ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
Standards Program
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!
Latest Magazine Issues
Jul 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
September 2025
Nuclear Technology
August 2025
Fusion Science and Technology
Latest News
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.
Michael Epstein, Hans K. Fauske, Charles F. Askonas, Marc A. Vial, Patricia Paviet-Hartmann
Nuclear Technology | Volume 163 | Number 2 | August 2008 | Pages 307-320
Technical Paper | Reprocessing | doi.org/10.13182/NT08-A3990
Articles are hosted by Taylor and Francis Online.
A Semenov-type analysis is made of the conditions for an exothermic runaway reaction in an "organic phase" (or "red oil") made up of tri-n-butyl phosphate (TBP) saturated with nitric acid (HNO3). Also, a theoretical framework is developed to predict the critical organic layer depth above which a runaway will occur when the organic layer rests on a layer of aqueous nitric acid ("aqueous phase"). Available calorimetry data on peak pressurization rates during vented TBP/HNO3 reactions are rationalized using orifice flow theory, which provides a simple criterion for the required vent area for vessel pressure relief during a red oil runaway. Finally, it is shown that the Tomsk-7 accident can be explained by a combination of weak reaction tempering at the vessel relief valve set pressure and insufficient venting capacity. The formulations for determining the onset of a TBP/HNO3 runaway outlined in this paper rely heavily on the empirical and semiempirical equations developed in the companion paper "Thermal Stability and Safe Venting of the Tri-N-Butyl Phosphate-Nitric Acid-Water ("Red Oil") System - II: Experimental Data on Reaction Self-Heat Rates and Gas Production and Their Correlation," Nuclear Technology, Vol. 163, p. 294 (2008), which deals with the chemical self-heat rate in the organic phase, the gas production rate in the organic phase, and the superficial gas velocity across the aqueous-organic interface of a two-layer organic over aqueous configuration.