ThomasVATTAPPILLIL_MScThesisPres_Sep2015_INPGrenoble

Analysis and Evaluation of
Accident Tolerant Fuel (ATF)
Concepts for
Water Cooled Reactors (WCR)
Thomas VATTAPPILLIL
MSc Thesis Defense (EMINE)
INP Grenoble, Sept 2015
1
9/2/2015T. VATTAPPILLIL MSc Thesis Defense

Overview
 Introduction
 Internship at IAEA
 Accident Tolerant Fuels (ATF)
 Method
 Technology Assessment
 Analysis of Current Fuel System
 ATF Requirements
 Evaluation process of current ATF Concepts
 Results
 Discussion
2

International Atomic Energy Agency3

4

International Atomic Energy Agency
 2 Internships at NPTDS
 1st: February to September 2013
 Development and implementation of Advanced Reactor
Information System (ARIS): https://aris.iaea.org/
 Organization and development of Consultancy Meeting for
R&D response to Fukushima Daiichi accident
 Educational rector simulator software
 Technology assessment for Newcomer Countries
 2nd: April to October 2015
 Design, drafting and publication of WCR booklet
 Simulator: DBA and BDBA evaluation
 Technology Assessment for Accident Tolerant Fuel
5

 1st: February to September 2013
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https://aris.iaea.org/

 2nd: April to October 2015
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Introduction: Accident Tolerant Fuel
 Direct response to Fukushima Daiichi accident
 Clear weaknesses in today’s fuel designs
 IAEA Lesson learned from Fukushima Daiichi Accident
 IAEA International Experts Meeting 8 (March 2015)
 US – DoE & US – NRC
 Part of constant fuel improvement effort to increase
safety of reactors
 Stakeholders
 Regulatory authorities (US – DoE, CEA,…)
 National laboratories and Universities (INL, MIT,…)
 Reactor technology vendors (Westinghouse, AREVA,…)
 Fuel designers organization (TVEL, GE,…)
8

 IAEA Activates on ATF
 IAEA Technical Working Group (TWG) on
Fuel Performance and Technology
 IAEA Technical Meeting (TM) on
ATF Concepts for LWR
 Participation in OECD – NEA ATF activities
 Coordinated Research Project (CRP): Analysis of Options
and Experimental Examination of ATF for WRC
 Thomas VATTAPPILLIL: Accident Tolerant Fuel for LWR
Report
9

 Term “Accident Tolerant” ambiguous
 No clear definition of ATF
“Fuels with enhanced accident tolerant are those that, in
comparison with the standard U02 - Zr system, can tolerate loss of
active cooling in the core for a considerable longer time period
while maintaining or improving the fuel performance
during normal operation.”
[Shannon Bragg - Sitton. Journal of Nuclear Materials, 2014]
 Basic Research
 Very large number of potential concepts for LWR
 Number of different approaches
 ATF not “silver bullet” to Nuclear Safety problems
10

Method: Overview
 Prerequisites for Technology Assessment
 ATF requirements
 ATF concept candidates
 Criteria for evaluation
 Technology Assessment
 Elimination of non – compatible candidates
 Evaluation
 ATF requirement
 Basic nuclear safety requirements
 Operational requirements
 Choice of best candidates
11

Prerequisites for Technology Assessment
 Current fuel system
 Light Water Reactors
 85% of reactors are LWR
 Most prevalent ones: PWR and BWR
 Currently used: UO2 – Zr system
 MOX – Fuel
 Much work done for Evolutionary Designs (GenIV)
 Target of analysis PWRs and BWRs
 Evaluation of requirements
 Nuclear Accidents
 Three Mile Island 2 (PWR - USA 1978, INES Lvl 5)
 Chernobyl (PWR VVER – UdSSR 1986, INES Lvl 7)
 Not considered due to unique design
 Fukushima Daiichi (BWR – Japan 2011, INES Lvl 7)
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 Three Mile Island 2 (Gen II PWR - USA 1978, INES Lvl 5)
 Key facts
 Equipment failure & Operator error
 Human machine interface error
 LOCA
 Fuel failure after 2,5 hours
 Peak Cladding Temperature ~ 2800°C
 Partial core melt and relocation to lower plenum
 Containment intact and Lower level of radioactive release
 Response
 Automatic shutdown systems
 Birth of nuclear safety culture
 Formation of INPO and NEI
13

 Fukushima Daiichi (Gen II BWR – Japan 2011, INES Lvl 7)
 6 BWR, units 3 suffered core meltdown (partial)
 Key facts
 9.7 magnitude earthquake and BDB Tsunami
 Extend station blackout conditions (Ex. SBO)
 Failure of ECCS
 Lack of long-term core cooling mechanism
 Lack of adequate emergency preparedness
 Fuel failure to various extends and times
 Peak Cladding Temperature >2800°C
 Excessive Hydrogen generation
 Containment breach and significant radioactive release via
multiple pathways
14

 Fukushima Daiichi (Gen II BWR – Japan 2011, INES Lvl 7)
 6 BWR, units 3 suffered core meltdown (partial)
 Reaction to accident
 Phase-out of nuclear energy (Germany & Switzerland)
 Enhanced emergency preparedness and response
 Regional emergency centers
 Offsite equipment
 Enhanced severe accident training
 Severe accident management systems (SAMS)
 Filtered venting system
 Hydrogen recombines
 Accident tolerant fuel development
15

 Main problems
 UO2 – Fuel
 Low thermal conductivity
 Lower specific heat capacities
 Melting points (higher if possible)
 Low fission product retention
 Zr – Fuel Cladding
 Large rate of oxidation reaction
 Large heat release via oxidation (“run-away” effect)
 UO2 – Zr system
 Large fuel cladding chemical interaction (FCCI)
 Large fuel cladding mechanical interaction (FCMI)
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 Summary of requirements for ATFs (concept specific):
 Compatibility with LWR operating environments
 High economical performance (burnups, longer cycle lengths,..)
 Dose rates < UO2 – Zr (fabrication, transport, handling, storage,…)
 Specific demands
 Fuel
 Higher thermal conductivity and lower specific heat capacities
 Increased Fission product retention
 Decreased operating temperatures (FCCI and FCMI)
 Cladding
 Lower rates of oxidation and heat release
 Improved thermomechanical properties to reduce fuel failures
(melting points, thermal conductivity, heat capacity, H
pickup,…)
17

Technology Assessment I
 1st attempt failed
 Wildcard search for ATF concepts
 Too many concepts
 Large amount of R&D
 Different Technology Readyness Levels (TRL)
 No comparison possibilities btw ATFs
 2nd attempt:
 Systematic Approach
 Classification ATF concepts into groups
 Elimination
1. Compatibility into LWR environment
2. Basic thermomechanical properties
3. Choice of best candidates
 Evaluation of research and implementation potential (no time)
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 Classification attempt
 Factor: change to current UO2 – Zr system
 1st attempt noticed 3 approach in ATF development
 Approach 0: UO2 + Zr system
 Approach 1: UO2 fuel + Zr clad + Coating
 Near - term technology
 Approach 2: UO2 fuel + New clad
 Mid – term technology
 Approach 3: New fuel + New clad
 Long – term technology
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 First set of realization
 Evaluation of ATF concept: Cost vs Risks
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Fuel Cycle
R&D
Feasibility Deployment
Development
Time
Performance
Approach 0 NA NA NA NA High
Approach 0
(w. SAMS)
NA NA NA NA Medium
Approach 1 Low Low Low Low Medium
Approach 2 Medium Medium Low Medium Medium
Approach 3 High High High High Low

 First set of Results
 Evaluation: Cost vs Risk
 General cost for development of new fuel concept
 Source: INL Advanced Fuel Cycle Campaign Working Group
 Experts suggest 20 – 25 yrs for full fuel concept commercialization
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 First set of realization
 Evaluation of ATF concept: Cost/Effort vs Risks
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Fuel Cycle
R&D
Feasibility Deployment
Development
Time
Performance
Approach 0 NA NA NA NA High
Approach 0
(w. SAMS)
NA NA NA NA Medium
Approach 1 Low Low Low Low Medium
Approach 2 Medium Medium Low Medium Medium
Approach 3 High High High High Low

 First set of conclusion
 Consideration of development timeline
 Current LWR predicted to operate for next 40 – 60 years
 Highest Cost vs Risk benefits
 Approach 1: Coatings
 Near-term deployable (~5 years to commercialization)
 Low cost due to minor change to fuel cycle
 Fabrication, development, safety testing, transport, etc…
 Low implementation of ATF requirements
 Approach 3: New Fuel + Cladding
 High cost due to largest change from current fuel cycle
 Long development and testing time (~ 20 – 25 years)
 New fabrication and test facilities
 Large fuel cycle refurbishment/development costs
23

 Approach 2: Cladding
 Mid-range development time (~ 5 -15 years)
 No or little experience within nuclear industry
 Low compatibility with UO2 base fuel
 Enrichment issues
 Important ATF requirements not fulfilled
 Assuming post-Fukushima requirements implemented
 No real enhancement to Approach 1: coating
 No improvements in economics
 Lower economical performance expected
 Approach 2: Possible cladding for new fuel systems
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 Focus of research of stakeholders
 Regulatory authorities & National Labs
 Approach I, 2 & 3
 Large resources and capabilities
 Long and short solutions needs
 Technology vendors
 Approach 1 & 3
 Large resources
 Long and short solutions needs
 Universities
 Approach 1 & 2
 Limited recourse
 Often computation or simulation analysis
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Technology Assessment II
 Step 2: Closer evaluation of ATF concepts
 Defining simple criteria for evaluation
 Valid as ATF are still development phase
 Irradiation, In-pile and large-scale test limited
 Criteria based on
 Enhanced Accident tolerance requirements
 Data from nuclear accidents
 Fuel Safety Criteria
 Enhancing economical performance
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 Step 2: Closer evaluation of ATF concepts
 Defining & Simple criteria for evaluation
 Approach 1
 Lower oxidation characteristics
 Protection of Zr - alloys cladding
 Approach 2
 Lower oxidation that Zr – alloys
 High robustness at high temperatures
 Approach 3
 All of above
 Superior thermal properties (conductivity, melting point,…)
 Better economical performance (burnup, cycle lengths,…)
 Fission product retention for BDBA
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 Lower heat release of oxidation
 Lower hydrogen generation
 Large melting points
 Economical factors
 Compatibility with Zr and H20
 Fabrication and Material
 Candidates
 Precious experience
 Chromia (CrO3)
Alumina (Al2O3)
Silica (SiO2)
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29

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 Most promising: Optimized Chromium Coating
 Currently developed by CEA
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32

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 Lower oxidation that Zr – alloys
 High robustness at high temperatures
 Lower PCCI and PCMI
 Regulators Criteria
 Max cladding temperature: 1204 °C
 Localized oxidation: max < 17 %
 Max H2 production: < 1 % all cladding reaction
 Mech. behavior post-quench: > 1 %
 Economical
 Low parasitic thermal neutron absorption
 Fabrication and availability
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 Approach 1: Cr, Al or Si are good for oxidation
 Neutronic penalties exclude: Cr
35
Figure 19 show HT robustness of clad materials

36

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 SiC disadvantages
 High parasitic thermal neutronic absorption
 Fabrication process problems: end-seals
 More useful with other base fuels
 Mo disadvantages
 Superior to Zr in thermomechanical aspects
 Bad corrosion in high temperatures environments
 High parasitic thermal neutronic absorption
 FeCrAL
 Clear winner
 Moderate parasitic thermal neutronic absorption
 Better suited with other base fuel
38

 Approach 3: New Fuel + New Cladding
 Part 1: ATF Requirements for Fuel
 Improved thermomechanical properties
 Higher thermal conductivity
 Lower heat Capacity
 Lower PCMI and PCCI
 Fission product retention
 Fuel cycle economics
 Heavy metal density
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 Higher thermal conductivity
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41
UO2 UN U - Mo U3Si2 FCM – UN
Thermal
conductivity
(W/mK)
4 20 37 20 19
Heat capacity
(J/kgK at
500°C)
300 230 145 230 230
Heavy metal
density
(g/cm3)
9.6 13.5 16.9 11.3 9.6
Melting Point
(°C)
2840 2762 1150 2762 2762

 UN: has heavy neutronic penalties (overcome N15)
 USi – Why U3Si2 and U3Si5
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 Fission production capabilities
 Fuel matrix of candidate high fissile density ceramic systems
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 Fission production capabilities
 Fuel matrix of candidate high fissile density ceramic systems
 Investigation have shown
 UN – U3Si5 –UB2 most promising ATF capabilities
 UN (50%) - U3Si5 (40%) – Kanthal AF
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 Investigation have shown
 UN – U3Si5 – UB2 most promising ATF capabilities
 UN (50%) - U3Si5 (40%) – Kanthal AF (FeCrAl)
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Conclusions
 Approach 1: Coating – Short-term solution
 Most promising: Improved Cr coating
 Approach 2
 Only continue research for nuclear application as part of
Approach 3
 Approach 3: New Fuel System – Long-term solution
 Most promising
 UN – U3Si5 – UB2 : ATF capabilities
 UN (50%) - U3Si5 (40%) – Kanthal AF (FeCrAl) : most similar to
UO2 – Zr
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Discussion of Results
 Only very overarching view of ATF
 PWR and BWR accident environments same
 Acceptable at this part
 Later more detailed studies need distinguishing
 Different motivation in ATF for Stakeholders
 Regulatory bodies: maximize safety
 Utilities and fuel vendors: maximize economics
 Universities: maximize funding
 National laboratories: maximize funding
 Concrete results: further LWR environment testing
47

Thank you for you
attention!
Questions please!
Thomas VATTAPPILLIL (tvattappillil@gmail.com)
3/09/2015
INP Grenoble, MSc Defense
48

ThomasVATTAPPILLIL_MScThesisPres_Sep2015_INPGrenoble

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