Dissolution of ThO sub(2): study of dissolution process with initial super(229)Th spike

• Published in: Journal of radioanalytical and nuclear chemistry Vol. 311; no. 1; pp. 225 - 235
• Main Authors: Myllykylae, E, Lavonen, T, Koivula, L, Ollila, K, Siitari-Kauppi, M
• Format: Journal Article
• Language: English
• Published: 01.01.2017
• ISSN: 0236-5731; 1588-2780
• DOI: 10.1007/s10967-016-4991-2

The sparingly soluble ThO sub(2) dissolution behaviour was studied under conditions that are expected to prevail in bedrock after the closure of the spent nuclear fuel disposal facility. The objective was to investigate the characteristics of initial dissolution of crystalline super(232)ThO sub(2) by adding super(229)Th tracer to the aqueous phase in the beginning of the 534 days experiment.The evolution of super(232)Th concentration and super(229)Th/ super(232)Th ratio were followed by sector field ICP-MS (inductively coupled plasma mass spectrometer). Selected samples were measured also by alpha spectrometry to compare the results from the used analysis techniques and they gave comparable results. In the early stage of dissolution there was no significant control by chemical equilibrium and the dissolution process seemed to be controlled by the stability of surfaces.