Waste tanks, Hanford site

High-level radioactive defense waste solutions, originating from plutonium recovery and waste processing operations at the U.S. Department of Energy s Hanford Site, currently are stored in mild steel-lined concrete tanks located in thick sedimentary beds of sand and gravel. Statistically designed experiments were used to identify the effects of 12 major chemical components of Hanford waste solution on radionuclide solubility and sorption. 

Accurate properties prediction for radionuclides, including actinides and lanthanides, to understand their migration in the vadose zone (e.g., the Hanford site), and their chemical behavior in waste tanks (e.g., Hanford and Savannah River)—such chemical reactivity information is needed for detailed subsurface and groundwater reactive transport models. 

J. L. Waite, Tank Wastes Discharged Directly to the Soil at the Hanford Site, Report WHC-MR-0227, Westinghouse Hanford Company, Richland, WA, April 1991. 

Multifunction Waste Tank Facility at the Hanford Site 1992-3 Operational Readiness of the HB-line at the Savannah River Site 1992-2 DOE s Facility Representative Program at Defense Nuclear Facilities 1992-1 Operational Readiness of the HB-line at the Savannah River Site... 

Recently, a Raman probe has been designed for a cone penetrometer for studying underground storage tanks at the Department of Energy site in Hanford [143]. These tanks contain a mixture of chemicals and radioactive waste and, with in-tank characterization of such mixtures, significant reduction in personnel exposure, analysis time, and cost is achieved relative to laboratory analysis. RS has been shown to be well suited for detecting many of the chemicals contain within the tanks [43,144,145]. For example, Marston have detected and identified nitrite (NO2), nitrate (N03 ), sulfate (SO4 ), chromate (CrO ),... 

The third example is compact cleanup units for waste treatment, mainly in consideration of the numerous radioactive sites, stemming from cold-war military developments [106]. The Hanford, Washington, USA, site with a multitude of seriously contaminated tank wastes is among them. Due to the unknown character of most polluting species, the installation of a central waste-treatment facility is said to be not the best and most inexpensive solution. Rather, small modular units, able to be individually adapted to various separation tasks, which are inserted into the tanks and perform cleanup on site, are seen as the proper solution. 

The advanced integrated solvent extraction and ion exchange systems are designed for the chemical pretreatment of waste retrieved from storage tanks at Department of Energy (DOE) sites (e.g., at INEL, Hanford, Savannah River). 

The liquid waste is stored for at least 6 y prior to solidification to reduce the decay heat (Fig. 16.8) by a factor of 10 or more. The first U.S. military fuel reprocessing wastes were stored as neutralized waste in mild steel tanks at the Hanford reservation in eastern Washington. These steel-lined, reinforced-concrete tanks were 500,000-1,000,000 gal in capacity with provisions for removal of waste heat and radiolysis products. Corrosion of several tanks occurred with the release of waste. Fortunately, the soil around these tanks retarded nuclide transport. A better (and more expensive) design for storage tanks was implemented at the Savannah River site in South Carolina consisting of a second steel tank inside of a Hanford-style tank. The storage of acid waste in these tanks has not encountered the corrosion problems seen with the Hanford tanks. 

Salts of actinides are very common in waste streams. In particular, nitrates, chlorides, and sulfates are found in tank waste streams that were formed by neutralization of highly acidic solutions at several DOE sites, such as Hanford and Savannah River. The aqueous solubility of these salts is very high, and hence, it is a challenge to stabilize them. As we shall see in case studies, the CBPC matrix has good promise in handling these waste streams. 

The most important consideration in tank design is minimization of corrosion. Originally two storage philosophies were believed to be equally safe in this respect (1) neutralized waste in mild steel tanks and (2) acid waste in stainless steel tanks. Almost three decades of experience have proved that only the latter satisfies all safety requirements. No leakage from stainless steel tanks has become known, whereas 20 out of 183 mild steel tanks at the Hanford and Savannah River sites developed leaks [L2]. It is now generally accepted that a minimum conosion rate can be maintained with suitable types of stainless steel and nitric acid concentrations in the range of 2 to 4 Af. If the HNO3 concentration falls below 1 M stress corrosion due to chloride ions may be promoted. 

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