t Jam'es -Nc,-aa'Ie -- L'ate's.:fro m-Q-uin-n Page 11

From: "Sandi<e, Steven" <SSandik@entergy.com>To: <JC(NJnrc.gov>Date: 11/22/05 10:15AMSubject: Latest from Quinn

Stuff we worked on last night....

<<H3 balance-DQ.xls>> <<NCD-SFDS-00-03.xls>> <<U2H3-2005-sources.xIs>>

And some 80-10 data, along with the gamma spec cover sheet from the local well digging at U2 FSB wall

<<80-1 0-etc.pdf>>

I am still collecting and preparing a spreadsheet for other 80-10 data back to 2000...Although we havecollected H-3 on Unit 2 storm drains for years, it has only recently been added to WinCDMS, so I amdigging it out of the Tritium data sheets.(I will ariange for it to be back-fitted into WinCDMS as well - we need to see and manage this trend....).

Steve SandikeEffluents /RMS.ENN Indian Point Energy CenterBuchanan, NY 10511-0308phone: )114-736-8455fax: E1 4-734-6010email: ssandik~entergy.com

:'!:.', - ,--O :' '- P fl4 -. .: -r

Date: November21, 2005

To: Dennis Quinn

From: Lawrence Dauer

Subject: Review of "Unit 2 Spent Fuel Pool Total Volume Loss Estimation"October27, 2005Indian Point Unit 2 Spent Fuel Pool Investigation Team

PURPOSE

Review the volume loss estimate methodology and conclusions as documented in theuUnit 2 Spent Fuel Pool Total Volume Loss Estimation" memo dated October 27, 2005(SEe Appendix A). The review will include the generation of regression results from thedata, the determination of confidence intervals about the predicted slope, estimating thechange in volume based on boron concentration, and a test of the utility of the model.

REVIEW

Regression Data

To check on the regression method, the boron concentration measurement data aslisted on Attachment 1 of the October 27, 2005, volume loss estimate (Appendix A)were entered into an Excel spreadsheet. Linear regression analyses were performedusilg the Excel analyses tools (ie. Regression). In addition, other statistical analyseswere performed.

The data is shown on Graph 1 attached and shows some variability over time that mayrepresent sampling and analysis variability as well as the potential for cyclical changesas evaporation and water additions occur over time. The resulting regression data issummarized below:

* S.- -- - .6

0

Boron Concentration (ppm) I YDays since Cycle 17 Start XN (number of observations) 47DF (degrees of freedom = N-2) 45R__ 0.01b [y-intercept] (ppm) 2407m [slope] (Appm) -0.0202SEm [standard error of slope] 0.0288

1 of 5

Confidence Interval About Slope

When using regression analyses for estimating the value of a slope or change in aparameter over time, it is important to consider that statistical linear regression istypically performed using a least-squares fit methodology to the data. This is the case inboih the Excel Regression tool results above and in the volume estimate beingreviewed. Therefore, the predicted (or estimated) slope can be considered the 'best fit'slope to the data, however the true slope will actually fall within a range of values. Inorder to assess this range, standard statistical regression analyses should utilize aconfidence interval about the slope method. The method uses the tabulated critical t-value (tri) from the t-distribution, based on the degrees of freedom (DF) and a two-tailedconfidence level of 95% (a= 0.05).

With a DF=45 for this data, the t~d(DF=45, a= 0.05) = 2.014.

The confidence interval about the slope is calculated from:

m +/- (tci x SEm)

In this case, the proper way to report the slope is with these confidence intervals. Forthe data in question, the estimated slope should therefore be listed as follows:

-0.0202 +/- 0.05808 ppm

therefore, the true slope is expected to fall within the following range:

-0.0783 to 0.0379 ppm

Estimating the Change in Volume Based on Boron Concentration

The change in volume can be estimated from the estimated slope range, using anestimate of the total U2 SFP volume. As assumed in the volume estimate beingreviewed, the volume of the Unit 2 SFP is based on dimensions of (30.67' x 34' x 39')and does not take into account any reduction in volume taken up by spent fuel and fuelracks (note that because of this, the value may result in a slight overestimate in anychange in volume). Total volume of the U2 SFP is estimated to be 304,200 gal. Theestimated change in volume (gpd) is listed below:

3- *.~~ I. O- S * -

Lower 95% | -0.0783 | -3.253E-05 | -9.9

Calculated slope -0.0202 -8.393E-06 -2.6

Upper 95% 0.0379 1.57E-05 +4.8

2 of 5

Testing the Utility of the Regression Model for Predicting Changes

The utility of the regression model for predicting changes in volume using the availabledata can be evaluated using a significance test of the regression slope. This is astandard statistical technique and is based on hypothesis testing. One can test thehypothesis if slope m = 0 or not, that is, if x (measurement days since cycle start) doesor does not contribute information for the prediction of y (boron ppm) over time, given themeasurement data available. For this case, the null hypothesis (Ho) is that the slope isactually equal to zero (i.e. there is no trending change in volume over time), thealternative hypothesis (Ha) is that the slope is not zero (i.e. that there is trending changein volume over time). This is a two-tailed test and it uses the following test statistic thatfollows the student t distribution with DF=N-2:

t= m/SEm

and we reject Ho if t < -tcm or t > t,,i at a= 0.05

In the case of the boron regression from U2 SFP, the test statistic and tcH are as follows:c,

t = -0.0202 / 0.0288 = -0.7004

tcri(DF=45, a=0.05) = 2.014

Thus, we will reject H0 if t < -2.014 or t > 2.014

And, since the calculated t-value is not less than or greater than tri we do not reject thenull hypothesis and conclude that the slope m = 0 in a statistical sense. At the 95%significance level (a= 0.05), the sample data does not provide sufficient evidence toconclude that the boron concentration (and hence the SFP volume) is changing overtime. In fact, this test would show that boron concentration or overall water volume arenot changing significantly over time within the boundaries of the error of sampling andanalyses of boron measurements performed to generate the regression.

It is instructive to also look at the statistical power (p-value) for this result. Statisticalsignificance is increased as the p-value decreases (i.e. a lower p-value represents ahigher confidence in the utility of a test, in this case the regression model). This p-valueis compared to our critical level of 0.05 (or 95% confidence).

A t = -0.7004 with DF = 45 gives a p-value = 0.4873.The resulting p-value is much largerthan 0.05 and represents a much lower confidence (-51%) in the test than is statisticallyacceptable. In order to conclude that there is an actual slope (m < 0, or m > 0) we musttolerate too high a risk. Therefore, we must again conclude that the slope m = 0 in astatistical sense.

3 of 5

CONCLUSIONS

Alt:hough the regression method results in a calculated loss of volume from the U2 SFPof *-2.6 gpd, the true slope will fall somewhere within the 95% confidence level range forthis; prediction and the range of these results is more appropriate to report. In thismanner, the regression model predicts that the true loss of volume from the U2 SFP isactually in the range of -9.9 gpd to + 4.8 gpd. As such, the true loss in volume couldvery well be zero (0) based on this method.

In a test of the utility of the model, it is found that at the 95% significance level (a= 0.05),the sample data does not provide sufficient evidence to conclude that the boronconcentration (and hence the SFP volume) is changing over time. In fact, this test wouldagain show that boron concentration or overall water volume are not changingsignificantly over time within the boundaries of the error of sampling and analyses ofboron measurements performed to generate the regression. The assignment of a hardand fast number for loss of volume from the U2 SFP based on this method and theavailable data would therefore not be appropriate.

The utility-of the model would certainly be increased if the spread of data were less or if.,;tthe actual trend in changing boron concentration were changing much more significantly -over time.

Wile the strictly rigorous statistical methodologies utilized in this review may differ fromthe methodology used in the earlier approach, ultimately the results of this reviewbasically agree with the following conclusions made in the "Unit 2 Spent Fuel Pool TotalVolume Loss Estimation" memo dated October 27, 2005 (See Appendix A):

* "chance alone may easily account for the difference in the mean boronconcentration"

* " The normal analytical variances are significant relative to the differences inreported concentrations over the current cycle"; and

* "The Student's t-test [between early and later means] shows that normal variation(chance) can account for differences in reported concentrations. Therefore, thedetection of the true nature of thc present pool loss rate is not as precise as we'dlike to have. From the boron data alone, the loss may actually be zero. More dataacquisition and analysis is recommended"

4 of 5

awrnit 2 Spent Fuel Pool Total Volume Loss Estimation'October 27, 2005.Inclian Point Unit 2 Spent Fuel Pool Investigation Team

Review Performed by:

Date:

Lawrence T. Dauer, PhD, CHP

_I

�n!% .�, - .. - . -n,* . -. . ,, t s

5 of 5

GRAPH I

Unit 2 SFP Boron, Cycle 17

2480

2460 +

2440E0.0.no

000

In

C,a)

2420 +e

."I -----

2400* .

2380 -

23600 50 100 150 200

Days Since Cycle 17 Start

250 300 350

APPENDIX A

"Unit 2 Spent Fuel Pool Total Volume Loss Estimation"October 27, 2005

Indian Point Unit 2 Spent Fuel Pool Investigation Team

A-1

APPENDIX A

Oct. 27, 2005Indian Point Unit 2Spent Fuel Pool Investigation Team

Unit 2 Spent Fuel Pool Total Volume Loss Estimation

Introduction:

The purpose of this evaluation is to provide a reliable computational estimate of the.current Unit 2 cycle's leakage of the spent fuel pool (SFP). The computation is performedby fitting the current cycle boron concentration function (of time) and calculating theslope. A negative slope indicates a boron loss, a positive slope indicates a boron increase,and a slope of zero indicates no boron change as a function of time. Then the slope(change rate of boron concentration) is divided by the average pool boron concentrationto yield the daily boron fractional change rate. This is then multiplied by the SFP volumeto cestimate the daily pool volume change rate. Chemistry department analyzes Unit 2 SFPfor boron concentration' at about a weekly frequency. There are forty-seven data points ofinterest at the time the analysis was performed.

Boron is a reasonably good solute to track because it has no reported carryover lossdufing evaporation of water at normal fuel pool temperatures. Its loss can be confidentlyassociated with a volume loss of the SFP inventory. Operations department maintainspool level within a fairly narrow band by periodically adding a makeup that is free ofbofic acid. The makeup compensates for evaporative losses.

An additional statistical test (Student's t-test) is also formed to see if late-cycle boronconcentrations are different from early-cycle mean boron concentration.

Background:

Possible boron losses and additions of interest from the SFP are:

* Pool leakage through the liner or a liner penetration, weld or appurtenance* Losses through external loop cooling components - such as pump seals* Losses through external loop demineralizer components* Draining of isolated cooling loop components to perform inspections, tests or

maintenance* Losses through draining supplemental cooling system components* Admixing volumes of similar borated systems - such as the SFP with cooling or

demineralizer loops that previously circulated RWST contents. Planned borated makeup.

There is little hard data on most of these losses and additions. Some notes pertaining tothe occurrence of losses or additions do not have accompanying detailed information. Forexample, System Engineering estimates that mechanical seal losses of the cooling pumps

A-2

APPENDIX A

are on the order of a drop or two a minute. Operator logs and condition reports wereexamined for any evolutions or conditions that document intentional system draining,additions containing borated water, or significant degraded component conditions; nonewere found or could be quantified. There's no data for the amount of pool water that mayhave been drained from the outage supplemental SFP cooling system when that systemwas removed. No planned borated makeup activities are noted in this current cycle.Maintenance replaced a cooling pump mechanical seal package in the August/Septembertimeframe.

Th- Unit 3 water processing operator and a former Unit 2 radwaste supervisor wereinterviewed to determine what other confounding activities could affect the amount ofpool water boric acid concentration. There are some differences in how several of theUnit 2 and Unit 3 borated systems are handled, especially with respect to outage recoveryand practices. Neither individual could identify a specific activity that could affect Unit 2SFP boric acid inventory through draindowns, transfers, or by leakage through pool gateswhen levels were unmatched.

As a result, no justified adjustment -data:is included that may color the basic computationof SFP boron loss and the leakage estimation that follows it.

Method/Analysis - Basic Loss Computation:

A simple linear regression on the current cycle SFP boron concentration data wascomposed in EXCEL. There were forty-seven included coordinates (boron concentration,date). The tabular data, statistical computations, and a plotted view for the concentrationfunction are provided in Attachment 1.

Th- mean concentration (47 data points) is 2404 ppm, the y-intercept is 2407 ppm, andthe slope is -0.0202 ppm/day. The Standard Deviation (S.D.) of the experimentalpopulation of the pool concentration is 18.7 ppin (under assumption of static trueconcentration). Standard error of the experimental pool concentration mean is 2.7 ppm.

Th. fractional daily boron loss is -.0202 ppm/day / 2404 ppm = -8.4E-6 per day. Fromlayout drawings of the FSB, the average N to S dimension is taken to be 30.7.feet, the Eto W dimension is 34 feet and the depth is taken to be 39 feet. The total volume is:

(30.7 x 34 x 39) cubic feet x 7.48 gal/ft3 = 304,000 gallons (+/- 10%). [Nofuel and rack volume displacement credited.]

The leakage rate is:

304,000 x -8.4E-6/day = -2.6 gpd.

A-3

APPENDIX A

Method/Analysis - Additional Check Using t-statistic Means Testing:

From the point-slope formula, it is evident that the total loss of boron in the pool from thestart of the current operating period is about 7 ppm or about 0.3%. This is considerablyles3 than the S.D. of the total sampled concentrations in the current cycle. To see if late-cycle concentrations can be thought of as normal variants of the early-cycleconcentrations, a Student's t-test was composed.

Th. test uses the forty-seven data points as follows:

* First sampling is the twenty earliest boron concentrations* Second sampling is the last ten boron concentrations* The means and their respective standard errors are computed* The combined standard error (SE) is computed* The degrees of freedom is computed using the Welch adjustment (adjustment for

potentially different sample variances)* From standard tables, the t-value at 95% CL is selected on the basis of degrees of

freedom computed* The means difference is compared to the product of the t-value and the SE; if the

difference is less than the product so formed, the means are confidently notdifferent from each other and the boron data alone is not suggestive of a boronloss.

Th- t-value and SE product is 10.3 ppm. The difference in actual means is 7.1 ppm;therefore, the means are not significantly different and the boron is not statisticallydifferent from the early to latter cycle stages. In other words, chance alone may easilyaccount for the difference in the mean boron concentration.

Conclusion:

Th. boron regression analysis is a proper method for computing boron loss of the SFP. Itis selectively affected by loss and addition activities that should be known to the extentpracticable. Computation of losses of boron corresponding to more than 10 gallons perday would probably be more reliable than those of a gallon or two per day. The normalanalytical variances are significant relative to the differences in reported concentrationsover the current cycle.

Thc Student's t-test shows that normal variation (chance) can account for differences inreported concentrations. Therefore, the detection of the true nature of the present poolloss rate is not as precise as we'd like to have. From the boron data alone, the loss mayactually be zero. More data acquisition and analysis is recommended.

A-4

APPENDIX A

Attachment 1Unit 2 Cycle 17 Data and Computation

-0.02020 slpe-0.0202D

y-Interopt S.D. (ppm)2407A2131 18.7

S.E. of Mean2.7

x Y# 47 471 0 24242 2 2410.3 6 23954 13 23925 20 24566 27 23967 42 24138 48 23909 55 2370

10 62 245211 69 239412 78 239813 83 239214 90 237715 97 240816 104 240717 111 241618 118 239819 125 239420 132 240021 139 240622 146 239423 153 240924 160 243225 167 239326 174 240427 181 241728 188 239929 195 239930 202 241131 209 246432 216 238733 223 240134 230 242035 237 239036 244 241137 251 241238 258 239539 265 238940 272 240341 279 239242 286 239943 293 237944 296 238745 300 240346 307 239847 314 24244849so515253645556

(AYW0

482014370310964912064892

1013461147201303501520241851861822481985362139302333822503282681762829842992503186003344343495243585773891203998314182984374774510124678054870225149765155925354235566005664305882846054126179106330856536166673686886114697047706552720900736186761136

000000000

(H)

04

36169400729

176423043025384447615776688981009409

1081612321139241562517424193212131623409256002788930276327613534438025408044368146656497295290056169595366300166564702257398477841817968584987616930009424993596

000000000

Unit 2 SFP BOrOn,A Cycle 1 7

2450

2350 .'2300 _3

2150

2100 5_

2050

2J000 1,, . t_

Dat pacycl SrAm

Vossl-2.6 gpd

fractional loss per day-8.4E-06

dimensions 30.67 N to S(fee) 34 E to W

39 deep

esimate frmSFP buildinggeneral plan

A-5

APPENDIX A

57 0 058 0 059 0 060 0 061 0 062 0 063 0 064 0 065 0 066 0 067 0 068 0 069 0 070 0 071 0 072 0 073 0 074 0 075 0 076 0 077 0 078 0 079 0 060 0 081 0 082 0 083 0 084 0 085 0 086 0 087 0 088 0 089 0 090 0 091 0 092 0 093 0 094 0 095 0 096 0 097 0 098 0 099 0 0

100. 0 0101 0 0102 0 0103 0 0104 0 0105 0 0106 0 0107 0 0108 0 0109 0 0110 0 0111 0 0112 0 0113 0 0114 0 0115 0 0116 0 0

A-6

q--

APPENDIX A

117 0 0118 0 0119 0 0120 0 0121 0 0122 0 0123 0 0124 0 0125 0 0126 0 0127 0 0128 0 0129 0 01[30 0 0131 0 0132 0 0133 0 0134 0 0135 0 0136 0 0137 0 0138 0 0139 0 0 ,.. ...140 0 0141 0 0142 0 0143 0 0144 0 0145 0 0146 0 0147 0 0148 0 0149 0 0150 0 0151 0 0152 0 0153 0 0154 0 0155 0 0156 0 0157 0 0158 0 0159 0 0160 0 0161 0 0162 0 0163 0 0164 0 0165 0 0186 0 0167 0 0168 0 0189 0 a170 0 0171 0 a172 0 0173 0 0174 0 0175 0 0176 0 0

A-7

APPENDIX A

177178179180181182183184185186187188189190191192193194195196197198199200201

o 00 00 0o 00 00 0o 0o 0o 00 00 0o 00 00 00 00 00 0O 0o 00 00 00 0o Oo O0 0

sumx4 OuL y17465 112998 17938867 1610457

x-bar y-bar sums:

159 2404

A-8

j - -

APPENDIX A

Attachment 2Early Cycle 17 Data and Statistics

-0.106B4 slope-0.10684

y4niercept S.D. (ppm)2410.83751 21.1

S.E. of Mean4.7

x y# 20 20

1 0 24242 2 24103 6 23954 13 23925 20 24566 27 23967 42 24138 48 23909 55 2370

10 62 245211 69 239412 76 239813 83 239214 90 237715 97 240616 104 240717 111 241618 118 239819 125 239420 132 2400

(xa0

482014370310964912064692

101346114720130350152024165186182248198536213930233382250328268176282964299250316800

(x?

04

36169400729

176423043025384447615776688981009409

1081612321139241562517424

-13.5 gpd

fractional loss perday-4.4E-05

dimensions 30.67 N to S(feet) 34 E toW

39 deep

estimate fromSFP buildinggeneral plan

0.008790004 C.V

A-9

APPENDIX A

171 0 0172 0 0173 0 0174 0 0175 0 0176 0 0177 0 0178 0 0179 0 0180 0 0181 0 0182 0 0183 0 0184 0 0185 0 0188 0 0187 0 0188 0 0189 0 0190 0 0191 0 0192 0 a193 0 0194 0 0195 0. 0196 0 0197 0 0198 0 0199 0 0200 0 0201 0 0

B11 112

SAnT~Y

12B0 48080 3073338 117320x-bae y-be guns:

84 2404

A-10

APPENDIX A

Attachment 3Student's t-test on

Cycle Boron Concentrations

..

x Y# 20 20

I 0 24242 2 24103 6 23954 13 23926 20 24566 27 23967 42 24138 48 23909 5S 2370

10 52 245211 69 239412 76 230813 83 239214 90 2377t5 97 240016 104 240717 III 24181S 118 239819 125 239420 132 240021222324282627282930313233343S3S3738394041424344

454647484950516253545S56

var S.D. (ppm) s2

446.5 21.1

8E of Mou X

0.J h? 4.7 # 100 0 1 258

4820 4 2 266

14370 36 3 272

31096 109 4 279

49120 400 5 2S6

64092 729 6 293

101346 1764 7 296

114720 2304 8 300

130350 =025 9 307

152D24 3644 10 314

185186 4761 tt

182248 5776 12

198536 6889 13

213930 8100 14

233382 8409 15

253280 10816 Is

288178 .712321 X 17

2S2964 13924 18

299250 15626 19

318800 17424 20

0 0 21

0 0 22

0 0 23

0 0 24

0 0 25

0 0 28

0 0 27

0 0 28

0 0 29

0 0 30

0 0 31

0 0 32

0 0 33

0 0 34

0 0 35

0 0 36

0 0 37

0 0 38

0 0 39a 0 40

0 0 41

0 0 42

0 0 43

0 0 440 0 45

0 0 46

0 0 47

0 0 48

0 0 49

0 0 50O 0 61

0 0 52

0 0 53

0 0 54

0 0 55

0 0 56

Y10

23962389

24032392

23992379

23S7240323982424

var

147.0

617910 6ta4633065 70225653610 739S4e67386 77841S68114 81796697047 6854970E552 87515720900 9000073618S 94249761136 9850o

a 0

a 0

0 00 0

0 0

0 00 0

0 a

0 0

0 a

0 0

0 0

0 00 00 00 00 00 0

0 00 00 00 00 00 0

0 0

0 0

0 0

0 0

0 aO 00 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 a0 00 0

0 0

0 00 0

0 00 0

S.D. (pprm

12.1S.E. of Mean

3.8

A-lI

APPENDIX A

177178179180181182183184185186187188199190191192193194195196197198199200201

o 0

o 0o 00 , 0

0 0o 0

0 0o 0

0 00 0o 0

0 0o 0

0 0o 0

0 0o 0

o ao 0o 0o 0

o 00 O.0'. '' 0; .. i'0 i "0

177I7T179180181182

183184

1

186187188189

190

191

192193194195

196197

198199200201

0 Co 0o o0 0o 0o 0o 0o 00 00 00 0o 00 0o *00 00 00 00 00 00 00 00 00 00 00 0

stxn X wm m1280 48080 3073338 117320x4war y-bar SUMs

84 2404

sm xi sum YJ23570 2399 8282004 780156x-ber y-or SM287 2397

Sh deris 1-iet

SEDF- 27.3 t-DF)

udWed dillactual dlf

6.081.70 Waih CoSMf10.3

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A-12