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Title: CHARACTERIZATION AND ACTUAL WASTE TESTS WITH TANK 5F SAMPLES

Abstract

No abstract prepared.

Authors:
; ; ;
Publication Date:
Research Org.:
SRS
Sponsoring Org.:
USDOE
OSTI Identifier:
903401
Report Number(s):
WSRC-STI-2007-00192
TRN: US0703499
DOE Contract Number:
DE-AC09-96SR18500
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; RADIOACTIVE WASTES; CHEMICAL ANALYSIS; STORAGE FACILITIES; SAMPLING; HANFORD RESERVATION

Citation Formats

Hay, M, Kim Crapse, K, Samuel Fink, S, and John Pareizs, J. CHARACTERIZATION AND ACTUAL WASTE TESTS WITH TANK 5F SAMPLES. United States: N. p., 2007. Web. doi:10.2172/903401.
Hay, M, Kim Crapse, K, Samuel Fink, S, & John Pareizs, J. CHARACTERIZATION AND ACTUAL WASTE TESTS WITH TANK 5F SAMPLES. United States. doi:10.2172/903401.
Hay, M, Kim Crapse, K, Samuel Fink, S, and John Pareizs, J. Mon . "CHARACTERIZATION AND ACTUAL WASTE TESTS WITH TANK 5F SAMPLES". United States. doi:10.2172/903401. https://www.osti.gov/servlets/purl/903401.
@article{osti_903401,
title = {CHARACTERIZATION AND ACTUAL WASTE TESTS WITH TANK 5F SAMPLES},
author = {Hay, M and Kim Crapse, K and Samuel Fink, S and John Pareizs, J},
abstractNote = {No abstract prepared.},
doi = {10.2172/903401},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Apr 30 00:00:00 EDT 2007},
month = {Mon Apr 30 00:00:00 EDT 2007}
}

Technical Report:

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  • The initial phase of bulk waste removal operations was recently completed in Tank 5F. Video inspection of the tank indicates several mounds of sludge still remain in the tank. Additionally, a mound of white solids was observed under Riser 5. In support of chemical cleaning and heel removal programs, samples of the sludge and the mound of white solids were obtained from the tank for characterization and testing. A core sample of the sludge and Super Snapper sample of the white solids were characterized. A supernate dip sample from Tank 7F was also characterized. A portion of the sludge wasmore » used in two tank cleaning tests using oxalic acid at 50 C and 75 C. The filtered oxalic acid from the tank cleaning tests was subsequently neutralized by addition to a simulated Tank 7F supernate. Solids and liquid samples from the tank cleaning test and neutralization test were characterized. A separate report documents the results of the gas generation from the tank cleaning test using oxalic acid and Tank 5F sludge. The characterization results for the Tank 5F sludge sample (FTF-05-06-55) appear quite good with respect to the tight precision of the sample replicates, good results for the glass standards, and minimal contamination found in the blanks and glass standards. The aqua regia and sodium peroxide fusion data also show good agreement between the two dissolution methods. Iron dominates the sludge composition with other major contributors being uranium, manganese, nickel, sodium, aluminum, and silicon. The low sodium value for the sludge reflects the absence of supernate present in the sample due to the core sampler employed for obtaining the sample. The XRD and CSEM results for the Super Snapper salt sample (i.e., white solids) from Tank 5F (FTF-05-07-1) indicate the material contains hydrated sodium carbonate and bicarbonate salts along with some aluminum hydroxide. These compounds likely precipitated from the supernate in the tank. A solubility test showed the material to be water-soluble consistent with the determined composition. The analytical data for the solid residues filtered from the oxalic acid solution and filtered oxalic acid indicate a large portion of the Tank 5F sludge used in the tank cleaning test dissolved into the oxalic acid. The results of a material balance calculation indicate a high percentage of the iron, uranium, sodium, and aluminum dissolved during both tests. Approximately half of the manganese, a small portion of the plutonium, and essentially none of the nickel dissolved during the tank cleaning tests. Additionally, the results show slightly higher dissolution of the sludge in the 75 C test compared to the 50 C test however, the amount of sludge dissolution gained by using the higher temperature remains small. Some uncertainty remains with respect to the amount of plutonium dissolved in the tank cleaning test. The neutralization of the filtered oxalic acid solutions from the cleaning test produced a large volume of solids ({approx}2X the original sludge mass after filtration and air drying). A large portion of the increase in solids could be attributed to the formation of sodium oxalate. The data from analysis of the solid residues filtered from the neutralization tests and the filtrate obtained indicate most of the iron, uranium, manganese, and a large portion of the aluminum precipitated during the neutralization tests. The data for the 50 C test and the 75 C test show good agreement with the exception of the amount of aluminum precipitated from the neutralization. The slower addition rate of the oxalic acid filtrate to the simulated Tank 7F supernate in the 75 C test might account for the smaller amount of aluminum precipitated and differences in the particle size/morphology and composition of the particulates. Some evidence of uranium separation from other sludge elements appears in the 75 C data. Data collected from the tank cleaning and neutralization tests indicates most of the uranium dissolved during the cleaning test with oxalic acid along with the iron, aluminum, and sodium in the sludge. During the neutralization of the oxalic acid, the majority of the uranium precipitates from solution along with the iron and other typical sludge elements. The CSEM results of the 75 C neutralization test provide some evidence of uranium separation from other sludge elements. However, the CSEM analysis looked at a very small amount of sample, which might not be representative of the bulk material and the sludge sample also showed areas of high uranium concentration. Additionally, how the test results will scale to the full-scale neutralization in a waste tank remains uncertain. The analysis of the oxalic acid filtrates indicates that only a small portion of the plutonium dissolved during the tank cleaning test. However, the analytical data from the solid residues filtered from the cleaning test contradict the solution data and indicate approximately half of the plutonium dissolved.« less
  • Forty three of the High Level Waste (HLW) tanks at the Savannah River Site (SRS) have internal structures that hinder removal of the last approximately five thousand gallons of waste sludge solely by mechanical means. Chemical cleaning can be utilized to dissolve the sludge heel with oxalic acid (OA) and pump the material to a separate waste tank in preparation for final disposition. This dissolved sludge material is pH adjusted downstream of the dissolution process, precipitating the sludge components along with sodium oxalate solids. The large quantities of sodium oxalate and other metal oxalates formed impact downstream processes by requiringmore » additional washing during sludge batch preparation and increase the amount of material that must be processed in the tank farm evaporator systems and the Saltstone Processing Facility. Enhanced Chemical Cleaning (ECC) was identified as a potential method for greatly reducing the impact of oxalate additions to the SRS Tank Farms without adding additional components to the waste that would extend processing or increase waste form volumes. In support of Savannah River Site (SRS) tank closure efforts, the Savannah River National Laboratory (SRNL) conducted Real Waste Testing (RWT) to evaluate an alternative to the baseline 8 wt. % OA chemical cleaning technology for tank sludge heel removal. The baseline OA technology results in the addition of significant volumes of oxalate salts to the SRS tank farm and there is insufficient space to accommodate the neutralized streams resulting from the treatment of the multiple remaining waste tanks requiring closure. ECC is a promising alternative to bulk OA cleaning, which utilizes a more dilute OA (nominally 2 wt. % at a pH of around 2) and an oxalate destruction technology. The technology is being adapted by AREVA from their decontamination technology for Nuclear Power Plant secondary side scale removal. This report contains results from the SRNL small scale testing of the ECC process using SRS sludge tank sample material. A Task Technical and Quality Assurance Plan (TTQAP) details the experimental plan as outlined by the Technical Task Request (TTR). The TTR identifies that the data produced by this testing and results included in this report will support the technical baseline with portions having a safety class functional classification. The primary goals for SRNL RWT are as follows: (1) to confirm ECC performance with real tank sludge samples, (2) to determine the impact of ECC on fate of actinides and the other sludge metals, and (3) to determine changes, if any, in solids flow and settling behavior.« less
  • Solubility testing with actual High Level Waste tank sludge has been conducted in order to evaluate several alternative chemical cleaning technologies for the dissolution of sludge residuals remaining in the tanks after the exhaustion of mechanical cleaning and sludge sluicing efforts. Tests were conducted with archived Savannah River Site (SRS) radioactive sludge solids that had been retrieved from Tank 5F in order to determine the effectiveness of an optimized, dilute oxalic/nitric acid cleaning reagent toward dissolving the bulk non-radioactive waste components. Solubility tests were performed by direct sludge contact with the oxalic/nitric acid reagent and with sludge that had beenmore » pretreated and acidified with dilute nitric acid. For comparison purposes, separate samples were also contacted with pure, concentrated oxalic acid following current baseline tank chemical cleaning methods. One goal of testing with the optimized reagent was to compare the total amounts of oxalic acid and water required for sludge dissolution using the baseline and optimized cleaning methods. A second objective was to compare the two methods with regard to the dissolution of actinide species known to be drivers for SRS tank closure Performance Assessments (PA). Additionally, solubility tests were conducted with Tank 5 sludge using acidic and caustic permanganate-based methods focused on the “targeted” dissolution of actinide species.« less
  • The Savannah River National Laboratory (SRNL) was requested by SRR to provide sample preparation and analysis of the Tank 5F final characterization samples to determine the residual tank inventory prior to grouting. Two types of samples were collected and delivered to SRNL: floor samples across the tank and subsurface samples from mounds near risers 1 and 5 of Tank 5F. These samples were taken from Tank 5F between January and March 2011. These samples from individual locations in the tank (nine floor samples and six mound Tank 5F samples) were each homogenized and combined in a given proportion into 3more » distinct composite samples to mimic the average composition in the entire tank. These Tank 5F composite samples were analyzed for radiological, chemical and elemental components. Additional measurements performed on the Tank 5F composite samples include bulk density and water leaching of the solids to account for water soluble species. With analyses for certain challenging radionuclides as the exception, all composite Tank 5F samples were analyzed and reported in triplicate. The target detection limits for isotopes analyzed were based on customer desired detection limits as specified in the technical task request documents. SRNL developed new methodologies to meet these target detection limits and provide data for the extensive suite of components. While many of the target detection limits were met for the species characterized for Tank 5F, as specified in the technical task request, some were not met. In a few cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. The Technical Task Request allows that while the analyses of these isotopes is needed, meeting the detection limits for these isotopes is a lower priority than meeting detection limits for the other specified isotopes. The isotopes whose detection limits were not met in all cases included the following: Al-26, Sn-126, Sb-126, Sb-126m, Eu-152 and Cf-249. SRNL, in conjunction with the plant customer, reviewed all these cases and determined that the impacts were negligible.« less