Measurement of Thermal and Mechanical Properties of Gd_2O_3-dispersed UO_2 Fuel for a Resource Saving and High Economic Efficient Nuclear Reactor.

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17360458
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear engineering
• Research Institution: Nagoya University
• Principal Investigator: MATSUI Tsuneo Nagoya University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (90135319)
• Co-Investigator(Kenkyū-buntansha): NAGASAKI Takanori EcoTopia Science Institute, Professor, エコトピア科学研究所, 教授 (40273289) ; ARITA Yuji EcoTopia Science Institute, Associate Professor, エコトピア科学研究所, 助教授 (50262879) ; IWASAKI Kouta Graduate School of Engineering, Associate Professor, 大学院工学研究科, 助手 (90359753)
• Project Period (FY): 2005 – 2006
• Keywords: oxide fuel / particle dispersion / thermal conductivity / UO_2 / Gd_2O_3

Research Abstract

The improvement in the thermal conductivity of nuclear fuels is important for raising the generating efficiency. In a light-water nuclear reactor, Gd_2O_3-doped UO_2 fuels, in which Gd_2O_3 works as a burnable poison, are used to control the early reactivity, although Gd_2O_3-doped UO_2 has a disadvantage of lower thermal conductivity than UO_2. High burnup fuels can be obtained by an increase in uranium enrichment, however, the enrichment also causes the decrease in the thermal conductivity of fuel pellets because of the increase in Gd_2O_3 content. In the present study, we prepared Gd_2O_3-dispersed UO_2 pellets, in which Gd_2O_3 particles dispersed in UO_2 matrix, and investigated the thermal and mechanical properties to evaluate the effectiveness as a new-type nuclear fuel.
10 wt.% Gd_2O_3-dispersed UO_2 was obtained by sintering the mixture of Gd_2O_3 particles and UO_2 powder at 2013K for 4h. The thermal conductivity (K) of Gd_2O_3-dispersed UO_2 decreased with increasing temperature in the temperature range of 300【less than or equal】T【less than or equal】1373 K. k was lager than that of 10 wt.% Gd_2O_3-doped UO_2, and the value was at most 1.5 times that of the Gd_2O_3-doped UO_2. The behavior (value and temperature dependence) of 10 wt.% Gd_2O_3-dispersed UO_2 was corresponding to that of 3 wt.% Gd_2O_3-doped UO_2. The Gd_2O_3-dispersed UO_2 pellet did not fracture when heated up to 2793 K at a rate of 40 K/s.
In the present study, it was found that the thermal conductivity of Gd_2O_3-dispersed UO_2 was larger than that of Gd_2O_3-doped UO_2, and that Gd_2O_3-dispersed UO_2 pellets had enough mechanical properties for practical use. These results are expected to contribute to the development of high burnup fuels and the reduction in generating cost.