A.N. Shirsat

Thermodynamic stability of RuTe2 solid by vapor pressure study

Abstract The vaporization behavior of the intermetallic compound RuTe 2 (s) was studied in the temperature range of 831–1148 K by the Knudsen effusion technique. As a prerequisite to the study, the nature of the vaporization equilibrium was first obtained. Phase analysis of the partially evaporated sample of RuTe 2 (s) from thermogravimetric experiment carried out in inert environment showed the TG residue to be a biphasic mixture of Ru(s) and RuTe 2 (s). This result together with the available thermodynamic information of Te vapor revealed that the compound incongruently volatilize as RuTe 2 (s)=Ru(s)+Te 2 (g). The equilibrium vapor pressure of Te 2 (g) derived from the measurement at the different temperatures could be expressed as ln( p /Pa)(±0.33)=−33231.2/ T +33.67 (831≤ T /K≤1148). The result of this study is discussed in the light of the reported data on the intermetallic compound.

Transport Properties of Gaseous and Volatile Fission Products in Thoria-based Fuels

Transport properties of gaseous and volatiles that constitute a significant fraction of the total fission products (FPs) in high burnup matrix play important role in the performance of nuclear fuel. The transport decides release and retention behaviors of the FPs and in turn governs the matrix swelling and mechanical interaction with clad. A detailed understanding of the various factors involved in the overall transport process of the individual species inside a dense fuel matrix is necessary in predicting the performance of a fuel in high burnup. An introduction to the well-established factors governing the thermal and athermal transports of gas and volatile FPs in the conventionally used urania-based fuels in high burnup is made at the beginning of this chapter, before elaborating the case of thoria-based fuels. The experimentally measured diffusion properties of xenon, and corrosive volatile like iodine and tellurium inside thoria-based matrices, virgin as well as high burnup Simfuel, are included in the elaboration. The transport properties of the species are closely compared for the two fuels in order to understand their relative performances in high burnup situation. The knowledge of high burnup performance is particularly important for the thoria-based fuel that has limited recycling option due to the handling problems of high activity from hard gamma emitting daughters.