Boildown Study on Supernatant Liquid Retrieved from AP-107 in May 2010

A boildown study was completed on a composite prepared from supernatant liquid grab samples retrieved from tank 241-AP-107 in May of 2010. The composite was a clear, yellow liquid containing no visible solids at hot cell ambient temperatures (25-27 °C). The density of the test composite was 1.216 g/mL at 26.8 °C. The boiling temperature curves generated at three reduced pressures—40-, 60-, and 80 Torr—displayed steadily increasing boiling temperatures with increasing volume reduction with no significant discontinuities. Only minimal foaming was observed after the volume reduction proceeded beyond 50 %WVR (percent waste volume reduction). The bulk densities (D{sub Bulk}{sup 18 °C}) and quantities of settled and centrifuged solids present were measured on samples of the boildown concentrates that were kept at 18 °C for 7-8 days. Estimated values of the bulk densities of the concentrates at 60-Torr boiling temperatures (D{sub Bulk}{sup 60 Torr}) were also calculated. Solids were observed in all boildown concentrates at process temperatures, at hot cell ambient temperatures (25-27 °C), and at 18 °C. The quantity of solids found in the cooled concentrates increased slowly through 50.2 %WVR. The quantity of solids found in concentrates after 54.0 %WVR was noticeably greater. Beyond 54.0 %WVR, the quantity of solids found in cooled concentrates increased dramatically. Analysis of boildown test samples indicated that sodium oxalate and sodium carbonate solids form in cooled concentrates after volume reduction of 8.4 %WVR or less. The major contributors to the large increase in the quantity of solids found in concentrates after 54 %WVR were sodium nitrate and sodium carbonate