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Nuclear Science and Engineering
Fusion Science and Technology
The blossoming of cooperation between the U.S. and Canada
The United States and Canadian nuclear industries used to be an example of how two independent teams of engineers facing an identical problem—making electricity from uranium—could come up with completely different answers. In the 1950s, Canada began designing a reactor with tubes, heavy water, and natural uranium, while in the U.S. it was big pots of light water and enriched uranium.
But 80 years later, there is a remarkable convergence. The North American push for a new generation of nuclear reactors, mostly small modular reactors (SMRs), is becoming binational, with U.S. and Canadian companies seeking markets and regulatory certification on both sides of the border and in many cases sourcing key components in the other country.
Kyle Remley, Farzad Rahnema
Nuclear Science and Engineering | Volume 183 | Number 2 | June 2016 | Pages 161-172
Technical Paper | doi.org/10.13182/NSE15-97
Articles are hosted by Taylor and Francis Online.
This paper presents a formulation for a method for the adaptive selection of angular flux expansion orders for use in COarse MEsh radiation Transport (COMET) method solutions to whole-core reactor problems. An important aspect of the COMET method is an assumed angular flux expansion on mesh interfaces. Previously, this expansion was held constant throughout a problem. However, the adaptive method described in this paper chooses the angular flux expansions automatically and allows them to vary between meshes. To demonstrate the method, a pressurized water reactor benchmark problem with UO2 and mixed oxide fuel assemblies is solved. Three different configurations for different insertions of control rods were considered. For all configurations, the agreement between the standard and adaptive COMET solutions was excellent, with eigenvalue agreement being 2 pcm or less and average pin fission errors never exceeding 0.1%. Increases in computational efficiency by factors of 2 to 2.6 were observed over standard COMET solutions employing the full flux expansion considered in the problem. In addition, a lower flux expansion suggested by literature as well as the results of the adaptive calculation was used in the standard COMET method to solve the problem. The adaptive COMET solution has a run time similar to this lower expansion, which is to be expected since many of the flux expansions chosen with the adaptive method match this lower flux expansion. The results of this study are encouraging and imply that adaptive COMET solutions improve upon the standard method by increasing computational efficiency when a flux expansion is used that is higher than required for desired accuracy. The method also limits the need for intuition and numerical experimentation in achieving flux expansions that result in COMET calculations that achieve satisfactory accuracy.