Closure of HLW Tanks Formulation for a Cooling Coil Grout

Abstract

The Tank Closure and Technology Development Groups are developing a strategy for closing the High Level Waste (HLW) tanks at the Savannah River Site (SRS). Two Type IV tanks, 17 and 20 in the F-Area Tank Farm, have been successfully filled with grout. Type IV tanks at SRS do not contain cooling coils; on the other hand, the majority of the tanks (Type I, II, III and IIIA) do contain cooling coils. The current concept for closing tanks equipped with cooling coils is to pump grout into the cooling coils to prevent pathways for infiltrating water after tank closure. This task addresses the use of grout to fill intact cooling coils present in most of the remaining HLW tanks on Site. The overall task was divided into two phases. Phase 1 focused on the development of a grout formulation (mix design) suitable for filling the HLW tank cooling coils. Phase 2 will be a largescale demonstration of the filling of simulated cooling coils under field conditions using the cooling coil grout mix design recommended from Phase 1.

Closure of HLW Tanks Phase 2 Full Scale Cooling Coils Grout Fill Demonstations

“…A unique characteristic of this grout is that it has a fairly long working time such that its physical properties change little over an extended period of time. The rheological properties, both yield stress and plastic viscosity, over a period of 90 minutes of continuous mixing, were essentially constant [5]. This grout also satisfied the piping pressure limit of 150 psig established by B. J. Adkins [4] during grout fill, for 1200 linear feet of 2" schedule 40 piping.…”

“…This data compares well to that of the pressure data. The grout density data from bench scale testing is 2.07 g/ml [5]. The density data indicates that the samples, as well as the bench scale are similar, but all the discharge samples were lower in value than the baseline and bench samples, indicating that the discharge samples had slightly more entrained air or voids.…”

“…The cooling coil grout composition and physical properties are provided in Table 2-1 [5]. This grout satisfies the processing requirements [1][2][3].…”

“…The wt% WC was used to provide information on the grout contents in the cooling coils relative to the batched grout at the mixer and on the length of the mixing zone between the grout and the water that was initially in the cooling coils. The density measurements were performed to compare the bench scale [5] result to the process results.…”

“…The overall task was divided into two phases. The first phase was the development of a grout formulation that satisfies the processing requirements for filling the HLW tank cooling coils [5]. The second phase of the task, which is documented in this report, was the filling of full scale cooling coils under simulated field conditions using the grout formulation developed in the first phase.…”