FHRs and the Future of Nuclear Energy

Presented to DOE FHR Workshop

At Oak Ridge National Laboratory Sept. 20-21, 2010

By Sherrell Greene Director, Nuclear Technology Programs Oak Ridge National Laboratory greenesr@ornl.gov, 865.574.0626

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Presentation Overview

• Nuclear energy success criteria – the Five Imperatives of Nuclear Energy

• FHR distinctives • FHRs as enablers of the Five

Imperatives of Nuclear Energy

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April 2010 DOE Nuclear Energy Roadmap establishes four objectives   Develop technologies and other

solutions that can improve the reliability, sustain the safety, and extend the life of current reactors

  Develop improvements in the affordability of new reactors to enable nuclear energy to help meet the Administration's energy security and climate change goals

  Develop sustainable nuclear fuel cycles

  Understand and minimize the risks of nuclear proliferation and terrorism

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The Five Imperatives of Nuclear Energy define success

1.  Extend life, improve performance, and sustain health and safety of the current fleet

2.  Enable new plant builds and improve the affordability of nuclear energy

3.  Enable the transition away from fossil fuels in the transportation and industrial sectors

4.  Enable sustainable fuel cycles

5.  Understand and minimizing proliferation risk

Abundant  Nuclear  Energy  

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FHR’s combine attributes and technologies of several different reactor types

MSRs

•  Fluoride Salt Coolants

•  Structural Materials •  Pump Technologies

GCRs

•  TRISO Fuels

•  Structural Materials •  Brayton Power Conversion

SFRs

•  Low Primary Pressures

•  Hot Refueling Technologies

LWRs

•  Water/Air-tolerant Coolants

•  Integral Primary Coolant Systems

FHRs

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Four FHR concepts have been developed in U.S.

AHTR = Advanced High Temperature Rx PB-AHTR = Pebble Bed Advanced High Temperature Rx

HEER (1000 MWt)

PB-AHTR (410 MWe)*

SmAHTR (125 MWt / 50 MWe) HEER = High Efficiency and Environmentally Friendly Nuclear Rx SmAHTR = Small Modular Advanced High Temperature Rx

AHTR (1235 MWe)*

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The potential benefits of FHRs stem directly from fundamental materials characteristics

Coolant

Tmelt (ºC)

Tboil (ºC)

Density (kg/m3)

Specific Heat

(kJ/kgºC)

Volumetric Heat

Capacity (kJ/m3ºC)

Thermal Conductivity

(W/mºC)

Kinematic Viscosity

(106m2/s)

Li2BeF4 (Flibe) 459 1430 1940 2.42 4670 1 2.9

59.5NaF-40.5ZrF4 500 1290 3140 1.17 3670 0.49 2.6

26LifF-37NaF-37ZrF4 436 2790 1.25 3500 0.53

31LiF-31NaF-38BeF2 315 1400 2000 2.04 4080 1 2.5

8NaF-92NaBF4 385 700 1750 1.51 2640 0.5 0.5

Sodium 97.8 883 82 1.27 1040 62 0.1

Lead 328 1750 10540 0.15 1700 18 0.1

Lead-Bismuth 125 1737 10000 0.14 1400 13 <0.1

Helium, 7.5 Mpa 3.8 5.2 20 0.29 11.0

Water, 7.5 Mpa 0 290 732 5.5 4040 0.56 0.1

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The principal challenges of FHRs also stem from fundamental materials considerations

Coolant

Tmelt (ºC)

Tboil (ºC)

Density (kg/m3)

Specific Heat

(kJ/kgºC)

Volumetric Heat

Capacity (kJ/m3ºC)

Thermal Conductivity

(W/mºC)

Kinematic Viscosity

(106m2/s)

Li2BeF4 (Flibe) 459 1430 1940 2.42 4670 1 2.9

59.5NaF-40.5ZrF4 500 1290 3140 1.17 3670 0.49 2.6

26LifF-37NaF-37ZrF4 436 2790 1.25 3500 0.53

31LiF-31NaF-38BeF2 315 1400 2000 2.04 4080 1 2.5

8NaF-92NaBF4 385 700 1750 1.51 2640 0.5 0.5

Sodium 97.8 883 82 1.27 1040 62 0.1

Lead 328 1750 10540 0.15 1700 18 0.1

Lead-Bismuth 125 1737 10000 0.14 1400 13 <0.1

Helium, 7.5 Mpa 3.8 5.2 20 0.29 11.0

Water, 7.5 Mpa 0 290 732 5.5 4040 0.56 0.1

Design  Challenges:  

•  High  coolant  mel6ng  temperatures  •  Code-­‐qualified  compa6ble    high  temp.  metals  

•  Maintenance  of  salt  chemistry  /  purity  •  Wet  refueling  at  high  temperature  

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2004 ORNL analyses* indicate cost of large FHRs can be lower than GCR and SFR power systems

FHR  Concept  Frac5on  of  S-­‐PRISM  

Cost  (1681  $/kWe)  

Frac5on  of  GT-­‐MHR  Cost  

(1528  $/kWe)  

AHTR-­‐IT  (1145  MWe,  800  C  Tcout)  

.55   .61  

AHTR-­‐VT  (1300  MWe,  1000  C  Tcout)  

.49   .53  

* Ingersoll et al., “Status of Preconceptual Design of the Advanced High-Temperature Reactor (AHTR), ORNL/TM-2004/104, May 2004

Cost  advantages:  •  Thin-­‐walled  vessels  and  piping  •  More  compact  reactor  and  primary  coolant  loops  •  Smaller  confinement/containment  systems  •  High  opera6ng  temperatures  and  thermal  efficiencies  

Abundant  Nuclear  Energy  

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Achievement of Imperative 3 depends on our success in delivering nuclear process heat for many applications

Abundant  Nuclear  Energy  

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Working temperatures of fluoride salts are well suited for variety of process heat applications

0 100 200 300 400 500 600 700 800 900 1000 110 1200 1300 1400 1500 1600 1700

Petro Refining

Oil Shale/Sand Processing

Cogeneration of Electricity and Steam

Steam Reforming of Nat. Gas & Biomass Gasification

Electrolysis, H2 Prod., Coal Gasification

NaF-BeF2 (57-43)

RbF-ZrF4 (58-42)

LiF-NaF-KF (46.5-11.5-42)

LiF-BeF2 (67-33)

NaF-ZrF4 (59.5-30.4)

Temperature (C)

Melts Boils

Abundant  Nuclear  Energy  

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FHR salt coolant heat transfer technologies were successfully demonstrated in MSRE for > 26,000 hr

Molten Salt Reactor Experiment (1965 – 1969)

600 ˚C LiF-BeF2 / Air Blast Radiator MSRE LiF-BeF2 Secondary Coolant Loop

Abundant  Nuclear  Energy  

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FHRs incorporate many attractive attributes for high-temperature process heat applications

Coolant  (Reactor  Concept)  

High  Working  Tempa  

High  Volumetric  

Heat  Capacityb  

Low  Primary  Pressurec  

Low  Reac5vity  With  Air  &  Waterd  

Water  (PWR)   #   #  Sodium  (SFR)         #Helium  (GCR)     # #  Salt  (AHTR)          

a FHR system working temperature functionally limited by structural materials capabilities b High coolant volumetric heat capacity enables constant temperature heat addition / removal (ηC = 1 – TC/TH ~ Carnot cycles), compact system architectures, and reduces pumping power requirements c Low primary system pressure reduces cost of primary vessel and piping, and reduces energetics of pipe break accidents d Low reactivity with air and water reduces energetics of pipe break accidents

Abundant  Nuclear  Energy  

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FHRs can implement or enable all three fuel cycle classes

• Once-Through –  Standard once-through U

fuel cycle – similar to NGNP / GCR fuel cycles

–  Once-through Th fuel cycle

• Modified Open –  “Deep Burn” – similar to

deep burn gas reactor fuel cycle

–  U-Th fuel cycles

•  Full Recycle –  Modified Open Cycle tier of

multi-tier Full Recycle

Abundant  Nuclear  Energy  

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FHRs have desirable non-proliferation attributes

• Qualitative comparative analysis: –  Better than LWRs and SFRs

•  TRISO fuel more difficult to reprocess than LWR and fast reactor fuels •  FHRs have lower fissile inventory than SFRs

–  Equivalent or better than gas cooled reactors •  Similar TRISO fuel (U; Th; or Deep Burn U,Pu,Np) •  Additional value of solidified salt coolant as barrier to fuel access?

• Systematic examination of FHR proliferation attributes is needed.

Abundant  Nuclear  Energy  

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FHRs show much promise as enablers of the Five Imperatives of Nuclear Energy

1.  Extend life, improve performance, and sustain health and safety of the current fleet

2.  Enable new plant builds and improve the affordability of nuclear energy

3.  Enable transition away from fossil fuels in the transportation and industrial sectors

4.  Enable sustainable fuel cycles

5.  Understand and minimize proliferation risk

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Summary •  FHRs show much promise as enablers of the Five

Imperatives of Nuclear Energy •  Much work is needed •  A balanced FHR R&D strategy is required

– System concept development should: •  Identify optimal system architectures and technologies for differing

applications •  Enable improved cost estimates •  Enable fuel cycle and non-proliferation assessments •  Inform technology and component R&D priorities

– FHR technology development should: •  Address key base technologies: coolants, materials, fuels, and I&C •  Address key component technologies: heat exchangers, pumps, valves •  Leverage ongoing NGNP and GCR R&D