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Liquid Fluoride Thorium Reactors without equations ∑ x<+- = -* ± An overview of liquid -fueled liquid-cooled thermal spectrum Thorium breeder reactors and why they matter. Rob Morse Science Engineer- Nuclear Option 2012. Power makes a difference. 2. Fuel for a lifetime?.

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Rob Morse Science Engineer- Nuclear Option 2012

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Liquid Fluoride Thorium Reactorswithout equations∑x<+-=-*±An overview of liquid-fueled liquid-cooled thermal spectrum Thorium breeder reactors and why they matter.

Rob Morse

Science Engineer- Nuclear Option

2012


Power makes a difference.

2


Fuel for a lifetime?

You consume a ball of coal 10 meters in diameter…

…or a ball or thorium 37mm in diameter.

LFTR wo Equations. Thorium power conference, Oct 2009


Reactor Basics

  • Reactors make heat through fission and decay. The heat is then converted into mechanical power and then to electrical power.

  • Fission is controlled by the neutron population around the nuclear fuel. More neutrons produce more fissions and more heat.

  • The neutron economy is tightly controlled by material properties, physics, and design.

4


The Absolutes

A power source must be-

Self regulating when it is ON

“Walk away” safe when it is OFF

Inherently safe in case of an ACCIDENT

LFTR wo Equations. Thorium power conference, Oct 2009

6


The Relative Strengths

Little or no radioactive waste

No bomb materials

Low cost per power delivered

Small physical size

Power on demand

A wide choice of building sites.

LFTR wo Equations. Thorium power conference, Oct 2009

7


Core Options

  • Standard pressurized water reactor (PWR)

    • Water flows over a core of ceramic fuel pins. Water acts as coolant and moderator. Reactivity is controlled by the moderator density and by control rods.

  • Liquid Fluoride Thorium reactor (LFTR)

    • A liquid fuel flows though a core of graphite. The fuel acts as coolant, the graphite as moderator. Reactivity is controlled by the fuel density.

8


LFTR Processing Details

Metallic Thorium feed stream

Pa-233

Decay Tank

Bismuth-metal Reductive Extraction Column

Fertile Salt

Fluoride

Volatility

Pa

233UF6

Recycle Fertile Salt

Uranium

Absorption-

Reduction

7LiF-BeF2

Recycle Fuel Salt

Core

7LiF-BeF2-UF4

Blanket

232,233,234UF6

Vacuum

Distillation

Two-Fluid Reactor

Hexafluoride

Distillation

xF6

“Bare” Salt

Fuel Salt

Fluoride

Volatility

Fission

Product

Waste

MoF6, TcF6, SeF6,

RuF5, TeF6, IF7,

Other F6

Molybdenum and Iodine for Medical Uses

9

Return


Metal Reduction Column

10


Temperature Stability

A power plant with a built in thermostat!

inlet outlet

Fuel-coolant

Graphite Moderator

reactivity

temperature

LFTR wo Equations. Thorium power conference, Oct 2009


Improved reactor design

reactivity

temperature

LFTR wo Equations. Thorium power conference, Oct 2009


The Reactor at “idle”

Fuel Loop

LFTR wo Equations. Thorium power conference, Oct 2009


Walk-Away Safe

14


Size matters!

Your nuclear waste is the size of a few grains of rice!

LFTR wo Equations. Thorium power conference, Oct 2009


Uranium vs Thorium as a Fuel

  • 0.7 % of Uranium is fissionable. The rest becomes nuclear waste.

  • Thorium is isotopically pure and converted to U233 for fuel.

  • For fuel cycle side-reactions see- http://en.wikipedia.org/wiki/Thorium_fuel_cycle

16


Lets Make Power

  • This is a picture of the waste heat coming from the original LFTR test cell.

  • The heat transfer fluid (molten salt) is at low pressure.

  • We can use a gas cycle, like a jet engine, to convert heat into mechanical power. (highly efficient)

  • These plants can run at partial load.

LFTR wo Equations. Thorium power conference, Oct 2009


Fuel or Waste

We want the fuel to fission rather than transmute.

U233- 90% fissions

U235- 83% fissions

P239- 50% fissions

P241- 25% fissions

LFTR wo Equations. Thorium power conference, Oct 2009


Myth of Half Life

  • What makes a radioactive material dangerous?

    • Even low energy beta decays can break organic bonds.

  • Is a material with a 1 second half life dangerous?

    • It is very dangerous..today. Tomorrow it is inert.

  • Is a 15 billion year half life dangerous? (Half of it has decayed since the big bang.) It has a very low activity, and we used it for hundreds of years.

  • How about a thousand year half life? It is both active and persistent.

19


Myth of Creating Radioactivity

  • If radiation is dangerous then we should do what we can to eliminate it from the environment. That is exactly what nuclear reactors do. They are the nuclear analog to chemical catalysis reactors; they accelerate natural processes.

  • The only way to “create” nuclear radiation is with particle accelerators. Conventional reactors simply accelerate decay towards stable elements.

20


Myth of Concentration

Thorium and uranium are dispersed in nature and they decay naturally. We concentrate them, and so concentrate their natural toxicity.

For safe disposal, should we re-disperse them and lower their effective activity, or sequester them and decrease our contact?

21


References

http://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor

http://www.scribd.com/doc/59204103/Thorium-presentation-Green-Energy-Forum-2008-07-25

http://www.thoriumenergyalliance.com/ThoriumSite/resources.html

http://moltensalt.org/references/static/downloads/pdf/NAT_MSBRrecycle.pdf

Thorium in 5 minutes (remix video) http://www.youtube.com/watch?v=uK367T7h6ZY

22


Outline

  • Motivations for Nuclear Power

  • LFTR overview

  • NuclearChemistry

  • Chemistry

  • Myths

  • Questions

23


Binding energy

24


Cross Section

The probability that the neutron interacts with the nucleus depends on the neutron’s speed. We describe the probability as an apparent SIZE of the nucleus. The larger the apparent size, the higher the probability. This is a geometric interpretation of a probabilistic quantum mechanical event.

Reaction equations are of the form-

Number of events/time = (neutron flux) (spatial density of target nuclei) ( cross section for the event )


Moderation and Rx Probabilities

LFTR wo Equations. Thorium power conference, Oct 2009


Speed?

LFTR wo Equations. Thorium power conference, Oct 2009


Nuclear Fission

28


Chart of the Nuclides for LFTR

Fissile Fuel!

Ref: http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=90&n=142

Uranium (92)

Protactinium (91)

Thorium (90)

B-

~27 days half-life

B-

~22 min half-life

+ N

Raw Material!

29


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