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Division Spotlight
Young Members Group
The Young Members Group works to encourage and enable all young professional members to be actively involved in the efforts and endeavors of the Society at all levels (Professional Divisions, ANS Governance, Local Sections, etc.) as they transition from the role of a student to the role of a professional. It sponsors non-technical workshops and meetings that provide professional development and networking opportunities for young professionals, collaborates with other Divisions and Groups in developing technical and non-technical content for topical and national meetings, encourages its members to participate in the activities of the Groups and Divisions that are closely related to their professional interests as well as in their local sections, introduces young members to the rules and governance structure of the Society, and nominates young professionals for awards and leadership opportunities available to members.
Meeting Spotlight
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
Standards Program
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
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.
Keiichi Saito
Nuclear Science and Engineering | Volume 37 | Number 3 | September 1969 | Pages 380-396
Technical Paper | doi.org/10.13182/NSE69-A19114
Articles are hosted by Taylor and Francis Online.
Input-noise sources in at-power reactors are formulated under the basic assumption that a set of macrostochastic variables characterizing the state of the reactors has Markoffian properties. An input-noise source is defined as the ratio between the power-spectral density of fluctuations in the reactor-power level and the square modulus of the source-transfer function. Random birth and death processes of neutrons give rise to a “white” contribution to the input source. Additional contributions are found which have the break (roll-off) angular frequencies determined by the relaxation time constants of the feedback effects on reactivity. These “non-white” terms come from fluctuations in neutron-reaction cross sections caused by temperature variations. The ratio of the non-white to the white terms increases as the reactor power increases. It also depends on the magnitude of the reactivity coefficients of feedback. Before one evaluates the magnitude of the non-white noise term, however, there should be knowledge of some statistical parameters relating the noise to random emission of energy by nuclear fissions, random exchange between the fuel and the coolant in heat transfer reactions and random removal through the coolant flow. The formula for analyzing the power-spectral density of the temperature fluctuations is also derived where the same unknown statistical parameters appear. Measurements of both the power and the temperature fluctuations will serve to determine these parameters whereby one will be able to obtain better information on the time constant and the reactivity coefficient of each feedback effect.