Influence of atomic displacement rate, neutron spectrum and irradiation temperature on radiation-induced ageing of power reactor components. FAST NEUTRON FLUX EFFECT ON VVER RPV’s LIFETIME ASSESSMENT. D . Е rak Ya . Shtrombakh , P . Platonov , А. А maev , Yu. Kevorkian, А. Chernobaeva - PowerPoint PPT Presentation
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FAST NEUTRON FLUX EFFECT FAST NEUTRON FLUX EFFECT ON VVER RPV’s LIFETIME ON VVER RPV’s LIFETIME ASSESSMENT ASSESSMENT D D . Е . Е rak rak Ya Ya . . Shtrombakh Shtrombakh , , P P . . Platonov Platonov , А. , А. А А maev maev , , Yu. Kevorkian, Yu. Kevorkian, А. А. Chernobaeva Chernobaeva Research Institute of Atomic Reactors Research Institute of Atomic Reactors Dimitrovgrad - Ulianovsk, Russia Dimitrovgrad - Ulianovsk, Russia October October 200 200 5 5 RUSSIAN RESEARCH CENTER “KURCHATOV KURCHATOV INSTITUTE INSTITUTE” Influence of atomic displacement rate, neutron spectrum Influence of atomic displacement rate, neutron spectrum and irradiation temperature on radiation-induced ageing and irradiation temperature on radiation-induced ageing of power reactor components of power reactor components
Transcript
FAST NEUTRON FLUX FAST NEUTRON FLUX EFFECT ON VVER RPV’s EFFECT ON VVER RPV’s LIFETIME ASSESSMENTLIFETIME ASSESSMENT
DD. Е. ЕrakrakYaYa. . ShtrombakhShtrombakh, , PP. . PlatonovPlatonov, А. , А.
ААmaevmaev, , Yu. Kevorkian, Yu. Kevorkian, А. А. ChernobaevaChernobaeva
Research Institute of Atomic ReactorsResearch Institute of Atomic Reactors Dimitrovgrad - Ulianovsk, Russia Dimitrovgrad - Ulianovsk, Russia
October October 20020055
RUSSIAN RESEARCH CENTER
““KURCHATOVKURCHATOV INSTITUTEINSTITUTE””
Influence of atomic displacement rate, neutron spectrum and Influence of atomic displacement rate, neutron spectrum and irradiation temperature on radiation-induced ageing of power reactor irradiation temperature on radiation-induced ageing of power reactor
componentscomponents
CONTENTCONTENT
VVER-440VVER-440• Why we should investigate Neutron Flux Effect in VVER Why we should investigate Neutron Flux Effect in VVER
Re-irradiation embrittlement Data Base is highly restricted
CUTTING OF TEMPLETS ALLOWED TO OBTAIN CUTTING OF TEMPLETS ALLOWED TO OBTAIN FIRST ACTUAL RESULTS OF THE 1FIRST ACTUAL RESULTS OF THE 1STST GENERATION GENERATION
RPV MATERIALS PROPERTIESRPV MATERIALS PROPERTIES
First templets results showed effectiveness of annealing procedure
The only way to predict RPV material behavior – accelerated irradiation in VVER-440 SS channels
REIRRADIATION OF TEMPLETS WAS PERFORMED IN REIRRADIATION OF TEMPLETS WAS PERFORMED IN
Location scheme of the surveillance chains in VVER-440/213 pressure
vessel
Full core – “high flux” irradiation
Reduced core – “low flux” irradiation
Are the irradiation conditions of specimens Are the irradiation conditions of specimens equal to RPV wall conditions?equal to RPV wall conditions?
TemperatureTemperature
Neutron FluxNeutron Flux
Is it correct to use the results Is it correct to use the results
of irradiated specimensof irradiated specimens
for RPV lifetime assessment? for RPV lifetime assessment?
Direct measurements of irradiation temperature carried out with Direct measurements of irradiation temperature carried out with thermocouples in surveillance channels of Kola NPP-3 showed that thermocouples in surveillance channels of Kola NPP-3 showed that overheat of surveillance specimens as compared to RPV inner surface in overheat of surveillance specimens as compared to RPV inner surface in the core region does not exceed 5°C.the core region does not exceed 5°C.
Tracing scheme of thermocouple
269,7 271,4270,6
265.3
01.10.0110-00
266.1
02.10.0114-30
265.9
02.10.0102-00
200
210
220
230
240
250
260
270
280
Te
mp
era
ture
, "С
70
80
90
100
He
at
po
we
r, %
COBRA project COBRA project resultsresults
SS capsules
Core barrel
Core center
Core center
Reactor pressure vessel
Flux Flux on SSon SS
Neutron flux on Neutron flux on SS 10-20 times SS 10-20 times higher than on higher than on inner surface of inner surface of RPV wall RPV wall
Flux effect study is very importantFlux effect study is very important
for VVER-440 RPV lifetime assessment.for VVER-440 RPV lifetime assessment.
In 1987 special program was In 1987 special program was startedstarted
MaterialsMaterials
MaterialsMaterials CC MnMn SiSi NiNi CrCr MoMo VV CuCu PP SS
Experimental data matrix consists of Experimental data matrix consists of 52 52 pointspoints
0 50 100 150 2000
20
40
60
80
100
120
140
160
180
200
220
240
y=x
correlation between predicted and experimental values
for low flux
correlation between predicted and experimental values
for high flux
low flux high flux
TK(e
xper
imen
tal)
,o C
TK=800(P+0,07Cu)F1/3, oC
Comparison of the data obtained after Comparison of the data obtained after
irradiation by high and low dose ratesirradiation by high and low dose rates
• Function dependence Function dependence TTКК==AAFFFF0.330.33 was was chosenchosen as inas in Russian GuideRussian Guide
• 95% upper and lower boundaries:95% upper and lower boundaries:
0.330.95 1FB A t n s F
The statistical test was used for the evaluationThe statistical test was used for the evaluation ofof difference between high and low fluxes datadifference between high and low fluxes data
• It tests the hypothesis that corresponding coefficients It tests the hypothesis that corresponding coefficients (A(AFF) of two models are equal) of two models are equal..
• Small (< 0.05) Small (< 0.05) РР-values means that hypothesis should -values means that hypothesis should be rejected (on 95% significance level), and each be rejected (on 95% significance level), and each data group should be described by its own model.data group should be described by its own model.
• Otherwise two data groups should be described by Otherwise two data groups should be described by one model.one model.
The results ofThe results of experimental data evaluation by experimental data evaluation by statistical teststatistical test
MaterialMaterial РР-value-value
BM 109868BM 109868 0.11 0.11 0.05 0.05
WWММ 12 12 0.24 0.24 0.05 0.05
WWММ 28 28 0.02 0.02 0.05 0.05
WWМ А2М А2 0.04 0.04 0.05 0.05
WWМ 37М 37 0.61 0.61 0.05 0.05
BM 108033BM 108033 0.01 0.01 0.05 0.05
Р-value=0.610.05
0 50 100 150 2000
50
100
150
200
250
300
95% boundary for high flux
95% boundary for low fluxlow flux
high flux
weld 37 low flux weld 37 high fluxT
K,o C
Fluence x 1018
, cm-2
Р-value=0.04 0.05
0 50 100 150 2000
50
100
150
200
250
300
high flux
low flux
95% boundary for low flux
95% boundary for high flux
weld A2 high flux weld A2 low flux
TK, o C
Fluence x 1018
, cm-2
Р-value=0.01 0.05
0 50 100 150 2000
50
100
150
200
250
300
95% boundary for high flux
95% boundary for low flux
high flux
low flux
BM 108033 low flux BM 108033 high flux
TK, o C
Fluence x 1018, cm-2
All experimental data All experimental data
0 50 100 150 2000
20
40
60
80
100
120
140
160
180
200
220
240
y=x
correlation between predicted and experimental values
for low flux
correlation between predicted and experimental values
for high flux
low flux high flux
TK(e
xper
imen
tal)
,o C
TK=800(P+0,07Cu)F1/3, oC
Experimental data for materials with high Experimental data for materials with high Cu-content show significant flux effectCu-content show significant flux effect
0 50 100 150 2000
20
40
60
80
100
120
140
160
180
200
220
240
y=x
correlation between predicted and experimental values
for low flux
correlation between predicted and experimental values
for high flux
low flux high flux
TK(e
xper
imen
tal)
,o C
TK=800(P+0,07Cu)F1/3, oC
For flux effect evaluation the difference in For flux effect evaluation the difference in ΔΔTTKK
was used:was used:
dd= = ΔΔ T TKK(low flux(low flux)- )- ΔΔ T TKK(high flux(high flux))
for the fluence 4x10for the fluence 4x101919 сm сm-2-2..
Correlation parameters (Correlation parameters (RR) between ) between dd and and PP and and CuCu contents contents
Dependence of flux effect on Dependence of flux effect on CuCu content content seems to beseems to be
RR РР--valuevalue
dd(4(410101919ccмм-2-2)) и и ССРР 0.280.28 0.30 0.30 0.05 0.05
dd(4(410101919ccмм-2-2)) и и ССCuCu 0.750.75 0.04 0.04 0.05 0.05
Flux effect dependence on Cu content.lux effect dependence on Cu content.
Preliminary estimation:Preliminary estimation:effect is significant if effect is significant if
Cu content more than ~0.13 %Cu content more than ~0.13 %
The results of mechanical tests of the VVER-The results of mechanical tests of the VVER-440 pressure vessel steels show that copper 440 pressure vessel steels show that copper influence on influence on ТТКК shift is insignificant for re- shift is insignificant for re-irradiationirradiation
0.12 0.14 0.16 0.18 0.20 0.22 0.240
50
100
150
200T
K, o C
Cu, %
It agrees with the data of It agrees with the data of microstructural studies of the microstructural studies of the steels in irradiated and annealed steels in irradiated and annealed conditions, and after re-conditions, and after re-irradiationirradiation
The microstructural studies of VVER-440 The microstructural studies of VVER-440 materials carried out by materials carried out by
P. Pareige,P. Pareige, O. ZabusovO. Zabusov and others,and others,
B. Gurovich, B. Gurovich, ЕЕ. . ККuleshovauleshova and others and others
show the followingshow the following::
• At primary irradiation of the RPV steelsAt primary irradiation of the RPV steels the the copper-enriched clusters occur. They are of 2-3 copper-enriched clusters occur. They are of 2-3 nm in diameter with high distribution density nm in diameter with high distribution density and are effective barriers for dislocation and are effective barriers for dislocation movementmovement..
• There is depletion of solid solution by copper There is depletion of solid solution by copper atoms.atoms.
Cu distribution in VVER-440irradiated weld
P.Pareige, O.Zabusov, M.Miller etc.
CC
• Copper content does not change in solid Copper content does not change in solid solution during annealing, there is coagulation solution during annealing, there is coagulation of copper-enriched clusters and formation of of copper-enriched clusters and formation of copper precipitates of diameter ~ 5 nm with copper precipitates of diameter ~ 5 nm with much smaller distribution density.much smaller distribution density.
• Large copper precipitates formed during Large copper precipitates formed during annealing are of low density annealing are of low density
• They are not effective barriers for dislocation They are not effective barriers for dislocation movementmovement
• There is no more intensive formation of copper There is no more intensive formation of copper clusters at re-irradiation.clusters at re-irradiation.
Cu in irradiated, annealed and re-irradiated VVER-440 weld
Copper precipitate in irradiated, annealed Copper precipitate in irradiated, annealed and re-irradiated VVER-440 weldand re-irradiated VVER-440 weld
The dependence of transition temperature The dependence of transition temperature
shift for VVER-440 pressure vessel materials shift for VVER-440 pressure vessel materials
on neutron flux is not expected under re-on neutron flux is not expected under re-
irradiation.irradiation.
Results of templets material studyResults of templets material study
CONCLUSIONS (1/2)CONCLUSIONS (1/2)
1.1. The work concerning establishment of fast The work concerning establishment of fast neutron flux influence on radiation embrittlement neutron flux influence on radiation embrittlement for VVER-440 pressure vessel materials has been for VVER-440 pressure vessel materials has been carried out using standard VVER-440 RPV carried out using standard VVER-440 RPV materials irradiated in the surveillance channels at materials irradiated in the surveillance channels at high of ~3high of ~310101212ссmm-2-2ss-1-1 and at low ~4 and at low ~410101111ссmm-2-2ss-1-1 fast neutron fluxes.fast neutron fluxes.
2.2. Flux effect occurs in VVER-440 pressure vessel Flux effect occurs in VVER-440 pressure vessel materials with the level of copper content higher materials with the level of copper content higher than ~ 0.13 %.than ~ 0.13 %.
CONCLUSIONS (2/2)CONCLUSIONS (2/2)
3. Radiation damage under re-irradiation does not 3. Radiation damage under re-irradiation does not depend on copper significantly.depend on copper significantly.
4.4. It is confirmed by the data of microstructure It is confirmed by the data of microstructure studies.studies.
5. There is no dependence of transition temperature 5. There is no dependence of transition temperature shift for the VVER-440 pressure vessel materials on shift for the VVER-440 pressure vessel materials on neutron flux under re-irradiation after annealing.neutron flux under re-irradiation after annealing.
The studies made within the last
10 years enables NPPs extend the
life time of annealed units for 15
years with licensing for each 5
years
Line of the further worksLine of the further works • The quantitative assessment of flux effect for The quantitative assessment of flux effect for
different values of fluence is necessary for the different values of fluence is necessary for the solution of practical problems of VVER-440/213 solution of practical problems of VVER-440/213 lifetime assessment. lifetime assessment.
• It requires development of models for radiation It requires development of models for radiation embrittlement under irradiation at high and at low embrittlement under irradiation at high and at low fluxes in wide range of fluence , based on modern fluxes in wide range of fluence , based on modern understanding of mechanisms of microstructural understanding of mechanisms of microstructural changes under irradiation.changes under irradiation.
Representative data on Kola NPP Unit 3 and 4 RPV steels radiation embrittlement
Neutron flux corresponds to RPV wall
Application of the reconstitution techniqueprovides representativenesof test results
RPVs VVER-1000
Low P and Cu contents
High Ni content in weld metal (Up to 1.9 %)
EOF depends on the primary Radiation Embrittlement
Elaborating RE depends are based on SS and research results
SS assembly
VVER-1000Research assembly
Melting monitors from VVER-1000 irradiation programs Surveillance program
Research program
314°C 308°C 302 °C 292 °C 288°C
304°C 300°C 293°C
The capsules with surveillance specimens are located above the core
baffle in a place with high neutron flux gradient
It is very important to use results with high accuracy fluence data
New radiation embrittlement dependence of VVER-1000 RPV steels based on SS and research results
The standard reference dependence specified in the Russian Guide for weld seams:
