ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Division Spotlight
Fuel Cycle & Waste Management
Devoted to all aspects of the nuclear fuel cycle including waste management, worldwide. Division specific areas of interest and involvement include uranium conversion and enrichment; fuel fabrication, management (in-core and ex-core) and recycle; transportation; safeguards; high-level, low-level and mixed waste management and disposal; public policy and program management; decontamination and decommissioning environmental restoration; and excess weapons materials disposition.
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!
Latest Magazine Issues
Apr 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
May 2025
Nuclear Technology
April 2025
Fusion Science and Technology
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.
Jean-Paul Deffain, Philippe Alexandre, Paul Thomet
Nuclear Technology | Volume 127 | Number 3 | September 1999 | Pages 267-286
Technical Paper | Fission Reactors | doi.org/10.13182/NT99-A3001
Articles are hosted by Taylor and Francis Online.
This feasibility study on core control using only the control rods is conducted with the TOPAZE algorithm - implemented in the CRONOS2 core calculation code - in its two versions: version 1 (minimization of the two-dimensional peak, imposed axial offset) and version 2 (minimization extended to three-dimensional, without imposed axial offset). The sensitivity analysis on the power peaks was carried out on the variations of the axial height of the burnable poisons and the type of grey or black control rod clusters. It is demonstrated that the reduction in the number of rod cluster controls allows a correct smoothing of the reactivity over the whole cycle, except for the end of cycle when control rods are moved upward.For load follow feasibility studies, several approaches, based on simulations performed with MISRITME have been evaluated: variation of the primary flow rate for axial offset control; use of a program, with temperature decreasing with the power; and finally, coupling of a temperature range, centered on a reference temperature with a negative gradient, to the French N4 reactor control mode Dispositif de Manoeuvrabilité Accrue: X (DMAX). It is shown that the return to equilibrium following a low threshold of 40% induces an additional penalty between 15 and 20% on the power peak. Solutions are suggested to globally reduce these peaks, which appear during all operating conditions.Two types of reactivity-induced accidents linked to clusters are studied: the removal of a rod cluster control assembly (RCCA) at full power (class III) and the ejection of a RCCA (class IV). It is also shown that ejection at zero power, with a released reactivity of 1.86 $, does not cause major damage to cladding and fuel. However, at full power, with the assumptions made, a partial melting of the pellet occurs without however creating fuel dispersion in the coolant.