A computer-controlled apparatus for performing pressure–composition–temperature measurements on metal hydrides with protium, deuterium, and tritium

Abstract

An apparatus for measuring protium, deuterium, and tritium pressure–composition–temperature (PCT) thermodynamic equilibrium behavior on metal hydrides has been designed, constructed, and operated with deuterium at the Weapons Engineering Tritium Facility at Los Alamos National Laboratory. The apparatus is capable of performing PCT measurements with the three hydrogen isotopes at a maximum pressure of 3.45 MPa, and sample temperatures in the range 25–300 °C. A personal computer that controls the system provides the capability for manual or automated operation. Two deuterium PCT isotherms on palladium at 51 and 70 °C were measured with the apparatus in the automated mode to demonstrate its operation. Comparison of the resulting isotherms with literature data showed a plateau pressure at 70 °C in close agreement with the literature value (57.06 kPa versus literature value of 57.33 kPa). The deuterium capacity at 70 °C in palladium at the high end of the isotherm was measured both by the PCT apparatus and by weighing the sample before and after the PCT measurement. The deuterium capacity determined by the PCT apparatus (D/M=0.624 at 144.52 kPa) agreed well with the value determined by the weight difference measurement (D/M=0.628, at 144.52 kPa). These values agreed closely with the literature value (D/M=0.629 at 144.52 kPa).