Discovery of Huge Lunar Thorium Deposit

Calliban · 2024-05-17 09:11:43

The Lunar Reconnaissance Orbiter has discovered a huge plug of granite, enriched in uranium and thorium on the lunar farside. Radioactive decay in the rock is making it substantially greater than the surrounding lithosphere.
https://www.space.com/moon-volcanoes-gr … ce-orbiter

The rock plug is some 50km across and 20km deep. Lunar granites are quite rare, so finding a concentrated deposit so large was not expected. Lunar granite contains up to 66ppm thorium.
https://agupubs.onlinelibrary.wiley.com … 05JE002592

Ignoring the uranium content, each cubic metre of this material contains enough thorium to give the granite an energy density some 1800x the equivelent mass of coal. This would amount to 27 billion tonnes of thorium.

Last edited by Calliban (2024-05-17 09:20:01)

tahanson43206 · 2024-05-17 09:22:01

This post is reserved for an index to posts that may be contributed by NewMars members.

Index item 1) http://newmars.com/forums/viewtopic.php … 96#p223196
In this post Calliban describes a possible pathway to 100% utilization of Nuclear fuel compared .4% in 2024 using Light Water Reactors

This new topic would appear to have some upside potential.

More detailed reports are likely when on-site equipment is available.

Per Google:

The chemical composition of granite is typically 70-77% silica, 11-13% alumina, 3-5% potassium oxide, 3-5% soda, 1% lime, 2-3% total iron, and less than 1% magnesia and titania. Volcanic rock of equivalent chemical composition and mineralogy is called rhyolite.

(th)

Calliban · 2024-05-17 09:30:03

If used in breeder or fast-fission reactors, the thorium contained in this deposit would meet the Earth's existing electricity needs for 8 million years. So this discovery is a substantial energy resource for the entire solar system. There are granites on Mars as well.
https://www.sciencedaily.com/releases/2 … 091506.htm

Last edited by Calliban (2024-05-17 09:31:39)

Calliban · 2024-05-17 09:50:42

This is interesting.
https://en.m.wikipedia.org/wiki/Lunar_terrane

A large part (10%) of the near side of the moon has thorium concentration of 4.8ppm. That works out at 0.05kg/tonne of surface material. That would amount to an energy content of 1000MWh/tonne if completely fissioned. I think that is definitely enough surplus energy to allow extraction of the thorium and its use as a fuel.

In fact, the thorium resources of the moon look quite vast. The previoys information I had read suggested that fissionable materials were rare outside of Earth. This casts doubt over that assumption.

Last edited by Calliban (2024-05-17 09:57:40)

Mars_B4_Moon · 2024-05-17 09:53:03

also very relevant to Mars since Thorium has also been discovered from satellites reading the Martian surface.

a discussion on India and the Hindu Nationalists investing

http://newmars.com/forums/viewtopic.php?id=6838

Last edited by Mars_B4_Moon (2024-05-17 09:54:51)

Calliban · 2024-05-17 10:44:35

Mars is very rich in deuterium. If we find similar thorium deposits on Mars, then we can build the muon catalysed fusion-fission hybrid reactor using a laser wakefield muon source. Deuterium gas would be contained in a high pressure tank, lined with lithium deuteride and surrounded by a thorium blanket. The d-d fusion reactions will yield neutrons, which will gradually breed tritium in the deuterium tank and will transmute li-6 in the LiD lining into tritium. Any neutrons leaking out will transmute the 232Th blanket into 233U, which is fissile fuel.

As reactor operation continues, a number of feedback effects come into play. More and more thorium is converted into uranium, which increases the heat production and multiplication factor for any neutrons leaking into the blanket. Neutrons streaming out of the blanket will then increase the breeding rate of tritium. As D-T fusion rate increases, the 14MeV neutrons it yields will start to fast fission the thorium, increasing power output and sending more neutrons into the tank, where they breed more tritium. As the blanket power output grows, a cross over point is reached, where the reactor will produce more electric power than the MCF drivers consume. At that point, it becomes a useful power source.

Such a reactor will ultimately function as a travelling wave. Fresh thorium blanket rods are added to the outside of the core and are gradually shuffled inwards, absorbing neutrons and generating more power as they approach the centre. Blanket rods are discharged from the centre after some 10% of actinide atoms have fissioned. This allows the reactor to consume pure thorium as fuel, without need for reprocessing. When we do get reprocessing online on Mars, we can use the spent fuel to make fresh nuclear fuel for Martian light water reactors. Hence the hybrid reactor, in addition to producing power, also functions as a fuel factory. By reprocessing the spent LWR fuel, we can send reprocessed thorium and minor actinides back to the hybrid reactor. In this way, we can extract 100% of the energy content of the nuclear fuel, as opposed to the 0.4% that we manage with a once through LWR cycle.

Last edited by Calliban (2024-05-17 10:47:36)

Calliban · 2024-05-19 07:28:03

The complete fission of 1kg of thorium (or its transmutation product 233U) releases about 20 million kWh of heat. That is enough to make 10 million kWh of electricity. If a powerplant sells electricity for $0.1/kWh, then this much electricity is worth $1 million. Natural uranium has an energy density only 5.6% greater.

With so much value gained from such a small mass of material, there are practically no limits to the amount of energy we can generate on Mars using uranium and thorium. If we import these materials from Earth and it costs $10,000 per kg to do so, then it would only add 0.1 cents to the cost of each kWh. For a while to come, it be cheaper to import fissionable material from Earth.

On Earth, basalt contains about 5ppm of thorium, which amounts to 0.174kg/m3. This means that each cubic metre of basalt contains enough thorium to yield some 3.7million kWh of nuclear heat, which would yield 1.8million kWh of electricity using an S-CO2 power conversion system. One cubic kilometre of basalt, would contain enough thorium to provide the present electrical demand of humanity for 103 years. For comparison, Olympus Mons is primarily basalt and has a volume of abount 2 million cubic kilometres.

In conclusion, I think there is enough thorium on Mars to power any human civilisation we can imagine there for a practically indefinite period. The bottleneck that prevents us from exploiting this unlimited energy is the slow rate of breeding using excess neutrons from fission. Whilst fast breeder reactors can produce more fissile fuel than they consume, the reality is that it will take decades for a sodium cooled fast breeder reactor to make enough plutonium or 233U, to start a second reactor. Using a fusion reaction to produce fast neutrons could do it a lot more quickly, because 14MeV neutrons will fast-fission 238U or 232Th without the need for breeding. By building these hybrid reactors, we can produce a lot of 233U very quickly and build as much nuclear generating capacity as a new colony needs on Mars.

Given recent development of the Laser Wakefield plasma accelerator and calculations showing that muon catalysed fusion can reach breakeven under the right conditions, there would appear to be no remaining technological barriers to development of a closed fuel cycle that gets 100% of the energy out of fissionable fuel. We can begin to develop this on Mars quite early in the colonisation process. Nuclear fuel will eventually become a valuable export industry for an industrial Mars.

The radioactive fission products contained in spent nuclear fuel, will be recovered by reprocessing. Many of these are too short lived to be useful, but the heat from their decay can be used as a minor source of energy. Radiothermal generators will be useful for producing power and keeping warm in isolated settlements on Mars, such as mining colonies. The longer lived fission products will have specific uses. Technetium is valuable as a corrosion inhibitor and is also a very useful chemical catalyst that works similarly to ruthenium. As a dehydrogenation catalyst, we can use it to build long chain hydrocarbons and alkenes from alkane feedstocks. Palladium and other noble metal fission products can be used as corrosion resistant coatings for nuclear reactor internals and nuclear fuel elements. Strontium 90 and Ceasium 137can both be used as radiothermal heat sources. Strontium especially will have uses as a long range probe power source and as a heat source for interplanetary ship propulsion. Hence nuclear waste is unlikely to become a problem on Mars. Industry will find uses for spent fuel isotopes as rapidly as they are being generated.

Last edited by Calliban (2024-05-19 08:11:12)

Calliban · 2024-05-19 08:26:37

Could we terraform Mars using thorium as the energy source? Mars has a surface area of 144.37 million km2. To make a breathable atmosphere, we would need to electrolyse about 5000kg of water for each square metre of surface. The production of 1kg of oxygen using electrolysis, takes about 13MJ of electricity. So the total electrical energy needed to terraform Mars with a breathable atmosphere, would be:

Q = 144.7million x 1 million x 5000 x 13MJ = 9.4E24 Joules.

1m3 of basalt contains 174 grams thorium and will produce 1.8 million kWh of electricity if the thorium is totally fissioned. So to terraform Mars using electrolysis, we would need the thorium contained in 1451 cubic kilometres of basalt. That is a cube some 7 miles aside. If we excavated it one Mars, it would be a square pit some 18.7 miles aside and 1 mile deep. On a terraformed Mars, it would end probably fill up with water and end up being a small sea.

Suppose we wanted to do this in a hundred years. How much nuclear power would we need? For each joule of electricity produced, we need roughly 2 joules of heat, with one being ejected as waste heat. So total nuclear thermal power generation would be:

Q = (9.4E24 x 2)/(100 x 365.25 x 24 x 3600) = 6E15W

That is equivelent to about 1 million large Earth based nuclear power reactors. By the time we do this on Mars, we will probably know how to build reactors that last 100 years. Given the extent of the power demand, economy of scale will drive the size of reactors higher. So instead of 1 million x 3GWe reactors, we are probably talking 1000x 3000GWe reactors. These will be huge power reactors, each one large enough to produce all the power used by humanity today.

The total waste heat produced by the reactors, will be 20.6W/m2 of Mars surface area. That is about 14% as much heat as Mars receives from the sun. So the reactors would actually warm Mars up by about 7K.

If we were building nuclear reactors this size, I think they would work differently to the linear tube heat based reactors that we use today. A reactor heat power of 6000GW, is 6TJ/s. That is the fission of 0.077kg of material per second. I think in a system that large, it would be more efficient to use the MCF neutron generators to create a focus at the centre of a spherical chamber and then to fire pellets of 233U into the neutron focus. The pellets will contain a core of lithium deuteride and deuterium tritium gas. Upon reaching the focus, fast-fission will rapidly heat the uranium to millions of Kelvin. The x-ray pressure will ignite the fusion charge and the resulting neutron shower will then completely fission the uranium. The resulting superheated plasma will be captured by a magnetic field and directed into a linear electric generator. This will convert the plsma energy into electricity with about 60% efficiency. Despite its enormous power, such a reactor could be relatively compact.

Last edited by Calliban (2024-05-19 09:00:15)

SpaceNut · 2024-05-19 11:07:18

We know that thorium is one of the choices for nuclear material, but we must build the reactor and mining the material before we can make use of it to power mars.

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Discovery of Huge Lunar Thorium Deposit

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