Wednesday, November 14, 2012

Osmium: The Best Radiation Shielding Material?

As the material of choice used as the radiation shielding in the warp nacelles of the first Starship Enterprise, is osmium the best radiation shielding material out there?

By: Ringo Bones

From a nuclear engineering standpoint, when the subject of using osmium as a radiation shielding material – every competent engineer will be concerned about costs. After all, even though the metal itself is not regularly flashed during the commodities segment of the NYSE – just by belonging in the platinum group of metals only makes one safely assume that osmium could be closer in price to either platinum or palladium – its other two siblings regularly monitored on the ticker tape of the commodities markets. Cost concerns aside, is osmium truly a better radiation shielding material in comparison to ones currently used – i.e. like lead, steel or concrete?

It was in the Season 2 episode of Star Trek: Enterprise titled The Catwalk – which was originally aired back in December 18, 2002 – where osmium was mentioned as the radiation shielding used in the warp nacelles of the Starship Enterprise. The subject came about because during a deadly radioactive storm in space threatens Enterprise, the entire crew took shelter in the starship’s warp nacelles which were the most shielded part of the ship against radiation. And given that most radiation shielding currently used are known for their relatively high density – i.e. lead, steel and concrete – does this mean that the densest nonradioactive we currently know, osmium at 22.5 grams per cubic centimeter at almost twice the density of lead, is the more ideal radioactive shielding material?

Using current International Atomic Energy Agency standards in commercial nuclear fission power plants – and future nuclear fusion power plants are more than likely to comply with this figure for safety of both human personnel and electronics – adequate shielding consists in reducing radiation levels to values approximately as follows: in the gamma radiation wavelengths – 2,750 Mev per square cm/second; fast neutrons – 75 neutrons per square cm/second; and thermal neutrons – 3,600 neutrons per square cm/second. For humans – and other humanoid carbon based life-forms and the electronic systems on the Starship Enterprise to perform efficiently, not to mention stay healthy, Captain Jonathan Archer would probably stick with the IAEA’s established occupational radiation level standards.


April Rain said...

Osmium is a common radiation shielding for warp nacelles of 22nd Century era NX class starships - like the Enterprise NX-01.

Sherry said...

Even though lead is a commonly used shielding against ionizing radiation - like X-Rays and gamma radiation - due to its lower cost, there hasn't been a published scientific comparison between which is better at blocking ionizing radiation - lead or osmium. Even though it is not currently running on the NY Mercantile Exchange stock ticker like its related cousins platinum and palladium, I think osmium on a per troy ounce basis, since it is indeed classified as a precious metal in the platinum group, is probably closer in price to palladium. Osmium is much denser / heavier than lead though and most materials that are very effective in shielding against X-Rays and gamma rays tend to have high density.

Ringo said...

Given that osmium has twice the density per cubic volume as lead, there's no published scientific comparison on how much more effective osmium is in blocking ionizing radiation like X-Rays and gamma rays - either in post World War II era nuclear fission power plant engineering literature and on-line scientific publications that I have encountered so far since 1995. Though I suspect that effectiveness in blocking ionizing radiation, the chosen material's atomic nucleus density also plays a part - i.e. elements with higher atomic numbers and atomic weights. There was an episode in Star Trek: Voyager were Captain Janeway entered a star-system where they detected presence of super-heavy non-radioactive / stable trans-uranic elements that put the Voyager's crew in "gold rush" mode since stable super-heavy elements with atomic numbers beyond uranium are very effective in blocking ionizing radiation. Imagine a super-heavy element which an aluminum foil thick specimen of which has the same X-Ray and gamma ray blocking power as that of 12-inches of lead.

Hendersonrose92 said...

I always thought that lead was the best shielding material. I guess I was wrong. I didn't know there were so many different kinds of materials that could protect you for radiation though. I like how you used a Star Trek reference to explain your point.