| Summary: | Pursuant to a 1986 NRC ruling, the MIT Reactor (MITR) is planning on converting from
the use of highly enriched uranium (HEU) to low enriched uranium (LEU) for fuel. Prior
studies have shown that the MITR will be able to operate using monolithic U-Mo LEU
fuel while achieving neutron fluxes close to that of an HEU core. However, to date,
detailed studies on fuel management and burnup while using LEU fuel have not been
performed. In this work, a code package is developed for performing detailed fuel
management studies at the MITR that is easy to use and is based on state-of-the-art
computational methodologies.
A wrapper was written that enables fuel management operations to be modeled
using MCODE, a code developed at MIT that couples MCNP to the point-depletion code
ORIGEN. To explicitly model the movement of the control blades in the MITR as the
core is being depleted, a criticality search algorithm was implemented to determine the
critical position of the control blades at each depletion timestep. Additionally, a graphical
user interface (GUI) was developed to automate the creation of model input files. The
fuel management wrapper and GUI were developed in Python, with the PyQt4 extension
being used for GUI-specific features.
The MCODE fuel management wrapper has been shown to perform reliably
based on a number of studies. An LEU equilibrium core was modeled and burned for 640
days with the fuel being moved in the same pattern every 80 days. The control blade
movement and nuclide concentrations were shown to be in agreement with what one
would intuitively predict. The fuel management capabilities of REBUS-PC and the
MCODE fuel management wrapper were compared by modeling the same refueling
scheme using an HEU core. The element power peaking factors for the two models
showed remarkable agreement.
Together, the fuel management wrapper and graphical user interface will help the
staff at the MITR perform in-core fuel management calculations quickly and with a
higher level of detail than that previously possible.
|
|---|