Dec 20 2016

New Radiation Resistant Metals

radiation-alloysThis is a bit of a wonky technical post, but that is actually a point I want to make. Often I find that the scientific advances that have the most potential get the least coverage, while interesting but incremental advances, or one-off findings, are given broad coverage with sensational headlines. This is an unfortunate artifact of how scientific news is communicated. First, a company’s or institution’s press office will determine if the new study or finding is press-worthy, and if so they will compose a press release. Then journalists and news outlets will decide if it is worth publishing, which usually means – can they spin it as a major breakthrough, creating or solving some “mystery”, a potential cure for some disease, or tie it to some science-fiction technology.

Meanwhile, real advances that are not “sexy” get overlooked. So when I saw this item I thought, this is likely to be one of those advances with huge potential but very little press coverage.

Researchers have figured out how to make metal alloys that are far more resistant to radiation damage than existing alloys. The key is mixing three or more different metals in equal proportions. They compared nickel to nickel-iron, nickel-cobalt-iron, and nickel-cobalt-iron-manganese-chromium. The alloys with three or more metals were 100 times more resistant to radiation damage than the pure nickel.

When metals are exposed to a lot of radiation at high temperature, they tend to swell. This can affect structures around them, but also causes them to become less dense, which can reduce their shielding efficacy. Further, the metals accumulate structural damage over time, limiting their lifespan.

When radiation hits a metal atom it can kick it out of the crystal structure. The atom can travel relatively far within the crystal, leaving behind a small hole that does not move as fast or far. This can result in a large number of holes coalescing into a larger cavity, which weakens the integrity of the metal.

The alloys, however, contain atoms of different sizes mixed together. This has the result of slowing the movement of atoms that get kicked out by the radiation, so they stay closer to their holes and are more likely to combine again with the hole, healing the structure and preventing the formation of cavities (as you can see in the picture above).

The obvious application of this knowledge is in nuclear reactors. The radioactive fuel needs to be stored in canisters, and the effectiveness and lifespan of those canisters is important to the safety of the reactors.

Another potential use could be in structures in space, which may be exposed to high levels of radiation (not as high as a nuclear reactor, but persistent over decades). The lifespan of the shielding of satellites, spacecraft, space stations, and even Moon or Mars bases could benefit from such alloys.

Other researchers are working on nanostructured alloys to have the same property – defect restoration producing radiation tolerance. The idea here is to structure the alloy to contain nanopores that essentially have the same effect as the alloys. The advantage of the alloys is that they are easier and cheaper to manufacture (at least for now).

There is also research looking at metal foams, which can be much more effective at absorbing different types of radiation for the same weight. This would be essential for radiation shielding in spacecraft where weight is a critical limiting factor. In fact, one of the technological limitations in getting people to Mars is shielding the crew compartment for the many months journey, including time they would spend on Mars. Improved radiation shielding could be critical to the feasibility of such missions.

As an aside, when reporting on this news item the Daily Caller claimed:

Nuclear power, even accounting for high-profile nuclear accidents, is already statistically the safest way of generating electricity. Coal power kills 280,000 people for every trillion kilowatt hours it produces. Rooftop solar kills 440 for the same amount of electricity. Nuclear energy only kills 90, by this measure, including deaths from disasters.

The link goes to an interesting Forbes article, which is worth a read itself. Nuclear has the best safety record partly because it generates so much electricity for the amount of infrastructure. As safe as, say, wind power is, you need a lot of wind turbines to create the same amount of electricity as nuclear, and the occasional turbine worker falling off to their death is enough to exceed total deaths from nuclear power.

The coal numbers are also interesting. World wide coal deaths are 10 times that of the US, which the article attributes to the clean air act, which they claim is the piece of legislation that has saved more lives than any other. This emphasizes the point that the health care costs alone of coal burning and other fossil fuel burning make it cost effective to switch to cleaner forms of energy, and should be considered in any comparison.

Where does the death toll from solar come from?

The large quantity of materials required for unconventional systems implies huge industrial efforts in mining, refining, fabricating, and constructing the collectors, storage systems and all related apparatus. Every form of industrial activity has an associated risk, which can be found through accident statistics compiled by national organizations. When all the multiplications and additions are done, we find that the risk from unconventional energy systems can be substantial.

This is another reason to give nuclear power a serious consideration when trying to figure out how we are going to shift our energy infrastructure (in time) to minimal CO2 emissions. This also brings us back to the current study – improved radiation shielding could make nuclear power even safer.

Conclusion

I am often reminded of the following quote:

“Amateurs talk about tactics, but professionals study logistics.”
– Gen. Robert H. Barrow, USMC (Commandant of the Marine Corps) noted in 1980

This stuck with me because of the realization that what seems interesting, exciting, and important to the lay person may not be the truly most important aspect of something. Experts may tend to focus on aspects of their field that seem boring, but are critically important. No one talks about the logistics of a major battle, but that is often where real victory or failure lies.

The same is true in many fields, including much of technology. In general it’s my sense is that material science is greatly important, but gets relatively little attention. Making a new metal alloy is just about as boring a news item as you can imagine, but these are the kinds of advances that have the real potential to be game-changers.

11 responses so far

11 thoughts on “New Radiation Resistant Metals”

  1. jimvic48 says:

    Interesting post. I agree with your points. These things often make me think of the difficulty of foreseeing unintended consequences of things. Once someone finds a “sexy” application of the discovery, that can, of course, more easily get people’s attention. Yesterday while on a long flight home to Washington state from Los Angeles with an hour delay for our connecting flight, I thought of perhaps a consequence I haven’t heard mentioned much regarding “robotic” cars. By the time I got home after 14 hours and well after midnight, this was only 4 hours less than the driving time to get home. So maybe in 15 years or so we will have autonomous cars perfected enough to sleep while they drive you. Then I might opt for the less expensive auto trip, letting the car drive me home while I rest better than I could on the plane. And get there only 4 hours later. I wonder how much impact this will eventually have on the airlines – that being the unintended consequence (among many others) of autonomous cars.

  2. Haggard says:

    I wonder how low the bias for determining the safety of various energy production methods in the Inhaber article was.

    For example, while it is likely true that there are deaths associated with materials that go into solar (or wind) power through mining, production, etc., how would you actually parse out the information to know that X amount of deaths occur in solar because of these activities. Directly.

    Perhaps solar or wind companies source their materials from raw producers, manufacturers, refiners, etc. with a higher safety record than the total average. Perhaps it is worse. How could we ever know, and then assign a number of deaths related to a particular industry that is meaningful? It seems like something that could be so complex to become almost meaningless, depending on how far into the data we choose to look.

    Are they comparing global production? A specific region? What about at the company level? Who is actually producing this stuff and what is their record? These could have enormous impacts on related deaths in industries such as mining or smelting where you could expect to see very large differences in safety and associated death, depending on where the materials are found and used.

    I’m just suspicious of an article that provides numbers like these, which at a glance, appear to be very generalized. It doesn’t appear that they used a complex method for determining deaths which were directly related, so that we can have an accurate estimation of actual death for unit of material produced in the energy production technologies that they look at. There seems to be a lot of variables here to tease out and I’m not clear on if they have done that accurately enough.

    Interesting idea though.

    I very much support this type of information at the consumer level. Personally, I want to know the average environmental impact of the things that I purchase so that I can make an informed decision related to my particular world view, in a similar way that I want to choose a form of energy with the least environmental and social impact. However, this is difficult to do. There is a lot of data to consider and accuracy seems to suffer at a certain point.

  3. FuzzyMarmot says:

    Dr. Novella– your ability to explain the excitement and importance of seemingly “boring” news items is what makes you one of the world’s greatest science communicators. Thank you for your work revealing the awesomeness of scientific discoveries that are often overlooked by the public.

    One of the most exciting things (for me) about the Lu et al alloys paper was the convergence of experiment and theory. The matching of simulation results with empirical work is very, very cool. The identification of materials with useful properties is great, but understanding and testing why they have these properties is even better!

  4. Haggard – Your point is valid. Indirect deaths are always going to be an inference. This does not mean the numbers are worthless, just should be taken with a grain of salt. They did compare US vs China vs International average, which was helpful. Since safety standards are generally regulated at the national level, this is reasonable.

    Some of the numbers are perfectly straightforward, like death due to falling off wind turbines during maintenance. I also think that excess deaths from asthma due to pollution, while a bit trickier, are pretty reliable. Deaths from mining and processing raw materials is the trickiest, but I think accounting for these deaths is reasonable.

    While I am a solar advocate, it is reasonable to ask – what exactly goes into building the number of solar panels necessary to generate the same amount of electricity as one nuclear power plant, and how can we estimate the cost and impact of building all those panels?

    FM – Thanks for the comment. It’s good to know my efforts are appreciated.

  5. Ivan Grozny says:

    “The obvious application of this knowledge is in nuclear reactors.”

    Let me guess…May not this be the reason media is not very excited?

  6. Haggard says:

    Associated deaths aside, which is interesting and worth considering, I think many people are turned off from nuclear power because of the long term fallout from just one mishap. So far, I think we’ve been somewhat lucky, if you can say that, with where some of the accidents have happened. If nuclear were to become the dominate source of energy, they would have to be more frequently placed near large populations.

    The industry is quick to point out safety, but the primary concern for me, and many others, is that if there is a problem, it can be incredibly serious and so long lasting that it ought to bump the risk factor up quite a lot, despite the track record so far and what the industry has to say about it. While nuclear may be safe on paper, so far – depending on who you’re asking – I think the disasters that we have seen show how incredibly dangerous they can be when things go wrong. For example, and not digging very deep, wikipedia gives an estimate of 4,000 deaths from Chernobyl.

    When we contrast this with things like coal or gas, it obviously becomes something worth thinking about, but I’m not sure I would support it until there is a better way to deal with the eventual disasters that are likely going to happen. Not to mention dealing with the by-product.

    Perhaps new materials like these will offer a workable solution. It’s certainly interesting science.

    Anyway, thanks for writing about these topics. It’s great that you touch on such complex issues and provide an opportunity to think about them in more detail.

  7. Sarah says:

    Dr. Novella, I’m curious – I remember reading a while ago (or even hearing from the Rogues) about a method of charging a plasma about a spaceship to deflect particles.

    Did that prove to be not a viable solution? I don’t see it mentioned often anymore.

  8. FuzzyMarmot says:

    Sarah- I was curious about this, too. “Active radiation shielding” seems to be a continuing exciting area of research, but the specific idea of using a plasma barrier appears to still be in the speculative phase of research.

    Here is a 2014 paper: https://arxiv.org/pdf/1406.1159v2.pdf

    Seems like scientists are still working on back-of-the-envelope calculations.

  9. haggard – it’s not luck. It is regulation and care. Chernobyl was due to poor safety measures. It was entirely preventable. Fukushima was arguably due also to insufficient safety measures and perhaps it was ill-conceived to build reactors in a tsunami zone.

    France, the US, and other countries have had safe nuclear for decades.

    The risks are manageable. I also see no reason to set aside the death numbers – they tell the real story.

    We can build reactors in stable and remote areas. We do need to dramatically improve our energy grid. This is an infrastructure project worth the investment. If we had a modern grid, we could place energy producers anywhere and balance production and demand better.

  10. RC says:

    @Haggard

    “– I think the disasters that we have seen show how incredibly dangerous they can be when things go wrong. For example, and not digging very deep, wikipedia gives an estimate of 4,000 deaths from Chernobyl.”

    Nuclear disasters are terrible (and as SN said, Chernobyl was largely about human error – there were a series of blunders that were largely caused by political issues in the wake of a service test) – but that 4000 number lines right up with the number of direct deaths per year in the coal mining industry (worldwide – USA is much safer than most).

    I think it’s instructive that we’re looking at a disaster 30 years ago as a sign that nuclear is dangerous, and ignoring that coal directly kills as many people every year (and that’s not even getting into pollution deaths).

  11. daedalus2u says:

    Another important metric to use in measuring the safety of a particular power source is how much the power costs in terms of person-years of labor.

    This is where nuclear power comes up short. Nuclear power is more expensive than solar, wind and natural gas turbines, so it takes more person-hours to purchase, and the nominal death rate associated with that increased person-hours should be included.

    Deaths due to a particular industry can be looked at as an unpriced externality of that industry. If you want to compare industries to each other, you need to include all externalities and then attach “prices” to them, so as to generate a basis for comparison. Simply ignoring externalities makes the comparison invalid.

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