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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Poster - 44: Development and implementation of a comprehensive end-to-end testing methodology for linac-based frameless SRS QA using a modified commercial stereotactic anthropomorphic phantom

Purpose: An end-to-end testing methodology was designed to evaluate the overall SRS treatment fidelity, incorporating all steps in the linac-based frameless radiosurgery treatment delivery process. The study details our commissioning experience of the Steev (CIRS, Norfolk, VA) stereotactic anthropomorphic head phantom including modification, test design, and baseline measurements. Methods: Repeated MR and CT scans were performed with interchanging inserts. MR-CT fusion accuracy was evaluated and the insert spatial coincidence was verified on CT. Five non-coplanar arcs delivered a prescription dose to a 15 mm spherical CTV with 2 mm PTV margin. Following setup, CBCT-based shifts were applied as per protocol. Sequential measurements were performed by interchanging inserts without disturbing the setup. Spatial and dosimetric accuracy was assessed by a combination of CBCT hidden target, radiochromic film, and ion chamber measurements. To facilitate film registration, the film insert was modified in-house by etching marks. Results: MR fusion error and insert spatial coincidences were within 0.3 mm. Both CBCT and film measurements showed spatial displacements of 1.0 mm in similar directions. Both coronal and sagittal films reported 2.3 % higher target dose relative to the treatment plan. The corrected ion chamber measurement was similarly greater by 1.0 %. The 3 %/2 mm gamma pass rate was 99% for both films Conclusions: A comprehensive end-to-end testing methodology was implemented for our SRS QA program. The Steev phantom enabled realistic evaluation of the entire treatment process. Overall spatial and dosimetric accuracy of the delivery were 1 mm and 3 % respectively.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Draft Genome Sequence of Mercury-Resistant Serratia sp. Strain SRS-8-S-2018

A mercury (Hg)-resistant Serratia sp. strain, SRS-8-S-2018, was isolated, followed by generation of its draft genome sequence, which indicated a genomic size of 5,323,630 bp composed of 5,261 coding sequences. A suite of genomic functions in strain SRS-8-S-2018 was identified, and these likely facilitate survival in a metalliferous soil habitat.

Gendy, Sherif↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-SRS Santa Rita Savanna

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-SRS Santa Rita Savanna. This is the FLUXNET version of the carbon flux data for the site US-SRS Santa Rita Savanna produced by applying the standard ONEFlux (1F) software. Site Description - The study site is located in the Santa Rita Experimental Range, approximately 45 km south of Tucson, Arizona, within the Sonoran Desert. The rangeland has undergone a shift from a semiarid grassland to a savanna due to the encroachment of the woody leguminous tree Prosopis velutina Woot., or velvet mesquite. A pair of adjacent watersheds of similar size ( 1.08 ha and 1.10 ha) was established to investigate the effects of mesquite removal on hydrologic processes. In 1974, diesel oil was applied basally to all trees in one watershed, with reapplication as needed and dead tree removal for wood, whereas the other watershed, where the flux tower is located, has continued in the woody plant encroachment process. In 2016, an herbicide process was applied to the area around the EC flux tower.

Vivoni, Enrique R.↗
DOE OSTI2011

MOBILIZATION AND CHARACTERIZATION OF COLLOIDS GENERATED FROM CEMENT LEACHATES MOVING THROUGH A SRS SANDY SEDIMENT

Naturally occurring mobile colloids are ubiquitous and are involved in many important processes in the subsurface zone. For example, colloid generation and subsequent mobilization represent a possible mechanism for the transport of contaminants including radionuclides in the subsurface environments. For colloid-facilitated transport to be significant, three criteria must be met: (1) colloids must be generated; (2) contaminants must associate with the colloids preferentially to the immobile solid phase (aquifer); and (3) colloids must be transported through the groundwater or in subsurface environments - once these colloids start moving they become 'mobile colloids'. Although some experimental investigations of particle release in natural porous media have been conducted, the detailed mechanisms of release and re-deposition of colloidal particles within natural porous media are poorly understood. Even though this vector of transport is known, the extent of its importance is not known yet. Colloid-facilitated transport of trace radionuclides has been observed in the field, thus demonstrating a possible radiological risk associated with the colloids. The objective of this study was to determine if cementitious leachate would promote the in situ mobilization of natural colloidal particles from a SRS sandy sediment. The intent was to determine whether cementitious surface or subsurface structure would create plumes that could produce conditions conducive to sediment dispersion and mobile colloid generation. Column studies were conducted and the cation chemistries of influents and effluents were analyzed by ICP-OES, while the mobilized colloids were characterized using XRD, SEM, EDX, PSD and Zeta potential. The mobilization mechanisms of colloids in a SRS sandy sediment by cement leachates were studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Actual-Waste Testing of Ultraviolet Light to Augment the Enhanced Chemical Cleaning of SRS Sludge

In support of Savannah River Site (SRS) tank closure efforts, the Savannah River National Laboratory (SRNL) conducted Real Waste Testing (RWT) to evaluate Enhanced Chemical Cleaning (ECC), an alternative to the baseline 8 wt% oxalic acid (OA) chemical cleaning technology for tank sludge heel removal. ECC utilizes a more dilute OA solution (2 wt%) and an oxalate destruction technology using ozonolysis with or without the application of ultraviolet (UV) light. SRNL conducted tests of the ECC process using actual SRS waste material from Tanks 5F and 12H. The previous phase of testing involved testing of all phases of the ECC process (sludge dissolution, OA decomposition, product evaporation, and deposition tank storage) but did not involve the use of UV light in OA decomposition. The new phase of testing documented in this report focused on the use of UV light to assist OA decomposition, but involved only the OA decomposition and deposition tank portions of the process. Compared with the previous testing at analogous conditions without UV light, OA decomposition with the use of UV light generally reduced time required to reach the target of <100 mg/L oxalate. This effect was the most pronounced during the initial part of the decomposition batches, when pH was <4. For the later stages of each OA decomposition batch, the increase in OA decomposition rate with use of the UV light appeared to be minimal. Testing of the deposition tank storage of the ECC product resulted in analogous soluble concentrations regardless of the use or non-use of UV light in the ECC reactor.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

LANL Response to SRS Requirement G-ESR-G-00035 Item 11 Bed Temperature Requirements, For the Addition of Direct Metal Oxidation Unit 3, Revision 0

Los Alamos National Laboratory has identified a number of plutonium-bearing materials that will be placed in storage in 3013 containers per requirements of DOE-STD-3013-2004, or DOE-STD-3013-2012 when it is implemented in the LANL contract. Before these items can be considered for storage at Savannah River Site, 20 points of agreement, described in Savannah River Site (SRS) document G-ESR-G-00035, Revision 1, must be documented and provided to SRS for review. These agreements include documentation that the requirements of the 3013 Standard are met and the storage facility’s safety envelope is not compromised. Point 11 of the 20 points is the requirement that material be stabilized at 950°C for a minimum of two hours prior to packaging. This report addresses the Point 11 requirement, describing the controls used during stabilization to ensure that the material is properly stabilized using a continuous process (Advanced Recovery and Integrated Extraction System [ARIES] direct metal oxidation [DMO] and recycle oxide calcination). These controls include verification of the furnace controller thermocouple profile and verification of the profiles for the calciner tube hot zone. This report is specific to Direct Metal Oxidation Unit 3 (DMO-3). The point 11 requirements for DMO-2 and muffle furnace oxidation are covered in reference. This report does not replace reference. The process and methodology used in this report are similar to that used for Direct Metal Oxidation Unit 2, or DMO-2, as documented in reference. This report documents the performance for ARIES DMO-3. The temperature on the outside of the calciner tube must be at least 1,032°C. The auger rotation rate set point will be dependent on the pitch of the installed auger. For an auger pitch of 1.297 in/rev the auger set point will be 0.0777 rpm or less, which allows for at least 132 minutes calcination time based on worst case conditions (i.e., lowest possible powder density at the lowest initial powder temperature, and under the least favorable heat transfer conditions, and with the least favorable auger pitch of the currently installed auger.) A new auger design may be used in future modifications of DMO-3 that has an auger pitch of 1.400 ± 0.025 inches which would change the required auger set point to 0.0707 rpm or less.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

LANL Response to SRS Requirement G-ESR-G-00035 Item 11 Bed Temperature, Revision 4

Los Alamos National Laboratory has identified a number of plutonium-bearing materials that will be placed in interim storage in 3013 containers per requirements of DOE-STD-3013- 2004, or DOE-STD-3013-2012. Before these items can be considered for storage at Savannah River Site, 20 points of agreement, described in Savannah River Site (SRS) document G-ESR-G-00035, Revision 1, must be documented and provided to SRS for review. These agreements include documentation that the requirements of the 3013 Standard are met and the storage facility’s safety envelope is not compromised. Point 11 of the 20 points is the requirement that material be stabilized at 950°C for a minimum of two hours prior to packaging. This report addresses the Point 11 requirement, describing the controls used during stabilization to ensure that the material is properly stabilized using either a batch (calciner boat) or continuous process (Advanced Recovery and Integrated Extraction System [ARIES] direct metal oxidation unit 2 [DMO-2] and recycle oxide calcination). These controls include verification of the furnace controller thermocouple profile and verification of the profiles for the two thermocouples located in the bed and/or calciner tube hot zone. Revision 4 to this document only modifies the ARIES DMO-2 process controls. Batch processing requirements are unchanged. Changes to the DMO-2 process include use of alternate augers with differing pitch values and reduction of the minimum powder bulk density value. The new DMO-3 unit requirements are covered in a separate document.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

SRS 2010 Vegetation Inventory GeoStatistical Mapping Results for Custom Reaction Intensity and Total Dead Fuels

This report of the geostatistical analysis results of the fire fuels response variables, custom reaction intensity and total dead fuels is but a part of an SRS 2010 vegetation inventory project. For detailed description of project, theory and background including sample design, methods, and results please refer to USDA Forest Service Savannah River Site internal report “SRS 2010 Vegetation Inventory GeoStatistical Mapping Report”, (Edwards & Parresol 2013).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Assessment of SRS ambient air monitoring network

Three methodologies have been used to assess the effectiveness of the existing ambient air monitoring system in place at the Savannah River Site in Aiken, SC. Effectiveness was measured using two metrics that have been utilized in previous quantification of air-monitoring network performance; frequency of detection (a measurement of how frequently a minimum number of samplers within the network detect an event), and network intensity (a measurement of how consistent each sampler within the network is at detecting events). In addition to determining the effectiveness of the current system, the objective of performing this assessment was to determine what, if any, changes could make the system more effective. Methodologies included 1) the Waite method of determining sampler distribution, 2) the CAP88- PC annual dose model, and 3) a puff/plume transport model used to predict air concentrations at sampler locations. Data collected from air samplers at SRS in 2015 compared with predicted data resulting from the methodologies determined that the frequency of detection for the current system is 79.2% with sampler efficiencies ranging from 5% to 45%, and a mean network intensity of 21.5%. One of the air monitoring stations had an efficiency of less than 10%, and detected releases during just one sampling period of the entire year, adding little to the overall network intensity. By moving or removing this sampler, the mean network intensity increased to about 23%. Further work in increasing the network intensity and simulating accident scenarios to further test the ambient air system at SRS is planned

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Alternative Chemical Cleaning Methods for High Level Waste Tanks: Actual Waste Testing with SRS Tank 5F Sludge

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 been 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.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Evaluation of no-MST operations in the SRS ARP for Hanford LAWPS

The Savannah River Site (SRS) Actinide Removal Process has been processing salt waste since 2008. This process includes a filtration step in the 512-S facility. Initial operations included the addition, or strike, of monosodium titanate (MST) to remove soluble actinides and strontium. The added MST and any entrained sludge solids were then separated from the supernate by cross flow filtration. During this time, the filter operations have, on many occasions, been the bottleneck process limiting the rate of salt processing. Recently, 512-S- has started operations utilizing “No-MST” where the MST actinide removal strike was not performed and the supernate was simply pre-filtered prior to Cs removal processing. Direct filtration of decanted tank supernate, as demonstrated in 512-S, is the proposed method of operation for the Hanford Low Activity Waste Pretreatment System (LAWPS) facility. Processing decanted supernate without MST solids has been demonstrated for cross flow filtration to provide a significant improvement in production with the SRS Salt Batches 8 and 9 feed chemistries. The average filtration rate for the first 512-S batch processing cycle using No-MST has increased filtrate production by over 35% of the historical average. The increase was sustained for more than double the amount of filtrate batches processed before cleaning of the filter was necessary. While there are differences in the design of the 512-S and Hanford filter systems, the 512-S system should provide a reasonable indication of LAWPS filter performance with similar feed properties. Based on the data from the 512-S facility and with favorable feed properties, the LAWPS filter, as currently sized at over twice the size of the 512-S filter (532 square feet filtration area versus 235 square feet), has the potential to provide sustained filtrate production at the upper range of the planned LAWPS production rate of 17 gpm.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

NESHAP Area-Specific Dose-Release Factors for Potential Onsite Member-of-the-Public Locations at SRS using CAP88-PC Version 4.0

The Environmental Protection Agency (EPA) requires the use of the computer model CAP88-PC to estimate the total effective doses (TED) for demonstrating compliance with 40 CFR 61, Subpart H (EPA 2006), the National Emission Standards for Hazardous Air Pollutants (NESHAP) regulations. As such, CAP88 Version 4.0 was used to calculate the receptor dose due to routine atmospheric releases at the Savannah River Site (SRS). For estimation, NESHAP dose-release factors (DRFs) have been supplied to Environmental Compliance and Area Closure Projects (EC&ACP) for many years. DRFs represent the dose to a maximum receptor exposed to 1 Ci of a specified radionuclide being released into the atmosphere. They are periodically updated to include changes in the CAP88 version, input parameter values, site meteorology, and location of the maximally exposed individual (MEI). In this report, the DRFs were calculated for potential radionuclide atmospheric releases from 13 SRS release points. The three potential onsite MEI locations to be evaluated are B-Area, Three Rivers Landfill (TRL), and Savannah River Ecology Lab Conference Center (SRELCC) with TRL’s onsite workers considered as members-of-the-public, and the potential future constructions of dormitories at SRELCC and Barracks at B-Area. Each MEI location was evaluated at a specified compass sector with different area to receptor distances and was conducted for both ground-level and elevated release points. The analysis makes use of area-specific meteorological data (Viner 2014). The resulting DRFs are compared to the 2014 NESHAP offsite MEI DRFs for three operational areas; A-Area, H-Area, and COS for a release rate of 1 Ci of tritium oxide at 0 ft. elevation. CAP88 was executed again using the 2016 NESHAP MEI release rates for 0 and 61 m stack heights to determine the radionuclide dose at TRL from the center-of-site (COS).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Literature review of the potential impact of glycolic acid on the technetium chemistry of srs tank waste

This document presents a literature study of the impact of glycolate on technetium chemistry in the Savannah River Site (SRS) waste system and specifically Saltstone. A predominant portion of the Tc at SRS will be sent to the Saltstone Facility where it will be immobilized. The Tc in the tank waste is in the highly soluble chemical form of pertechnetate ion (TcO 4 - ) which is reduced by blast furnace slag (BFS) in Saltstone, rendering it highly insoluble and resistant to leaching.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Radionuclide field lysimeter experiment (RadFLEx): geochemical and hydrological data for SRS performance assessments

The SRNL Radiological Field Lysimeter Experiment (RadFLEx) is a one-of-a-kind test bed facility designed to study radionuclide geochemical processes in the Savannah River Site (SRS) vadose zone at a larger spatial scale (from grams to tens of kilograms of sediment) and temporal scale (from months to decade) than is readily afforded through laboratory studies. RadFLEx is a decade-long project that was initiated on July 5, 2012 and is funded by six different sources. The objective of this status report is as follows: 1) to report findings to date that have an impact on SRS performance assessment (PA) calculations, and 2) to provide performance metrics of the RadFLEx program. The PA results are focused on measurements of transport parameters, such as distribution coefficients (Kd values), solubility, and unsaturated flow values. As this is an interim report, additional information from subsequent research may influence our interpretation of current results. Research related to basic understanding of radionuclide geochemistry in these vadose zone soils and other source terms are not described here but are referenced for the interested reader.

58 GEOSCIENCES↗
DOE OSTI2019

Characterization of oxide films on aluminum materials following reactor exposure and wet storage in the SRS L-Basin

This report describes the characterization of oxide films on one cropped piece of 6061, one 6063, and one cropped piece that could have been either 6061 or 6063 aluminum-based alloy, stored wet for up to approximately 40 years in L-Basin on the Savannah River Site (SRS). One 6061 cropping was from a Missouri University Research Reactor (MURR) fuel element. The 6063 piece was from a cropping from a Universal Sleeve Housing (USH). The Mark-16B fuel assembly could have been either 6061 or 6063 based on design drawings. Both the Mark-16B and USH were used in SRS Production Reactors. Characterization of the as-received oxides includes the oxide morphology, thickness, structure, and chemical composition. The aim is to characterize the oxide layer on aluminum cladding and fuel components that have reactor service and long-term basin storage service.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Evaluation of the current state of knowledge for thermolysis of organics within SRS waste forming Volatile Organic Compounds (VOCs)

The 2017 report Flammable Gas Generation Mechanisms for High Level Liquid Waste Facilities, X-ESRG- 00062 Rev. 1, assessing mechanisms for flammable gas generation acknowledged the presence of flammable organics, concluding that available data indicated their concentrations pose a minor contribution (e.g., <5%) to the composite lower flammable limit. Savannah River Remediation (SRR) chartered the Savannah River National Laboratory (SRNL) to perform a more detailed assessment of available and emerging data to assess the current state of knowledge for formation of Volatile Organic Compounds (VOCs) from thermolysis of organics in Savannah River Site (SRS) caustic tank waste. Based on the assessment as detailed herein, SRNL concludes that sufficient evidence exists to demonstrate formation of methane, in addition to hydrogen, does occur during thermolysis of SRS high level waste containing organics under select conditions. This assessment cannot reliably quantify the amount of methane that forms. Nevertheless, the potential rates are sufficient – methane generation rates of approximately 30% and 100% those of hydrogen generation rates for Tank 38 radioactive waste and a high boiling point (HBP) simulant waste, respectively – to advise that ongoing program efforts be enhanced to include additional analysis for off-gas generation for concentration and screening measurements for other possible flammable species.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Radar Derived Rainfall and Rain Gauge Measurements at SRS

Over the years rainfall data for the Savannah River Site has been obtained from ground level measurements made by rain gauges. These instruments have inherent errors or biases that can impact the measured rainfall totals but are assumed as ground truth for most climatological and weather applications. With the development of weather radar technologies, various methods to derive rainfall totals from radar reflectivity values have been developed and have continued to improve. The Z-R relationship, which uses an exponential relationship to estimate rainfall rate based on radar reflectivity values, provides estimates of rainfall amounts (Z-R Level III) for locations within the radar’s detection range. The recently developed Multi-Radar Multi-Sensor (MRMS) dataset combines reflectivity-based estimates using the Z-R relationship with a network of gauges and other rainfall estimates to produce a refined set of precipitation estimates for each grid point within its domain. Comparisons were done between gauge observations and radar estimates for various SRS locations to assess whether radar derived estimates are representative of rainfall measurements at the site. Results obtained show good agreement between radar derived amounts and ground measurements, with MRMS showing stronger correlations and lower spread than Z-R Level III estimates. Outliers and errors observed appear to be related to hydrometeor classification schemes. In general, MRMS proved to provide sufficiently representative estimates of daily rainfall amounts to replace existing SRS rain gauge measurements.

54 ENVIRONMENTAL SCIENCES↗