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Title: PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE

Abstract

Radioactive high level waste (HLW) sludge generated as a result of decades of production and manufacturing of plutonium, tritium and other nuclear materials is being removed from storage tanks and processed into a glass waste-form for permanent disposition at the Federal Repository. Characterization of this HLW sludge is a prerequisite for effective planning and execution of sludge disposition activities. The radioactivity of HLW makes sampling and analysis of the sludge very challenging, as well as making opportunities to perform characterization rare. In order to maximize the benefit obtained from sampling and analysis, a recommended list of physical property and chemical measurements has been developed. This list includes distribution of solids (insoluble and soluble) and water; densities of insoluble solids, interstitial solution, and slurry rheology (yield stress and consistency); mineral forms of solids; and primary elemental and radioactive constituents. Sampling requirements (number, type, volume, etc.), sample preparation techniques, and analytical methods are discussed in the context of pros and cons relative to end use of the data. Generation of useful sample identification codes and entry of results into a centralized database are also discussed.

Authors:
Publication Date:
Research Org.:
SRS
Sponsoring Org.:
USDOE
OSTI Identifier:
907771
Report Number(s):
LWO-PIT-2007-00058
TRN: US0703299
DOE Contract Number:
DE-AC09-96SR18500
Resource Type:
Conference
Resource Relation:
Conference: Materials Science and Technology Conference
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; HIGH-LEVEL RADIOACTIVE WASTES; VITRIFICATION; SAMPLE PREPARATION; SAMPLING; SLUDGES; CHEMICAL ANALYSIS; PHYSICAL PROPERTIES

Citation Formats

Hamm, B. PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE. United States: N. p., 2007. Web.
Hamm, B. PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE. United States.
Hamm, B. 2007. "PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE". United States. doi:. https://www.osti.gov/servlets/purl/907771.
@article{osti_907771,
title = {PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE},
author = {Hamm, B},
abstractNote = {Radioactive high level waste (HLW) sludge generated as a result of decades of production and manufacturing of plutonium, tritium and other nuclear materials is being removed from storage tanks and processed into a glass waste-form for permanent disposition at the Federal Repository. Characterization of this HLW sludge is a prerequisite for effective planning and execution of sludge disposition activities. The radioactivity of HLW makes sampling and analysis of the sludge very challenging, as well as making opportunities to perform characterization rare. In order to maximize the benefit obtained from sampling and analysis, a recommended list of physical property and chemical measurements has been developed. This list includes distribution of solids (insoluble and soluble) and water; densities of insoluble solids, interstitial solution, and slurry rheology (yield stress and consistency); mineral forms of solids; and primary elemental and radioactive constituents. Sampling requirements (number, type, volume, etc.), sample preparation techniques, and analytical methods are discussed in the context of pros and cons relative to end use of the data. Generation of useful sample identification codes and entry of results into a centralized database are also discussed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2007,
month = 5
}

Conference:
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  • This paper describes the results of the analyses of High Level Waste (HLW) sludge slurry samples and of the calculations necessary to decay the radionuclides to meet the reporting requirement in the Waste Acceptance Product Specifications (WAPS) [1]. The concentrations of 45 radionuclides were measured. The results of these analyses provide input for radioactive decay calculations used to project the radionuclide inventory at the specified index years, 2015 and 3115. This information is necessary to complete the Production Records at Savannah River Site's Defense Waste Processing Facility (DWPF) so that the final glass product resulting from Macrobatch 5 (MB5) canmore » eventually be submitted to a Federal Repository. Five of the necessary input radionuclides for the decay calculations could not be measured directly due to their low concentrations and/or analytical interferences. These isotopes are Nb-93m, Pd-107, Cd-113m, Cs-135, and Cm-248. Methods for calculating these species from concentrations of appropriate other radionuclides will be discussed. Also the average age of the MB5 HLW had to be calculated from decay of Sr-90 in order to predict the initial concentration of Nb-93m. As a result of the measurements and calculations, thirty-one WAPS reportable radioactive isotopes were identified for MB5. The total activity of MB5 sludge solids will decrease from 1.6E+04 {micro}Ci (1 {micro}Ci = 3.7E+04 Bq) per gram of total solids in 2008 to 2.3E+01 {micro}Ci per gram of total solids in 3115, a decrease of approximately 700 fold. Finally, evidence will be given for the low observed concentrations of the radionuclides Tc-99, I-129, and Sm-151 in the HLW sludges. These radionuclides were reduced in the MB5 sludge slurry to a fraction of their expected production levels due to SRS processing conditions.« less
  • Hanford tank waste consists of about 190 million curies in 54 million gallons of highly radioactive and mixed hazardous waste stored in underground storage tanks at the Hanford Site in Washington State. The tank waste includes solids (sludge), liquids (supernatant), and salt cake (dried salts that dissolve in water to form supernatant). The tank waste will be remediated through treatment and immobilization to protect the environment and meet regulatory requirements. The U.S. Department of Energy's (DOE's) preferred alternative to remediate the Hanford tank waste is to pretreat the waste by separating it into low-activity waste (LAW) and high-level waste (HLW),more » followed by immobilization of the LAW for on-site disposal and immobilization of the HLW for ultimate disposal in a national repository. This paper describes the crucible-scale vitrification and associated wasteform product tests in support of the WTP at Hanford. The two different LAW glasses produced in this study were from pretreated Envelope A (Tank 241-AN-103) and Envelope C (Tank 241-AN-102) waste. The HLW glass was produced from Tank C-106 HLW sludge and the HLW radionuclide products separated from Hanford Site tank samples AN-103, AN-102 and AZ-102. Pretreatment of these three supernates consisted of characterization, strontium and transuranics removal by precipitation and filtration, and final Cs-137 and Tc-99 removal by ion exchange (IX). The glasses were produced from formulations supplied by Vitreous State Laboratory of the Catholic University of America (CUA). Formulations were based on previous surrogate testing and the actual characterization data from the radioactive feed streams. Crucible-scale vitrifications were performed in platinum/gold crucibles in a custom-designed furnace fit with an offgas containment system. Both LAW and HLW melter feed slurries were evaporated, calcined, and then melted at 1150 degrees C. The LAW and HLW glasses were heat-treated per a modeled centerline cooling curve for the LAW canister and HLW canister, respectively.« less
  • The Savannah River Site, SRS, is currently pursuing an aggressive program to empty its High Level Waste, HLW, tanks and immobilize its radioactive waste into a durable borosilicate glass in the Defense Waste Processing Facility, DWPF. To create a batch of feed for the DWPF, several tanks of sludge slurry are combined into one of the million gallon, i.e. 3.79E06 liters, feed tanks for DWPF. A batch of feed nominally consists of 500,000 gallons, i.e. 1.89E06 liters. After a batch of feed is prepared, a portion of the batch, 26,500 liters, is transferred to DWPF. This batch is then chemicallymore » adjusted in the Chemical Processing Cell, CPC, prior to being fed to the melter to make the final product; canisters filled with glass. During the processing of the third batch, or Sludge Batch 2, of feed through the DWPF CPC, pumping and transfer problems were noted. These problems hindered the processing of the feed through the CPC, and thus impacted canister production in DWPF. In order to investigate the root cause of these problems, data were collected and evaluated for possible trends. One trend noted was the relationship between the pH, solids loading concentration, and temperature of the feed. As any one of these three variables changed, the rheological properties of the feed appeared to change. To determine the dependency of the rheological property, samples were obtained and shipped to Savannah River National Laboratory's, SRNL, Shielded Cells Facility. The samples were processed under two sets of conditions and rheological measurements obtained. The results of the SRNL studies showed that the ending pH of the samples impacted the rheological properties of the sample. Lowering the pH of the sludge slurry resulted in lower plastic viscosity and yield stress values,thus alleviating the processing problems. Increasing the solids loading typically increased both the plastic viscosity and yield stress. There was minimal or no dependency on temperature.« less
  • High-level radioactive sludge at the Savannah River Site (SRS) will be processed at the Defense Waste Processing Facility (DWPF) into durable borosilicate glass wasteforms. The sludges are analyzed for elemental content before processing to ensure compatibility with the glass-making processes. Noble metal fission products in sludge, can under certain conditions, cause problems in the glass melter. Therefore, reliable noble metal determinations are important. The scheme used to measure noble metals in SRS sludges consists of dissolving sludge with hot aqua regia followed by determinations with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ICP-Mass Spectroscopy (ICP-MS) techniques. ICP-MS is the preferredmore » method for measuring trace levels of noble metals in SRS radioactive waste because of superior sensitivity. Analytical results are presented for the two major types of SRS sludge.« less
  • This paper presents measurements of the concentrations of 42 of the long-lived U-235 fission products in a high-level radioactive waste sludge stored at Savannah River Site. The 42 fision products make up 98% of the waste sludge. We used inductively coupled plasma-mass spectroscopy for the analysis. The relative yields for most of the fission products are in complete agreement with the known relative yields for the beta decay chains of the two asymmetric branches of the slow neutron fission of U-235. Disagreements can be reconciled based on the chemistry of the fission products in the caustic waste sludges, the neutronmore » fluences in SRS reactors, or interferences in the ICP-MS analyses. This paper presents measurements of the concentrations of 42 (98%) of the long-lived U-235 fission products in a high-level radioactive waste sludge stored at the Savannah River Site. We analyzed the sludge with inductively coupled plasma-mass spectroscopy. The relative yields for most of the fission products agree completely with the known relative vields for the beta decay chains of the two asymmetric: branches of the slow neutron fission of U-235. The chemistry of the fission products in the caustic waste sludges, the neutron fluences in SRS reactors, or interferences in the ICP-MS analyses explain the differences in the measured and calculated results.« less