). These distributions

! contain the number of indications in a given voltage bin.

! As a result of the calculational procedure used in generating the EOC voltage distribution (e.g., probability of detection adjustment), fractional indications are present in many of the E0C voltage bins. To account for these fractional indications, the staff assumed (similar to the licensee) that the 4

number of bursts in one simulation of the E0C voltage distribution was the sum of the number of tubes that burst. As a result, suppose in one simulation j that one indication was projected to burst and three " fractional" indications j burst (suppose these three fractional indications were one-tenth of an j indication, three-tenths of an indication, and eight-tenths of an indication).

l Then the number of tubes burst in this particular simulation would be 2.2 i indications (1 + 0.1 + 0.3 + 0.8). Using this approach (i.e., the fractional

! indication approach), the staff estimated the mean and the 95% upper

! confidence limits on the probability of burst for each of the four steam i generators. The values are listed in Table 5 along with the licensee's ,

i estimates. I 4 Table 5

! Conditional Probability of Burst (Fractional Indication Approach)

Steam Licensee's NRC's Mean Licensee's Upper NRC's Upper ,

Generator Mean Estimate Estimate 95% Estimate 95% Estimate A 2.70 x 10'5 3.12 x 10'5 3.73 x 10'5 4.20 x 10'5 B 2.30 x 10'5 2.88 x 10'5 3.26 x 10'5 3.93 x 10*5 C 6.80 x 10 5 7.58 x 10'5 8.33 x 10'5 9.17 x 10'5 D 6.37 x 10'5 5.58 x 10'5 7.84 x 10'5 6.98 x 10'5  ;

4 l

Evaluation of the data provided in Table 5, indicates general agreenent between the staff and licensee results. One difference between the methodology used by the staff and that used by the licensee in determining the conditional probability of burst was the starting voltage distribution of the program. The licensee started with a BOC voltage distribution and the staff

started with the E0C voltage distribution. Since the licensee adjusted the B0C voltage distribution for growth and non-destructive examination uncertainty, which is consistent with the methodology for projecting the E0C voltage distribution, this difference in the methodologies should not result in any significant difference in the resultant probability of burst provided the random number generator used in the licensee's program have a sufficient period to avoid repeating the sequence of random numbers.

To ascertain the variability of the probability of burst from one set of simulations to the next, the staff performed the calculation for steam generator "D" three additional times. Each time the calculation was i performed, one million simulations were conducted. The results are provided I in Table 6. '

Table 6 Conditional Probability of Burst for Steam Generator D (Fractional Indication Approach)

Run Licensee's NRC's Mean Licensee's Upper NRC's Upper Mean Estimate Estimate 95% Estimate 95% Estimate 1 6.37 x 10~5 5.58 x 10'5 7.84 x 10~5 6.98 x IO'S 2 5.87 x 10 7.30 x 10'5 3 7.14 x 10 5 8.69 x 10 5 4 7.02 x 10~5 8.56 x 10~5 The probability of burst results provided in Table 6 indicate that the licensee's mean and upper 95% estimates fall between the staff's lowest and highest estimates for these quantities.

Since fractional indications can not exist, the staff developed another coproach for calculating the probability of burst. This approach involves sampling the cumulative distribution function (CDF) associated with the E0C

• oltage distribution by the total number of indications in the steam generator. If the number of indications in the steam generator was not an integer value, it was rounded to the next highest integer value. (For

. example, in steam generator "B", which contains 205.3 indications, it was I assumed that 206 indications were i:. this steam generator. The E0C CDF for  ;

this steam generator was then sa:apled 206 times for one sinulation.) This j approach is referred to as the CDF approach, and it avoids having to account for the fractional indications and possible underestimates in the frequency of multiple bursts (i.e., in the fractional indication case discussed previously, since four indications were involved in determining that there were 2.2 bursts it may be postulated that 2 tubes burst, 3 tubes burst, or 4 tubes burst). ,

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5 The rssults of the staff's calculations using the CDF approach are provided in Table 7. For comparison purposes, the staff estimates for the fractional indication approach are also provided. The EOC voltage distributions used for both of the calculations (i.e., the fractional indication calculation and the CDF calculation)-were consistent. In addition, the number of simulations was consistent (i.e., one million simulations per steam generator for both the CDF and fractional indication approach).

Table 7 Conditional Probability of Burst (COF and Fractional Indication Approach)

Steam NRC's Mean NRC's Mean NRC's Upper 95% NRC's Upper Generator Estimate Estimate Estimate 95% Estimate (Fractional) (CDF) (Fractional) (CDF)

A 3.12 x 10'5 2.50 x 10 4.20 x 10~5 3.49 x 10'5 B 2.88 x 10'5 2.00 x 10'5 3.93 x 10~5 2.91 x 10~5 l C 7.58 x 10'5 6.90 x 10 9.17 x 10'5 8.43 x 10'5 D 5.58 x 10'5 6.70 x 10'5 6.98 x 10'5 8.21 x 10~5 l Based on the results provided above, the staff concludes that the results obtained by the licensee are reasonable.

5.0 -Determination of the Primarv-to-Secondary Leakaae Under Postulated

-Accident Conditions In Table 5-2 of the licensee's 90-day report, e:timates of the 95%/95% upper tolerance limit for the primary-to-secondary leak rate under postulated accident conditions were provided. To verify the licensee's estimates for the leak rate under postulated accident conditions, the staff performed independent calculations using the E0C voltage distributions listed in Tables 1.through 4 (i.e., the staff E0C voltage distributions). These distributions ,

contain the number of indications in'a given voltage bin. Four hundred thousand simulations of the EOC distribution for each steam generator were performed in determining the staff's estimate of the 95%/95% estimate of the leak rate under postulated accident conditions.

Similar to the calculation of the probability of burst, the staff adjusted the leak rate of a single fractional indication by multiplying the leak rate for one indication by this fractional amount. That is, if the leak rate for a 1.0 volt indication was determined te b'e0.0001 gallons per minute (gpm) and there was two-tenths of a 1.0 volt indication, the corresponding leak rate for this fractional indication would be 0.00002 gpm. Using this approach (i.e., the fractional indication approach), the staff estimated the 95% upper confidence limit associated with the 95th percentile leak rate for each of the four steam generators. The values are listed in Table 8 along with the licensee's estimates.

1 6 ,

4 Table 8

Leak Rate Calculations (Fractional Indication Approach)

Steam Licensee's 95%/95% NRC's 95%/95%

- Generator Estimate (gpm) Estimate (gpm) i A 0.00213 0.00247

B 0.00173 0.00197

{ C 0.00752 0.00719 i 0 0.00685 0.00605 i

l To ascertain the variability of the 95%/95% leak rate from one set of 4'

simulations to the next, the_ staff performed the calculation for steam generator "C" three additional times. Each time the calculation was performed, four hundred thousand simulations were conducted. The results are provided in Table 9.

! Table 9 Leak Rate Calculations for Steam Generator C (Fractional Indication Approach)

Run  !

Licensee's 95%/95% NRC's 95%/95%

Estimate (gpm) Estimate (gpm)  !

1 -0.00752 0.00719 2 0.00719 3 0.00727 4 0.00722 i I 6.0 Comoarison of Proiected E0C Conditions to As-Found Conditions l Since this was'the licensee's first implementation of the repair criteria described in GL 95-05, no meaningful comparison between the projected and ,

as-found steam generator conditions could be made. Future 90-day reports to be provided by the licensee will permit such a comparison.

1 In these subsequent comparisons, consideration should be given to the growth rate distribution used in projecting the EOC voltage distribution.

Implementing the criteria in GL 95-05 could potentially permit a licensee to use a bounding growth rate for projecting the E0C voltage distribution in one cycle and a generator-specific growth rate in a future cycle. Suppose a projected E0C voltage distribution was determined using a bounding growth rate distribution in one cycle and this distribution was conservative when compared  :

to the'as-found conditions (i.e., projected EOC actual EOC ). The licensee  ;

could then conclude that the methodology was effe>ctive. Furthersupposethat

7 for the next cycle (i.e., "x+1") a generator-specific growth rate distribution rather than a bounding growth rate distribution was used in the projection of the E0C voltage distribution. Since the licensee changed the type of growth rate distribution used (i.e., bounding versus generator-specific), a more appropriate comparison for determining the effectiveness of the methodology at projecting the EOC voltage distribution may be to re-perform the original E0C, projections with a generator-specific growth rate and to compare this

• projection with the as-found conditions.

7.0 Summary The staff' independently assessed the licensce's calculations of the E0C j voltage distribution, the conditional probability of burst given a steam line break, and the postulated primary-to-secondary leakage during a steam line break. As discussed above, the licensee's results were consistent with those obtained by the staff. Several items which the licensee should consider in implementing the GL 95-05 voltage-based tube repair criteria are discussed throughout the report (e.g., use of the limiting growth rate in determining the tube repair limits, use of WCAP-14277 Equation 3.5 versus Equation 3.6, j comparing projected to actual E0C voltage distributions, avoiding the use of fractional indications, etc.).

Principal Contributor: K. Karwoski Date: April 23,1997

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i Table 1 Projected End-of-Cycle 7 Voltage Distribution (Steam Generator "A")

i f Voltage sin Licensee Estimate staff Estimate 0.0 0.00000000 0.00000000 l.

0.1 0.64326000 0.64125000 l

0.2 6.79934921 6.80440271 ]

O.3 19.52454867 19.50791938 t j

O.4 34.01640275 33.98197140 l

~

! 0.5 44.15465258 44.10307066

l. 0.6 44.98415413 44. % 295167 0.7 40.84262222 40.809613 % 1 0.8 31.74184400 31.73812278  !

0.9 22.94063425 22. % 587910  !

l 1.0 15.34746276 15.37272474 1.1 9.77714467 9.82701488 l 1.2 6.03130334 6.07358578

, 1.3 3.51621178 _

3.55632763 j I 1.4 1.97509392 2.00702492 1

{ 1.5 1.11974511 1.13180632

! 1.6 0.64124905 0.63854005 1.7 0.38757928 0. TOC 457 1.8 0.23795524 0.22371610

! 1.9 0.14369947 _

0.13357857 l 2.0 0.08335861 0.07569456 . l 2.1 0.04037034 0.03634345 2.2 0.02031049 0.01796340 2.3 0.01128258 0.00995869 2.4 0.00593453 0.00506698 2.5 0.00245827 0.00212915 2.6 0.00092712 0.00080628 2.7 0.00030737 0.00026819  ;

2.8 0.00009000 0.00008413 ,

2.9 0.000029Et 0.00003071 f 3.0 0.00002000 0.00001000 3.1 0.00000400 0.00000600 3.2 0.00002000 0.00000200 3.3 0.00000000 0.00000100 3.4 0.00000000 0.00000000 3.5 0.00000000 0.00000000 3.6 0.00000000 0.00000000 3.7 0.00000000 0.00000000 3.8 0.00000000 0.00000000 3.9 0.00000000 0.00000000 4.0 0.00000000 0.00000000 4.1 0.00000000 O.00000000 4.2 0.00000000 0.00000000 4.3 0.00000000 0.00000000 4.4 0.00000000 0.00000000 4.5 0.00000000 0.00000000

>4.5 0.00000000 0.00000000 r

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

9 Table 2 Projected End-of-Cycle 7 Voltage Distribution (Steam Generator "B")

Voltage Bin Licensee Estimate Staff Estimate 0.0 0.00000000 0.00000000 0.1 0.00000000 0.00000000 0.2 3.53007742 3.52240776 0.3 16.15029237 16.14219826 0.4 28.21760868 28.18901136 0.5 32.98519286 32.96769830 0.6 33.03897603 33.01648953 0.7 27.85192052 27.82256165 0.8 21.77482545 21.77127528 0.9 15.38773706 15.39406917 1.0 10.07070951 10.08560058 1.1 6.44336228 6.45806133 1.2 3.94460287 3.96595851 1.3 2.30167976 2.32078556 1.4 1.30737543 1.32465037 1.5 0.79167548 0.YY898792 1.6 0.53922164 0.53536353 1.7 0.36790808 0.36087802 1.8 0.24264367 0.23721895 1.9 0.16247331 0.15811029 2.0 0.10043859 0.09826214 2.1 0.05795462 0.05696056 2.2 0.03318314 0.03261441 2.3 0.01865409 0.01867600 2.4 0.01006054 0.01019653 2.5 0.00526246 0.00539647

' 2.6 0.00257279 0.00288899 2.7 0.00144823 0.00152016 3

2.8 0.00086322 0.00094734 2.9 0.00056069 0.00054164 3.0 0.00033863 0.00031824 3.1 0.00018591 0.00015522 3.2 0.00010753 0.00010005 3.3 0.00004824 0.00005597 3.4 0.00002077 0.00002169 3.5 0.00000938 0.00000840 3.6 0.00000469 0.00000630 3.7 0.00000067 0.00000210 3.8 0.00000134 0.00000140 3.9 0.00000134 0.00000000 4.0 0.00000000 0.00000000 4.1 0.00000000 0.00000000 4.2 0.00000000 0.00000000 4.3 0.00000000 0.00000000 4.4 0.00000067 0.00000000 4.5 0.00000000 0.00000000

>4.5 0.00000000 0.00000000

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l Table 3 Projected End-of-Cycle 7 Voltage Distribution (Steam Generator "C")

i i

Voltage sin Licensee Estimate Staff Estimate l

0.0 0.00000000 0.00000000 l 0.1 0.00000000 0.00000000 0.2 22.40257244 22.39980330 0.3 75.78468987 75.70052450 0.4 111.15334290 111.08803860 0.5 126.50120113 126.44612610 0.6 111.99369550 111.91661860 j 0.7 89.42768525 89.41381060 1

0.8 67.08187382 67.08438370 0.9 46.72630232 46.79536740 1.0 30.96804620 31.04056660 1.1 19.58334985 19.65766760 I 1.2 12.00004487 12.07648160 1.3 7.05413383 7.12872970 1.4 4.00008985 4.06058390 1.5 2.47455184 2.48497980 1.6 1.76867506 1.74057040 1.7 1.28701199 1.25355890 1.8 0.90448383 0.87689540 1.9 0.58775984 0.57641630 2.0 0.375082 % 0.36800180 2.1 0.24352576 0.23972180 2.2 0.15212503 0.15017890 2.3 0.08905048 0.08813000 2.4 0.04927783 0.04926720 2.5 0.02630908 0.02720410 2.6 0.01444728 0.01502620 2.7 0.00829656 0.00882660 2.8 0.00507701 0.00518150 2.9 0.00306185 0.00311630 3.0 0.00188804 0.00193050 3.1 0.00110010 0.00103950 3.2 0.00058015 0.00060490 3.3 0.00033865 0.00030380 3.4 0.00016968 0.00016340 3.5 0.00007983 0.00009020 3.6 0.00003907 0.00005120 3.7 0.00002139 0.00002040 3.8 0.00000968 0.00000920 3.9 0.00000468 0.00000540 4.0 0.00000267 0.00000170 .

4.1 0.00000167 0.00000070 4.2 0.00000000 0.00000170 4.3 0.00000000 0.00000000 4.4 0.00000000 0.00000000 j 4.5 0.00000000 0.00000000 1

>4.5 0.00000000 0.00000000 1

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11 t

Table 4 Projected End-of-Cycle 7 Voltage Distribution (Steam Generator "D")

Voltage Bin Licensee Estimate Staff Estimate 0.0 0.00000000 0.00000000 01 0.64548400 0.64245189 L2 7.58508000 7.58618276 0.3 33.15388968 33.14307016 0.4 67.31953801 67.24080637 0.5 81.81047120 81.72773590 0.6 79.89'51293 79.85055971 0.7 66.48760903 66.47680763 0.8 49.54576657 49.53283006 0.9 33.82843763 33.84607182 1.0 20.47764560 20.52405998 1.1 11.71883045 11.79422052 1.2 6.63888769 6.72028551 1.3 3.68915826 3.75817728 1.4 2.11403470 2.16020673 1.5 1.49239881 1.50648293 1.6 1.35615283 1.33407416 1.7 1.23741964 1.19854287 1.8 0.98329372 0.95361046 1.9 0.72869885 0.71033311 2.0 0.50604688 0.4 % 05520 2.1 0.32574525 0.32091601 2.2 0.19743654 0.19704795 2.3 0.11622585 0.11743322 2.4 0.06662372 0.06792101 2.5 0.03764624 0.03901913 2.6 0.02157598 0.02226118 2.7 0.01274517 0.01300324 2.8 0.00777943 0.00805339 2.9 0.00498413 0.00504023 3.0 0.00310275 0.00296487 3.1 0.00176548 0.00176023 3.2 0.00098787 0.00098739 3.3 0.00050426 0.00052079 3.4 0.00024747 0.00023545 3.5 0.00012777 0.00014107 3.6 0.00006972 0.00007458 3.7 0.00003238 0.00002839 3.8 0.00001769 0.00001540 3.9 0.00001035 0.00000360 4.0 0.00000801 0.00000440 4.1 0.00000267 0.00000170 4.2 0.00000100 0.00000070 4.3 0.00000100 0.00000100 4.4 0.00000100 0.00000000 4.5 0.00000000 0.00000000

>4.5 0.00000000 0.00000000

Figure 1 PROJECTED EOC VOLTAGE DISTRIBUTIONS Steam Generator A 50 r

40 I~

E -

8 1,'

g30 l j E

_C

).820 ,

l F

E

$ i. I:

i 10 e l'

e O m I f It' 2 ' " '@ mi- __iiiiiiiiiiiiiiii 0.1b b3b I ib bib -b.9b 1.1b 1.3b 1.58 11.9b E.1b b.3b E.58 b.76 E.96 E.1b b.3b b.50 0.5 Bobbin Voltage I NRC Licensee 1044sr-97, 0817 24 AM

e Figure 2 PROJECTED EOC VOLTAGE DISTRIBUTIONS Steam Generator B 35 j' !'

30 I

11 r 25 i g .

-8 m-m <

j 20 s  ;

o ,

g 15 .

n

'E I l 10 p.

L i r

5 e

o i . . ,  ; @ m im _i_i_ r_i_-_. i_i i i i i i i i i i i i 0.16 b '. b.'5 b" b.~h a 4' 0.3 '; b.9 b b I.1 1.3 1.5b 1.70 I.96 5.1b 5.3b 5.5b 5.7b i.96 5.1b 5.3b 5.50 Bobbin Voltage

. NRC Licensee 10Mw47, 0817 52 AM

Figure 3 PROJECTED EOC VOLTAGE DISTRIBUTIONS Steam Generator C 140 l

120 1

l'

,100 l a

8  :

1 ,

.0 80 l E

, i o l' g 60

_a , .

jj E

l 4

Z 40 I

l' 20 I: ,,

r 15 21 =

0 t t - ti i t -- i i i i i t i t i i i t f

ON -b.3b2b.-b'b jb.7b J .10.96 1.1b 1.3b 'I.78 1.5 1.98 U.ib E.3b E.5b E.7b $.90 b.1b 5.3b 5.50 Bobbin Voltage NRC h Licensee 16 Mar-97. OS 18 46 AM

Figure 4 PROJECTED EOC VOLTAGE DISTRIBUTIONS Steam Generator D 100 80 11 i.

E ,

60

% 1

.E o ,

, f

$ 40  !

E .

l l

20  !) ap ,

F r

!]

0 ' I-- i I ' ' -- ' t E R]n - =2 ' ' ' ' ' ' ' ' ' ' ' ' '

O.16 6' .36'6' .'5b'6.76 6.9' b 1.1 A1.3 1.5 1.7 'I.9b b.1b 0.30 0.5b b.70 0.9b b.1b b.3b b.50 Bobbin Voltage w" 4 NRC Licensee 104ter47, 081928 AM

_ _ _ _ _ _ _ _