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
Education, Training & Workforce Development
The Education, Training & Workforce Development Division provides communication among the academic, industrial, and governmental communities through the exchange of views and information on matters related to education, training and workforce development in nuclear and radiological science, engineering, and technology. Industry leaders, education and training professionals, and interested students work together through Society-sponsored meetings and publications, to enrich their professional development, to educate the general public, and to advance nuclear and radiological science and engineering.
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.
J. P. Duarte, J. J. Rivero, P. F. Frutuoso E Melo, A. C. M. Alvim
Nuclear Technology | Volume 185 | Number 2 | February 2014 | Pages 109-126
Technical Paper | Reactor Safety | doi.org/10.13182/NT12-149
Articles are hosted by Taylor and Francis Online.
This paper develops a finite difference and a semianalytical model to evaluate the thermal behavior of fuel rods during a hypothetical reactivity-induced transient (absorber rod ejection) in a pressurized water reactor (PWR). The calculations are carried out for two different reactor core designs, namely, for a typical PWR core with typical fuel rods and for a modified PWR core containing annular fuel rods. The overall dimensions of the core internals and fuel assemblies are unchanged, and the total number of fuel assemblies is the same in both designs. The finite difference code was verified on the results provided by the semianalytical model. In the calculations, two point models were used (neutron kinetics to compute the fission power of the reactor; power balance of coolant in the active core region). The point models were coupled to the one-dimensional, finite difference heat conductivity model to calculate the radial temperature profile in the solid and the annular cylindrical pellets (UO2). The latter are the constituent part of annular fuel rods cooled both on their external and internal surfaces. The fuel, cladding, and fluid temperatures were evaluated for the annular and the solid fuel design in the hot spot, where the maximum allowable power rating of rods is 2.5 times higher than the average one. It was assumed that before the transient, (a) the reactor with annular fuel runs continuously at higher nominal power (150%) and at higher nominal coolant flow rate (150%) at the core inlet than the reference reactor with solid fuel (100%) and (b) the modified and the reference reactors have the same coolant temperature at the core inlet and the same temperature rise of coolant along their core. These conditions correspond to a 150% power uprate of the reference reactor. The coupled models require limited computational resources only. The calculated results showed that during the transient, in the annular fuel pellet, the temperatures peaked at considerably lower values, even at 150% power, than in the solid pellets at 100% power. These evaluations show that in the case of the reactivity-induced transient analyzed, the annular fuel cooled from both sides has a better safety performance than the solid fuel cooled only on its external surface.
