Cluster dynamics modelling of Cu-enriched precipitations in RPV Model Alloys during thermal ageing

Transcription

1 Cluster dynamics modelling of Cu-enriched precipitations in RPV Model Alloys during thermal ageing Zhengcao LI( 李正操 ) School of Materials Science and Engineering Tsinghua University zcli@tsinghua.edu.cn

2 Contents 1. Status and Updated Policy of Nuclear Energy after Fukushima Accident 2. APT and CD studies on Cu-enriched precipitations in RPV Model Alloys during thermal ageing

3 Energy Demand More Power, less CO GDP/Billion

4

5 Nuclear Power Source: Limited Number of Plants ~ 400 NPPs in the World, only 17 in China Mainland Capacity: MWe

6 Capacity Plan of Nuclear Energy 60 Nuclear Power Capacity till GWe

7 NPPs distribution Hongyanhe Unit under construction Haiyang Tianwan Operating unit Site under planning Qinshan Sanmen Fuqing Ningde Daya Bay/ LingAo Taishan Fangchenggang Yangjang Changjiang

8 Influence of Fukushima Accident Premier Wen Jiabao emphasized the nuclear safety in China after Fukushima Accident on March 16 th : (1) Immediately organized to conduct a comprehensive safety inspection of nuclear facilities in the whole country. (2) Strengthen the safety management of operating nuclear facilities. (3) Comprehensively review NPPs under construction, immediately stop the construction of the ones which do not meet safety standards. (4) Pay close attention to the preparation of nuclear safety planning, and suspend approval of nuclear power projects.

9 Response for the above: No accident of or above INES level-2. Currently operating NPPs: Generally meet the safety standard of China and IAEA. NPPs under construction (e.g. AP1000, EPR): Designed to have higher safety level, and construction quality are well controlled. Problems found: Lack of management standards under possible accidents. More safety measures against natural disasters needed.

10 On Oct 24, 2012, the Central government passed: Plan on nuclear power safety ( ); Plan on nuclear power development ( ); On Jan 1, 2013, the central government issued: Energy Development 12th Five-Year Plan ; China Restarts approval of new nuclear power plants after Fukushima Accident?

11 Goals by 2015 Thus, gradually resume to normal construction under meeting safety requirement; By 2015, 30% of China's power will be generated from solar, wind and other renewable sources, as well as from nuclear energy. By 2015, generating capacity of NPPs in China will reach 40 gigawatts. Present 17 nuclear reactors, providing 14.8 gigawatts another 29 reactors under construction, adding 31.7 gigawatts

12 For future new NPPs NPPs Operation Policy - Only built in coastal areas tentatively. (before 2015) - Have to incorporate third-generation nuclear-safety technology that meets the highest international safety standards. For NPPs already running or approved - Inspection on current safety status billion RMB government project on upgrading current NPPs safety level, mainly based on the lessons learnt from Fukishima.

13 Issued Projects Based on Lessions learnt from Fukushima Accident I. Reactor Performance Estimation and Respond Strategy under Natural Disaster 2. Seismic; 3. Flooding; 4. multiple external disasters Natural Environment 1. prevention & mitigation of severe accidents NPPs II. Design of Emergency Equipment for Possible Accident 5. passive emergency power 6. mitigation equipment & systems 7. hydrogen control device 8. rescue robot 9. passive heat export system III. Environment Contamination Prevention 10. low-altitude fast measurement technology for radioactive contamination survey 11. monitoring and radiation protection for nuclear accident radioactive effluent 12. Emergency treatment technology and process for radioactive wastewater 13. Emergent recovery technology for radionuclide contamination environment

14 New Generation Reactors High Temperature Gas-cooled Reactor -by Tsinghua University -first criticality in Dec getting into grid in Jan 2003 Fast Breed Reactor -by CIEA -ran successfully on July 21 st, 2011 Liquid Salt Fluoride Thorium Reactor -by CAS

15 University/Institute Activities Collaborative Innovation Center on Advanced Nuclear Energy Science and Technology Joint R&D Center of State Nuclear Power Technology Co. Ltd with Tsinghua University Joint Lab of Nuclear Materials and their Service Safety of CGNPC with Tsinghua University Joint Lab of Advanced Nuclear Materials of Tsinghua University (Beijing and Hsinchu) Institute of Nuclear Energy Safety Technology, Chinese Academy of Science

16 National Major Project: HTGR Target: to build HTR-PM demonstration plant with power of 200MWe Operation and safety demonstration tests on HTR-10, coupled with gas turbine cycle; R&D on key technology of commercial HTGR, construction of the HTR-PM demonstration plant; R&D on future technology, including hydrogen production, fuel, VHTR, etc.

17 Graphite Materials Issues in HTGR Structures & Properties Oxidation Vessel steel weld (effects of irradiation) High Temperature materials Turbine materials Control Rod Recent activities: Possible Impurities Non-ignorable Irradiation Swelling High temperature Gas Corrosion Decrease waste (C-14 and H-3)

18 National Major Project: APWR Advanced PWR AP1000 CAP1400 CAP1700 Common Issues In-core Severe Accidents Corrosion Hydrochemistry Ageing Management Facilities Design & Evaluation Advanced Fuel Cable Design Properties of Nuclear Materials

19 PWR Ageing Management Project 1 Establishment of Codes and Standards 2 Irradiation Embrittlement of RPV 3 Degradation of components of 1st Circuit 4 Electrical Cables of Instruments and Control Facilities 5 Inspection, Monitoring and Mitigation Technologies 6 Ageing Management Technical Assessment 7 Database

20 Contents 1. Status and Updated Policy of Nuclear Energy after Fukushima Accident 2. APT and CD studies on Cu-enriched precipitations in RPV Model Alloys during thermal ageing

21 RPV Embrittlement Mechanisms Solute clusters CRPs, Mn-Ni-Si Matrix damage : Dislocation loops or vacancy clusters Segregation Phosphorus in GB

22 Thermal Ageing T: 450 Time: 0h-300h, every 20h Vickers Hardness Load:1kg Time: 15s Testing point: 20 Repetition: 16 Series Cu Ni Mn Si Fe-Cu M Fe- Cu-Si Fe- Cu-Ni Fe- Cu- Ni-Mn wt% M M M M M M Thermo-Electric Power Reference: Constantan(55Cu-45Ni) Heater power: 30mW Temperature of cold junction: 305K Temperature difference: ~0.6K Repetition: 5 Correlations? 3-D Atom Probe Cluster Dynamics

23 Counts Counts Counts Atom probe result of CRPs in Fe-0.5Cu Aging 56 hrs, ΔHv10 nm number density:1.16x10 23 m -3 Guinier radius:1.67 Aging 150 hrs, ΔHv38 number density:1.13x10 23 m -3 Guinier radius:2.63 nm Aging 200 hrs, ΔHv40 number density:9.72x10 22 m -3 Guinier radius:2.85 nm C u Cluster radius (nm) Clusters radius (nm) Clusters diameter (nm)

24 Change in hardness (Hv) Hardness Change of Fe-0.5Cu Alloy 50 M3 Fe-0.5Cu Precipitates growing Thermal aging 150 hours Thermal aging 200 hrs Hardness peak Early nucleation stage Hardness change is 10 0 Load = 9.8N (1kgf) Aging time (hours)

25 Change in hardness (Hv) Effect of Nickel on hardening Comparison Fe-Cu-Ni material with Fe-Cu material Fe-0.5Cu- Fe-0.5Cu- 0.8Ni 0.6Ni Fe-0.5Cu M19 M18 M3 Fe-0.5Cu M19(0.5Cu-0.8Ni), 150h Cu Ni Ni +0.8Ni Load = 9.8N (1kgf) -10 M Aging time (hours) Cu Ni Mn Si Ni addition delays the hardening process. M2 8 M2 7 M1 9 M M M Nd: 1.32E+23 m -3 Vf: 9.73E-04 r: 2.26 nm

26 Change in hardness (Hv) Effect of Manganese on hardening Comparison Fe-Cu-Ni-Mn material with Fe-Cu-Ni material Fe-0.5Cu-0.8Ni-1.4Mn M28 Fe-0.5Cu-0.6Ni-1.4Mn M27 Fe-0.5Cu-0.8Ni Fe-0.5Cu-0.6Ni M19 M Ni+1.4Mn +0.6Ni +0.8Ni 0.5Cu-0.8Ni-1.4Mn, 140 h Cu Ni+1.4Mn Cu Ni Mn Si M M M M Load = 9.8N (1kgf) Aging time (hours) M M M Nd: 4.64E+22 m -3 Vf: 1.12E-03 r: 3.44 nm Mn addition accelerates the hardening process.

27 Change in hardness (Hv) Effect of Silicon on hardening Comparison Fe-Cu-Si material with Fe-Cu material Fe-0.5Cu-0.2Si M10 M9 M3 Fe-0.5Cu-0.1Si Fe-0.5Cu Fe-0.5Cu +0.1Si +0.2Si Cu Si M10(0.5Cu-0.2Si), 150 h Cu Ni Mn Si 20 M M M M M M Load = 9.8N (1kgf) M Nd: 9.93E+22 m -3 Vf: 9.20E-04 r: 2.46 nm Aging time (hours) Si addition accelerates the hardening; but the magnitude of peak hardening may not be affected by the amount of Si.

28 H1+H2 Correlation of solute atoms reduction from matrix Hardness can be assumed by H=H 1 +H 2 +H 3 H 1 : Inherent hardness of the ferrite matrix itself. (constant during aging) H 2 : The matrix solute atoms strengthening contribution H 3 : Precipitate strengthening contribution Fe-0.5Cu +0.2Si +0.8Ni +0.8Ni+1.4Mn +0.1Si +0.6Ni +0.6Ni+1.4Mn H 360 [ Cu 2 matrix Solute atoms in matrix reduce along aging ] Aging time (hours) ΔH 3 (= ΔH - ΔH 2 ) is better description for mechanical property changes occurred by CRP formation.

29 Precipitate strengthening hardness change Correlation precipitates hardening with precipitates volume fraction, Cu amount in precipitates Trying to correlate precipitation hardening ΔH 3 to 3DAP results Fe-0.5Cu +0.1Si +0.2Si +0.6Ni +0.8Ni +0.8Ni+1.4Mn (Square root of Vf) * [Cu] Internal structure of CRPs should be considered to evaluate the correlation of hardening and CRPs

30 Modeling by Cluster Dynamics Chemical kinetic technique Particularly adapted to the modelling of the evolution of clusters Cluster molecule algebraic representation Precipitate Cu n Ni p (n,p) Chemical reaction Ex. absorption of a copper atom by a cluster size (n,p): Cu n Ni p + Cu Cu n+1 Ni p (n,p) + (1,0) (n+1,p)

31 C( n, p, t) t n', p' J ( n', p') ( n, p) n', p' J ( n, p) ( n', p') Ordinary differential equations Tool of resolution: Mathematica Ensemble of reactions of transition towards (n,p) Ensemble of reactions of transition away from (n,p) Microstructure parameters, such as cluster size, radius, volume fraction and number density, are obtained from the solution.

32 Cluster Dynamics / APT Results cluster size and average precipitate radius Fe-Cu Binary Alloy

33 Cluster Dynamics / APT Results volume fraction and number density Fe-Cu Binary Alloy

34 Cluster Dynamics / APT Results cluster size and average precipitate radius Fe-Cu-Ni Ternary Alloy

35 Cluster Dynamics / APT Results volume fraction and number density Fe-Cu-Ni Ternary Alloy

36 Comparing Fe-Cu & Fe-Cu-Ni alloys Nucleation rate of Fe-0.5Cu alloy and Fe-0.5Cu-0.8Ni alloy Additional Ni accelerates the nucleation of the Cu-enriched precipitates

37 Cluster number density Comparing Fe-Cu, Fe-Cu-Ni, Fe-Cu-Ni-Mn alloys Fe-0.5wt%Cu Fe-0.5wt%Cu- 0.8wt%Ni Fe-0.5wt%Cu- 0.8wt%Ni- 1.4wt%Mn

38 APT/CD suggest: Si, Ni and Mn atoms addition accelerated precipitates nucleation. Mn and Si accelerate the hardening of alloys. Ni addition suppresses hardening. Further Considerations: What happens in the matrix? Ni, Mn and Si at the precipitate-matrix interface What happens at grain boundaries/dislocations Fast diffusion paths & heterogeneous nucleation sites

39 Thanks for Contributors: L.Liu, L.Chen (TU) N.Sekimura (UT) N.Soneda, K.Nishida (CRIEPI)