1

Thorium Fuel Cycle

SHAWN ROBINSONNUCLEAR PHYSICS12/1/15

2Discovery of Thorium

Thorium was discovered in 1828 by the Swedish chemist Jons Jakob Berzelius as thorite (ThSiO4)

232Th has Half Life Of 1.4 E10 years! No stable Isotopes Fertile not Fissile Atomic Number: 90 Atomic Weight: 232.03806 Phase at Room Temperature: Solid Element Classification: Metal

3Why Thorium when we have Uranium?

Cross section σy = 7.34b, 85; σf <1µb Fast Flux reduces unwanted isotopes

Thorium Requires high energy neutron flux

Transitioning Thorium Breeds fuel

4Flaws of Liquid Drop Model

B(A,Z) A= 232, Z=92 Binding energy approximation: 12.83

Mev/A Actual Binding Energy : 7.615 Mev/A

5It’s Magic, You Know!

Double Magic number Z=92, A=232 Closed Shell, Jπ = 0 Making it super stable Explains The long half life

6Thorium In Action

Fission product Distribution

Thorium to 233 Uranium fuel

7Thorium Decay

Mainly Alpha Decay D-Double Magic! 208

82Pb Ultra Stable

8Thorium In Nature Predicted abundance of about 15 parts per million in the earth’s

crust (.0007%), many times greater than that of uranium. More thorium energy available than all fossil fuels and other

nuclear sources combined It’s decay thought to be responsible for the earth’s internal

temperature.

Magnified Green Thorite crystal

9The FLiBe Juice

FLiBe (Li2BeF4) is a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2).

Molten FLiBe flowing sample's green tint is from dissolved uranium tetrafluoride.

Melting point of 459 °C, a boiling point of 1430 °C, and a density of 1.94 g/cm3. Its heat capacity is 4540 kJ/m3

Molten FLiBeFleeb (Plumbus)

10Thorium is Safe!

The fissile material weapon quality is evaluated by considering three properties:

The critical mass is different for different isotopic composition of Pu;

weapon yield degradation due to pre-initiation caused by spontaneous fission neutrons;

weapon stability degradation caused by heat emission. No enrichment facilities No 239 Pu generation

11Sustainable Thorium!

Sustainable Thorium processing

12References & Images

http://www.thegreenage.co.uk/tech/thorium-nuclear-energy/ https://en.wikipedia.org/wiki/Thorium_fuel_cycle http://www.world-nuclear.org/info/current-and-future-generation/t

horium/

http://www-pub.iaea.org/mtcd/publications/pdf/te_1450_web.pdf http://www.halexandria.org/dward472.htm Sustainability 2012, 4(8), 1933-1945; doi:10.3390/su4081933 http://education.jlab.org/itselemental/ele090.html http://mpa.ac.uk/muarc/school/Thorium_nuclear_clock.pdf

13Questions?