Thermophysical properties of U3Si2 to 1773 K

Abstract

a b s t r a c tUse of U 3 Si 2 in nuclear reactors requires accurate thermophysical property data to capture heat transfer within the core. Compilation of the limited previous research efforts focused on the most critical property, thermal conductivity, reveals extensive disagreement. Assessment of this data is challenged by the fact that the critical structural and chemical details of the material used to provide historic data is either absent or confirms the presence of significant impurity phases. This study was initiated to fabricate high purity U 3 Si 2 to quantify the coefficient of thermal expansion, heat capacity, thermal diffusivity, and thermal conductivity from room temperature to 1773 K. Datasets provided in this manuscript will facilitate more detailed fuel performance modeling to assess both current and proposed reactor designs that incorporate U 3 Si 2 .

Critical evaluation and thermodynamic optimization of the (U + Bi), (U + Si) and (U + Sn) binary systems

“…The optimised heat capacities of intermetallic compounds in the present work are shown in figure 5, with the reported experimental data of White et al [43,44]. The heat capacities of aU 3 Si, bU 3 Si, and U 3 Si 5 were optimised on the base of the reported experimental values from White et al [43,44]. Heat capacities of the remaining compounds USi 3 , U 3 Si 2 , U 5 Si 4 , USi, U 9 Si 17 (USi 1.88 ) and USi 2 were determined using the Neumann-Kopp rule [64] guided by the known heat capacity data of aU 3 Si, bU 3 Si, and U 3 Si 5 .…”

“…As mentioned in section 2.2, a further experimental work is required to verify the existence of USi 2 and U 5 Si 4 . The optimised heat capacities of intermetallic compounds in the present work are shown in figure 5, with the reported experimental data of White et al [43,44]. The heat capacities of aU 3 Si, bU 3 Si, and U 3 Si 5 were optimised on the base of the reported experimental values from White et al [43,44].…”

“…However, further careful thermodynamic modelling of the (U + Si) binary system is still required, due to the omission of phases USi 2 [32,33] and U 4 Si 5 [14] in the previous calculated phase diagram by Berche et al [14]. The same is true for the recently reported heat capacity data of White et al [43,44].…”

“…O'Hare et al [42] reported the enthalpy of formation of U 3 Si as (À26.05 ± 4.8) kJ Á molatom À1 using fluorine bomb calorimetry. Recently, the heat capacities of compounds U 3 Si and U 3 Si 5 were investigated by White et al [43,44]. There are no experimental data reported for the thermodynamic properties of the liquid phase.…”

The Future of Low-Carbon Electricity

“…These materials aim to increase high-temperature steam oxidation resistance versus the reference zirconium-based cladding materials that failed at Fukushima (43). In addition, high-performance fuel materials that enhance thermal properties are under consideration (44), such as thermal diffusivity, and improved retention of radioactive fission products (45), aiming to increase safety in severe accidents. The development of new materials for the extreme environment of a nuclear reactor is aiming to solve various scientific, regulatory, and operational challenges (39).…”