Convergence Studies using Method of Characteristics Solver for the Reduced-Moderation Water Reactor Model


Convergence studies and Sensitivity analyses are an important computational objective required for observing the fuel behaviour with respect to the reactor physics integration parameters. In this paper, reactor physics integration parameters have been analysed for the Reduced-Moderation Water Reactor (RMWR) using method of characteristics (MoC) deterministic code WIMS in order to observe the effect on criticality while investigating the sensitivity of these parameters. The efficient converged results of RMWR lattice can be obtained by using the higher angular approximation. Sensitivity analyses are, therefore, performed for the candidate fuels: Pu-UO2 and Th-UO2 for the RMWR fuel assembly. Deterministic code WIMS solves the multigroup neutron transport equations using a characteristics method that integrates the transport equation over characteristic directions. WIMS integrates the differential form of the Boltzmann transport equation along explicit tracks through the geometry which goes in a straight line; reflect off the sides of the model. This characteristics method can be utilised only to those geometries for which tracking routines can be written. Therefore, this paper investigates and discusses the effect of various integration parameters such as mesh, polar angle, azimuthal angle and tolerance on criticality value in WIMS. Two types of RMWR fuel assembly models: 1D Axial slab model and 3D lattice models are investigated for this Convergence studies in order to observe the consistency/discrepancy of the integration parameters.

Meeting Name

2018 Pacific Basin Nuclear Conference, PBNC 2018 (2018: Sep. 30-Oct. 5, San Francisco, CA)


Nuclear Engineering and Radiation Science

Keywords and Phrases

3D modeling; Boltzmann equation; Criticality (nuclear fission); Experimental reactors; Fuels; Integration; Plutonium compounds; Sensitivity analysis; Thorium compounds; Uranium dioxide; Azimuthal angle; Boltzmann transport equation; Characteristics method; Differential forms; Method of characteristics; Neutron transport equation; Reduced moderation water reactors; Transport equation; Light water reactors

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Document Type

Article - Conference proceedings

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© 2018 PBNC 2018 - Pacific Basin Nuclear Conference, All rights reserved.

Publication Date

01 Sep 2018