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Relational equation between elongation and indent data based on ageing time of CSP and CR cable jacket
2007. 10. 162007. 10. 16
KEPRI KEPRI JongJong--SeogSeog KimKim
[email protected]@kepri.re.kr
IAEA 2007 PLIM(IAEA-CN-155/046)
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Why Condition Monitoring?Why Condition Monitoring?
Plant cables have 30~ 40 years lifePlant cables have 30~ 40 years lifeAfter 30~40 years, what do I have to do?After 30~40 years, what do I have to do?
Replace all of the plant cable because the lifetime is expired?
IEEE383 suggests several methods for life extensionIEEE383 suggests several methods for life extensionReduce conservatism after temperature monitoring of plant cable)Condition monitoring of actual aging degradationOIT, FT-IR, indenter and ultrasonic is used for non-destructive evaluationIndent methodology is one of condition monitoring programs
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breakbreak--elongation test according to ASTM D412 has been widely used elongation test according to ASTM D412 has been widely used for the life evaluation of cablefor the life evaluation of cableit is not easy to apply this method to the cable of operating NPit is not easy to apply this method to the cable of operating NPPP� Dumbbell specimen from plant cable is needed for break-elongation testOne of alternatives is indenting test which non destructively meOne of alternatives is indenting test which non destructively measures asures
the aging of cable jacketthe aging of cable jacketRelational equation is needed to use Indent data instead of BreaRelational equation is needed to use Indent data instead of Breakk--
elongation dataelongation data� Need comparison of two data since indent method is not a standard method� We decided to develop relational equation between elongation and indenting� CSP and CR cable jacket is used for relational equation between elongation and indenting
1. Introduction1. Introduction
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2. Test Method(1/5)2. Test Method(1/5)
Accelerated agingAccelerated agingElectric ovens shown on Fig. 1 was used for accelerated aging of cablesDumbbell specimens for elongation test and 100mm long cables forindenting test were preparedAccelerated aging during 48hours, 72hours, 96hours, 168hours and 164hours at the each temperature of 116℃, 126℃, 136℃ and 146℃Air cooled for 24 hours after finishing the accelerated aging
BreakBreak--elongation testelongation testDestructive aging evaluation method which measures the elongation length after elongates aged dumbbell specimens until they are brokenDumbbell specimens in accordance with ASTM D412 ‘Die C’ dimensionSpeed of 500±50mm/min during break-elongation testUsed specially designed machine which can elongate 5 cable specimens at one time as shown on Fig. 2
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▲▲▲▲ Fig. 1 electric Heating Chamber
▲▲▲▲ Fig 2. Cable elongation tester
▲▲▲▲ Computer screen of Break-elongation test
① body plate of upper specimen grips② upper specimen grip③ lower specimen grip④ load cell
2. Test Method(2/5)2. Test Method(2/5)
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2. Test Method(3/5)2. Test Method(3/5)
Indenting testIndenting testIndenting test is non destructive aging evaluation method which measures the hardness of cable by pressing a cable surface with steel probe at the vertical directionPortable cable indenter as shown on Fig.3 was used for this test� Composed of cable clamp assembly, probe, load cell assembly, PDA, replaceable
Li-Ion Battery2mm round and 0.56mm edge of truncated con type probe was used for indentingPressing load was limited to 0.5kgf to protect damage of cable jacketIndenting depth didn’t go over 0.7mm for every cable specimensFig.4 shows “deviation-speed” curve for various type of probes0.56mm flat edge probe and moving speed of 0.031 mm/sec were chosen for best accuracyFig. 5 shows detail of indent probe.
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▲▲▲▲ Fig. 3 Portable cable indenter
▲ Internal part of indenter
2. Test Method(4/5)2. Test Method(4/5)
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▲▲▲▲ Fig. 4 Deviations of modulus according to the probe types and speeds
▲▲▲▲ Fig. 5 Truncated cone type probe
2. Test Method(5/5)2. Test Method(5/5)
“0.56con” mean cone type probe of 0.56mm flat edge, “2.0ball” mean ball type probe of 2.0mm ball edge.
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▲ Break-elongation for aging time of CSP cables
▲ Break-elongation for aging time of CR cables
3. Test Result 3. Test Result
▲ Indent modulus for aging time of CSP cables
▲ Indent modulus for aging time of CR cables
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▲ Elongation - modulus for CSP cables(116 ℃)
▲ Elongation - modulus for CSP cables(146 ℃)
4. Relation between Elongation and Modulus(1/3)4. Relation between Elongation and Modulus(1/3)
▲ Elongation - modulus for CR cables(116 ℃)
▲ Elongation - modulus for CR cables(146 ℃)
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4. Relation between Elongation and Indent depth(2/3)4. Relation between Elongation and Indent depth(2/3)
▲ Elongation & indent depth for CSP cables(116 ℃) ▲ Elongation & indent depth for CR cables(116 ℃)
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4. Relation between Elongation and Indent depth(3/3)4. Relation between Elongation and Indent depth(3/3)
Relation between elongation and indent modulusRelation between elongation and indent modulusAging rate in elongation test is break-elongation rate which comes from length of aged specimen divided by that of un-aged specimenIndent modulus is a value which comes from the indent load divided by depthElongation rate and indent modulus have reverse linear relationship
Relation between elongation and indent depthRelation between elongation and indent depthElongation length is elongation length at break pointIndent depth is the value at the designated indent loadElongation length and indent depth have proportional linear relationship
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▲▲▲▲ Fig. 9 Relation between elongation & modulus for CSP
▲▲▲▲ Fig. 10 Relation between elongation-modulus for CR
2.50/ 3.9 6( / )te e E P d −
=
1 .9 65 2 0 ( )te h=2.140/ 2.2 6( / )te e E P d −
=
▲▲▲▲ Fig. 11 Relation between elongation & indent depth for CSP
▲▲▲▲ Fig 12 Relation between elongation-indent depth for CR
2 .57310( )te h=
1 .9 65 2 0 ( )te h=
5. Relational Equation between Elongation5. Relational Equation between Elongation--Indent(1/2)Indent(1/2)
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Elongation and indent data have proportional relationFig. 9 and Fig. 10 show relationship between elongation rate andindent modulus for CSP and CR cables aged at 116℃, 126℃, 136℃ and 146℃ during 48, 72, 77, 88, 93, 94, 96, 168, 264, 312 hoursFig. 11 and Fig. 12 show relationship between elongation length and indent depth for CSP and CR cablesRelational equations between elongation and indent are described as equation (1) ~ (4)� (1) Elongation-indent modulus for CSP cable :� (2) Elongation-indent modulus for CR cable :� (3) Elongation-indent depth for CSP cable :� (4) Elongation-indent depth for CR cable :
5. Relational Equation between Elongation5. Relational Equation between Elongation--Indent(2/2)Indent(2/2)
2.57310( )te h=
2.140/ 2.2 6( / )te e E P d −
=
2.50/ 3.9 6( / )te e E P d −
=
1.96520( )te h=
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CR CableCSP Cable
12.97mm(10%)18.87mm(14.6%)
Deviations of Indent Modulus Related
9.87mm(7.9%)11.84mm(9.2%)
Deviations of Indent Depth Related
▼ Table 1 Deviation of elongation corresponding to modulus and indent depth
6. Review of Relational Equation6. Review of Relational Equation
Analyzed deviation between actual data and equation dataDeviation of indent modulus and indent depth for CSP and CR cables are described on table 114.6% average deviation for CSP cable and 10% average deviation for CR cable at the equation of elongation rate and indent modulus is observed9.2% average deviation for CSP cable and 7.9% average deviation for CR cable at the equation of elongation length and indent depth are observedEquation for indent depth and elongation length had better accuracy than that of indent modulus and elongation rate
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▲ Activation energy by elongation - modulus for CSP
▲ Activation energy by elongation - modulus for CR
7. Comparison of Activation energy(1/2)7. Comparison of Activation energy(1/2)
▼ Activation energy (ev) at 50% break-elongation rate(%) and indent modulus rate(%)
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7. Comparison of Activation energy(2/2)7. Comparison of Activation energy(2/2)
Instead of selecting a data at 50% breakInstead of selecting a data at 50% break--elongation rate for the calculation elongation rate for the calculation of activation energy, we compared activation energies of every 5of activation energy, we compared activation energies of every 5% % decrement for breakdecrement for break--elongation rates and every 5% increment for indenter elongation rates and every 5% increment for indenter modulusmodulusFor the CSP cable jacketFor the CSP cable jacket� 0.885ev at 50% break-elongation rate were showed� 0.962 ~ 0.945ev at indenter modulus increasing rate of 15% ~ 25%� Indenter modulus showed 1.08 times value of break-elongationFor the CR cable jacketFor the CR cable jacket� 0.793ev at 50% break-elongation rate were showed� 0.8 ~ 0.809ev were showed at modulus increasing rate of 30% ~ 40%� Indenter modulus showed 1.01 times value of break-elongation
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Relational equations between elongation and indent were obtainedRelational equations between elongation and indent were obtainedCoefficients in the equation were different according to the matCoefficients in the equation were different according to the material typeerial type
Good convergence was observed when indent depth was used as equGood convergence was observed when indent depth was used as equation ation factor instead of indenting modulusfactor instead of indenting modulusIt was verified that elongation data can be delivered by indentIt was verified that elongation data can be delivered by indent data if we data if we
had enough amount of experiment result for various material typehad enough amount of experiment result for various material typeActivation energy can be calculated by using indent methodologyActivation energy can be calculated by using indent methodology if cable if cable
is composed of relative hard material is composed of relative hard material likelike CR cable jacketCR cable jacketIndent methodology will be useful to evaluate the aging conditiIndent methodology will be useful to evaluate the aging condition of plant on of plant
used cable without destructing the operating cables used cable without destructing the operating cables
8. Conclusion8. Conclusion
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9. Lessons learned and future plan9. Lessons learned and future plan
Lessons learned during life extension of used cables in KoriLessons learned during life extension of used cables in Kori--1 NPP1 NPP�� Natural ageing of 30 years was not severe than expectedNatural ageing of 30 years was not severe than expected�� Radiation ageing does not give severe damage to electric insulaRadiation ageing does not give severe damage to electric insulation tion resistance(IRresistance(IR) of ) of cable if DBA does not follow itcable if DBA does not follow it�� Actual ohm heat of power cable was not severe as they did durinActual ohm heat of power cable was not severe as they did during EQ testg EQ test�� Ageing of plant cable will not be severe if it is not heated coAgeing of plant cable will not be severe if it is not heated continuously (Polymer ntinuously (Polymer material has recovering character during rest time depend on matmaterial has recovering character during rest time depend on material type)erial type)
Future plan of cable condition monitoring Future plan of cable condition monitoring �� New project will be started for nonNew project will be started for non--destructive cable aging diagnosis(2008. 4 ~ 2010. 6) destructive cable aging diagnosis(2008. 4 ~ 2010. 6) �� Have a plan of developing automatic indenting mini robot duringHave a plan of developing automatic indenting mini robot during this projectthis project
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Thank you !!!
