The role of aging in resolving the ferrocyanide safety issue

Babad, H.; Meacham, J.E.; Simpson, B.C.; Cash, R.J.

doi:10.2172/10179634

Cited by 11 publications

(11 citation statements)

References 4 publications

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“…These "aging" reactions have been discussed by many workers, coworkers (1992, 1995), Babad et al (1993), and Camaioni and coworkers (1994,1995).…”

Section: Reaction Energies and Adiabatic Temperaturesmentioning

confidence: 85%

Calculation of reaction energies and adiabatic temperatures for waste tank reactions

Burger¹

1993

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SummaryContinual concern has been expressed over potentially hazardous exothermic reactions that might occur in Hanford Site underground waste storage tanks. These tanks contain many different oxidizable compounds covering a wide range of concentrations. Several compounds may be in concentrations and quantities great enough to be considered a hazard in that they could undergo rapid and energetic chemical reactions with nitrate and nitrite salts that are present it heated to the initiating or critical temperature. The chemical hazards are a function of several interrelated factors, including the amount of energy (heat) produced, how fast it is produced, and the thermal absorption and heat transfer properties of the system. The reaction path(s) will determine the amount of energy produced and kinetics will determine the rate that it is produced. The tanks also contain many inorganic compounds inert to oxidation. These compounds act as diluents and can inhibit exothermic reactions because of their heat capacity and thus, in contrast to the oxidizable compounds, provide mitigation of hazardous reactions.In this report the energy that may be released when various organic and inorganic compounds react is computed as a function of the reaction-mix composition and the temperature. The enthalpy, or integrated heat capacity, of these compounds and various reaction products is presented as a function of temperature; the enthalpy of a given mixture can then be equated to the energy release from various reactions to predict the maximum temperature which may be reached. This is estimated for several different compositions. Alternatively, the amounts of various diluents required to prevent the temperature from reaching a critical value can be estimated. Reactions W i g different paths, forming different products such as N20 in place of N2 are also considered, as are reactions where an excess of caustic is present. Oxidants other than nitrate and nitrite are considered briefly.The relative available energy per unit mass of the various oxidizable compounds, or "fuels," that may be present ranges from 1 to about 25. Stoichiometric mixes with oxidant, e.g., fuel plus the required amount of sodium nitrate (NaNO,) for a complete reaction, compared on a mass basis, also show large differences. This "energy density" covers a range of 1 to about 5.A consequence of different stoichiometries for different fuels is that an excess of sodium nitrate or nitrite for one reactant may be a deficiency for another. This is significant since excess nitrate or nitrite is an excellent heat sink, especially at elevated temperatures.The efficiency of various compounds as heat sinks, i.e., their enthalpies, vary greatly. In the wastes water is the most significant material at temperatures up to slightly above 100°C. From 100°C to about 300°C the greatest effect is probably from hydrated salts, with some contribution from concentrated caustic solutions. The loss of water from these materials requires a large energy input, some 50% to 100% greater than f...

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“…These "aging" reactions have been discussed by many workers, coworkers (1992, 1995), Babad et al (1993), and Camaioni and coworkers (1994,1995).…”

Section: Reaction Energies and Adiabatic Temperaturesmentioning

confidence: 85%

Calculation of reaction energies and adiabatic temperatures for waste tank reactions

Burger¹

1993

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“…Recent aging studies of ferrocyanide waste show that the combined effects of temperature, radiation, and pH during 38 years or more of storage would have destroyed most of the ferrocyanide originally added to the tanks (Babad et al 1993;Lilga et al 1993Lilga et al , 1994Lilga et al , and 1995. This prediction has been confirmed by the tank samples analyzed.…”

Section: Ferrocyanide Evaluationmentioning

confidence: 83%

Tank characterization report for single-shell tank 241-BY-110

Schreiber¹

1996

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Papa 1 Of 1 -1 EDT 6 1 7 5 4 1 - TO:(Receiving Organization) From: ( O r i g i n a t i n g Organization) D i s t r i b u t i onData Assessment and I n t e r p r e t a t i o n . P r o i . l P r o s . / D e D t . / D i v . :6. Design Authority/ Design AgentlCog. O r i g i n a t o r Remarks:This document i s being released i n t o t h e supporting document system f o r r e t r i evabi 1 i t y purposes -96-020 (WHC 1995b). As a result of the analyses addressed by this report, the tank meets the "safe" category based on the decision limits of the ferrocyanide data quality objective (DQO) (Schreiber 1995(Schreiber , 1996b. However, tank 241-BY-110 meets the "conditionally safe" category as defined by the organic DQO. 1994), the Data Requirements for the Ferrocyanide Safety Issue Developed through the Data Quality Objectives Process (Meacham et al. 1994), the Test Plan for Samples From HanfordWaste , TY-103, U-105, U-107, U-108, and U-109 (Meacham 1995), the Data Quality Objective to Support (Turner et al. 1995), and the Historical ES-4 WHC-SD-WM-ER-591 Rev. 0 (Simpson and McCain 1995). Analyses for all cores included energetics, moisture content, total alpha activity, density, metals, cyanide, anions, total organic carbon, and an organic screen analysis (Schreiber 1996a). Resolution of the Organic Complexant Safety Issue Model Evaluation Data RequirementsTotal alpha activity results for all cores were well below the safety screening limit of 29.7 pCi/g; the highest average subsegment result was 0.238 pCi/g, indicating the potential for a criticality event is low.Thermogravimetric analysis showed that the tank is drier than predicted by Agnew et al. Before samples were removed from the tank, combustible gas meter readings were taken from inside the vapor space as required by the safety screening DQO (Dukelow et al. 1995).No result was greater than one percent of the lower flamability limit, satisfying the DQO requirement that the results be less than 25 percent of the lower flammability limit. These measurements are consistent with the findings of a previous headspace sampling effort . However, measurements in the drill string indicate that radiologically generated gases accumulate in the waste. The gases are rapidly dispersed when encountered during sampling. Present operational measures (application of flammable gas controls during sampling) appear to be prudent and appropriate when performing intrusive in-tank activities, because H2 concentrations of 24 percent have been observed in the drill string vapor space.Remaining material from the sampling event has been set aside for pretreatment studies as identified in the pretreatment DQO.Table ES-2 shows concentration and inventory estimates for the most prevalent analytes and analytes of concern. These concentrations are based on the 1995 analytical results.

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“…Recent aging studies of ferrocyanide waste show that the combined effects of temperature, radiation, and pH during 38 years or more of storage would have destroyed most of the ferrocyanide originally added to the tanks (Babad et al 1993;Lilga et al 1993Lilga et al , 1994Lilga et al , 1995Lilga et al and 1996. This prediction has been confirmed by the tank samples analyzed to date.…”

Section: Ferrocyanide Degradationmentioning

confidence: 84%

Tank characterization report for single-shell tank 241-BY-106

Bell¹

1996

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The role of aging in resolving the ferrocyanide safety issue

Cited by 11 publications

References 4 publications

Calculation of reaction energies and adiabatic temperatures for waste tank reactions

Calculation of reaction energies and adiabatic temperatures for waste tank reactions

Tank characterization report for single-shell tank 241-BY-110

Tank characterization report for single-shell tank 241-BY-106

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