Quarterly report on the Ferrocyanide Safety Program for the period ending June 30, 1994

Meacham, J.E.; Cash, R.J.; Dukelow, G.T.

doi:10.2172/10173268

Cited by 1 publication

(1 citation statement)

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“…Although measured temperatures in these tanks continue to drop due to a progressive decrease in radioactivity and the highest temperature recently recorded is 53°C (Meacham et al 1994), there has been speculation as to the possibility of "hot spots" forming in the tanks as a result of radiolytic heating. It has been hypothesized that "hot spots" may form if a localized increase in radioactive Cs, and hence high temperatures, could be created during slow convective if Cs-Ni ferrocyanide solids show retrograde solubility (McGrail et al 1993).…”

Section: O Introductionmentioning

confidence: 99%

Solubility of ferrocyanide compounds. Ferrocyanide Safety Project, Interim report FY1994

Rai¹,

Felmy²,

Smith³

et al. 1994

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The solubility of cs,NiFe(CN),(c) as a function of NaOH and temperature was determined to ascertain whether C@iFe(CN),(c) shows retrograde solubility (Le., decreasing solubility with increasing temperature), which would have bearing on the possible formation of "hot spots" in the tanks and thus the safety of the ferrocyanide tanks. The results show that the aqueous concentrations of Cs in equilibrium with Cs,?NiFe(CN),(c) at 25"C, 60"C, 75"C, and 90°C are similar (within the limits of experimental error), indicating that Cs,?NiFe(CN),(c) does not show retrograde solubility. To understand general solubility relationships of Ni,Fe(CN),(c) and to determine the influence on solubility of high electrolyte concentrations (e.g., NaNO,) that are commonly encountered in the ferrocyanide tanks, the solubility of Ni,Fe(CN),(c) as a function of CsNO,, NiCl,, and NaNO, was determined. In general, Ni,Fe(CN),(C) is fairly insoluble and shows slightly increased solubility at high electrolyte concentrations only. For Ni,Fe(CN),(c) in NiCl,, the aqueous Fe concentrations show first a decrease and then an increase with the increase in NiCL, concentrations. The increase in Fe concentrations at high Ni concentrations appears to be the result of replacement of Fe by Ni in the Ni,Fe(CN),(c) structure. For Ni,Fe(CN),(c) in CsNO, and at 0.001 M N%Fe(CN),, the cs is quantitatively removed from solution at low added Cs concentrations and appears to approach the final solid composition of Cs,?NiFe(CN),(c). The solubility of Ni,Fe(CN),(c) in NaNO, and at 0.001 M Na,Fe(CN), shows an increase in Ni concentrations to about 0.5 mg/L at NaNO, concentrations > 1 .O M. These increased Ni concentrations may be the result of substitution of Na for Ni in the solid phase.

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Section: O Introductionmentioning

confidence: 99%