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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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Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2025)
February 3–6, 2025
Amelia Island, FL|Omni Amelia Island Resort
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!
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Three nations, three ways to recycle plastic waste with nuclear technology
Plastic waste pollutes oceans, streams, and bloodstreams. Nations in Asia and the Pacific are working with the International Atomic Energy Agency through the Nuclear Technology for Controlling Plastic Pollution (NUTEC Plastics) initiative to tackle the problem. Launched in 2020, NUTEC Plastics is focused on using nuclear technology to both track the flow of microplastics and improve upstream plastic recycling before discarded plastic can enter the ecosystem. Irradiation could target hard-to-recycle plastics and the development of bio-based plastics, offering sustainable alternatives to conventional plastic products and building a “circular economy” for plastics, according to the IAEA.
G. S. Gangwani, S. P. Tewari, L. S. Kothari
Nuclear Science and Engineering | Volume 61 | Number 1 | September 1976 | Pages 78-89
Technical Paper | doi.org/10.13182/NSE76-A28463
Articles are hosted by Taylor and Francis Online.
The results of a detailed and systematic study of time-dependent, space-dependent, and steady-state neutron spectra in different assemblies of various H2O-D2O mixtures in the temperature range of 253 to 21 K are reported. By the matrix diagonalization method, the multigroup Boltzmann diffusion equation was solved to obtain asymptotic and transient spectra in assemblies at 253 K, with buckling values ranging from 0 to 0.4 cm−2. Mixtures with D2O content of 20, 50, and 80 wt% are considered. The calculated values of the fundamental mode decay constant and the diffusion parameters are compared with the experimental values reported by Salaita and Robeson. The multigroup time-independent source-free Boltzmann equation was also diagonalized to obtain spatial eigenvalues and eigenfunctions. By using these eigenfunctions, neutron spectra and the effective diffusion length L(x), at different distances from the source plane, were calculated at 253 K. The asymptotic values of L(x) compare fairly well with those calculated by using the measured values of D0 and in mixtures with a D2O content of 20, 50, and 80%. For the steady-state problem, the multigroup inhomogeneous Boltzmann diffusion equation was solved by the matrix inversion method for assemblies at 77 and 21 K with buckling values ranging from 0 to 0.1113 cm-2. Mixtures with D20 content of 0, 5, 10, 20, ... 90, 95, and 100% are considered. At 21 K, the relative usefulness of different assemblies as cold-neutron sources is discussed. For some selected assembly sizes, we determined the optimum H2O-D2O mixtures that would give maximum cold-neutron flux. The optimum mixtures for buckling values of 0.1113, 0.0158, and 0.001 cm-2 are those with nearly 30, 70, and 90% D2O, respectively; the corresponding gain factors for graphite-filtered neutrons are 1.85, 4.17, and 13.57, respectively. We find that in mixtures, as in the cases of H2O and D2O ice, cooling an assembly below 21 K does not decrease the effective temperature of the neutron distribution below that obtained at 21 K.
