Importance of materials for sustainable nuclear energy

Transcription

1 Common EESC-EERA Event / EUSEW 2012 Brussels, 18 June 2012 Importance of materials for sustainable nuclear energy L. Malerba - SCK CEN Joint Programme Nuclear Materials SubProgramme coordinator (on behalf of the JPNM board)

2 Why nuclear energy? E=mc 2 A lot of energy from very little amount of fuel (1 g U = 2 toe) Energy continuously available in large quantity Low CO 2 Counteract climate change

3 Nuclear fission in a nutshell + Energy = (M 1 -M 2 )c 2 neutron + fissile nucleus ( 235 U) Mass: M 1 fission fragments + 3 n Mass: M 2 (waste) fertile nucleus ( 238 U) + n fissile nucleus ( 239 Pu) (similar chains produce also minor actinides - waste)

4 Why nuclear energy?

5 Other strengths of nuclear energy Stable prices low compared to other sources Stable supply of energy reduced price volatility Security of supply uranium in many and stable countries uranium and fuel can be stored

6 Why no nuclear energy 1.Proliferation (misuse to build weapons) 2.Exhaustion of resources (non-renewability) 3.Nuclear waste (radioactive pollution) 4.Consequences of severe accidents (e.g. Fukushima) These problems should not be minimised: they must be faced

7 Nuclear waste Once-through or open fuel cycle If spent fuel pins are stored as they are Volumes are relatively large (include both low and high activation materials) Decay heat of the spent fuel needs to be addressed Radiotoxicity will last for about 250,000 yrs

8 Nuclear waste Fully closed fuel cycle If spent fuel is reprocessed Volumes of waste are reduced If moreover fast reactors are used to burn the minor actinides: Decay heat is reduced Raditoxicity will last for less than 500 yrs

9 Nuclear waste Accelerator-driven systems receive extra neutrons from proton accelerator Innovative concept, inherently safe Core can be loaded with U- free fuel Myrrha - SCK CEN ADS can be used to burn all long-lived waste: Pu & MA or only MA Max. theoretical transmutation rate can be reached

10 Nuclear waste Importance of materials Materials allowing construction of FR/ADS will help reduce volume, radiotoxicity and storage time of high level longlived waste Development of materials able to withstand long-term repository conditions (corrosion-resistant) is also key

11 Severe accidents - causes Human factors Irresponsible or simply wrong human behaviour Deliberate human action against nuclear plants (never occured, but ) Inadequate design Underestimation of potential severity of accidental conditions Lack of consideration of combination of factors (earthquake+tsunami+power loss ) Inadequate knowledge of the response of materials to given (accidental) conditions

12 Severe accidents - remedies Human factors Irresponsible or simply wrong human behaviour better training, safety culture, independent & passive safety systems Deliberate human action against nuclear plants (never occured, but ) this possibility should be included in risk assessment Inadequate design Underestimation of potential severity of accidental conditions stricter design rules, margins and procedures (defense in depth), Lack of consideration of combination of factors (earthquake+tsunami+power loss ) more thorough risk assessments Inadequate knowledge of the response of materials to given (accidental) conditions importance of understanding the behaviour of materials

13 Severe accidents Importance of materials Failure is ultimately always the consequence of a material that breaks or ceases to fulfill its duty Safety systems allow an accident to be avoided after failure High performance materials combined with physical understanding of materials behaviour allow failure to be avoided

14 The answer: GenIV reactors + ADS Liquid Sodium Cooled Fast Reactor (SFR) Liquid Lead Cooled Fast Reactor (LFR) Gas Cooled Fast Reactor (GFR) (Very) High Temperature Reactor (HTR) SuperCritical Water Cooled Reactor (SCWR) Accelerator Driven System (ADS) Molten Salt Reactor (MSR) Keywords: high temperature, fast reactor, special coolant,

15 In summary Problem Mitigation Proliferation Political Resources exhaustion Nuclear waste Severe accidents Modular reactors Advanced reprocessing Fast reactors Close fuel cycle High temperature reactors Higher burnup Close fuel cycle Fast reactors Accelerator-driven systems Safety culture & safety systems explicitly on the agenda Advanced materials GenIV reactors and High performance materials

16 Requirements on materials High temperature-resistance high pressure) Radiation resistance Compatibility with (super-critical)water / liquid metal / gas Research on Nuclear Materials

17 Role of the JPNM

18 Summary & Conclusions Nuclear energy offers intrinsic benefits, including low CO 2 emission, but has to improve safety, reduce waste, preserve resources and reduce proliferation risk, to be made more sustainable GenIV reactors concepts adress these issues and are expected to mitigate and largely solve them Materials science plays a key role along the path of more sustainable nuclear energy

19 The end