Daniel CooperDepartment of Materials Science and EngineeringThe University of Sheffield

Supervisors: Mark Rainforth (University of Sheffield, Department of Materials Science and Engineering)Mark Ogden (University of Sheffield, Department of Chemical Engineering)Karl Whittle (University of Liverpool, Centre for Materials and Structures)Tim Abram (University of Manchester, School of Mechanical, Aerospace and Civil Engineering)

Daniel CooperDepartment of Materials Science and EngineeringThe University of Sheffield

Supervisors: Mark Rainforth (University of Sheffield, Department of Materials Science and Engineering)Mark Ogden (University of Sheffield, Department of Chemical Engineering)Tim Abram (University of Manchester, School of Mechanical, Aerospace and Civil Engineering)Karl Whittle (University of Liverpool, Centre for Materials and Structures)

Doctoral Academy Conference 2016, Sheffield – 21st June 2016

Materials for Molten Salt Nuclear Reactors

Contents

• The need for nuclear power

• How can we improve nuclear power?

• What is a molten salt nuclear reactor?

• Materials challenges

• Corrosion of materials

• What do I do?

2

Correlation of GDP per capita and power consumption

3David J. C. MacKay, Sustainable Energy – Without the Hot Air, 2008, p.231

Worldwide Greenhouse Gas Emissions

4David J. C. MacKay, Sustainable Energy – Without the Hot Air, 2008, p.12

Why Nuclear Power?

5

One uranium fuel pellet in today’s

reactors provides the same energy as

about one ton of coal

Higher energy density⇒ less land & less waste

“But Dan, what about nuclear waste?”

The really bad waste, the stuff that lasts thousands of years, from all past and future nuclear power in the UK is enough to fill just 95 double decker buses…

6NDA, DECC, 2013 UK Radioactive Waste Inventory: Waste Quantities from all Sources, 2013

Current Nuclear Reactors – Water-cooled

7

Disadvantages of Water-cooled Reactors

8Top Left: EPA/TEPCO. Bottom Right: Olander, Journal of Nuclear Materials, 389, 1-22 (2009)

Right: Fuel rods, before and after

Solid fuel ⇒ premature removal, lower fuel use and added cost

Pressurisation ⇒ Safety risk and added cost

Left: Fukushima Dai-ichiunderwent rapid pressure loss as a result of a hydrogen explosion.

What should we change?

9

Design the reactor so that in an accident it shuts down naturallyThis will make it cheaper and safer

Use a liquid fuel to avoid the problems with solid fuelThis will allow the fuel to stay in the reactor longer

Design our reactors so that they can utilise waste material as fuel

Molten Salt as a Coolant

10

Change coolant from water to molten salt– no need to pressurise

H2O H2O

H2O H2O

H2O

H2OH2OH2O

H2O

H2O

H2O

H2O H2O

H2OH2OH2O

Air

Solution Na+

Na+

Cl-

Cl-

Na+

Na+

Cl-

Na+

Na+

Cl-

Na+Cl- Cl-Cl-

Cl-

Weaker Hydrogen Bonds Stronger Ionic Bonds

GIF-002-00, “A Technology Roadmap for Generation IV Nuclear Energy Systems”, December 2002.

Molten Salt Reactors

11

History of molten salt reactors

Change of policies, funding lost because other projects were further developed

12Left: Proving the Principle by Stacy, Susan M., U.S. Department of Energy, Idaho Operations Office. ISBN 0-16-059185-6, chapter 13.Right: ORNL Photo 67051-64.

Aircraft Reactor Experiment (ARE), 1954 Molten Salt Reactor Experiment (MSRE), 1965-1969

Materials Requirements

13Ignatiev and Surenkov, “Material Performance in Molten Salts”, Comprehensive Nuclear Materials, 2012, pp. 221-250.

Materials requirements

High melting point

High-temperature mechanical

strength

Corrosion resistant

Resistant to radiation damage

Which materials?

14

Plastic?✗High melting point✗ Mechanical properties✗Radiation damage resistant~ Corrosion Resistant

Glass?~ High melting point✗ Mechanical properties✓ Radiation damage resistant✓ Corrosion Resistant

Ceramic?✓ High melting point~ Mechanical properties✓ Radiation damage resistant✓ Corrosion Resistant

Metal?✓ High melting point✓ Mechanical properties✓ Radiation damage resistant✓ Corrosion Resistant

Basics of Corrosion

15E. McCafferty, Introduction to Corrosion Science, 2010.

Corrosion in Molten Salts

Oxygen and water removed to prevent corrosionUse argon gas to maintain pressure, chemically

unreactiveStill get corrosion driven by fuel, waste and salt

movement16

𝑂2(𝑔) + 4𝑒−⇌2𝑂2−

𝐻2𝑂 + 2𝑋−⇌𝑂2− + 2𝐻𝑋𝐻2𝑂 + 𝑋−⇌𝑂𝐻− + 𝐻𝑋

What do I do?

2. Prepare samples of materials

3. Expose to molten salts

4. Create electrical circuits to

understand reactions

5. Examine materials after

corrosion

1. Use understanding of properties

to drive material choice

17

Mechanical alloying Spark plasma

sintering Micropreparation

Metals, Binary Carbides and Mn+1AXn Phases

18

Transition Metale.g. Titanium

Metal Carbidee.g. Titanium Carbide

Mn+1AXn Phasee.g. Titanium Aluminium Carbide

Ceramic Metallic

Strong Ductile

High temperature oxidation resistant Machinable

High temperature corrosion resistant

Thermally and electrically conductive

Creep resistant Thermal shock resistant

Mn+1AXn Phases – Structure and Properties

19Whittle et al., 2010, Acta Mater., 58, 13, 4362.

n = 1 ⇒ 211n = 2 ⇒ 312n = 3 ⇒ 413

What is the impact of this research?

20

Effect

Application

My Work Chemical properties of MAX phases

Molten Salt Nuclear Reactors

Cheaper, more efficient nuclear

power

High-temperature

chemical processing

Longer material lifetime,

reduced cost

Jet Turbine Blades

Improved fuel efficiency for air

travel