Alternative High-Level Waste Treatments at the Idaho National Engineering and Environmental Laboratory (1999) / Chapter Skim
Currently Skimming:
8 Tank and Bin Closure
8 Tank and Bin Closure
Pages 71-80
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 71... ...
The quotation marks around emptied emphasize that the bins and tanks will contain some residual waste due to limitations of the present drawdown systems and the difficulty of achieving complete decontamination. These storage systems are presently monitored continuously and actively controlled, and it is assumed that such monitoring and control will continue for several decades while final disposition is being carried out.
|
From page 72... ...
TANK SYSTEMS: CHARACTERIZATION A heel composed of both solution and sludge deposits is anticipated in the bottom of the tanks (Spaulding et al., 1998~. The present characterization data on solutions in the tank are available for process control and engineering design purposes, but these data are probably not a reliable predictor of the composition of the bottom heel, because there may be an enrichment of hazardous elements and radioactive isotopes in the sludge portion (Spaulding et al., 1998~.1 To determine the level of decontamination and the degree of immobilization for closure, characterization of the heel is essential.
|
From page 73... ...
Characterization of the tanks has the goal of providing data for the following two goals: 1. process control of liquids that are removed by the existing steam jet and airlift for subsequent treatment (i.e., parameters needed for the design and testing of chemical process steps used in the downstream processes to treat the liquid waste)
|
From page 74... ...
TANK SYSTEMS: STABILIZATION The degree of stabilization (e.g., via addition of grout) needed for the hazardous chemical elements and radioactive isotopes remaining in the tank is determined by the mobility of these species in the environment after the loss of physical containment (e.g., a breach in the tank wall by corrosion)
|
From page 75... ...
Although regulatory procedures often do not use risk assessment calculations as a means for establishing a safe condition, risk assessments provide a rationale for trade-offs among various technical considerations. Two such considerations are the degree of decontamination of the tank interior that is to be achieved and the requisite quality of mixing between injected grout and residual sludge.
|
From page 76... ...
As described in the characterization section above, the bin sets have limited access points, and the monitoring and control system would probably require alteration before any insitu decontamination operations could occur. However, alterations of hardware to properly satisfy eventual closure would best be done before the start of calcine removal operations, and actions taken during calcine retrieval will impact the success of bin decontamination.
|
From page 77... ...
BIN SET SYSTEMS: STABILIZATION As stated above, the clean closure option for the bins has been deemed impractical (Dahlmeir et al., 1998~. Therefore, the approach for defining closure specifications is based on a risk assessment of the residual calcine left in the bin.
|
From page 78... ...
One potential outcome of such a site risk analysis is that all treatment options may have similar public risk, but that risk to personnel will be lowest for the closure option with the least manpower activity involved. If the calcine is retrieved and separated into fractions that are stored and/or disposed of at the site but not in the bins or tanks, then one would expect little change in public risk.
|
From page 79... ...
The bin sets in their present form have pressure relief valves to release gas if it accumulates in the bins. Characterization of samples of calcine show that gas evolution in sealed containers occurs when the calcine is heated above 200 °C due to decomposition of the nitrate (Garcia, 1997~.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.