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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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A new ANSI/ANS standard for liquid metal fire protection published
ANSI/ANS-54.8-2025, Liquid Metal Fire Protection in LMR Plants, received approval from the American National Standards Institute on September 2 and is now available for purchase.
The 2025 edition is a reinvigoration of the withdrawn ANS-54.8-1988 of the same title. The Advanced Reactor Codes and Standards Collaborative (ARCSC) identified the need for a current version of the standard via an industry survey.
Typical liquid metal reactor designs use liquid sodium as the coolant for both the primary and intermediate heat-transport systems. In addition, liquid sodium and NaK (a mixture of sodium and potassium that is liquid at room temperature) are often used in auxiliary heat-removal systems. Since these liquid metals can react readily with oxygen, water, and other compounds, special precautions must be taken in the design, construction, testing, and maintenance of the sodium/NaK systems to ensure that the potential for leakage is very small.
N. Tralli, J. Agresta
Nuclear Science and Engineering | Volume 10 | Number 2 | June 1961 | Pages 132-141
Technical Paper | doi.org/10.13182/NSE61-A25949
Articles are hosted by Taylor and Francis Online.
The spherical harmonic (P3) approximation to the Boltzmann equation is applied to the case of a finite cylinder, with symmetry about the axis of the cylinder. Solutions are obtained for the case of a neutron source proportional to cos Bzz where z is measured along the axis of the cylinder and Bz2 is the axial buckling. These solutions are then expanded in terms of Bz and only terms of order Bz2 or less are retained. The approximate solutions are then used to calculate the thermal utilization of a cell of finite height composed of a natural uranium rod surrounded by a D2O moderator as a function of the axial buckling. The resultant expression for the utilization has the form where f(0) is the utilization of the cell of infinite height and the constant L2 corresponds to the thermal diffusion area in two-group theory. Results are obtained for several cells and compared with those obtained using other calculational methods.
