Impact of weight percent gadolinium and the number of its fuel rods on the neutronic and safety parameters. (November 2021)

• Record Type: Journal Article
• Authors: Uguru, Edwin Humphrey; Bin Ahmad Sapli, Mohd Faiq; Sani, S.F. Abdul; Khandaker, Mayeen Uddin; Rabir, Mohamad Hairie; Karim, Julia Abdul; Bradley, D.A.
• Is Part Of: Radiation physics and chemistry. Volume 188(2021)
• Publication Date: 2021-11
• Subjects: Gadolinium -- Neutronic -- Reactivity -- Safety parameters -- Small modular reactor -- Thorium; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2021.109686
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: Control of neutron multiplication in a nuclear reactor is fundamental in achieving stable reactor power. The present study has sought to determine the impact of gadolinium weight percent (w/o) in respect of the number of fuel rods on the neutronic and safety parameters of (Th, U)O2 fuel in a Westinghouse small modular reactor. The MCNPX 2.7 integrated with CINDER90 fuel depletion code was used. The results show that the k-infinite and reactivity swing peak decrease with increasing gadolinium weight percent, with the highest and lowest k-infinite recorded in the fuel assembly containing zero (0) and 12 w/o, respectively. The largest and lowest reactivity swing curve occurs in the fuel assembly with 3.6 and 12 w/o at ~15 and ~35 GWd/THM, respectively. It shows that the impact of gadolinium w/o and the number of fuel rods on k-infinite follow similar trend. Conversely, the reactivity swing curve is observed to flatten with increasing gadolinium w/o but increases with increase in the number of gadolinium burnable absorber fuel rods. These phenomenological variations suggest that flat reactivity swing and power control can be achieved within 9.2–12 w/o gadolinium although not without economic penalty on fuel utilisation. Highlights: The reactivity swing-peak decreases with gadolinium weight percent. Reactivity swing curve increases with increasing number of gadolinium fuel rods. Large gadolinium weight percent impacts negatively on FTC. Large gadolinium weight percent impacts positively on MTC. Gadolinium is not economically viable at and above 12 w/o.