My research is focused on the chemical corrosion aspect of fuel performance modeling, such as cladding oxidation and CRUD formation. CRUD (Chalk River Undesirable Deposit) forms because iron and nickel ions and particulates enter the primary coolant due to the corrosion of the pressure vessel, steam generator tubes, pipes, valves, and other components. The iron and nickel deposit as CRUD on the upper region of the fuel rods where temperature is the greatest. CRUD is of concern for several reasons, one of which is CRUD Induced Power Shifts (CIPS), also known as Axial Offset Anomaly (AOA), which occurs in pressurized water reactors due to the boron that accumulates in the CRUD. Because boron is an effective neutron absorber, boric acid is added to the coolant in commercial pressurized water reactors to control reactivity. This boron becomes concentrated in the CRUD where it can depress the local neutron flux, causing power output to decrease in the upper core. AOA can often ultimately result in the down-rating of the reactor. I am working to further develop a chemistry code that models CRUD growth and composition called MAMBA (MPO Advanced Model for Boron Analysis). MAMBA works in conjunction with other codes to predict AOA.
Email: jrizk@vols.utk.edu