The Liquidus Temperature of Nuclear Waste Glasses: An International Round‐Robin Study

Eight institutions from four countries participated in a round‐robin study to determine the precision and bias of a liquidus temperature ( T _L ) procedure for waste glasses being adopted by ASTM International as ASTM C 1720‐11. The participants of the round‐robin study were asked to measure three different glasses with one or a combination of the following T _L measurement methods: a gradient temperature ( GT ) method, a uniform temperature ( UT ) method, and/or a crystal fraction extrapolation ( CF ) method. The T _L values reported by different institutions are generally consistent. The precision of T _L measurements with each method was evaluated and is presented herein. The round‐robin glasses were all previously studied at Pacific Northwest National Laboratory and included ARG ‐1 (Glass A), Zr‐9 (Glass B), and AmCm2‐19 (Glass C), with measured T _L values spanning the temperature range of 960–1240°C. A precision (i.e., standard deviation) for T _L has been obtained from the data, even though the data were not acquired for all three glasses using all three methods from each participating organization. Also, the article provides a brief overview and the importance of the T _L measurement.