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Materials Science & Technology
The objectives of MSTD are: promote the advancement of materials science in Nuclear Science Technology; support the multidisciplines which constitute it; encourage research by providing a forum for the presentation, exchange, and documentation of relevant information; promote the interaction and communication among its members; and recognize and reward its members for significant contributions to the field of materials science in nuclear technology.
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2025 ANS Annual Conference
June 15–18, 2025
Chicago, IL|Chicago Marriott Downtown
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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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Smarter waste strategies: Helping deliver on the promise of advanced nuclear
At COP28, held in Dubai in 2023, a clear consensus emerged: Nuclear energy must be a cornerstone of the global clean energy transition. With electricity demand projected to soar as we decarbonize not just power but also industry, transport, and heat, the case for new nuclear is compelling. More than 20 countries committed to tripling global nuclear capacity by 2050. In the United States alone, the Department of Energy forecasts that the country’s current nuclear capacity could more than triple, adding 200 GW of new nuclear to the existing 95 GW by mid-century.
Ivars Neretnieks
Nuclear Technology | Volume 71 | Number 2 | November 1985 | Pages 458-470
Technical Paper | Radioactive Waste Management | doi.org/10.13182/NT85-A33698
Articles are hosted by Taylor and Francis Online.
The diffusivities measured by various investigators of several species in compacted bentonite clay have been compiled and analyzed. Small anions diffuse slower than an uncharged molecule such as methane. Large anions move orders of magnitude slower still. The actinides thorium, uranium, plutonium, neptunium, and americium are considerably retarded by sorption effects. Their movement can be explained by pore diffusion with retardation. Cesium, strontium, and protactinium move considerably faster than can be explained by these effects. The faster mobility is probably due to surface migration. A simplified model is presented by which the importance of the backfill barrier in retarding the radionuclides can be assessed. It is based on the computation of the evolution of the concentration profile of the diffusing nuclide in the backfill. Using this model, the flow rate out from the backfill to the flowing water can be compared to the inflow into the backfill due to leaching. A second model treats nuclides with solubility limitations in a similar way. A diagram is presented where the maximum outflow or concentration of a nuclide from the backfill can be determined as a function of barrier thickness and nuclide diffusivity and decay constant. Using the experimentally obtained diffusivities, it is found that a 0.375-m-thick backfill will eventually let through practically all 129I, 99Tc, 226Ra, 231Pa, 234U, 235U, 238U, and 237Np. The maximum release rate for 137Cs, 90Sr, 239Pu, 240Pu, and 243Am will decrease by one to three orders of magnitude compared to the leach rate. Americium-241 will decay to insignificance in the backfill.
