ML051330056

Enclosure 4, Quad Cities Strain Gage Uncertainty Evaluation, SIA File No.: EXLN-17Q-302, Revision 0, Dated April 25, 2005

ML051330056
Person / Time
Site:	Quad Cities
Issue date:	04/25/2005
From:	Dorfman L, Fujikawa K Structural Integrity Associates
To:	Office of Nuclear Reactor Regulation
References
EXLN-17Q-302, Rev 0
Download: ML051330056 (12)

Text

ENCLOSURE 4 "Quad Cities Strain Gage Uncertainty Evaluation," SIA File No.: EXLN-17Q-302, Revision 0, dated April 25, 2005

Structural Integrity CALCULATION File No.: EXLN-17Q-302 Associates, Inc. PACKAGE Project No.: EXLN-17Q PROJECT NAME: Strain Gage Uncertainty for Steam Dryer Load Definition CLIENT: Exelon Generation Co., LLC Contract / P.O. No.: 00083767 PLANT: Quad Cities Unit 2 CALCULATION TITLE: Quad Cities Strain Gage Uncertainty Evaluation Project Mgr. Preparer(s) &

Document Affected Approval Checker(s)

Revision Pages Revision Description Signature & Signatures &

Date Date 0 1-9 Initial Issue K. K. Fujikawa L. S. Dorfman App A 4/25/05 4/25/05 K. K. Fujikawa 4/25/05 Page 1 of 9 SIFonn F2001R2

Table of Contents 1 INTRODUCTION ............................................... 3 2 QUAD CITIES STRAIN GAGE DATA ACQUISITION .............................................. 3 2.1 Full Scale Range, Resolution Calculation and Scaling Factor ............................................... 3 2.2 Uncertainty Analysis ................. 4 4;

3 REFERENCES .......... 9 APPENDIX A UNCERTAINTY ANALYSIS SPREADSHEET........................................................... Al List of Figures Figure 1: Wheatstone Bridge.7 Figure 2: Electrical Schematic for Quad Cities Unit 2 .8 StructuralIntegritync.FileNo.: EXLN-17Q-302 Revision: 0 Revison 0 (Associates, Inc. Page 2 of 9

1 INTRODUCTION This calculation determines the dynamic pressure resolution and uncertainty for the strain gage measurements that will be taken at Quad Cities Unit 2 (QC2) during the upcoming 2005 outage.

2 QUAD CITIES STRAIN GAGE DATA ACQUISITION Strain measurements will be made at Quad Cities Unit 2 (QC2). The data acquisition system including signal conditioning and DAS is entirely different than that used at Dresden; although the strain gages are the same. For Dresden the strain gages and completion resistors were assembled as a completed bridge, for QC2 the completion resistors will be installed near the DAS in the signal conditioner.

This document reviews the calculations to determine the pressure from the strain measurements and provides the dynamic pressure resolution and uncertainty.

Figure I is a diagram of the Wheatstone Bridge. The weldable strain gages provided by Hitech Products, Inc. (HPI) for this task were installed in the circumferential direction and connected to the opposite arms of the Wheatstone bridge with completion resistors inserted in the other two arms.

Figure 2 provides a schematic for the QC2 DAS. The strain gages are spliced to shielded pair electrical cable, fed through the primary containment penetration to a strain gage cabinet that includes the strain gage signal conditioner and amplifier (Kyowa DPM-71A). The signal conditioner provides bridge balance and amplification. The DPM-71A will be shunt calibrated to provide a system sensitivity of IOOPC/V.

The amplified signal is then fed into a LMS SCADAS data acquisition system with a PQFA voltage amplifier. The amplifier provides amplification (+/-0.0625 -. 10 V input range), anti-alias filtering, A/D conversion (24 bit) and storage to disk.

2.1 Full Scale Range, Resolution Calculation and Scaling Factor In this configuration the bridge will add the two arms according to the following equation.

pi= ( AR, _AR2 +AR1 _ A-R4 (A)

XI=4 RI J?2 1?I R4 where VO = output voltage of the bridge Vi= bridge excitation voltage R is the change in gage resistance, AR, divided by the gage resistance, R, due to an applied strain, c, for each arm of the bridge.

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For this case, R2 and R4 are completion resistors thus AR2 = AR4 = 0 (no resistance change due to strain) and AR - R 3 ~- for strain in the same plane along the pipe. Equation A is reduced to RI R3 R 4 (AR, + AR3 2 AR AR (B) or R-(---r 2-=) ) (B) 4 RI ~4~ R 2R The applied strain, c, changes the gage resistance according to the formula AR

-= GFe (C)

R where GF is the dimensionless gage factor provided by the gage manufacturer that relates the strain to the change in resistance.

Equation C then becomes V/= 2 GFe or £= -F (D)

YVI 2GF The DPM-7]Aprovides full scaleinputranges of d100 to I0,OOOpcproviding+/-1V out forthe full scale input.

Assuming that the input range of the LMS PFQA amplifier is set to +/-lV (+/-100iic), the A/D resolution can be calculated as follows:

The AID, converter is 24 bits or 224 bits for the full input range of 2V (200pc), providing an A/D resolution of (200/224 ) = 0.000012p£.

Assuming the same relationship between the pipe's internal pressure to the hoop strain is the same as Dresden [1], 0.251 pc/psi will be used to determine the Full Scale range and A/D resolution in pressure Full Scale Range = 1 00pz /0.251 pc/psi =+/- 398psi and the A/D Resolution = 0.000012pe /0.251pc/psi = 0.000048psi.

2.2 Uncertainty Analysis The uncertainty analysis combines the uncertainty of the strain-to-pressure calculation and the measurement system. The strain as measured in the circumferential direction is the superposition of the strain in the circumferential and that due to the Poisson effect of the axial strain due to the internal pipe pressure.

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The hoop and axial stress are calculated from the equations 2p 2 2

2PdH_d (E) and a Pd (F)

The hoop strain is the strain in the circumferential direction minus v times the axial strain as shown in the following equation aH - V6L,(G O

ell E (G)

Substituting Equations E and F into Equation G yields Pd (2-v)

H E(d2_d2) (H) where the strain per unit pressure is

___ d?(2 - v) p E(d2-d2) or p( Cd(-v) where CFH= Hoop stress due to internal pressure, psi GL= Axial stress due to internal pressure, psi E,,= Hoop strain, pin/in p = unit applied internal pressure, psi di= pipe inside diameter, in do- pipe outside diameter, in E = Young's Modulus, psi v= Poisson's ratio.

Equation (J) relates the internal pipe pressure to the measured strain.

The overall uncertainty is determined by a SRSS method used for random errors. The nominal (no error) pressure is calculated first. Then the pressure is calculated again by changing each variable in the equation by the amount of the potential error, one variable at a time. The new pressure calculated for each variable with the error is then subtracted from the nominal pressure and squared. This is done for each case where there is an uncertainty in the parameter of the pressure equation. Each case's squared difference from the nominal is summed and the square root taken of the result.

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The nominal values are as follows:

di=17.93 in d=20 in E= 27.9xlo6 psi v=0.3 GF = 2.0 E= I 001t, the full scale range.

The accuracy values are as follows:

di= 2.8% (ASME Code worst case) do= 0.625% (ASME Code worst case)

E = 5% (SI metallurgist, common practice) v 0 (SI, common practice)

GF = 2% per gage, for 2 gages (SRSS) =2.8% (HP], Reference 2)

The uncertainty for c, Absolute Strain Error (ASE) is found in Reference 2 for a quarter bridge as ASE = (GF2 + OEE 2)0 5 or for a half bridge as (2(GF2 ) + OEE2 )0 5 where OEE = overall electronics error, 1.1% (Reference 2)

GF = Gage Factor of 2.0 (HPI).

The uncertainty for c is calculated as ASE = 3.03%.

For QC2 the error will be minimized by making actual pipe thickness (ultrasonic) and outer diameter measurements. Assuming that do can be measured with an error of 10 mils and the thickness can be measured (ultrasonic) within 20 mils the error becomes do =0.05%

di = 0.22%.

The overall uncertainty on the measurement and conversion to pressure is 6.3% (see Attachment A).

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Vi g -strain gage, 350ohm l l cr - completion resistor, 350 ohm Figure 1: Wheatstone Bridge StructuralIntegrity File No.: EXLN-1 7Q-302 Revision: 0 Associates, Inc. Page 7 of 9

Kyowa DPM-71A Signal Conditioner 350 Ohm 100microstrainNolt GF: 2.0 L DAS Figure 2: Electrical Schematic for Quad Cities Unit 2 Structural Integrity File No.: EXLN-1 7Q-302 Revision: 0 Associates, Inc. Page 8 of 9

3 REFERENCES

1. E-mail from Guy DeBoo (Exelon) to K. Fujikawa (SI) and L. Dorfman (SI), dated 2/1/05, "Dresden MS Line Strain Gage Information," SI File No. EXLN-1 7Q-201.

2. Y. Dayal, "Exelon Corporation Quad Cities Unit 2 Nuclear Power Plant Dryer Instrumentation Uncertainty", GE-NE-0000-0037-1951-01 Rev 0, February 2005, SI File No. EXLN-1 7Q-202.

tutrlnertlFile t

Structural Integrity Associates, Inc.

No.: EXL-N-17Q-302 Q j 0 lRevision:Pg~f Revision:

Page of .

APPENDIX A UNCERTAINTY ANALYSIS SPREADSHEET Structural Integrity File No.: EXLN-17Q-302 Revision: 0 4 Associates, Inc. PageAl of A2

Quad Cities 2 Accuracy with improved diameter measurements Accuracy Nominal Nominal Values Plus di 17.93 0.22% 17.969446 do 20 0.05% 20.01 E 2.79E+07 5% 29295000 v 0.3 0 0.3 GF 2 2.8% 2.056 E 0.0001 3.03% 1 0.000103 I Nominal + di I + do I +E I t SRSS I Pressure 400.818621 391.86341 1 402.86113 1 420.85955 1412.96343 Theta 4070.5524 4085.0112 -400.81862 400.81862 Uncert*Theta . I 8.9552154 12.0425056 -20.040931 I 12.144804 169484 Pressure = 400.81862 psi + 25.169484 psi

% Error 6.3%

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