RADIATION DAMAGE IN HIGH Ni-WELD OF Ni-Cr-Mo-V TYPE

Transcription

1 RADIATION DAMAGE IN HIGH Ni-WELD OF Ni-Cr-Mo-V TYPE M.Brumovsky, M.Kytka, R.Kopriva UJV REZ, CZECH REPUBLIC Degradation of primary components of Pressurised Water Cooled Nuclear Reactors: IAEATechnical Meeting 5-8 November 213, Vienna, Austria

2 OBJECTIVES OF THE PROJECT TWO MAIN OBJECTIVES OF THIS PROJECT: MOST OF WELDS IN RPVs FOR WWER-1 HAVE HIGH CONTENT OF NICKEL MOSTLY ABOVE 1.5 MASS % THERE ARE NO RELEVANT DATA FOR IRRADIATION DAMAGE/EMBRITLEMENT OF THIS TYPE OF WELDS FOR HIGH NEUTRON FLUENCE, BEYOND DESIGN FLUENCE ACCORDING TO THE MODELLING OF RADIATION DAMAGE, IN SUCH TYPE OF STEELS (I.E. WITH HIGH NICKEL CONTENT), PHASE OF Ni-Mn-Si-(P) IS CREATED DURING IRRADIATION HAVING LATE BLOOMING EFFECT SUCH BEHAVIOR COULD BE UNACCEPTED FOR LIFETIME EXTENSION OF THESE TYPE OF RPVs

3 Weld metal - Sv 12Kh2N2MAA MATERIAL CHOSEN FOR THE IRRADIATION Table 3.1. Chemical composition (mass. %). C Mn Si Cr Ni Mo V P Cu

4 IRRADIATION Irradiation was performed in NRI research reactor LVR-15. The material was irradiated to different fluences, approximately: from 1.9x1 19 to 9.5x1 19 n.cm -2 (E > 1 MeV). The irradiation parameters: irradiation temperature - (288 ± 1) C flux (E > 1 MeV) - cca 4 x 1 11 cm -2 s -1 inert atmosphere - He, Ar pressure kpa The irradiation device was equipped with thermocouples. The fluence of neutrons was measured with the activation detectors. When considering the requested total fluence following types of detectors were chosen: Ti, Fe, Ni, Cu (1 %) and Co (1 %). 3

5 Rp, Rm, MPa A, Z, % TENSILE PROPERTIES - UNIRRADIATED Rp Rm 4 A Z T, C T, C 4 MATERIAL/WELD WITH RELATIVELY HIGH TENSILE PROPERTIES

6 5 TREND CURVES

7 drp, drm, Mpa Neutron fluence dependence of yield strength (R_p.2) and tensile stress (R_m) static tensile testing at room temperature drp/24 C drm/24 C F, E23 m-2 6

8 drp/29 C, drm/29 C, Mpa Neutron fluence dependence of yield strength (R_p.2) and tensile stress (R_m) static tensile testing at +29 o C drp/29 C drm/29 C F, E23 m-2 7 SHIFTS ARE SLIGHTLY LOWER THAN FOR TESTING AT RT

9 Impact energy W_t [J] CHARPY IMPACT TESTS unirradiated unirradiated specimen set 1 specimen set 1 specimen set 2 specimen set 2 2 specimen set 3 specimen set 3 specimen set 4 specimen set 4 specimen set 5 specimen set Temperature [ C] 8

10 K JC (1T) (MPa.m 1/2 ) STATIC FRACTURE TOUGHNESS TESTS Unirradiated Unirradiated Irradiated-specimen set No. 1 Irradiated-specimen set No. 1 Irradiated-specimen set No. 2 Irradiated-specimen set No. 2 Irradiated-specimen set No. 3 Irradiated-specimen set No. 3 Irradiated-specimen set No. 4 Irradiated-specimen set No. 4 Irradiated-specimen set No. 5 Irradiated-specimen set No Temperature ( o C) 9 PRE-CRACKED CHARPY SIZE SPECIMENS WERE TESTED SLOPE/SHAPE IS NOT CHANGED

11 dhv Hardness diagram for unirradiated and irradiated specimens n ~.6 dhv F, E+23 m-2 1 HARDNESS TREND CURVE IS CONSISTENT WITH USED PREDICTIONS

12 drp, drm, MPa Comparison of static tensile testing results radiation hardening at room and operation (+29 o C) temperature n ~.7 = drp/24 C drm/24 C drp/29 C drm/29 C F, E+23 m-2 11 SHIFTS AT IRRADIATION TEMPERATURE ARE SLIGHTLY SMALLER THAN AT RT BUT EXPONENT n IN POWER LAW IS HIGHER THAN FOR HARDNESS

13 dt, C Comparison of transition temperature shifts from Charpy V-notch impact notch toughness tests for different energy criteria n ~ 1 dtt_kcv5 dtt_41j 6 dtt_kcv6 dtt_68j F, E+23 m-2 12 CHARPY SHIFTS ARE CONSISTENT FOR DIFFERENT ENERGETICAL CRITERIA BUT EXPONENT IN POWER LAW n ~ 1

14 dt, C Comparison of transition temperature shifts from Charpy V-notch impact notch toughness tests for different criteria n= dtt_41j dtt_pr dtt_hl F, E+23 m-2 13 CHARPY SHIFTS ARE CONSISTENT FOR DIFFERENT CRITERIA BUT EXPONENT IN POWER LAW n ~ 1 1.1

15 dt, C Two different approaches to the fluence dependence of transition temperature T41J shifts dtt_41j F, E+23 m-2 14 TREND CURVE OF CHARPY SHIFTS CAN BE FITTED ALSO BY OTHER WAY (?!)

16 dt, C Two different approaches to the fluence dependence of transition temperature T41J shifts dtt_41j F, E+23 m-2 15 TREND CURVE OF CHARPY SHIFTS CAN BE FITTED ALSO BY OTHER WAY (?!)

17 dt_41j, dt, C Comparison of transition temperature shifts from notch impact and static fracture toughness testing dtt_41j n= F, E+23 m-2 16 BOTH TREND CURVES HAVE SIMILAR EXPONENT ( n ~ 1) BUT WITH QUITE DIFFERENT SLOPE

18 dt_41j, dt, C Comparison of transition temperature shifts from notch impact and static fracture toughness testing dt, C dtt_41j n=1 n= F, E+23 m-2 17 BOTH TREND CURVES HAVE SIMILAR EXPONENT ( n ~ 1) BUT WITH QUITE DIFFERENT SLOPE

19 CORRELATION BETWEEN PROPERTY CHANGES 18

20 Correlation between yield strength increase with increase in hardness, notch impact transition temperature T41J shift and static fracture toughness T shifts dt41j,dt; C; dhv LINEAR LAW : n ~ drp, MPa drp-dt41j drp-dhv drp-dt 19 ALL THREE TREND CURVES HAVE SIMILAR EXPONENT (n ~ 1)

21 Correlation between yield strength increase with increase in hardness, notch impact transition temperature T41J shift and static fracture toughness T shifts dt41j,dt; C; dhv drp-dt41j drp-dhv drp-dt drp, MPa 2 POWER LAW n(drp-dt41j)=1.55; n(drp-dhv=.7; n(drp-dt)=1.2

22 dt41j, dt68j, C Possible correlation between yield strength increase and transition temperatures T41J and T68J shifts drp-dt41j drp-dt68j drp, MPa 21 ANOTHER POSSIBLE FITTING OF THE CORRELATION (?!)

23 dt41j, dt68j, C Possible correlation between yield strength increase and transition temperatures T41J and T68J shifts drp-dt41j drp-dt68j drp, MPa 22 ANOTHER POSSIBLE FITTING OF THE CORRELATION (?!)

24 Correlation between transition temperature shifts dt41j and dt dt ~ 1.6 dt_41j 23 UNEXPECTED HIGH COEFFICIENT OF CORRELATION ~ 1.6

25 IGF, % IGF, % IGF, % FRACTOGRAPHY -KCV KCV, J.cm-2 LSE T USE T-T41J, C LSE T USE F, E+23 m-2 LSE T USE 24 LOW PORTION OF IGF AND ONLY AT LOW CHARPY ENERGIES AND BELOW T41J

26 IGF, % IGF, % IGF, % FRACTOGRAPHY -KJC KJC, MPa.m,5 LSE LT UT T-T, C LSE LT UT F, E+23 m-2 LSE LT UT LOW PORTION OF IGF AND ONLY BELOW T

27 IGF, % FRACTOGRAPHY KCV vs.kjc LSE-KJC LT-KJC UT-KJC LSE-KCV T-KCV USE-KCV T-T41J, T-T, C 26 LOW PORTION OF IGF AND ONLY BELOW TRANSITION TEMPERATURES

28 CONCLUSIONS Tensile, impact, static fracture toughness testing and hardness measurement results show a monotonic increase of radiation hardening and embrittlement of the material on fast neutron fluence. Correlation between changes in hardness, yield strength increase, notch impact transition temperatures shifts and static fracture toughness MC transition shifts have been obtained. Linear dependence between transition temperature shift T41J and T can be used but shifts in T are much larger than in T41J. Dependence between yield strength increase and hardness increase is also described by linear dependence but correlation between yield strength increase and transition temperature T41J shift is probably more complicated. 27

29 CONCLUSIONS Neutron fluence dependencies in transition temperature shifts dt41j and dt can be described by power law with exponent n close to one. 28

30 CONCLUSIONS IAEA VERLIFE (Guidelines for evaluation of integrity and lifetime of components and piping in NPPs with WWER type reactors during operation, App.III+ Russian RD :, - for weld metal m F TF AF F, m =,8; (24) A F = 1 exp( 2 C eq ), о С (25) where C eq C Ni C Mn C, if 3 C Ni Si, if C C Mn Ni C C 3 Mn Si C 3 Si ; (26) 29 1 =,73; 2 =,883; 3 = 3,885;

31 dtk, C COMPARISON OF NEW DATA WITH VERLIFE PREDICTION CURVES F, E+22 m-2 (.5 MeV) МШ 3 МШ 3-95% dtt_41j 3

32 CONCLUSIONS No changes in slope of the MC fracture toughness curves have been observed even for high neutron fluences. Also no late blooming effect in neutron fluence dependence was found.. APT study performed by B.Radiguet et al. in Université de Rouen showed solutes (Mn, Ni, Si, Cu, P) clusters located in the matrix or along dislocation, their density is increasing with neutron fluence but their radius remain practically constant. Further study will be necessary to resolve late blooming phase case 31

33 CONCLUSIONS Ratio of IGF in fracture surfaces in both notch impact and static fracture toughness tests is relatively low (maximum up to 12 %) and is concentrated mainly to lower shelf energy and lower transition temperature region and is not increase with neutron fluence. 32

34 CONCLUSIONS Thus it seams that fluence dependence of irradiation damage (hardness, yield strength increase, transition temperature shifts) for high nickel steels is very steep and exponent in power function is in the interval between.8 and 1, i.e. practically linear dependence of radiation damage on neutron fluence 33

35 This project was realized within the EU FP6 programme LONGLIFE THANK YOU FOR YOUR ATTENTION 34