Radioactive heat source

Murthy R., van Westrenen W., and Fei Y. (2003) Experimental evidence that potassium is a substantial radioactive heat source in planetary cores. Nature. 423, 163-165. 

The biological influence on sulfur in the lithosphere may be more fully appreciated by briefly reviewing geological evolution with reference to sulfide mineralisations as summarised by various authors (Watson, 1973 Lacy, 1975). The postulated early events in the sequence are accretion and separation into core, mantle and crust, accompanied by a decline in the thermal gradient with loss of radioactive heating sources. The early crust was very thin and mantle sulfide readily surfaced to be preserved as the volcanogenic... 

In addition to stable elements, radioactive elements are also produced in stars. The unstable but relatively long-lived isotopes °K, Th, and make up the internal heat source that drives volcanic activity and processes related to internal convection in the terrestrial planets. The short-lived transuranium elements such as Rn and Ra that are found on the Earth are all products of U and Th decay. 

Were all of these newly discovered substances also new elements This question would not be answered for some years but there was a flurry of other major discoveries to keep the protagonists occupied. Pierre Curie discovered that radioactivity released large quantities of heat (Curie and Laborde 1903) which appeared mysterious—as if the heat was coming from nowhere. This discovery provided an extra heat source for the Earth and reconciled the estimates of a very old Earth, based on geological estimates, with the young age calculated by Lord Kelvin from cooling rates. The year 1903 also witnessed the first demonstration that a-decay released He (Ramsay and Soddy 1903). The build up of He was soon put to use to date geological materials, initially by Rutherford in 1905 who calculated the first ever radiometric age of 500 Myr for a pitchblende sample, and then by Strutt who examined a wide variety of minerals (Strutt... 

Another isotopic anomaly, discovered in Allende inclusions, concerns magnesium, for which an intrinsically low abundance in these samples makes its isotope ratios sensitive to small effects. Certain of the inclusions show a correlation between 26Mg and 27 Al, indicating an origin of excess 26Mg from radioactive decay of 26 A1 (mean life 1 Myr), the existence of which had previously been postulated as a heat source for meteorite parent bodies (Fig. 3.32). Other short-lived activites that seem to have been alive in the early Solar System are 10Be (mean life 2.2 Myr) from a correlation of 10B with 9Be, and 41Ca (mean life 0.15 Myr) from a correlation of... 

The plasma energy recycle and conversion (PERC) process is an indirectly heated ex situ thermal recycling and conversion technology. According to the vendor, it treats hazardous waste, mixed radioactive waste, medical waste, municipal solid waste, radioactive waste, environmental restoration wastes, and incinerator ash in gaseous, hquid, slurry, or solid form. The technology uses an induction-coupled plasma (ICP) torch as its heat source coupled to a reaction chamber system to destroy hazardous materials. 

This suggests that the heat source had actually been mixed into outer layers and its effect began to dominate the light curve from t 26 d. From the observational side, Phillips (1988) noted that the changes and kinks of the color started from t = 25 d, which may indicate the appearance of heat flux due to radioactive decays. 

Both production of and demand for transplutonium elements are relatively stable, and pressurized ion exchange processes that have been used for several years are entirely satisfactory for these requirements. Three general areas can be visualized which could require extension of these methods. These are (a) tracer-scale separations in the shortest possible time for very shortlived isotopes in nuclear research (b) separations similar to those utilized now, but on a much larger scale, perhaps because of radioactive waste processing or production of heat sources ... 

As radioactive decay heat sources that in conjunction with thermoelectric conversion... 

The temperature at the aerosol layer in Neptune s atmosphere is about -346°F (-210°C), which is close to the temperature at the main cloud level in Uranus s atmosphere, and the effective temperatures of the atmospheres of both Uranus and Neptune were found to be close to this temperature. One would expect Neptune s visible troposphere and lower stratosphere to be about 59°F (15°C) colder than those of Uranus because of Neptune s greater distance form the Sun (30.1 a.u. vs. 19.2 a.u.) instead, the temperatures of these parts of the atmospheres of both planets are found to be about the same. Neptune s atmosphere seems to be considerably warmer than it would be if it received all or nearly all its heating from sunlight, as seems to be the case for Uranus. This is another indication that Neptune has a powerful internal heat source, unlike Uranus, which has at most a weak internal heat source (compatible with radioactivity in its interior) or none at all. Voyager 2 infrared observations confirmed this the emission to insolation ratio was found to be 2.6 from them instead of... 

Equations (5.7) and (5.8) are known as Carnot s equations. In Eq. (5.7) the smallest possible value of I (2cl is zero the corresponding value of Tc is the absolute zero of temperature on the kelvinscale. As mentionedin Sec. 1.5, this occurs at (—273.15°C). Equation (5.8) shows tliat the thennal efficiency of a Carnot engine can approach miity only when Tu approaches infinity or Tc approaches zero. Neither of these conditions is attainable all heat engines therefore operate witli thennal efficiencies less than unity. The cold reservoirs naturally available on eartli are die atmosphere, lakes and rivers, and the oceans, for which Tc — 300 K. Hot reservoirs are objects such as furnaces where the temperature is maintainedby combustionof fossil fuels and nuclear reactors where the temperature is maintainedby fission of radioactive elements. For these practical heat sources, T 600 K. Witii these values,... 

Polonium releases a great deal of energy during its radioactive breakdown. This property has led to the development of compact heat sources for specialized purposes, such as use on space probes (see photo on page 448). 

The energy released by polonium during its radioactive breakdown is used in compact heat sources in space probes. This is the Mariner 10, launched November 3, 1973, on the first trip to the planet Mercury. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA). 

One of the starting points in calculating the thermal history of the early Earth is the observed mismatch between the present-day heat production rate and the rate of heat loss. Today the total thermal flux for the Earth is about 41 TW (Davies, 1998). When this is compared with the present-day radioactive heat production of 20 TW it is clear that the Earth has another source of heat in addition to its radioactive heat. This heat source is thought to be the residue of "old heat" dating from the formation and differentiation of the Earth. 

In addition to stable elements, radioactive elements are also produced in stars. The unstable but relatively long-lived isotopes °K, Th, and are the internal heat source that drives volcanic activity and processes related to internal convection in the terrestrial planets. The short-lived transuranium elements such as Rn and Ra that are found on the Earth are all products of U and Th decay. These isotopes are sometimes used as tracers of natural terrestrial processes and cycles. Long-lived isotopes, such as Rb and Sm, are used for the precise dating of geological samples. When the solar system formed, it also contained several short-lived isotopes that have since decayed and are now extinct in natural wstems. These include A1, Pu, Pd, and 1. Al, with a half-life of less than 1 Ma, is particularly important because it is a potentially powerful heat source for planetary bodies and because its existence in the early solar system places tight constraints on the early solar system chronology. 

The iron would not be molten and flow, however, without a continuous heat source to keep it from solidifying. Radioactive fission energy from uranium and thorium decay has long been the assumed source of the heat in the core, and still provides that heat, but not enough to have sustained a magnetic field for 4 billion years. 

Sanders, Robert. Radioactive Potassium May Be Major Heat Source in Earth s Core. Available online. URL berkeley.edu/ news/media/releases/2003/12/10 heat.shtml. Accessed on August 5, 2009. This press release from the University of California, Berkeley, describes an experiment that has simulated conditions deep beneath Earth s crust and tested a geodynamo model involving potassium 40. 

The available data suggest that heat sources for melting primitive bodies (presumably chondritic in chemical composition and texture) that yielded differentiated meteorites were within rather than external to parent bodies. Important sources no doubt include impact shock-heating and radioactive heating from radionuclides - both extant and and extinct... 

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