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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Solubility of {sup 238}U radionuclide from various types of soil in synthetic gastrointestinal fluids using “US in vitro” digestion method

238U radionuclide is a naturally occuring radioactive material that can be found in soil. In this study, the solubility of 238U radionuclide obtained from various types of soil in synthetic gastrointestinal fluids was analysed by “US P in vitro” digestion method. The synthetic gastrointestinal fluids were added to the samples with well-ordered, mixed throughly and incubated according to the human physiology digestive system. The concentration of 238U radionuclide in the solutions extracted from the soil was measured using Induced Coupling Plasma Mass Spectrometer (ICP-MS). The concentration of 238U radionuclide from the soil samples in synthetic gastrointestinal fluids showed different values due to different homogenity of soil types and chemical reaction of 238U radionuclide. In general, the solubility of 238U radionuclide in gastric fluid was higher (0.050 – 0.209 ppm) than gastrointestinal fluids (0.024 – 0.050 ppm). It could be concluded that the US P in vitro digestion method is practicle for estimating the solubility of 238U radionuclide from soil materials and could be useful for monitoring and risk assessment purposes applying to environmental, health and contaminated soil samples.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Initial Assessment of Cover Degradation Features at the Mexican Hat, Utah, UMTRCA Disposal Site - 19556

The Mexican Hat, Utah, Uranium Mill Tailings Radiation Control Act (UMTRCA) Title I Disposal Site is located on the Navajo Reservation in southeast Utah. The US Nuclear Regulatory Commission licensed the site to the US Department of Energy Office of Legacy Management (LM) for custody and long-term care. LM manages long-term surveillance and maintenance activities at the site with the principal goal of protecting human health and the environment. The disposal cell was designed to encapsulate low-level radioactive mill tailings and other residual radioactive materials (RRM) in a way that minimizes the need for active maintenance and limits radon gas emanation and precipitation infiltration. The disposal cell has a multicomponent cover, consisting of a 60 cm thick (24 inch), low-permeability, bentonite-amended radon barrier, overlain by a 15 cm thick (6 inch) sandy gravel bedding/filter layer and a 30 cm thick (12 inch) riprap erosion-protection layer. Under UMTRCA, designs intended to control and contain RRM shall be effective for up to 1000 years, to the extent reasonably achievable and, in any case, for at least 200 years. In 2016, multiple subtle depressions were identified on the rock cover along the toe and lower portions of the northeast side slope of the disposal cell. Due to concerns regarding potential impacts to disposal cell performance and erosion resistance, evaluations of the depressions and cell cover design and construction were initiated. The evaluations included reviews of the disposal cell as-built drawings and supporting design calculations for the rock cover components. Also, in 2017, a weather monitoring station was installed at the site to collect continuous site-specific meteorological data, and repeatable ground-based light imaging, detection, and ranging (lidar) topographical and aerial photogrammetry surveys were implemented to monitor for potential changes in the surface depression features. The evaluations also included visual inspections of the depressions, and in 2018, small-area manual excavations of the rock cover components (test pits) were performed to observe the conditions of the cover components, scan for radioactivity, and observe evidence of erosion on the surface of the radon barrier material. Voids and incisions were discovered within the radon barrier on the north and northeast side slopes of the disposal cell. Visual observations at test pits indicate that the bedding/filter material is highly segregated and may not be in conformance with the disposal cell engineering and construction design specifications. Post-construction development of a weak to strongly cemented material has also been observed immediately below the base of the bedding layer in test pits with observed radon barrier degradation. A series of radiological surveys have been performed at the site, and radiological readings have not exceeded natural background conditions in the vicinity of the site. Thus, the site remains protective of human health and the environment. Implementation of continuous radiological monitoring at the site will be initiated in fall 2018 through the deployment of radon cups and thermoluminescent dosimeters to obtain data that provides supporting evidence that the disposal cell remains protective of human health and the environment. Evaluations to determine the cause(s) of the depression features and associated radon barrier erosion are ongoing. Possible mechanisms of cover degradation identified thus far include segregated bedding material that would allow for higher precipitation runoff velocities, resulting in erosion of the radon barrier; post-construction cementation of radon barrier or aeolian material that could negatively affect the performance of the radon barrier; cation exchange leading to the development of cementation; and aeolian deposition affecting precipitation runoff. Moreover, geotechnical sampling and testing is planned to verify spatial cover conditions relative to design specifications. The resulting information will be used to identify possible causes for the surface depressions and associated radon barrier degradation, gain insight on potential long-term performance implications along the side slopes of the disposal cell, and identify potential corrective actions. (authors)

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

VLLW/Exempt Waste Assay at AWE Using Cronos - 12001

Previous studies have indicated that waste bag photon monitors, such as the CANBERRA Cronos-11, have the potential to assay photon emitting uranium (U) and plutonium (Pu) contaminated wastes at the new UK VLLW/exempt waste thresholds of 1 Bq/g U and 0.15 Bq/g Pu. However, the technique has limitations associated with the operation of its plastic scintillation photon detectors. These include the absence of isotopic information and a variable detector background that is modified by the chemical and physical composition of the waste as well as the presence of any naturally occurring radioactive material (NORM). Hence, it is vital to operate Cronos in a low/non-fluctuating background environment and segregate wastes according to isotopic fingerprint, NORM concentration and waste composition. This paper presents results from subsequent Cronos measurements on a range of uncontaminated waste materials, contaminated wastes from Pu and U facilities and a National Physical Laboratory (NPL) waste package standard. The results were consistent with other assay techniques and show that Cronos can be used for exempt waste assay provided that it is operated in a low/non-fluctuating background area and the waste is well segregated before monitoring. (author)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Oak Ridge National Laboratory EPA Approval Letters and Historical Documentation for a Modification in Applying 40 CFR Part 61 Appendix D

Appendix D of Title 40 Part 61, “Methods for Estimating Radionuclide Emissions,” of the Code of Federal Regulations (CFR) provides a procedure that US Department of Energy (DOE) facility owners and operators can use to estimate radionuclide emissions to the atmosphere for dose calculations instead of measuring emissions for minor sources under 40 CFR Part 61, Subpart H, “National Emission Standards for Emissions of Radionuclides Other than Radon from Department of Energy Facilities.” The procedure assumes that any radioactive material heated above 100°C is completely vaporized and emitted to the atmosphere. In 1991, the DOE Oak Ridge Reservation (DOE-ORR) requested approval to use different release fractions (RFs) for uranium because of its high melting and boiling points (1,132°C and 3,818°C, respectively). In response to the request, Environmental Protection Agency (EPA) Region IV approved the use of modified RFs for elemental uranium provided no reaction had taken place to alter its chemical form. In 2015, DOE-ORR requested approval to use different RFs for radioactive tungsten, also because of its high melting and boiling points (3,410°C and 5,660°C, respectively). EPA Region IV approved the use of modified RFs for heated radioactive tungsten metal. In accordance with the two precedents set for heating uranium and radioactive tungsten metals, in 2016, DOE-ORR requested approval to use modified RFs in similar fashion for other radioactive solid metals and compounds with melting and boiling points above 500°C that might be heated above 100°C in future research projects and experiments, and again, the EPA Region IV granted approval to use modified RFs for the list of compounds. This document contains the EPA approval letters and historical documentation used in the process to obtain approval for the use of alternative Appendix D emission factors. The approval to DOE-ORR allows modifying the existing regulatory RFs to 1 when radioactive solid metals and compounds are heated to temperatures greater than or equal to the boiling point of the solid, to 10 -3 when radioactive solid metals and compounds are heated to temperatures greater than or equal to 90% of the melting point and less than the boiling point of the solid, and to 10 -6 when radioactive solid materials are heated to temperatures above ambient air temperature but below 90% of the melting point of the solid.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

MAR flow mapping of Analytical Chemistry Operations (Preliminary Report)

The recently released Supplemental Directive, NA-1 SD 1027, updates the radionuclide threshold values in DOE-STD-1027-92 CN1 to reflect the use of modern parameters for dose conversion factors and breathing rates. The directive also corrects several arithmetic errors within the original standard. The result is a roughly four-fold increase in the amount of weapons-grade nuclear material allowed within a designated radiological facility. Radiological laboratory space within the recently constructed Radiological Laboratory Office and Utility Building (RLUOB) is slated to house selected analytical chemistry support activities in addition to small-scale actinide R&D activities. RLUOB is within the same facility operations envelope as TA-55. Consolidation of analytical chemistry activities to RLUOB and PF-4 offers operational efficiency improvements relative to the current pre-CMRR plans of dividing these activities between RLUOB, PF-4, and CMR. RLUOB is considered a Radiological Facility under STD-1027 - 'Facilities that do not meet or exceed Category 3 threshold criteria but still possess some amount of radioactive material may be considered Radiological Facilities.' The supplemental directive essentially increases the allowable material-at-risk (MAR) within radiological facilities from 8.4 g to 38.6 g for 239 Pu. This increase in allowable MAR provides a unique opportunity to establish additional analytical chemistry support functions in RLUOB without negatively impacting either R&D activities or facility operations. Individual radiological facilities are tasked to determine MAR limits (up to the Category 3 thresholds) appropriate to their operational conditions. This study presents parameters that impact establishing MAR limits for RLUOB and an assessment of how various analytical chemistry support functions could operate within the established MAR limits.

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

Mathematical Calibration of Modular Plastic Scintillators for Various Assay Applications - 17322

Plastic scintillators provide an inexpensive option to assay and characterize radioactive material. Due to the low cost it is generally possible to an array of large numbers of plastic scintillators to achieve high measurement efficiencies. The beta only thin plastic scintillators used in the Argos contamination monitors provide a convenient and reliable scintillator package that can be grouped together to form an assay system. Mathematical calibrations, using MCNP, have been produced for this detector that allow for rapid construction of various custom measurement geometries. The calibrations were constructed by comparing a series of measurements made with a number of beta and beta/gamma emitting nuclides. Characterization of the beta scintillators utilized beta emitting nuclides that included spectra from low average energy, e.g. C-14, to relatively high average energy, e.g. Sr/Y-90. In order to perform the calibration, custom versions of the standard Argos scintillators were produced that provide an MCA output for spectroscopic investigation. The spectra were then compared to detailed MCNP models in an iterative process to energy calibrate and efficiency calibrate each detector type. The validated models and energy calibrations were then tested against a number of volumetric geometries to confirm that the model would translate well to any other geometry. These validated models can then be used to rapidly construct custom measurement geometries for material measurement and screening. Two examples of measurement applications include a beta screening system for dirt on a conveyor belt and a flow through beta liquid assay system. The mathematical calibration process, validation results, and a number of application examples are discussed. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

An evaluation of nearest neighbor averaging's improvements to the measurement sensitivity of wide-area radiological scanning instruments - 15560

Through the Sandia National Laboratories (SNL) New Mexico Small Business Assistance (NMSBA) program, Sandia worked with the Environmental Restoration Group (ERG) Inc. to verify and validate a novel algorithm used to determine the scanning Critical Level (Lc) and Minimum Detectable Concentration (MDC) (or Minimum Detectable Areal Activity) for the 102F scanning system. Through the use of Monte Carlo statistical simulations the algorithm mathematically demonstrates accuracy in determining the Lc and MDC when a nearest-neighbor averaging (NNA) technique was used. To empirically validate this approach, SNL prepared several spiked sources and ran a test with the ERG 102F instrument on a bare concrete floor known to have no radiological contamination other than background naturally occurring radioactive material (NORM). The tests conclude that the NNA technique increases the sensitivity (decreases the Lc and MDC) for high-density data maps that are obtained by scanning radiological survey instruments. It is further described in Sandia Laboratories document number SAND2014-16522. (authors)

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

Guidance on Radiochronometry

Radiochronometry is the measurement of radioactive materials and their decay products to determine the “age” of the material. It differs from the practice of geochronology in that the materials (samples) are man-made, and in that the timespan of interest is confined to the nuclear era, i.e., since the discovery of fission in 1939. In radiochronometry, the “age” of the material ideally records the time when the sample was manufactured, or produced in the final form that is analyzed in the laboratory. It is an important predictive signature in a nuclear forensic investigation which can help in the attribution to a source. The calculation of this “age” can only be made if a model is invoked that allows simplification of the parent radionuclide to daughter isotope decay equation. The simplification required for this model is that the parent was purified completely from all traces of its daughter product at the time of sample preparation. Then, this “age” should be described as the “model age” from which a “model date” in the past can then be calculated. For this model date to represent the date of sample preparation, two other assumptions are required to be true. The first is that the material has remained a closed system since that time (i.e., that there has been no loss or gain of either parent or daughter), and the second is that the analyses are accurate.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2020

Development of a Convolutional Neural Network Classifier for Data Starved Spectra - 20199

The Institute for Clean Energy Technology (ICET) at Mississippi State University is exploring the utility of machine learning in augmenting its mobile radiation surveying platforms, which are currently being developed as means to survey depleted uranium contaminated areas in support of remediation and decommissioning efforts. Mobile survey platforms provide a means to efficiently scan large areas of interest while reducing human exposure to radiation and other hazards. The survey platforms can also be used for scanning for any gamma emitting isotope in addition to depleted uranium. The spectral data that the platforms collect may be data starved with relatively low counts and poorly defined spectral features depending on the speed of the platforms and scintillation detector selection. Such data-starved spectra are difficult to use for isotope identification, requiring advanced knowledge of the possible radionuclides that could be present and environmental factors that could attenuate signals or introduce background noise. These factors in combination with the volume of survey data increases the time it takes to perform analysis of survey data when the source type is unknown. There are a number of algorithms in the field of machine learning that can be used to classify data that would be challenging and time-consuming for a human to identify. Supervised machine learning algorithms train models based on extensive amounts of human-labeled training data. Once sufficiently trained, these models can be used to quickly make high-fidelity predictions on new data. Convolutional neural networks are machine learning algorithms that excel in learning representations of 'shapes'. They do this by taking numerical input data and convolving them with spatial feature detectors referred to as filters. These filters are incrementally adjusted to reduce the prediction error on the data during the backpropagation step of training. Discussed in this paper is the development of a convolutional neural network classifier (CNNC) that can utilize spectral survey data for source discrimination and isotope identification. Bench-top laboratory experiments data using LaBr{sub 3}(Ce) scintillation detectors were used to train and evaluate the performance of the developed CNNC. The CNNC is capable of discriminating a variety of gamma emitting source types, differentiating different forms of uranium (depleted vs. natural), and estimating the amount of uranium for a known geometry. The discussed CNNC may be useful in scenarios where survey systems are deployed in situations where hazardous radioactive material maybe present, but the type is unknown. When used in remediation applications the CNNC can be used to screen-out false positives, helping reduce remediation costs. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

A versatile Johansson-type tender x-ray emission spectrometer

We present a high energy resolution x-ray spectrometer for the tender x-ray regime (1.6–5.0 keV) that was designed and operated at Stanford Synchrotron Radiation Lightsource. The instrument is developed on a Rowland geometry (500 mm of radius) using cylindrically bent Johansson analyzers and a position sensitive detector. By placing the sample inside the Rowland circle, the spectrometer operates in an energy-dispersive mode with a subnatural line-width energy resolution (~0.32 eV at 2400 eV), even when an extended incident x-ray beam is used across a wide range of diffraction angles (~30° to 65°). The spectrometer is enclosed in a vacuum chamber, and a sample chamber with independent ambient conditions is introduced to enable a versatile and fast-access sample environment (e.g., solid/gas/liquid samples, in situ cells, and radioactive materials). The design, capabilities, and performance are presented and discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Real breakthrough in detection of radioactive sources by portal monitors with plastic detectors and New Advanced Source Identification Algorithm (ASIA-New)

Radiation Portal Monitors (RPM) with plastic detectors represent the main instruments used for primary border (customs) radiation control. RPM are widely used because they are simple, reliable, relatively inexpensive and have a high sensitivity. However, experience using the RPM in various countries has revealed the systems have some grave shortcomings. There is a dramatic decrease of the probability of detection of radioactive sources under high suppression of the natural gamma background (radiation control of heavy cargoes, containers and, especially, trains). NORM (Naturally Occurring Radioactive Material) existing in objects under control trigger the so-called 'nuisance alarms', requiring a secondary inspection for source verification. At a number of sites, the rate of such alarms is so high it significantly complicates the work of customs and border officers. This paper presents a brief description of new variant of algorithm ASIA-New (New Advanced Source Identification Algorithm), which was developed by the Rapiscan company. It also demonstrates results of different tests and the capability of a new system to overcome the shortcomings stated above. New electronics and ASIA-New enables RPM to detect radioactive sources under a high background suppression (tested at 15-30%) and to verify the detected NORM (KCl) and the artificial isotopes (Co- 57, Ba-133 and other). New variant of ASIA is based on physical principles, a phenomenological approach and analysis of some important parameter changes during the vehicle passage through the monitor control area. Thanks to this capability main advantage of new system is that this system can be easily installed into any RPM with plastic detectors. Taking into account that more than 4000 RPM has been installed worldwide their upgrading by ASIA-New may significantly increase probability of detection and verification of radioactive sources even masked by NORM. This algorithm was tested for 1,395 passages of different transports (cars, trucks and trailers) without radioactive sources. It also was tested for 4,015 passages of these transports with radioactive sources of different activity (Co-57, Ba-133, Cs-137, Co-60, Ra-226, Th-232) and these sources masked by NORM (K-40) as well. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

Smart Planning for Radioactive Source Transport Advanced Tools for Increased Safety and Efficiency

End-of-life (EOL) management of high-activity radioactive sources is made uniquely challenging by the inherent risks associated with storage and transportation of these sources, the complex logistics involved, and the strict requirements for regulatory compliance. Traditional methods lack comprehensive tools for accurate site assessments and precision planning for the transportation of radioactive sources. They also frequently fail to provide the adaptability required to consider diverse operational environments, resulting in inefficiencies and potential safety concerns. This paper introduces a novel software solution developed to address these issues by integrating advanced technologies such as light detection and ranging (LiDAR)-based 3D environment modeling, smart dynamic route planning, and customizable measurement functionalities. This software enables detailed terrain visualizations, facilitating thorough environmental assessments and enabling users to virtually navigate, analyze, and plan site-specific operations. Among the key features are a user-centric interface for virtual navigation, precise site measurement tools for site evaluations, interactive visualizations that highlight potential operational hazards, dynamic route planning capabilities, and real-time collision detection to promote safe workflows. By demonstrating the effectiveness of this tool through real-world application, the present work underscores the tool’s potential to revolutionize radioactive source EOL management by improving operational efficiencies, minimizing risk, and advancing the state of practice to achieve suitable and secure radioactive material handling.

99 - GENERAL AND MISCELLANEOUS↗
DOE OSTI2014

Determination of activation products and resulting decommissioning implications for the Varian TruBeam linear accelerator - Paper 52

Modern medical linear accelerators used for the treatment of cancers are capable of operating at electron energies as high as 20 MeV. Above electron energies of 6 MeV, a measurable dose rate is obtained at the isocenter after beam termination. This is attributed to the activation of linear accelerator components through photonuclear reactions and neutron capture. Photons are produced as Bremsstrahlung during the collision of high-energy electrons with a heavy metal target, typically comprised of copper or tungsten. When photons exceeding the nucleon binding energy interact with a nucleus, neutrons are ejected. In the process of neutron capture, neutrons produced through ({gamma}, n) reactions are absorbed by a nucleus and the excess energy is emitted as a photon. Over the lifetime of an accelerator many components, such as the target, flattening filter, collimators, jaws, and treatment couch, are activated through these interactions. Although dependent on operating conditions, linear accelerators have an expected lifetime of 7 to 10 years. In Canada, at the end of their service, accelerators are typically sold for scrap, returned to a remanufacturing enterprise, or if the machine is still operational it can be retasked for continued use. Since many of the accelerator components have been exposed to a neutron fluence and activated to various extents, the requirements of the Canadian Nuclear Substance and Radiation Device regulations apply prior to final removal from the hospital. For shipments to the USA, there are exemption regulations to be considered. NRC regulation 10CFR 30.71 Schedule B lists a number of common radionuclides and the specific exemption quantity. Below these levels, radioactive materials may be freely transported from Canada to the USA without prior licensing from the Canadian Nuclear Safety Commission (CNSC) or United States Nuclear Regulatory Commission (NRC). (authors)

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

New Advanced Source Identification Algorithm (ASIA-NEW) for radiation monitors with plastic detectors

Radiation Portal Monitors (RPM) with plastic detectors represent the main instruments used for primary border (customs) radiation control. RPM are widely used because they are simple, reliable, relatively inexpensive and have a high sensitivity. However, experience using the RPM in various countries has revealed the systems have some grave shortcomings. There is a dramatic decrease of the probability of detection of radioactive sources under high suppression of the natural gamma background (radiation control of heavy cargoes, containers and, especially, trains). NORM (Naturally Occurring Radioactive Material) existing in objects under control trigger the so-called 'nuisance alarms', requiring a secondary inspection for source verification. At a number of sites, the rate of such alarms is so high it significantly complicates the work of customs and border officers. This paper presents a brief description of new variant of algorithm ASIA-New (New Advanced Source Identification Algorithm), which was developed by the authors and based on some experimental test results. It also demonstrates results of different tests and the capability of a new system to overcome the shortcomings stated above. New electronics and ASIA-New enables RPM to detect radioactive sources under a high background suppression (tested at 15-30%) and to verify the detected NORM (KCl) and the artificial isotopes (Co-57, Ba-133 and other). New variant of ASIA is based on physical principles and does not require a lot of special tests to attain statistical data for its parameters. That is why this system can be easily installed into any RPM with plastic detectors. This algorithm was tested for 1,395 passages of different transports (cars, trucks and trailers) without radioactive sources. It also was tested for 4,015 passages of these transports with radioactive sources of different activity (Co-57, Ba-133, Cs-137, Co-60, Ra-226, Th-232) and these sources masked by NORM (K-40) as well. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Science & Technology Review July/August 2016

At Lawrence Livermore National Laboratory, we focus on science and technology research to ensure our nation’s security. We also apply that expertise to solve other important national problems in energy, bioscience, and the environment. Science & Technology Review is published eight times a year to communicate, to a broad audience, the Laboratory’s scientific and technological accomplishments in fulfilling its primary missions. The publication’s goal is to help readers understand these accomplishments and appreciate their value to the individual citizen, the nation, and the world. In this issue for the months of July and August 2016, there are two features: one on Science and Technology in Support of Nuclear Nonproliferation, and another on Seeking Out Hidden Radioactive Materials. Then there are highlights are three research projects--on optics, plasma science, and the nature of neutrinos--along with a news section and patents and awards.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Maxine: A spreadsheet for estimating dose from chronic atmospheric radioactive releases

MAXINE is an EXCEL© spreadsheet, which is used to estimate dose to individuals for routine and accidental atmospheric releases of radioactive materials. MAXINE does not contain an atmospheric dispersion model, but rather doses are estimated using air and ground concentrations as input. Minimal input is required to run the program and site specific parameters are used when possible. Complete code description, verification of models, and user’s manual have been included.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

Cement As a Waste Form for Nuclear Fission Products: The Case of 90 Sr and Its Daughters [Cement As a Container for Nuclear Fission Products: The Case of 90 Sr and Its Daughters]

One of the main challenges faced by the nuclear industry is the long-term confinement of nuclear waste. Because it is inexpensive and easy to manufacture, cement is the material of choice to store large volumes of radioactive materials, in particular the low-level medium-lived fission products. It is therefore of utmost importance to assess the chemical and structural stability of cement containing radioactive species. Here, we use ab initio calculations based on density functional theory (DFT) to study the effects of 90 Sr insertion and decay in C–S–H (calcium-silicate-hydrate) in order to test the ability of cement to trap and hold this radioactive fission product and to investigate the consequences of its β-decay on the cement paste structure. We show that 90 Sr is stable when it substitutes the Ca 2+ ions in C–S–H, and so is its daughter nucleus 90 Y after β-decay. Interestingly, 90 Zr, daughter of 90 Y and final product in the decay sequence, is found to be unstable compared to the bulk phase of the element at zero K but stable when compared to the solvated ion in water. Furthermore, cement appears as a suitable waste form for 90 Sr storage.

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

Managing Waste Inventory and License Limits at the Perma-Fix Northwest Facility to Meet CH2M Hill Plateau Remediation Company (CHPRC) American Recovery and Reinvestment Act (ARRA) Deliverables - 12335

CH2M Hill Plateau Remediation Company (CHRPC) is a prime contractor to the U.S. Department of Energy (DOE) focused on the largest ongoing environmental remediation project in the world at the DOE Hanford Site Central Plateau, i.e. the DOE Hanford Plateau Remediation Contract. The East Tennessee Materials and Energy Corporation (M and EC); a wholly owned subsidiary of Perma-Fix Environmental Services, Inc. (PESI), is a small business team member to CHPRC. Our scope includes project management; operation and maintenance of on-site storage, repackaging, treatment, and disposal facilities; and on-site waste management including waste receipt from generators and delivery to on-site and off-site treatment, storage, and disposal facilities. As part of this scope, M and EC staffs the centralized Waste Support Services organization responsible for all waste characterization and acceptance required to support CHPRC and waste generators across the Hanford Site. At the time of the CHPRC contract award (August 2008) slightly more than 9,000 cubic meters (m{sup 3}) of legacy waste was defined as 'no-path-forward waste'. A significant portion of this waste (7,650 m{sup 3}) comprised wastes with up to 50 grams of special nuclear materials (SNM) in oversized packages recovered during retrieval operations and large glove boxes removed from the Plutonium Finishing Plant (PFP). Through a collaborative effort between the DOE, CHPRC, and Perma-Fix Environmental Services, Inc. (PESI), pathways for these problematic wastes were developed that took advantage of commercial treatment capabilities at a nearby vendor facility, Perma-Fix Northwest (PFNW). In the spring of 2009, CHPRC initiated a pilot program under which they began shipping large package, low gram suspect TRU (<15 g SNM per container), and large package contact and remote handled MLLW to the off-site PFNW facility for treatment. PFNW is restricted by the SNM limits set for the total quantity of SNM allowed at the facility in accordance with the facility's radioactive materials license(s) (RML). While both CHPRC and PFNW maintain waste databases to track all waste movements, it became evident early in the process that a tool was needed that married the two systems to better track SNM inventories and sequence waste from the point of generation, through the PFNW facility, and back to the Hanford site for final disposition. This tool, known as the Treatment Integration and Planning Tool (TIPT), has become a robust planning tool that provides real-time data to support compliant and efficient waste generation, transportation, treatment, and disposition. TIPT is developing into the next generation tool that will change the way in which legacy wastes, retrieval wastes and decontamination and decommissioning operations are conducted on the Plateau Remediation Contract (PRC). The real value of the TIPT is its predictive capability. It allows the W and FMP to map out optimal windows for processing waste through the PFNW facility, or through any process that is in some way resource limited. It allows project managers to identify and focus on problem areas before shipments are affected. It has been modified for use in broader applications to predict turnaround times and identify windows of opportunity for processing higher gram wastes through PFNW and to allow waste generators, site-wide, to accurately predict scope, cost, and schedule for waste generation to optimize processing and eliminate storage, double handling, and related costs and unnecessary safety risks. The TIPT addresses the years old problem of how to effectively predict not only what needs to be done, but when. 'When' is the key planning parameter that has been ignored by the generator and processor for many years, but has proven to be the most important parameter for both parties. While further refinement is a natural part of any development process, the current improvements on the TIPT have shown that prediction is a powerful consideration. Even in lean times expected for the foreseeable future, the improved TIPT continues to play a central role in managing our way through those times to assure facilities remain viable and available. It is recommended that other major remediation projects and waste processing facilities incorporate a tool such as TIPT to improve customer-commercial supplier communications and better optimization of resources. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗