ML20113H505

Rev 0 to Licensing Topical Rept Nutech Feedwater Nozzle Bypass Leakage Monitoring Sys,App:Results for Browns Ferry Unit 1

ML20113H505
Person / Time
Site:	Browns Ferry
Issue date:	09/05/1986
From:	Froehlich C, Kleinsmith M, Taylor M NUTECH ENGINEERS, INC.
To:
Shared Package
ML20113H494	List: ML20113H493 ML20113H496 ML20113H499 ML20113H505
References
XTV-01-104-R00, XTV-1-104-R, NUDOCS 9208040122
Download: ML20113H505 (13)

Text

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- I .LI XTV-01-104 Revision 0 September 1906

,, File Number:

165.1501.0101

• IICE!1 SING TOPICAL REPORT tJUTECll F""DWATER tJOZZLE DYPASS LEAKAGE MONITORING SYSTEM APPEtJDIX: RESULTS FOR BROWNS PERRY UNIT 1 Prepared for Tennessee Valley Authority Prepared by NOTECll Engineers, Inc.

San Jose, California Prepared by: Approved by:

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't tv M. E. Kleinsmith C. !! . Froetlich, P.E.

Project Engineer Engineering Manager a

Issued by:

lb t$1}fj //. Datc: Syka,&., . [, j Q B (o Moses Tay[or, dr., P.E.

Project Manager 9208040122 9207P9 PDR ADOCK O$000259 P PDR p(jf{))

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• REVISION CONTROL SHEET Liccasing 'Ibpical Ferort 165.1501.0104

[ TITLE: IUllCl! Ithter ibzzle Rfpass laakage m nitoring System DOCUMENT FILE NUMDCH:  :

Artendix: Fesults for Bttuns I'( rry Unit 1 .

1 11 . G. Cofie/ Technical Leader ucc INITI A Ls N AME / TITLE M. E. Kleinsmith/ Project Engineer f/g g IN411 A LS NAME/ TITLE INITI A LS N AME / TITLE I

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-- $.h TABLE OF CottTENTS

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1.0 INTRODUCTION

, A.1 l 2.0 DISCUSSION A.1 j 3.0 iMET!!OD OF ANALYSIS A.2 4.0 RESULTS A.4 5.0 FATIGUE USAGE FACTOR A.4 1

6.O RECOMMENDATIONS A.5 l

7.0 REFERENCES

A.10 TABLE I A.6 TABLE II A.6 TABLE III A.6 TABLE IV A.7 FIGURE 1 A.8 A.9 FIGURE 2

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1.0 INTRODUCTION

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The feedwater nozzles of Tennessee Valley Authority's Browns Ferry Unit I nuclear power plant were modified by installing triple thermal sleeve spargerI This t

' modification was made to minimize thermal sleeve bypass leakage, which leads to rapid thermal cycling due to turbulent mixing o. nld feedwater and hot reactor water. Rapid th on cycling h .as been identified as the major cause of observed cracking of feedwater nozzles, as discussed in NUREG-0619 (Reference 1).

NUTEC's provided Tennessee Valley Authority with a leaka91 monitoring system (LMS) to monitor the effec-tiveness of the new thermal sleeves in preventing leakage. Data taken from the LMS during plant opere. tion (June it, 1984 tc March 18, 1985, see Reference 2) was sent to NUTECH for analysis. That analysis is now complete and-results are presented in his report.

2.0 DISCUSSION The leakage monitoring system consists of four thermo-couples attached to the outside of each of the 6 fe awater nozzles (one at the top and three at.the bottom). These thermocouples monitor the' nozzle's k,

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• l L-outside temperature downstream of the thermal sleeve seal. The temperature at this location correlates well with the amount of bypass leakage; the greater the leakage the lower the temper'ature. .

tl 3.0 METHOD OF ANALYSIS The first step in analyzing each nozzle for leakage is to group the data by reactor power level (or percent feedwater flow) and then average the data frem the bottom three thermocouples for each nozzle. Each thermocouple data point is then expressed as a factor of the difference between reactor and feedwater tempera-tures. This' process is referred to as normalization (see Reference 3).

T -T pg T/C (1)

TN"T RX -T FW Uhere Tg = Normalized temperature T = Bottom average temperature T/C Tpg = Feciwater temperature T RX = Reactor temperature The leakage rate may now be calculated from XTV-01-104 A.2 nut.e_c.1.

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- $.D T -T j x 1.5 gpm (2)

( L " [T o -T 1.5 Where L = Analytically determined leakage rate in gallons per minute e'

To = Analytically determined normalized temperature at 0 leakage T1.5 = Analytically determined normalized temperature at 1.5 gpm leakage To and T1 .5 were determined from finite element analysis of the Browns Ferry faedwater nozzle configuration (Reference 5). Based upon the Browns Ferry data and analysis, NUTECH selected 0.57 for T o and 0.12 for T1.5 in the Browns Ferry 1 leakage calculations.

Substituting To and T1.5 back into equation (2) gives 0.57 - T 0.57 - T L = C0 .57 - 0 12 x 1.5 = [ 0.45 x 1.5 (3)

Therefore, equation (3) is the equation for bypass leakage around the triple-sleeve spargers at Browns Ferry 1.

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4.0 RESULTS

'- 1 The analysis of the LMS data at Browns Ferry 1 revealed that no significant bypass leakage is present at any of the feedwater nozzles. This result was to b'e expected I

' since these spargers are newly installed. Tables I, II, and III summarize the results of teakage calculations done at 100%, 90%, and 80% feedwater flow rates (Ref'erence 4). Negative values should be interpreted as zero leakage.

5.0 FATIGUE USAGE FACTOR I

Since there is no leakage around the thermal sleeves, M there la minimal contribution to the fatigue usage factor due to rapid thermal cycling. Figure 1 is a plot of fatigue usage factor vs. constant leaktge over a 40-year period for the Browns Ferry 1 station (based on the thermal duty map presented in Table IV, from Reference 5). As can be seen from this figure, the t

contribution to the fatigue usage factor is quite small I

for' leakage rates.of about 1.0 gpm or less. However, the fatigue usage factor increases rapidly for leakages above this level. The usage factor for a leakage rate of 1.5 gpm is 0.543 after 40 years, which is-less than the code-al owable value of 1.0.

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' Pigure 2 presents a graph of LMS temperatures versus leakage (Reference 4). As the temperature falls below about 390*F, the correlation'with leakage b eaks down.

If the temperature does fall below 390', the leakage is quite high as is the usage factor.

6.0 RECOMMENDATIONS _

The newly instr.Aled triple sleeve spargers were not leaking as of March 1985. However, continued tempera-ture monitoring of the outside surface of the feedwater nozzles is important to assure that with time, any leakage that may occur is detected.

Data should be taken on an hourly basis when the plant is in start-up or shut-down, and bi-weekly when the _

plant is at or near full power. This data should be plotted versus time, to determine trends of thermal sleeve seal performance. Step changes in the calculated leakage rate may be an indication of a malfunction in the LMS.

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[ LEAKAGE CALCULATED AT POWER = 100% (Reference 4i NOZZLE LEAKAGE (GPM) 1

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2 -0.140 -

3 0.039 o

4 -0.329 5 -0.264 6 -0.084 Table II LEAKAGE CALCULATED AT POWER = 905 (Reference 4)

NOZZLE LEAKAGE (GPM) 1 -0..'11 2 -0.154 N 3 0.019 4 -0.345

, S -0.288 6 -0.102 Table III LEAKAGE CALCULATED A'.' POWER = 80% (Reference 4)

NOZZLE LEAKAGE (GPM) 1 -0.149 2 -0.129 3 0.052 4 -0.323 5 -0.265 6 -0.064 i XTV-01-104 A.6 nutgcj

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Table IV l

[ BROWNS PERRY PLANT SPECIFIC THERMAL DUTY MAP (Reference 5) 1 Region,  % Power _ Hours / year, Rx Temp _ FW Temp 1 100.00 5528.00 ' 539.00 372.00 2 95.00 1195.00 539.00 ' 360.0C 3 ,, 80.00 373.00 539.00 350.00 4 70.00 302.00 539.00 337.00 5 50.00 94.00 539.00 315.00 6 50.00 3.00 539.00 289.00 7 40.00 42.00 , 539.00 305.00 8 40.00 14.00 539.00 240.00 9 32.00 14.00 539.00 185.00 10 23.00 12.00 539.09 175.00 11 23.00 8.00 539.00 120.00 12 15.00 16.00 539.00 120.00 13 5.00 64.00 530.00 120.00

-14 5.00 14.00 470.00 120.00 hkhy 15 5.00 10.00 360.00 120.00 16 5.00 40.00 240.00 ,

120.00 17 5.00 46.00 51:2.00 210.00 18 5.00 29.00 298.00 210.00 19 5.00 13.00 536.00 300.00 20 0.00 43.00 340.00 300.00 21 1.00 .40 360.00 350.00 22 2.00 1.78 350.00 190.00 23 2.00 1.38 340.00 125.00 24 2.00 .25 330.00 70.00 25 2.00 1.60 400.00 190.00 l

26 3.00 .38 340.00 160.00 27 0.00 900.00 70.00 70.00 I

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40 YEAR USAGE FACTORS AT CONSTANT LEAKAGE

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1. 5 0 0.25 0.5 0.75 1 1.2 5 LEAKAGE (GPM1 I

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7.0 REFERENCES

1. NUREG-0619, "BWR Feedwater Nozzle and Control Rod Drive Return Line Nozzle Cracking," April 1980.

2. Unit 1 Leakage Monitoring System and Main Steam / Reactor Feedwater' Pressure and Temperature, dated June 1984 through March 1985, File No.

165.1501.0015.

3. " Licensing Topical Report - NUTECH Feedwater Nozzle Bypass Leakage Monitoring System," Rev. O, dated October 1982, File No. 165.1501.0018.

4. NUTECH Calculation Package, " Browns Ferry Unit 1 Leakage Monitoring System Leak Rate Prediction, Rev. O, File No. 165.1501.0102.

5. " Structural Integrity Assessment of Browns Ferry Feedwater Nozzles," Rev. O, Document No. XTV 003, File No. 165.1501.0017.

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