Lattice thermal expansions of NpN, PuN and AmN

Thermochemical and thermophysical properties of minor actinide compounds

“…The thermal expansions of NpN, PuN and AmN were determined from the temperature dependence of the lattice parameters measured by the high-temperature X-ray diffractometry [16]. The diffractometer installed in a glove box with a purified argon gas atmosphere was used to prevent the samples from hydrolysis and/or oxidation during handling and measurements.…”

Thermal expansion of TRU nitride solid solutions as fuel materials for transmutation of minor actinides

“…Details of the method and purity of the oxides were described elsewhere [4]. To prepare the solid solution samples of (Np,Am)N and (Pu,Am)N, the single-component nitrides were mixed at the Np/Am and Pu/Am atomic ratios of unity, and then compacted into tablets at a pressure of 200 MPa.…”

“…The goniometer installed in a glove box with purified argon atmosphere was employed to avoid the hydrolysis and oxidation of samples during handling and measurements. Details of the technique were described elsewhere [4]. The atmosphere of the sample chamber was kept with the N 2 + 4%H 2 mixed gas flow of 500 ml/min purified by passing through the columns of moisture and oxygen absorber.…”

“…Although a dilatometer is applied to measure the thermal expansion of a bulk specimen directly, the thermal expansion of crystal lattice measured by a high temperature X-ray diffraction (XRD) method is more fundamental data to understand the expansion behavior. Recently we have succeeded in measuring the lattice thermal expansion of NpN, PuN and AmN [4]. Since the MA-bearing nitride fuel will consist of the solid solution among actinide mononitrides, the composition dependence of thermal expansion is the subject to be investigated.…”

“…together with the lattice parameters a 293 at the reference temperature 293 K, and the upper limit of temperature range, T max . The maximum deviation from the fitted curve was 0.00008 nm for (Pu 0.59 Am 0.41 )N at 1375 K, and within 0.00004 nm for the other data points.The values of a 293 for the solid solution samples were compared with those calculated by the Vegard's law using the lattice parameters of the constituent nitrides: namely 0.48956, 0.49050, 0.49915 nm for NpN, PuN, AmN, respectively[4], 0.5027 nm for CmN[8], and 0.45763 nm for ZrN obtained in this work. Thea 293 values for (Np 0.55 Am 0.45 )N, (Pu 0.59 Am 0.41 )N and (Np 0.21 Pu 0.52 -Am 0.22 Cm 0.05 )N agreed reasonably with the calculated values of 0.4939, 0.4940 and 0.4928 nm, respectively.…”