Ferrocyanide safety project task 3 ferrocyanide aging studies FY 1994 annual report

Lilga,; Alderson, E.V.; Kowalski, Dariusz; Lumetta, M.R.; Schiefelbein, G.F.

doi:10.2172/10196541

Cited by 10 publications

(18 citation statements)

References 25 publications

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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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Section: Ferrocyanide Degradationmentioning

confidence: 84%

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

Bell¹

1996

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“…3 and 4). Other aspects of alkali metal nickel ferrocyanide solubility, including the insolubility of the cesium-containing materials, and hydrolysis have been described in previous reports (Lilga et al , 1993(Lilga et al , 1994. In addition, mechanisms of contacting deep sludges layers with caustic have been discussed (McGrail et al 1993;McGrail 1994).…”

Section: Work Accomplishedmentioning

confidence: 92%

“…The results of Aging Studies will directly assist in determining which strategy will ensure safe storage of the ferrocyanide waste in the tanks and how the ferrocyanide safety issue can be resolved. In previous ferrocyanide waste aging studies utilizing flowsheet simulants (Lilga et al , 1993(Lilga et al , 1994, redissolution of Na,NiFe(CN), in caustic solutions was shown to occur and was studied under a variety of conditions. Products of the dissolution are soluble Fe(CN)64 and insoluble Ni(0HX.…”

Section: Thementioning

confidence: 99%

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Ferrocyanide safety project ferrocyanide aging studies FY 1995 annual report

Lilga¹,

Alderson²,

Hallen³

1995

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SummaryThis annual report gives the results of the work conducted by the Pacific Northwest Laboratory in FY 1995 on Task 3 of the Ferrocyanide Safety Project, Ferrocyanide Aging Studies. Aging refers to the dissolution and hydrolysis of simulated Hanford ferrocyanide waste in alkaline aqueous solutions by radiolytic and chemical means. The ferrocyanide simulant primarily used in these studies was driedIn-Farm-lB, Rev. 7, prepared by Westinghouse Hanford Company to simulate the waste generated when the In-Farm flowsheet was used to remove radiocesium from waste supernates in single-shell tanks at the Hanford Site. In the In-Farm flowsheet, nickel ion A d ferrocyanide anion were added to waste supernates to precipitate sodium nickel ferrocyanide, Na,NiFe(CN),, and co-precipitate radiocesium. Once the radiocesium was removed, supernates were pumped from the tanks, and new wastes from cladding removal processes or from evaporators were added. These new wastes were typically highly caustic, having hydroxide ion concentrations of over 1 M and as high as 4 M. The Aging Studies task is investigating reactions this caustic waste may have had with the precipitated ferrocyanide waste in a radiation field.In previous Aging Studies research, N%NiFe(CN), in simulants was shown to dissolve in basic solutions, forming insoluble Ni(OH), and soluble Na,Fe(CN),. The influence on solubility of base strength, sodium ion concentration, anions, -and temperature was previously investigated. Destruction of ferrocyanide anion by hydrolysis to form ammonia and formate ion was found to be promoted by gamma irradiation. Increasing temperature and gamma dose rate increased the rate of hydrolysis, as indicated by the amount of ammonia formed with time. Ammonia was found to be radiolyzed in the gamma field. The change in concentration of formate ion generally paralleled that of ammonia but was three to four times less concentrated. Total soluble iron concentrations were found to decrease in what appeared to be a pseudo-first-order fashion. The nickel concentration tended to increase, sometimes to 90% redissolution. Aluminum added to the hydrolysis solution had relatively little effect and may have slightly promoted hydrolysis.. In FY 1995 Aging Studies work, temperature and gamma dose rate effects were further investigated. Consistent with prior work, as the temperature or the gamma dose rate increased, the rate of hydrolysis also increased. As an approximation, ammonia production with time was described as being linear. Rate constants for ammonia production followed a linear Arrhenius relationship and also increased linearly with increasing applied gamma dose rate. Rate constants for ammonia production at other conditions could be predicted with use of the temperature and dose rate relationships.Ammonia was found to be destroyed in the gamma environment. Rate constants of 1.1 x Mlday at an applied dose rate of 1.07 x l@ Rad/h, and 2.1 x lo4 Mlday at 8.91 x 103 Rad/h were measured for this process. Formate ion destruction was found to occur at...

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“…A literature search revealed work that indicated that sodium nickel ferrocyanide decomposed (aged) to lower energy compounds when exposed to a typical Hanford Site tank environment (Babad et al 1993). Studies with waste simulants corroborate that ferrocyanide decomposes under waste tank conditions (Lilga et al 1993(Lilga et al , 1994(Lilga et al , and 1995. Three parameters (temperature, exposure to high pH, and radiation dose) strongly affect the rate of decomposition.…”

Section: Ferrocyanide Aging (Question #1)mentioning

confidence: 99%

High priority tank sampling and analysis report

Brown¹

1998

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Ferrocyanide safety project task 3 ferrocyanide aging studies FY 1994 annual report

Cited by 10 publications

References 25 publications

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

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

Ferrocyanide safety project ferrocyanide aging studies FY 1995 annual report

High priority tank sampling and analysis report

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