Organic Tanks Safety Program: Waste aging studies

Camaioni, D. M.; Samuels, W. D.; Lenihan, B. D.; Clauss, S.A.; Wahl, Karen L.; Campbell, James A.

doi:10.2172/10105395

Cited by 19 publications

(29 citation statements)

References 33 publications

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“…Experiments with waste simulants (Camaioni et al 1994(Camaioni et al , 1996(Camaioni et al , and 1998 show that organic complexants age to lower energy forms when exposed to heat andlor radiation in an environment similar to the waste tanks. The major organic complexants, hydroxyethylethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), citrate, and glycolate degraded to low energy products such as carbonate, formate, and oxalate.…”

Section: Does Sample Analysis Confirm the Model That Organic Complexamentioning

confidence: 99%

High priority tank sampling and analysis report

Brown¹

1998

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Section: Does Sample Analysis Confirm the Model That Organic Complexamentioning

confidence: 99%

High priority tank sampling and analysis report

Brown¹

1998

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“…The wastes are dynamic chemical reaction systems that continually produce new substances as the organic complexants and organic solvents undergo radiolysis and chemical conversion (Meisel et al 1992(Meisel et al , 1993Camaioni et al 1994;Barfield et al 1995). The principal products of many of the reactions have been defined in the past few years, but the complexity of the wastes ensures that many surprise molecules that…”

Section: Surprise Molecule Examplementioning

confidence: 99%

A risk-based focused decision-management approach for justifying characterization of Hanford tank waste. June 1996, Revision 1; April 1997, Revision 2

Colson¹,

Gephart²,

Hunter³

et al. 1997

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OverviewThis report describes a disciplined, risk-based decision-making approach for determining characterization needs and resolving safety issues during the storage and remediation of radioactive waste stored in H d o r d tanks. The strategy recommended uses hteractive problem evaluation and decision analysis methods commonly used.in industry to solve problems under conditions of uncertainty (i.e., lack of perfect knowledge). It acknowledges that problem resolution comes through both the application of high-quality science and human decisions based upon preferences and sometimes hard-to-compare choices. It recognizes that to M y resolve a safety problem, the controlling waste characteristics and chemical phenomena must be measurable or estimated to an acceptable level of confidence tailored to the decision being made.Critical interactive steps in the recommended strategy are to establish safety/risk resolution (and tank waste remediation) goals i d e n q key waste characteristics, physical conditions, and chemical reactions that control problemts) of interest 0 assess problem using existing data and information evaluate uncertainty in data, model, and risk estimates 0 compare cosvrisk of alternative safety resolution, mitigation, or control options evaluate whether or not resolution goals are achieved --If goals are achieved, the problem is solved.--If goals are not achieved, perform new data collection or modeling to reduce uncertainty and/or implement new safely controls/mitigation measures. make decisions and take actions consistent with findings iterate process as needed.Important attributes of the recommended strategy are that it keeps analyses and risk models as simple as the problem requires by matching problem solving methods (tools) and activities to problem resolution needs is risk based and recognizes uncertainty in knowledge of complex waste system characteristics and behavior uses only datahformation of hown quality to support decision making recognizes that understanding a problem and potential resolution actions is an evolving process uses expert knowledge and judgment independent of the U. S . Department of Energy for technical review. Peer Review Copy iiiIn the recommended strategy, waste characterization is performed as an integrated activity inseparable fi-om tank operation, safety resolution, or, waste remediation activities. In this setting, characterization actions can be justified as cost-saving measures to reduce or control risk.This report is designed to develop an understanding of the recommended strategy and the role of specific methods (tools) by painting numerous pictures of the same landscape from different perspectives. Starting with the Overview and Executive Summary and continuing through the Introduction, the strategy and implementation tools are introduced and placed in context of the problems addressed. In Chapter 2.0, the strategy is presented as an iterative, step-by-step process to show how it can be implemented. Finally, Chapter 3.0 illustrates facets of the strategy by ...

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“…These compounds have undergone aging to more oxidized products over the years that they have been stored (Camaioni et al 1995(Camaioni et al , 1996Carlson 1997). Decomposition products that have been identified include sodium ethylenediaminetriacetate (ED3A), sodium nitrilotriacetate (NTA), sodium iminodiacetate (IDA), sodium ethylenediaminediacetate (EDDA), sodium oxalate, and sodium formate (Campbell et al 1994(Campbell et al , 1995(Campbell et al , 1996. The energy content of the aged oxidation products is less than the energy content of the starting materials (Burger 1995) and the eventual product of the oxidative reaction sequence is sodium carbonate.…”

Section: General Features Of Organic Reactions In Hanford Wastesmentioning

confidence: 99%

“…The complexity of the chemistry is shown in the simplified reaction path for EDTA, which omits many intermediates, in Figure 3.1. The products that are designated in bold face have been detected in tank waste (Campbell et al 1994(Campbell et al ,1995(Campbell et al ,1996. Glycine has been shown to be a reaction product in laboratory work (Ashby et al 1994;Barefield et al 1995;Camaioni et al 1996Camaioni et al , 1997.…”

Section: Pathways To Aged Oxidized Organic Compoundsmentioning

confidence: 99%

“…Investigations at PNNL (Campbell et al 1993(Campbell et al ,1994(Campbell et al ,1995(Campbell et al ,1996 have shown that these two nitrogen-containing complexants have been substantially been converted into other nitrogen-containing compounds, including the anions of ED3A, NTA and IDA, or oxalate, formate and carbonate ions during the years of storage. The chemical reaction pathways for the formation of these compounds and other intermediate oxidation products are outlined in Figure 3.1 for the oxidative decomposition of EDTA, and other representative chemical pathways for the degradation of HEDTA were described in Section 3.…”

Section: Ammonia From Organic Sourcesmentioning

confidence: 99%

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Chemical pathways for the formation of ammonia in Hanford wastes

Stock¹,

Pederson²

1997

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This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important).Reduction of nitrite ions is believed to be the most important source of ammonia. Whether by radiolytic or thermal routes, nitrite reduction reactions proceed through nitrogen dioxide, nitric oxide, the nitrosyl anion, and the hyponitrite anion. Nitrite ion is also converted into hydroxylamine, another important intermediate on the pathway to form ammonia. These reaction pathways additionally result in the formation of nitrous oxide and molecular nitrogen, whereas hydrogen formation is produced in a separate reaction sequence.The oxidative degradation of trisodium EDTA and tetrasodium HEDTA also yields ammonia and other nitrogenous gases. The complexants react with nitric oxide and nitrogen dioxide to produce oxidized compounds that subsequently undergo hydrolysis, eventually liberating ammonia. Amides and nitriles are intermediates in these long reaction sequences. , The direct reaction of hydrogen with nitrous oxide and nitrogen can account for only negligible quantities of ammonia in Hanford tanks. Thermal reactions require high temperatures (AOOOC), high pressures, and the presence of catalysts, to proceed at significant rates. Similarly, radiolytic yields for direct reactions of hydrogen with nitrogen and nitrous oxide under tank conditions are expected to be very small.Oxygen can substantially alter the yields of nitrogenous gases. Two principal pathways have been identified. Oxygen intercepts radicals produced in thermal and radiolytic reactions that would otherwise eventually result in the formation of nitrogen, nitrous oxide and ammonia. Oxygen also reacts directly with complexants and intermediates to yield oxalate ion. The hydrogen yield is often increased in the presence of oxygen.

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Organic Tanks Safety Program: Waste aging studies

Cited by 19 publications

References 33 publications

High priority tank sampling and analysis report

High priority tank sampling and analysis report

A risk-based focused decision-management approach for justifying characterization of Hanford tank waste. June 1996, Revision 1; April 1997, Revision 2

Chemical pathways for the formation of ammonia in Hanford wastes

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