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The corrosion results in not only material degradation but also causes CRUD generation in the primary coolant. The axial offset anomaly (AOA) or CRUD Induce Power Shift (CIPS) is caused by CRUD accumulation on the fuel assemblies. It also causes an increase in Occupational Radiation Exposure (ORE). Therefore, in this work, activated CRUD behavior due to 54Mn, 59Fe, 58Co, 60Co, and 51Cr has been studied under primary coolant flow transient and power perturbations in a System Integrated Advanced and Modular Reactor (SMART). The “Activated CRUD particles” ACP-SMART code is used to study the primary coolant activity under parabolic corrosion rate. The SMART reactor core has been modeled in OpenMC, and respective group fluxes have been generated. The ACP-SMART, coupled with OpenMC, is modeled and implemented in MATLAB. A dynamic grid load following model and a kinetic coastdown model is implemented in ACP-SMART in terms of the ratio of the coolant kinetic energy and the kinetic energy stored in the rotating parts of a pump (β). The response of 54Mn, 59Fe, 58Co, 60Co, and 51Cr activity in primary coolant due to linear, monotonically, and asymptotically coastdown has been investigated. The 59Fe and 54Mn showed higher sensitivity relative to the 58Co, in primary coolant activity corresponding to the dynamic grid load following. However, the 59Fe and 58Co activities are more sensitive to coastdown. Nearly all the radioisotopes showed similar behavior under monotonic flow perturbation. 58Co and 54Mn have shown a catastrophic behavior in the primary coolant activity under asymptotically coastdown.

The existing commercial nuclear power plants (PWR and BWR) utilize the oxide fuels, i.e., UO2. This fuel selection is not questionable, where the safety and economy are the top priority in the nuclear industry. In this work, the potential advantages of microencapsulated fuels to System Integrated Modular Advanced Reactor “SMART” has been explored. The UN and UCO have been considered as the candidate fuel material for the SMART reactor. The detailed design and fuel assembly configurations with different fuel types of the SMART reactor have been investigated for criticality with depletion (burn up), fuel and moderator temperature coefficients, and power peaking factor using OpenMC. The fissile and fertile fuel elements with coated particles are embedded in graphite matrices. The results are presented with a review of attributes and potential benefits. The nitride fuel has an advantage of mechanical stability, enhanced thermal conductivity, and high fuel density compared to dioxide fuel (UO2). The melting point of standard fuel, UN, and UCO are similar. Thus, they have higher safety margins under NPP's operating conditions. Therefore, nitride (UN) and carbide (UCO) fuel types are more attractive than standard uranium oxides because they are safer and beneficial. The dioxide fuel (UO2) is considered as the reference and compared with candidate material. The neutronic assessment within SMART core specification examined the effective multiplication factor, thermal flux distribution, axial and radial power distribution, and power peaking factor at the beginning, and end of the fuel cycle.