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
Robotics & Remote Systems
The Mission of the Robotics and Remote Systems Division is to promote the development and application of immersive simulation, robotics, and remote systems for hazardous environments for the purpose of reducing hazardous exposure to individuals, reducing environmental hazards and reducing the cost of performing work.
Meeting Spotlight
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
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
June 2025
Nuclear Technology
Fusion Science and Technology
May 2025
Latest News
Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
E. Bomboni, N. Cerullo, G. Lomonaco
Nuclear Science and Engineering | Volume 162 | Number 3 | July 2009 | Pages 282-298
Technical Note | doi.org/10.13182/NSE162-282
Articles are hosted by Taylor and Francis Online.
The pebble bed gas-cooled reactor is one of the most promising concepts among the Generation III+ and Generation IV reactors. Currently, the pebble bed modular reactor (PBMR) design, both U and Pu and minor actinide fueled, is being developed. Modeling the arrangement of coated particles (CPs) inside a spherical region like a pebble seems to be an important issue in the frame of calculations. To use the (relatively) old Monte Carlo codes without any correction, some approximations are often introduced. Recent Monte Carlo codes like MCNP5 and some new original subroutines that we have developed allow the possibility of obtaining more detailed and more physically correct geometrical descriptions of this kind of system. Some studies on modeling pebbles and pebble bed cores have already been carried out by other researchers, but these works are substantially limited to AVR-type UO2-fueled pebbles. However, the impact of approximated models on fuel mass, reactivity, and reactor life prediction has not yet been investigated for new PBMR-type pebbles.At the same time, an assessment of introducing a stochastic CP arrangement is not so widespread. Analyzing two PBMR pebbles, one Pu- and the other U-fueled, this paper focuses on quantifying errors due to the different approximations generally used to describe the CP lattice inside a high-temperature reactor pebble bed core, as far as mass of fuel, reactivity, and burnup simulation are concerned. This aim was reached also through a new feature implemented in the MCNP5 code, i.e., capability to treat (pseudo) stochastic geometries. Later, we compared the initial mass of fuel, keff, and isotopic evolution versus burnup of some approximated pebble models with the reference model, built by means of this new MCNP5 feature.