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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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The 2025 edition is a reinvigoration of the withdrawn ANS-54.8-1988 of the same title.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.
Alfred L. Mowery, Jr., Raymond L. Murray
Nuclear Science and Engineering | Volume 14 | Number 4 | December 1962 | Pages 401-413
Technical Paper | doi.org/10.13182/NSE62-A26249
Articles are hosted by Taylor and Francis Online.
This paper is devoted to the exposition and illustration of a technique the authors have designated as the generalized variational method (GVM). The analysis is based on the variational approach and is an outgrowth of investigations in the hyper circle method. In essence, the GVM consists of considering the trial functions that appear symmetrically (quadratically) in a positive-semidefinite variational principle as independent functions. A proposition was proved to demonstrate generally that the approximate eigenvalue obtained from the GVM is at least as accurate as the geometric average of the associated approximate eigenvalues. Also, a conjecture was proposed that the accuracy of the generalized variational eigenvalue is comparable to that of a variational result employing a trial function incorporating the dimensionality of both associated trial functions. The application of the GVM to the perturbation-variational method yielded results that firmly establish the method. The generalized method completes the perturbation-variational method by providing the formerly missing even-order approximate results. For illustration, the GVM was employed to solve a bare reactor with a grey control sheet. Using Ray-leigh-Ritz optimized cosine series and optimized pyramid functions as associated solutions, the generalized variational eigenvalue accuracy indicated the effective combination of the dimensionalities of the associated trial functions.