The daily load follow capability of the Smart reactor core without the soluble boron change in the primary coolant

Smart is an integral pressurized water reactor which has a pressurizer, 8 steam generators and 4 reactor coolant pumps on the inside of the reactor vessel. The thermal power of the core is 330 MW. The core has 57 17 x 17 rectangular fuel assemblies with a 200 cm effective height and the core reactivity is controlled by 25 control rod assemblies and the soluble boron in primary coolant. The core power control is based on the predetermined core outlet temperature with ± 1.5 C allowance so that the pressure change of the pressurizer is minimized for the power variation. The capability of the load follow operation is evaluated for a daily load follow scheme of 12-3-6-3, the power variation of which is from 100% to 50%. The evaluation is performed by 3-dimensional core simulations with the xenon transient calculation for the beginning and the end of cycles. Three major parameters axial offset, radial and three dimensional peaking factors related to operation limits are analyzed. It shows that all of those are varied, within limits with enough margins, without the change of the soluble boron in the primary coolant but with the automatic control rod movement only. (Author)