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Dushyant Mukkamala

Calculate Radiation Shielding for Radioactive Materials with Wolfram|Alpha

December 19, 2011 —
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We are pleased to add our latest work in the domain of radiation shielding to our ever-widening repertoire of highly technical and challenging areas. Although this was one of the earliest features added to Wolfram|Alpha, we have now significantly expanded the functionality of the area that permits users to ask about the shielding efficacy of numerous materials against multiple radiation sources. Most importantly, we have now included the computations for shielding against that most dreaded radiation—the gamma ray. We think these new features will be extremely useful in helping people to better understand the common shielding gadgets they might see every day (such as at the dentist’s office or when getting an X-ray).

At launch we had information only for beta radiation (electron beam) but now have added alpha particles, protons as well as photons to our collection. Additionally, we have significantly improved the natural-language capabilities in this domain. For example, asking Wolfram|Alpha “At what thickness of lead is 3 MeV gamma radiation halved in intensity?” immediately returns the thickness of the lead sheet as the result. Or maybe you’re interested in figuring out how far alpha particles travel through air. Just ask, “What thickness of air will shield 5 MeV alpha particle radiation?” What if there is a glass window? Once again, the query is at your fingertips: “What is the maximum electron radiation that a 2″ thick plate glass can block?

What is the maximum electron radiation that a 2" thick plate glass can block?

Additionally, we have long had extensive information on all the radioactive isotopes present on our planet, which we have now combined with the new shielding protection data. For example, iodine-131 and cesium-137 are two of the prominent radioactive isotopes that are commonly used for a variety of purposes. A quick look at iodine-131 shows us that the primary decay mode for this isotope is beta radiation, and we have now added an approximate calculation to show what thickness of some common materials would block this radiation. We can look up the same information for cesium-137 as well. This is quite useful information, as iodine-131 is used extensively in medical imaging as well as biological and chemical research, and cesium-137 can be used in the treatment of cancer, in measuring metal thickness and fluid flows in industrial settings, and in the irradiation of food and spices.

We hope these new features are useful for radiation workers who work with radioactive materials and various shielding requirements on a daily basis as well as for casual users who want to find information about isotopes and associated ionizing radiation and the protective shielding measures. We now have detailed coverage of the shielding behavior against alpha, beta, and gamma radiation and are working toward extending our work to include more particulate radiation (neutron and more).


How about UV radiation? Wolfram Alpha does not know about “At what thickness of glass is UV radiation halved in intensity?”

Posted by Michal December 20, 2011 at 12:24 pm

This is a nice addition to Wolfram Alpha.

However, the stopping of electrons by a thickness of material is better measured by extrapolated range (R_ex) rather than CSDA range. CSDA refers to the total path length of the electron, which is not a straight line but a tortuous path through the material. Extrapolated range is measured by the transmission of electrons through a thickness of material, and is the thickness of material at which the transmission fraction approaches zero. CSDA range is significantly longer than extrapolated range.

Extrapolated range is not available on NIST’s ESTAR web page, but you could convert to it using Tabata’s 1996 paper in Nuclear Instruments and Methods, B.

–Brian, nuclear engineering grad student

Posted by Brian December 20, 2011 at 4:08 pm

    @ Brian and Michal –
    Thank you for the feedback. We continue to improve our data in this area and have passed along your suggestions to the members of our team.

    Posted by The Wolfram|Alpha Team December 22, 2011 at 11:02 am

It is great to see how far Wolfram Alpha has developed. I honestly hope that we will never have so much radioactive materials here in Germany, that we will have to use this function… However from a technical perspective it is a great Addon. Thanks to WA Team and Merry Christmas.

Posted by Jenny December 26, 2011 at 12:19 pm

This information is certainly very useful to me in my field (nuclear physics). One additional feature that would be great would be to add decay radiation information for each of the radioactive isotopes (i.e. energy of emitted gamma rays, beta / alpha particles, conversion electrons, etc.). Level information is currently provided, but the actual energy of the gamma rays / particles emitted is more useful in most cases. This information can readily be obtained from the National Nuclear Data Center at Brookhaven National Lab (

Posted by Brent January 9, 2013 at 8:13 am

Very useful.

Posted by Corey April 3, 2015 at 8:08 pm