Hawaii Heat from Natural Radioactivity

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BY MICHAEL FOX PHD – In recalling my wonderful visits to the incredible Big Island in Hawaii, my mind goes back to the continuing eruption of Kilauea, which has been continuing since 1983 (https://tinyurl.com/28fa9ak).

An estimated 500,000 cubic meters of molten lava flow into the ocean there daily. What is the huge source of heat which melts 500,000 cubic meters of solid rock daily?


Nothing man-made has ever come close to matching the power and energy requirements to produce this amount of molten material. Much of this energy comes from the accumulated heat from radioactive decay in the earth.  Obviously this leads to contemplating the volcanoes there and the formation of the entire Island chain.  They too are all volcanic in origin.

Natural radioactivity was discovered by Antoine Becquerel in France in 1896.  Natural radioactivity (of which the public knows very little) impacts our lives in many ways (https://tinyurl.com/3275g).

Making simple assumptions from soil analyses of uranium and thorium in the Earth, and conceding that too little is known about the interior of the Earth, one can estimate that there are about 8 trillion tons of uranium and 20 trillion tons of thorium in the Earth. I assume that there is no nuclear reactor at the core of the Earth that produces huge amounts of energy as well, although this assumption may not be the case. (https://tinyurl.com/2bywnkh).

We have a very limited understanding of the interior geologic structures and layers of the Earth, (https://tinyurl.com/2drtwob ), even less about the myriad possibilities of the geochemistry and related chemical distributions.  Specifically, we can only speculate about the distribution of dozens of radioactive materials.

We know the half-lives of these radioactive substances and the energies released, we can estimate the total energy released within the Earth, and it is very large.
The total energy from the decay of the uranium in the Earth is about 20 trillion Btu/hr.  This is the energy equivalent of burning about 1 million tons of coal per hour.
This is enough coal to operate 2400 1000 MW (e) coal plants or about 3 times the entire electrical generation capacity of the U.S (https://tinyurl.com/ya86p8j).

This heat is being generated every second of our lives right beneath our feet.  And so we don’t exaggerate, this decay energy underestimates the total energy being generated in the Earth by radioactive decay.  This almost certainly has been continuing since the beginning of the Earth, 4.5 billion years ago.

While it is an estimate, it provides and indication of the large magnitudes of the energy involved with this subtle, prevalent, natural, but largely unknown source of “nuclear” energy.

This estimate is for only uranium-238 decay, and does not include the decay energy of the uranium decay products, or the energy of decay of the thorium chain, of from other natural radioactivity, which involve more than 10 times more additional energy than the amounts above.

Discussion of assumptions in this simple model

1. Considers only the energy of decay of U-238 alpha energy. = 4.197 Mev

There is a total of 45.1 Mev of energy released in the entire U-238 decay chain.  This assumption would drastically underestimate the energy of the total U-238 decay chain.

2.  Completely ignores the decay energies of the Thorium-232 decay chain totaling 45.5 Mev per Th-232 decay.

This assumption would also drastically underestimate the total energy released in radioactive decay of Thorium-232.

3.  Assumes uniform distribution of U-238 and Th-232 throughout the Earth.

Mineral separation, stratification, concentration, and depletion are common geological observations in the Earth today.  Basalts are known to be deficient in Uranium and Thorium.  Granites and monazites are known to have elevated amounts of uranium and thorium.  A molten core of the earth provides a heated environment suitable for separations of molten minerals of differing solubilities.  Current geological theory assumes most of the Earth’s core is molten iron, and thus may have below average amounts of uranium and thorium.  The assumption of uniform distribution may overstate the amount of these materials in the Earth.

4.  Assumes no operating nuclear reactor at the core of the Earth.

Transporting the Heat to the Surface
There is a lot of energy released by natural radioactive decay, and the Earth is a big planet.  Additionally, the Earth has had billions of years of time for the radioactive heat to accumulate in the interior and be conducted to the surface.  Since the Earth is comprised mostly of silicates, sulfates, carbonates, (materials commonly known to be insulators) the heat transfer rate is particularly slow.  This facilitates the large temperature buildup throughout the Earth’s interior, to such a point that the Earth becomes heated, even molten in the interior.

The inner core is now believed to be solid iron and an outer core molten iron; there is a huge amount of energy released throughout most of the Earth’s interior. Ever hear of or seen lava?

Since heat always flows from high to low temperatures, the heat in the Earth’s interior is slowly conducted to the Earth’s surface, which produces noticeable effects to the prepared observer.  This energy in fact impacts us in our everyday life.  Deep gold mines in South Africa (12,000 ft deep) have virgin rock temperatures of 160 Fo.  The energy released in Yellowstone Park geysers and hot springs and pools at other geothermal facilities comes from this energy source.  This is the energy which is released in volcanic eruptions.  This is the energy which facilitates earthquakes, collisions of tectonic plates, and the formation of mountain ranges.  The tectonic plates supporting the continents would be immobile were it not for the presence of molten magma upon which they slowly move and collide.

Natural Nuclear Reactors
Another impact of natural radioactivity occurred in Gabon, Africa about 2 billion years ago.  It was discovered in uranium mines in the 70s by the French. There is conclusive evidence that natural nuclear reactors operated in the ore bodies, producing huge amounts of energy and all of the fission products we know today.  They operated nearly 2 billion years ago.  More than a dozen reactor zones have been identified in the mines, including evidence that as much as 5 tons of plutonium was produced.   All of the radioactive fission products made today in nuclear reactors were produced in these natural versions, unconfined, and immersed in water.

This mine has provided extraordinary scientific and geological data about what happens when radioactivity is released to the environment, completely unconfined and immersed in water, which was necessary for the reactors to operate.

Since the discovery of natural radioactivity in 1896 112 years have passed.  It is part of our natural environment; it has been in our environment for billions of years, and will remain so for billions more.  The people of the America have been uninformed of this common source of radioactivity for more than a century and have been horrendously betrayed by those who have intentionally used radioactivity to frighten the public.  Radioactivity is used widely in industry and medicine.  It is past time that the public and its leaders become familiar with the rest of their natural environment. When will the environmentalists learn about the environment?