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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The 2025 edition is a reinvigoration of the withdrawn ANS-54.8-1988 of the same title.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.
G. G. Smith, J. Hardy, D. Klein, J. A. Mitchell
Nuclear Science and Engineering | Volume 9 | Number 4 | April 1961 | Pages 421-429
Technical Paper | doi.org/10.13182/NSE61-A25906
Articles are hosted by Taylor and Francis Online.
The relative U238 resonance capture integrals of 0.387-in. diameter UO2 and uranium metal fuel rods have been measured as well as the spatial distributions of the captures in each type of rod. The effective resonance integral of the UO2 rod was found to be 1.30 ± 0.02 times that of the . uranium metal rod. This difference is due to the lower density of uranium atoms and the presence of oxygen moderation in the UO2 fuel rod. The relative importance of each of these two effects was determined by means of U-Zr and U-Al alloy fuel rods. Of the 0.30 excess of the UO2 resonance capture integral over that of the uranium metal, 0.15 ± 0.02 was contributed by the lower U238 atom density of the UO2 rod, and the remaining 0.15 was attributed to oxygen moderation. Work done by Hellstrand (5) gives a value of 1.41 ± 0.03 for the U238 resonance capture integral for the UO2 rod relative to that of the uranium metal rod. Furthermore, by evaluating his expression for the resonance integral of a metal rod at a value of S/M corresponding to a “low-density” uranium metal rod (U238 atom density equal to that of the UO2 rod) of 0.387-in. diameter, one obtains a density effect of 1.32. These discrepancies can be attributed, at least partially, to a differing flux spectrum at energies above 30 kev in the present experiment as compared with Hellstrand's experiment. Whereas the high-energy flux is depleted in his experiment, there was an appreciable flux peak present in the TRX measurements.
