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2025 annual assessments out for U.S. reactors
The Nuclear Regulatory Commission has released its 2025 annual performance assessments of the country’s 95 operating commercial nuclear reactors. And of the 95 reactors, all but five earned the highest marks.
Nuclear power plant assessments can fall under one of five categories: Licensee Response, Regulatory Response, Degraded Cornerstone, Degraded Performance, and Unacceptable Performance. Ninety reactors fell under Licensee Response, the highest performance category in safety and security. Plants that achieve this level of performance are subject to a Reactor Oversight Process (ROP) baseline inspection.
V. Dykin, I. Pázsit
Nuclear Technology | Volume 183 | Number 3 | September 2013 | Pages 354-366
Technical Paper | Fission Reactors / Thermal Hydraulics | doi.org/10.13182/NT13-A19424
Articles are hosted by Taylor and Francis Online.
This paper reports on the development and application of a method of emulating bubbly flow by generating bubbles with random sampling methods. The purpose of the modeling is that by using the simulated random two phase flow as input, one can generate "synthetic" neutron noise signals by convoluting the input with a simplified neuronic transfer function, on which the possibility of reconstructing the axial void profile from in-core neutron noise measurements can be studied by standard spectral noise analysis methods. The long term goal of this work is to elaborate methods of neutron noise analysis, by which the local void fraction in a boiling water reactor can be determined by measurements. In this preliminary stage, two methods for the reconstruction of the axial void and the velocity profiles are discussed. The first method is based on the break frequency of the neutron auto-power spectrum, whereas the second method only utilizes the information in the transit time of the void fluctuations between axial pairs of neutron detectors. A clear and monotonic relationship between the chosen observables and the two-phase flow properties was found, but an accurate determination of the void fraction requires further development and testing of the various unfolding alternatives.