GROUT TEMPERATURE MEASUREMENTS IN 105-R DISASSEMBLY BASIN D AND E CANAL

The 105-R Reactor Disassembly Basin Grout Placement Strategy Report (SRNL-TR-2009-00157) identifies various portions of the facility that will undergo an in-situ decommissioning process. The estimated residual radioactive contamination in the 105-R facility is shown in Figure 1. Cementitious grout formulations developed by SRNL are being used to immobilize and isolate the radioactive contamination in existing below grade portions of the 105-R building as shown by the gray-hatched area in Figure 2. A Zero Bleed flowable fill was formulated for both dry placement and for underwater placement. The first major area in the 105-R Disassembly Basin to undergo the grouting process was the D&E Canal and an underlying void space known as the Chase. Grout temperature data was needed to ensure that the grout mix design was on the correct grout curing trajectory to meet the material compressive strength requirement of 50 pounds per square inch. Initial grout temperature measurements were needed to confirm and optimize grout mix design fresh property characteristics; i.e. material strength, and set time. Grout curing temperature is an integrating fresh property characteristic that is used to estimate cementitious material strength in accordance with the Standard Practice for Estimating Concrete Strength by the Maturity Method, ASTM C 1074. The Maturity Method is used in the construction industry to estimate in-place strength of concrete to allow the start of critical construction activities; e.g. formwork removal, removal of cold weather protection, opening of roadways to traffic, etc. Applying this methodology provides an expeditious means to estimate in-place grout strength based on compressive strength laboratory results. The Maturity Method results define the relationship between strength-time and age-time that may be utilized in the field for estimating strength after a given time of placement. Maturation curves were developed under the 105-R Reactor Disassembly Basin Cementitious Materials Laboratory Test Plan (SRNL-TR-2009-00175) to establish grout mix maturation indices for this relationship. Temperature data collected from the D&E grout placement will be evaluated against these maturation indices in a subsequent analysis. Grout temperature data outside the maturation indices highlight the opportunity to adjust the grout mix design for future placements. The pre-existing grout placement will not be removed since this material will comply with strength requirements under the normal curing duration. SRNL designed a standalone measurement system to collect grout mass placement temperature data in the D&E Canal. Four vertical poles instrumented with thermocouples were positioned in the canal prior to grout placement. The thermocouples were connected to stand-alone, battery-powered data recorders mounted nearby that were configured to take temperature recordings every 10 minutes for up to 100 days. Unfortunately, after just 2 weeks, data collection was terminated because the thermocouple wires connecting the data loggers to the thermocouple poles were severed during construction activities. This report will highlight the unique challenges in designing a data collection system for the D&E canal, describe the temperature measurement system and its installation, and present calculated as well as measured temperature values