The Application of the Physicochemical Properties of Boiling Bitterns to the Interpretation of Brine Migration Experiments Related to Salt Repositories

Abstract

An important unresolved question with respect to employing mined cavities in bedded rock salt as high level radioactive waste repositories concerns the behavior of small quantities of included bittern brines (Mg, Na, K, Ca//C1, SO₄, Br-H₂O). These bittern brines have been shown to migrate at significant rates under the influence of a thermal gradient such as would be imposed by emplacement of high level waste (1). However, present estimates of the rate of migration of the bitterns range considerably because there is a lack of physicochemical data at the relevant compositions, concentrations, temperatures and pressures to solve the rate equations. This lack of appropriate physicochemical data for bitterns saturated with halite and the failure of theoretical models to address movement along grain boundaries have emphasized the need for field and large scale laboratory tests to measure the rate and quantities of brine which actually arrive at an individual waste canister (2, 3). In this report we present experimental data applicable to interpretation of the results of field and large-scale laboratory tests aimed at quantifying the brine migration phenomenon.