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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
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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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Latest News
ARPA-E announces $40 million to develop transmutation technologies for UNF
The Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E) announced $40 million in funding to develop cutting-edge technologies to enable the transmutation of used nuclear fuel into less-radioactive substances. According to ARPA-E, the new initiative addresses one of the agency’s core goals as outlined by Congress: to provide transformative solutions to improve the management, cleanup, and disposal of radioactive waste and spent nuclear fuel.
Vikas Pandey, Suneet Singh
Nuclear Science and Engineering | Volume 188 | Number 2 | November 2017 | Pages 187-197
Technical Paper | doi.org/10.1080/00295639.2017.1350003
Articles are hosted by Taylor and Francis Online.
The nonlinear stability analysis of an advanced heavy water reactor (AHWR) is performed to investigate global stability. The global stability perspective predicts the exact stability boundary of the system, which is valid for small as well as large disturbances in the system. Recently, the local or linear stability boundary and bifurcation of limit cycles has been discussed for an AHWR. However, the studies were not sufficient to predict global stability of the system. In this work, advanced bifurcation analysis is carried out for an AHWR, which unfolds multistable or unstable states. The region of multistability is observed due to the presence of steady states and multiple limit cycles. The global stability boundary is marginally away from the local stability boundary, the region beyond which the global stability boundary is safe for operation due to the nonexistence of nonlinear phenomena, such as limit cycles. The local stability boundary is basically a Hopf bifurcation boundary as limit cycles (i.e., nonlinear phenomena) emerge from these points. Subcritical or supercritical Hopf bifurcations excite unstable limit cycles (ULCs) or stable limit cycles (SLCs), respectively, and these limit cycles end on the global stability boundary. The subcritical Hopf bifurcation is considered as hard or dangerous bifurcation due to the presence of ULCs in the linearly stable region, which gains stability on the global stability boundary and in which SLCs surround ULCs. Therefore, a region of bistability between the local and global stability boundary is present for subcritical Hopf. The supercritical Hopf is generally considered as the soft and safe bifurcation because of SLCs in the linearly unstable region. Due to this fact, it is assumed that in the supercritical Hopf region the global and local stability boundaries are the same. However, in this work ULCs in the linearly stable region for supercritical Hopf bifurcation are observed along with SLCs, which is an uncommon phenomenon in nuclear reactors. The presence of ULCs surrounding SLCs are observed both in the stable and unstable side on the parameter plane for supercritical Hopf. For the safe operation of a nuclear reactor, identification of the region of global stability is of paramount interest.