Neutronics design of VVER-1000 fuel assembly with burnable poison particles

• Published in: Nuclear engineering and technology Vol. 51; no. 7; pp. 1729 - 1737
• Main Authors: Tran, Hoai-Nam, Hoang, Van-Khanh, Liem, Peng Hong, Hoang, Hung T.P
• Format: Journal Article
• Language: Korean
• Published: 2019
• Subjects: Burnup reactivity; VVER-1000; Power peaking factor; Burnable poison; Fuel assembly
• ISSN: 1738-5733; 2234-358X

This paper presents neutronics design of VVER-1000 fuel assembly using burnable poison particles (BPPs) for controlling excess reactivity and pin-wise power distribution. The advantage of using BPPs is that the thermal conductivity of BPP-dispersed fuel pin could be improved. Numerical calculations have been conducted for optimizing the BPP parameters using the MVP code and the JENDL-3.3 data library. The results show that by using $Gd_2O_3$ particles with the diameter of $60{\mu}m$ and the packing fraction of 5%, the burnup reactivity curve and pin-wise power distribution are obtained approximately that of the reference design. To minimize power peaking factor (PPF), total BP amount has been distributed in a larger number of fuel rods. Optimization has been conducted for the number of BPP-dispersed rods, their distribution, BPP diameter and packing fraction. Two models of assembly consisting of 18 BPP-dispersed rods have been selected. The diameter of $300{\mu}m$ and the packing fraction of 3.33% were determined so that the burnup reactivity curve is approximate that of the reference one, while the PPF can be decreased from 1.167 to 1.105 and 1.113, respectively. Application of BPPs for compensating the reduction of soluble boron content to 50% and 0% is also investigated.