Monte Carlo analysis of the CROCUS benchmark on kinetics parameters calculation

Comparison of Direct and Adjoint k and α-Eigenfunctions

“…An application related to the effective kinetics parameters is the estimation of the reactor period and the sub-criticality level of the system. Both quantities can also be measured during experiments by the pulsed neutron source method [1] and reactor noise analysis methods [2,4]. The choice of the optimal adjoint weighting function (ϕ † α or ϕ † k ) in order to compare the results computed from numerical simulations to those obtained from measurements depends on the procedure and the techniques adopted during the experiment.…”

“…A preliminary comparison for this facility between fundamental α-eigenp time dependent calculations has been carried out in [26]. Moreover, the kinetics ters of the CROCUS core for the k-eigenvalue formulation has been previously co in [4] and the associated reactivity was examined in [27]. In the following, we w tigate the behaviour of the fundamental forward and adjoint modes of the k and lations for this core, and we will then examine the impact of their respective shap kinetics parameters and on the reactivity.…”

“…The fundamental eigenmodes will puted by using TRIPOLI-4 ® over 111 energy meshes and along 14 fuel pin positio the core center to the outer region, denoted by the red rectangular regions in Figu number of cycles and the particles per cycle simulated for these configurations a in Table 16 for the forward simulations and in Table 17 for the adjoint simulation A preliminary comparison for this facility between fundamental α-eigenpairs and time dependent calculations has been carried out in [26]. Moreover, the kinetics parameters of the CROCUS core for the k-eigenvalue formulation has been previously computed in [4] and the associated reactivity was examined in [27]. In the following, we will investigate the behaviour of the fundamental forward and adjoint modes of the k and α formulations for this core, and we will then examine the impact of their respective shapes on the kinetics parameters and on the reactivity.…”

“…Assessing the asymptotic behaviour of a nuclear system is intimately related to computing the dominant direct (Here and throughout the manuscript, the terms 'direct' and 'forward' are equivalently used.) eigenmode and the associated dominant eigenvalue of the configuration under analysis, which is central in several applications in reactor physics, including pulsed neutron reactivity measurements [1] and reactor period analysis [2][3][4]. Furthermore, for several key reactor coefficients, such as kinetics parameters, sensitivities to nuclear and material data, or perturbations [5][6][7][8][9][10], bilinear forms involving both the direct and the adjoint fundamental eigenfunctions are required.…”

Contribution to the verification of the MORET 5 code using the CROCUS reactor physics benchmark

“…Comparisons are made mainly on reactivity values with the Monte Carlo MCNP5 45 and MCNP6 codes using the ENDF/B-VII.0 evaluation for nuclear data, as well as 46 with TRIPOLI results (Zoia et al, 2016) using also a library based on the same 47 evaluation. The results using the data processed by MCNP are compared with those 48 using data processed with the homemade GAIA processing tool (Haeck et al, 2015).…”