Impact of control rod adjustment on core neutronics during irradiation

In recent years, due to the development of boron-free PWRs (in the form of SMRs), there has been a growing interest to assess in the impact of control rod position history on core neutronics [1], [2].
Similarly to boron-free SMRs (of the PWR type), fast reactors do not use a homogeneous reactivity-control approach, resulting in control rods being the only control means for these reactors. Due to the tight spatial neutronic coupling of fast neutron reactor cores, there are uncertainties regarding whether the impact of long-term control rod insertion will remain localized or not.
Recent developments in the Monte-Carlo transport code OpenMC provide the capability of performing depletion calculations coupled to criticality searches to ensure that control rods stay at a critical height throughout the cycle. 
The project’s objective is to leverage this capability to assess the impact of control rod’s position history on the core neutronics of a Lead Fast Reactor (LFR). This will be achieved by comparing:
•    depletion calculations where the control rod height isn’t adjusted despite the fuel burn-up and the fission products poisoning, which corresponds to the typical approach used in reactor design,
•    and controlled depletion calculations, where at each depletion step the control rod height is adjusted to ensure criticality. 
The impact of these two different depletion schemes will be assessed by a differential analysis of some figures of merit, for example:  integral parameters (such as reactivity, cycle length); local quantities (such as actinide and fission products inventory at the assembly level and the power distribution); reactor safety parameters, (such as the temperature coefficients).
Emphasis will be placed on explaining the causes of the observed difference in the parameters studied, with the goal to extrapolate this knowledge to different LFR designs or other types of fast reactors. 
The student is expected to perform the simulations and the analysis of the results, and to develop the tools necessary for the post-processing of simulation data for the analysis.

[1] P. Devaux, « Développement d’un schéma de calcul neutronique pour la modélisation du pilotage des SMR (Small Modular Reactors) sans bore soluble », Thèse, Université Grenoble Alpes, 2022. 
[2] M. Guyot et V. Gautier-Ottou, « Impact of control rod history on physics parameters in a soluble- boron-free small-sized pressurized water reactor », proceedings M&C 2019 2019, p. 1562‑1571.

Het vereiste minimumdiploma van de kandidaat

• Master in de ingenieurswetenschappen

De vereiste achtergrondkennis van de kandidaat

• Nuclear reactor physics

Geschatte looptijd

Integrated in the BNEN programme.