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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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The RAIN scale: A good intention that falls short
Radiation protection specialists agree that clear communication of radiation risks remains a vexing challenge that cannot be solved solely by finding new ways to convey technical information.
Earlier this year, an article in Nuclear News described a new radiation risk communication tool, known as the Radiation Index, or, RAIN (“Let it RAIN: A new approach to radiation communication,” NN, Jan. 2025, p. 36). The authors of the article created the RAIN scale to improve radiation risk communication to the general public who are not well-versed in important aspects of radiation exposures, including radiation dose quantities, units, and values; associated health consequences; and the benefits derived from radiation exposures.
Thomas S. Bustard, Frank T. Princiotta, Harold N. Barr
Nuclear Technology | Volume 9 | Number 4 | October 1970 | Pages 572-583
Radioisotope | doi.org/10.13182/NT70-A28767
Articles are hosted by Taylor and Francis Online.
A new reentry protection material has been developed which acts as a thermal switch. It is a composite material, consisting of a ceramic foam uniformly impregnated with a metal which coats the ceramic foam structure. The composite is a thermal conductor [k ≅ 5 Btu/(ft h °F)] below the melting point of the metal impregnant and switches to an insulator [k ≅ 0.1 Btu/(ft h °F)] above its melting point. This switching effect is irreversible. Materials investigated to date are silica, alumina, and zirconia foams with silver and copper as the metal impregnants. These combinations yield a thermal switch which is activated at the melting point of the impregnants, i.e., 1762°F for silver and 1982°F for copper. Other metals can be utilized to increase or decrease the switching temperature. These composite materials have specific application to radioisotope fueled space power systems. For this application, the material selected would be placed around the fuel capsule, allowing the heat to pass through with only a small temperature differential incurred. When exposed to a reentry heat pulse, the material would switch to an insulator, thereby allowing intact and safe reentry of the capsule. Thermal conductivity testing and plasma jet testing have been performed and indicate that the composite material is an effective reentry protection material.