Thursday, December 23, 2010

Can Neptunium Be Used As A Nuclear Bomb?

Even though current fission type nuclear bombs either use plutonium-239 or uranium-235, can neptunium be used as a viable substitute in a similar fission type bomb?

By: Ringo Bones

Most nuclear weapons systems - i.e. fission type nuclear bombs / atomic bombs / fission type bombs that trigger thermonuclear weapons systems – in existence either use plutonium-239 or uranium-235 as the active component in order for it to explode thousands of times more powerful than the same weight and volume of chemical high explosive. But, is it possible to use neptunium – a transuranic element – instead of either plutonium or uranium in a fission type bomb?

Strangely enough, the neptunium bomb or neptunium fission-type nuclear device was first proposed in Nazi-era Germany by the cosmogonist and physicist Baron Carl Friedrich von Weizsäcker in a secret report dated July 17, 1940. Just a few months before, neptunium was just been discovered by Glenn T. Seaborg and its most stable isotope, neptunium-239, was later produced by Edwin M. McMillan and Philip H. Abelson at the University of California in Berkeley, when they bombarded uranium with neutrons.

Even though it was Seaborg and team who were credited in the discovery of neptunium, it was Dr. Enrico Fermi who attempted to manufacture element number 93 – or neptunium – by bombarding uranium-238 with neutrons and observing the electrons emitted after neutron capture producing neptunium-239. The chemical properties of neptunium and plutonium were investigated on a tracer scale several years before these transuranic elements were isolated in visible amounts from the uranium-graphite atomic pile. The development of the atomic bomb was materially expedited by the preliminary knowledge of the chemical properties of the radioactive isotopes of neptunium-239 and plutonium-238.

Ever since the fission nuclear power facilities went online several years after World War II that also serve as a valuable source of nuclear weapons grade / fissile material like plutonium-239, these plants also produce large quantities of neptunium-237 with a half-life of 2.2 million years as a by-product of plutonium-239 production. By contrast, plutonium-239 popularly used in fission type nuclear weapons systems and initiator of thermonuclear weapons systems, only has a half-life of 24,360 years. For all intents and purposes, neptunium is considered as radioactive waste in the production of weapons-grade plutonium. Neptunium in trace amounts is found in nature as a result of low-level spontaneous transmutation reactions in uranium ores, brought about by neutrons which are present, usually fro the naturally occurring fission of uranium.

Prior to 9/11 and the then growing “popularity” of the threat of dirty bombs, the common wisdom adopted by the world’s nuclear energy regulatory groups like the International Atomic Energy Commission or IAEA is that, having been stripped of its weapons-grade uranium and plutonium, waste from spent nuclear reactor fuel assemblies poses only the problem of finding a safe means of long-term storage. However, waste from spent nuclear reactor fuel assemblies are still pregnant with elements like neptunium which, despite their never having been used in World War II era deployed nuclear weapons systems by America, are every bit as fissionable as their better-known transuranic elements like plutonium-239 and uranium-235.

Thus, by defining the problem exclusively in terms of fissionable uranium and plutonium – i.e. plutonium-239 and uranium-235 – the historical basis of all past bombs – the IAEA has inadvertently opened the door to a very curious future. As far as I know in our post-9/11 world, there are no controls yet for neptunium, tons of which still languish in radioactive waste repositories around the world. Those repositories are intended to keep us humans safe from radiation, rather than the radioactive waste safe from persons bent on mining it for fissionable elements – elements like neptunium that were originally rejected for weapons use simply because they were uncompetitive – i.e. makes for a bulkier fission type nuclear bomb, harder and costlier to chemically purify, etc. – in comparison to plutonium-239 and uranium-235, not because they will not do the job.

Technetium: Obscurest Subject of the Periodic Kingdom?

Despite of being and having the title of the first artificially produced element, does technetium qualify as the obscurest subject of the “Kingdom” of the Periodic Table of Elements?

By: Ringo Bones

Even though it’s more popular cousin named plutonium has been hogging the geopolitical headlines since the end of World War II as the most famous artificially produced element, it was in fact technetium – atomic number 43, chemical symbol Tc – that was the first artificially produced element back in 1937 – by Emilio Segré and Carl Perrier of Italy. The name technetium is derived from the Greek word technetos meaning artificial. As the first man-made element, it was originally produced by the atomic bombardment of molybdenum.

Technetium’s original preparation back in 1937 was from neutron and deuteron bombardment of molybdenum. In a nuclear reactor, substantial amounts of technetium results from the decay of the molybdenum-99 isotope – a uranium-235 fission product. Beta emission of molybdenum-99 gives technetium-99. This isotope eventually is converted to ruthenium-99. Separation of technetium from uranium is accomplished by converting both to chlorides. Hydrogen peroxide treatment gives uranium oxychloride and hydrogen sulphide action on the remaining solution to which platinum chloride is added gives technetium sulphide and platinum sulphide. The sulfides dissolve in aqueous ammonia in which technetium oxide can be distilled from an acidified solution. The metal is prepared by converting the oxide to ammonium technetate followed by hydrogen reduction.

Later, the element was found among the fission products of uranium. During the mid to late 1960s, technetium sells for around 3,000 US dollars an ounce – while gold during that time sells for about 38 US dollars an ounce. Then and now, the going rate for technetium is probably closer to 100 times the going rate for gold. Currently, technetium and its alloys are used as superconductors. It is also used in radiation therapy and in minute quantities, technetium acts as a corrosion inhibitor for steel.

Technetium also played an important role in astronomy during the discovery by Paul W. Merrill of substantial amounts of technetium in so-called S stars, as shown by their spectroscopic analysis, has been interpreted as a clear evidence of stellar evolution in the relatively recent past due to the 300,000-year half-life of technetium’s longest-lived isotope - which is very short in comparison to the presumed lifespan of the universe. Even though it is – at the moment – languishing in obscurity in comparison to its more famous man-made cousin named plutonium, nevertheless, technetium still has something important to contribute to our 21st Century scientific community.

Friday, December 17, 2010

Is Aluminum the Cheapest Noble Metal?

Given that once purified it essentially becomes inactive towards oxygen, does aluminum pass muster as the cheapest noble metal around?

By: Ringo Bones

The textbook definition of a noble metal states that any metal that is chemically inert or inactive especially towards oxygen qualifies as a true-blue noble metal which aluminum seems to qualify as such. By comparison, copper – the last time I checked in the commodities index – is much more expensive than aluminum and corrodes much faster in air. And if you include most recent environmentally pro-active recycling adverts stating that it takes probably over 100 years for a discarded aluminum can to recycle itself back to bauxite, you might be forgiven for wondering whether aluminum is indeed a true-blue noble metal, but is there any truth to this?

Indeed, there was a time when aluminum was considered to be a noble metal. When aluminum was newly discovered by Sir Humphry Davy back in 1827, there was a 20-year period when obtaining aluminum by “conventional” smelting methods from bauxite made the metal about a little over twice as expensive as gold. Charles Louis Napoleon Bonaparte – more famously known as Napoleon III – favors aluminum over gold during his time since then existing methods of refining aluminum made it a little over twice as expensive as gold.

Fortunately we have Charles Martin Hall to be thankful for making aluminum cheap enough to wrap our sandwiches in. Hall was the first to develop the modern method – an in currently the most economically viable method – of extracting aluminum from bauxite clay in an electric arc furnace. Because of this, 30% of the cost of aluminum comes from the cost of electricity needed to free the metal from oxygen. Strangely enough, Mother Nature can also create Her own samples of pure aluminum metal during those exceedingly rare circumstances when lightning hits a bauxite-rich lava.

In truth, aluminum does react to atmospheric oxygen at room temperature, although unlike iron, aluminum does not corrode when it reacts to oxygen. Instead it forms a silvery gray oxide that sticks tightly on its surface. The main mirror of the Hubble Space Telescope has its surface coated with a very thin layer of aluminum fluoride to protect it from oxidation. Aluminum is chemically reactive enough to form useful compounds – like aluminum hydroxide which is often mixed with gasoline to create napalm. And despite the advances of high strength non-metal composites, aluminum is still used in the aircraft construction industry because of the metal’s high strength-to-weight ratio. In fact, it was Nikola Tesla who first prophesized that airplane making will only become profitable industry when we find a cheap way to produce aluminum.