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Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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FPoliSolutions demonstrates RISE, an RIPB systems engineering tool
The American Nuclear Society’s Risk-informed, Performance-based Principles and Policy Committee (RP3C) has held another presentation in its monthly Community of Practice (CoP) series. Former RP3C chair N. Prasad Kadambi opened the October 3 meeting with brief introductory remarks about the RP3C and the need for new approaches to nuclear design that go beyond conventional and deterministic methods. He then welcomed this month’s speakers: Mike Mankosa, a project engineer at FPoliSolutions, and Cesare Frepoli, the company’s president, who together presented “Introduction to RISE: A Digital Framework for Maintaining a Risk-Informed Safety Case for Current and Next Generation Nuclear Power Plants.”
Watch the full webinar here.
W. R. Waltz, J. F. Walter
Nuclear Technology | Volume 10 | Number 2 | February 1971 | Pages 160-167
Technical Paper and Note | Reactor | doi.org/10.13182/NT71-A30923
Articles are hosted by Taylor and Francis Online.
Comparisons of calculation and experiment have been performed to test the adequacy of fewgroup subcritical diffusion theory in predicting neutron detector response induced from material changes in a subcritical water-moderated reactor. In many operations involving material changes in a subcritical reactor, it is desired to monitor changes in the multiplication factor (Keff) of the system to ensure the safety of an operation by avoiding an accidental close approach to criticality. This monitoring procedure is accomplished by the introduction of artificial neutron sources to the system and by the proper interpretation of changes in neutron detector readings in terms of Keff. Because of the rather complicated involvement of the source-core-detector system, proper interpretation of detector response observed during these operations can only be achieved by the availability to predict detector response obtained from an accurate calculational model. Comparisons of calculation to experiment show that diffusion theory may be used successfully for these purposes; however, certain limitations of the model must be recognized and avoided. The breakdown of the calculational model in certain cases can be related ultimately to the inability of few-group diffusion theory to predict the absolute magnitude of detector flux for large distances through a water (or metal-water) shield. This inability can result in inaccuracies in predicted count rate response when applied to a specific source-core-detector arrangement with the characteristic that a given material change results in gross changes in the axial flux distribution. These effects can be overcome by the suitable positioning of the neutron source and detector relative to the subcritical assembly.
