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Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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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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Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
J. T. Mihalczo, E. D. Blakeman, V. K. Paré, T. E. Valentine, D. J. Auslander
Nuclear Technology | Volume 103 | Number 3 | September 1993 | Pages 346-379
Technical Paper | Nuclear Criticality Safety | doi.org/10.13182/NT93-3
Articles are hosted by Taylor and Francis Online.
The subcritical neutron multiplication factors k for two parallel, axially separated, flat cylindrical tanks separated up to 57.91 cm in air and containing enriched uranyl (93.1 wt% 235U) nitrate solution (71.6-cm-i.d. tanks, 8.91-cm solution thickness, 1.555 g/cm3 solution density, and 404 g U/ℓ uranium density) were measured by the 252Cf-source-driven noise analysis method with measured k values varying from 0.99 to 0.80. These measurements were performed at the Los Alamos National Laboratory (LANL) Critical Experiments Facility in 1989 and were part of the program of Westinghouse Idaho Nuclear Company (WINCO) to benchmark calculations for the design of the new storage system at Idaho National Engineering Laboratory. Initial subcriticality measurements by the source-jerk method at LANL had indicated that at a calculated neutron multiplication factor k = 0.95, the measured k was 0.975. This discrepancy was of concern to WINCO because the new storage facility was being designed with a k limit of 0.95, and thus, half of the criticality safety margin of the storage design was equal to the discrepancy between early measurements and calculations. The 252Cf-source-driven noise analysis measurements confirmed the validity of the calculational methods. In addition to providing the neutron multiplication factor from point-kinetics interpretation of the data, these measurements also provided the auto-power and crosspower spectral densities as a function of frequency, which can be calculated directly with recently developed Monte Carlo methods and thus could also be used to validate calculational methods and cross-section sets. As with previous measurements with loosely coupled systems, a modified point-kinetics interpretation was successfully used to obtain neutron multiplication factors for measurements with the californium source and detectors located on the same tank. Although the californium source is located on axis but asymmetrically in the system, the detectors adjacent to the radial surface were sufficiently far apart that the correlated information was from long fission chains, which are distributed throughout the system of two tanks. The subcritical neutron multiplication factors obtained from the break frequency noise analysis method agreed with those from the 252Cf-source-driven noise method. These measurements confirmed the criteria from previous experiments for location of the source and detectors to obtain the neutron multiplication factor by using a modified point-kinetics interpretation of the data and again verified the usefulness of this method for interacting systems.