Grout Long Radius Flow Testing to Support Saltstone Disposal Unit 6 Design - 13352
- Savannah River National Laboratory, Savannah River Nuclear Solutions, LLC, Savannah River Site, Aiken, SC 29808 (United States)
- Savannah River Remediation, LLC, Savannah River Site, Aiken, SC 29808 (United States)
The Saltstone Facility, located within the Savannah River Site (SRS) near Aiken, South Carolina, consists of two facility segments: The Saltstone Production Facility (SPF) and the Saltstone Disposal Facility (SDF). The SPF receives decontaminated legacy low level sodium salt waste solution that is a byproduct of prior nuclear material processing. The salt solution is mixed with cementitious materials to form a grout slurry known as 'Saltstone'. The grout is pumped to the SDF where it is placed in a Saltstone Disposal Unit (SDU) to solidify. SDU 6 is referred to as a 'mega vault' and is currently in the design stage. The conceptual design for SDU 6 is a single cell, cylindrical geometry approximately 114.3 meters in diameter by 13.1 meter high and is larger than previous cylindrical SDU designs, 45.7 meters in diameter by 7.01 meters high (30 million gallons versus 2.9 million gallons of capacity). Saltstone slurry will be pumped into the new waste disposal unit through roof openings at a projected flow rate of about 34.1 cubic meters per hour. Nine roof openings are included in the design to discharge material into the SDU with an estimated grout pour radius of 22.9 to 24.4 meters and initial drop height of 13.1 meters. The conceptual design for the new SDU does not include partitions to limit the pour radius of the grout slurry during placement other than introducing material from different pour points. This paper addresses two technical issues associated with the larger diameter of SDU 6; Saltstone flow distance in a tank 114.3 meters in diameter and quality of the grout. A long-radius flow test scaled to match the velocity of an advancing grout front was designed to address these technology gaps. The emphasis of the test was to quantify the flow distance and to collect samples to evaluate cured properties including compressive strength, porosity, density, and saturated hydraulic conductivity. Two clean cap surrogate mixes (Saltstone premix plus water) were designed to simulate slurry with the reference Saltstone rheology and a Saltstone with extra water from the process flushing operation. Long-radius flow tests were run using approximately 4.6 cubic meters of each of these mixes. In both tests the pump rate was 0.063 liters/second (1 gpm). A higher pump rate, 0.19 liters/second (3 gpm), was used in a third long-radius flow test. The angle of repose of the grout wedges increased as a function of time in all three tests. The final angles of repose were measured at 3.0 deg., 2.4 deg., and 0.72 deg.. The pump rate had the largest effect on the radial flow distance and slope of the grout surface. The slope on the pour placed at 0.19 liters/second (3 gpm) was most representative of the slope on the grout currently being pumped into SDU 2 which is estimated to be 0.7 deg. to 0.9 deg. The final grout heights at 1/3 of a meter from the discharge point were 115, 105, and 38 cm. Entrapped air (≥ 0.25 cm bubbles) was also observed in all of the mixes. The entrapped air appeared to be released from the flows within about 3.1 meters (10 feet) of the discharge point. The bleed water was clear but had a thin layer of floating particulates. The bleed water should be retrievable by a drain water collection system in SDU 6 assuming the system does not get clogged. Layering was observed and was attributed to intervals when the hopper was being cleaned. Heat from the hydration reactions was noticeable to the touch. (authors)
- Research Organization:
- WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
- OSTI ID:
- 22221342
- Report Number(s):
- INIS-US-13-WM-13352; TRN: US14V0535042297
- Resource Relation:
- Conference: Waste Management 2013 - WM2013 Conference: International collaboration and continuous improvement, Phoenix, AZ (United States), 24-28 Feb 2013; Other Information: Country of input: France; 13 refs.
- Country of Publication:
- United States
- Language:
- English
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