The potential for criticality following disposal of uranium at low-level waste facilities: Uranium blended with soil

The purpose of this study was to evaluate whether or not fissile uranium in low-level-waste (LLW) facilities can be concentrated by hydrogeochemical processes to permit nuclear criticality. A team of experts in hydrology, geology, geochemistry, soil chemistry, and criticality safety was formed to develop achievable scenarios for hydrogeochemical increases in concentration of special nuclear material (SNM), and to use these scenarios to aid in evaluating the potential for nuclear criticality. The team`s approach was to perform simultaneous hydrogeochemical and nuclear criticality studies to (1) identify some achievable scenarios for uranium migration and concentration increase at LLW disposal facilities, (2) model groundwater transport and subsequent concentration increase via sorption or precipitation of uranium, and (3) evaluate the potential for nuclear criticality resulting from potential increases in uranium concentration over disposal limits. The analysis of SNM was restricted to {sup 235}U in the present scope of work. The outcome of the work indicates that criticality is possible given established regulatory limits on SNM disposal. However, a review based on actual disposal records of an existing site operation indicates that the potential for criticality is not a concern under current burial practices

Carnivore Translocations and Conservation: Insights from Population Models and Field Data for Fishers (Martes pennanti)

Translocations are frequently used to restore extirpated carnivore populations. Understanding the factors that influence translocation success is important because carnivore translocations can be time consuming, expensive, and controversial. Using population viability software, we modeled reintroductions of the fisher, a candidate for endangered or threatened status in the Pacific states of the US. Our model predicts that the most important factor influencing successful re-establishment of a fisher population is the number of adult females reintroduced (provided some males are also released). Data from 38 translocations of fishers in North America, including 30 reintroductions, 5 augmentations and 3 introductions, show that the number of females released was, indeed, a good predictor of success but that the number of males released, geographic region and proximity of the source population to the release site were also important predictors. The contradiction between model and data regarding males may relate to the assumption in the model that all males are equally good breeders. We hypothesize that many males may need to be released to insure a sufficient number of good breeders are included, probably large males. Seventy-seven percent of reintroductions with known outcomes (success or failure) succeeded; all 5 augmentations succeeded; but none of the 3 introductions succeeded. Reintroductions were instrumental in reestablishing fisher populations within their historical range and expanding the range from its most-contracted state (43% of the historical range) to its current state (68% of the historical range). To increase the likelihood of translocation success, we recommend that managers: 1) release as many fishers as possible, 2) release more females than males (55–60% females) when possible, 3) release as many adults as possible, especially large males, 4) release fishers from a nearby source population, 5) conduct a formal feasibility assessment, and 6) develop a comprehensive implementation plan that includes an active monitoring program

Site Safety and Health Plan (Phase 3) for the treatability study for in situ vitrification at Seepage Pit 1 in Waste Area Grouping 7, Oak Ridge National Laboratory, Oak Ridge, TN

This plan is to be implemented for Phase III ISV operations and post operations sampling. Two previous project phases involving site characterization have been completed and required their own site specific health and safety plans. Project activities will take place at Seepage Pit 1 in Waste Area Grouping 7 at ORNL, Oak Ridge, Tennessee. Purpose of this document is to establish standard health and safety procedures for ORNL project personnel and contractor employees in performance of this work. Site activities shall be performed in accordance with Energy Systems safety and health policies and procedures, DOE orders, Occupational Safety and Health Administration Standards 29 CFR Part 1910 and 1926; applicable United States Environmental Protection Agency requirements; and consensus standards. Where the word ``shall`` is used, the provisions of this plan are mandatory. Specific requirements of regulations and orders have been incorporated into this plan in accordance with applicability. Included from 29 CFR are 1910.120 Hazardous Waste Operations and Emergency Response; 1910.146, Permit Required - Confined Space; 1910.1200, Hazard Communication; DOE Orders requirements of 5480.4, Environmental Protection, Safety and Health Protection Standards; 5480.11, Radiation Protection; and N5480.6, Radiological Control Manual. In addition, guidance and policy will be followed as described in the Environmental Restoration Program Health and Safety Plan. The levels of personal protection and the procedures specified in this plan are based on the best information available from reference documents and site characterization data. Therefore, these recommendations represent the minimum health and safety requirements to be observed by all personnel engaged in this project

Hybrid Resiliency-Stressor Conceptual Framework for Informing Decision Support Tools and Addressing Environmental Injustice and Health Inequities

While structural factors may drive health inequities, certain health-promoting attributes of one’s “place” known as salutogens may further moderate the cumulative impacts of exposures to socio-environmental stressors that behave as pathogens. Understanding the synergistic relationship between socio-environmental stressors and resilience factors is a critical component in reducing health inequities; however, the catalyst for this concept relies on community-engaged research approaches to ultimately strengthen resiliency and promote health. Furthermore, this concept has not been fully integrated into environmental justice and cumulative risk assessment screening tools designed to identify geospatial variability in environmental factors that may be associated with health inequities. As a result, we propose a hybrid resiliency-stressor conceptual framework to inform the development of environmental justice and cumulative risk assessment screening tools that can detect environmental inequities and opportunities for resilience in vulnerable populations. We explore the relationship between actual exposures to socio-environmental stressors, perceptions of stressors, and one’s physiological and psychological stress response to environmental stimuli, which collectively may perpetuate health inequities by increasing allostatic load and initiating disease onset. This comprehensive framework expands the scope of existing screening tools to inform action-based solutions that rely on community-engaged research efforts to increase resiliency and promote positive health outcomes

In situ techniques for the characterization and monitoring of a radioactively contaminated site for in situ vitrification

A treatability study was in October 1993 to evaluate the application of in situ vitrification (ISV) to an old seepage pit used for the disposal of radioactive liquid waste at the Oak Ridge National Laboratory (ORNL). This pit is one of seven inactive seepage pits and trenches at ORNL. During the 3 months that the pit was operated as a disposal facility, it is estimated to have received approximately 398 curies of mixed fission products, primarily {sup 137}Cs, {sup 90}Sr, and {sup 106}Ru. Based on data from analysis of sludge from another pit, the activities for waste sludge in Pit 1 decay corrected to 1993 have been roughly estimated to be 71 and 17.5 curies of {sup 137}Cs, and {sup 90}Sr, respectively. The {sup 106}Ru, with a half-life of 367 days, has decayed completely in the 42 years since its disposal in the pit Earthen fill material was added to the pit in 1981, and the pit area was then covered with an approximately 4--6 inch thick asphalt surface. Because so little information necessary for the effective and safe ISV of Pit 1 was available, the first phasm of the treatability study focused on site characterization activities. Several in-situ techniques were developed and used during characterization to ascertain the pit`s lateral and vertical dimensions hydraulic and hydrologic properties, soil composition, contaminant inventory, and lateral and vertical distribution of radionuclides. At the end of the treatability study, this characterization effort will be evaluated to determine which properties were the most useful for designing and controlling the ISV process. Such information will be invaluable in efficiently and safely gathering characterization data for the remediation of the other seepage pits and trenilim at ORNL via ISV or alternative remediation techniques. This abstract briefly describes some of the major components of the field characterization activities and their results

In situ vitrification demonstration at Pit 1, Oak Ridge National Laboratory. Volume 2: Site characterization report of the Pit 1 area

A treatability study was initiated in October 1993, initially encompassing the application of in situ vitrification (ISV) to at least two segments of Oak Ridge National Laboratory (ORNL) seepage Pit 1 by the end of fiscal year (FY) 1995. This treatability study was to have supported a possible Interim Record of Decision (IROD) or removal action for closure of one or more of the seepage pits and trenches as early as FY 1997. The Remedial Investigation/Feasibility Study for Waste Area Grouping (WAG) 7, which contains these seven seepage pits and trenches, will probably not begin until after the year 2000. This treatability study will establish the field-scale technical performance of ISV for (1) attaining the required depth, nominally 15 ft, to incorporate source contamination within and beneath the pits; (2) demonstrating field capability to overlap melt settings that are necessary to achieve fused, melted segments of the source contamination; (3) demonstrating off-gas handling technology for accommodating and minimizing the volatilization of {sup 137}Cs; (4) demonstrating adequate site characterization techniques to predict ISV melting kinetics, processing temperatures, and product durability; and (5) promoting public acceptance of ISV technology by demonstrating its safety, implementability, site impacts, and air emissions and by coordinating the treatability study within the regulatory closure process. This report summarizes the site characterization information gathered through the end of September 1996 which supports the planning and assessment of ISV for Pit 1 (objective 4 above)

Tracer-level radioactive pilot-scale test of in situ vitrification for the stabilization of contaminated soil sites at ORNL

A field demonstration of in situ vitrification (ISV) was completed in May 1991, and produced approximately 12 Mg of melted earthen materials containing 12.7 mCi of radioactivity within 500 g of sludge in amodel of an old seepage trench waste disposal unit. Past waste disposal operations at Oak Ridge National Laboratory have left several contaminated seepage sites. In planning for remediation of such sites, ISV technology has been identified as a leading candidate because of the high risks associated with any retrieval option and because of the usual high quality of vitreous waste form. Major isotopes placed in the test trench were {sup 137}Cs and {sup 90}Sr, with lesser amounts of {sup 6O}Co, {sup 241}Am, and {sup 239,240}Pu. A total of 29 MWh of electrical power was delivered to the ground over a 5-day period producing a melt depth of 8.5 ft. During melting, 2.4% of the {sup 137}Cs volatilized from the melt into an off-gas containment hood and was captured quantitatively on a high efficiency particulate air filter. No volatilization of {sup 90}Sr, {sup 241}Am, or {sup 239,240}Pu was detected and > 99.993% retention of these isotopes in the melt was estimated. The use of added rare earth tracers (Ce, La, and Nd), as surrogates for transuranic isotopes, led to estimated melt retentions of >99.9995% during the test. The molten material, composed of the native soil and dolomitic limestone used for filling the test trench, reached a processing temperature of 1500{degrees}C. Standardized leaching procedures using Product Consistency Testing indicated that the ISV product has excellent characteristics relative to other vitreous nuclear waste forms

In situ vitrification demonstration at Pit 1, Oak Ridge National Laboratory. Volume 1: Results of treatability study

A treatability study was initiated in October 1993 to apply in situ vitrification (ISV) to at least two segments of Oak Ridge National Laboratory (ORNL) seepage Pit 1 by the end of fiscal year (FY) 1995. This treatability study was later extended to include all of Pit 1 and was performed to support a possible Interim Record of Decision or removal action for closure of one or more of the seepage pits and trenches beginning as early as FY 1997. This treatability study was carried out to establish the field-scale technical performance of ISV for (1) attaining the required depth, nominally 15 ft, to incorporate source contamination within and beneath the pits; (2) demonstrating field capability for the overlap of melt settings which will be necessary to achieve fused, melted segments of the source contamination; (3) demonstrating off-gas handling technology for accommodating and minimizing the volatilization of {sup 137}Cs; (4) demonstrating adequate site characterization techniques to predict ISV melting kinetics, processing temperatures, and product durability; and (5) promoting public acceptance of ISV technology by demonstrating its safety, implementability, site impacts, and air emissions and by coordinating the treatability study within the regulatory closure process. In April 1996 an expulsion of an estimated 10% of the 196 Mg (216 tons) melt body occurred resulting in significant damage to ISV equipment and, ultimately, led to an indefinite suspension of further ISV operations at Pit 1. This report summarizes the technical accomplishments and status of the project in fulfilling these objectives through September 1997

Tracer-level radioactive pilot-scale test of in situ vitrification for the stabilization of contaminated soil sites at ORNL

A field demonstration of in situ vitrification (ISV) was completed in May 1991, and produced approximately 12 Mg of melted earthen materials containing 12.7 mCi of radioactivity within 500 g of sludge in amodel of an old seepage trench waste disposal unit. Past waste disposal operations at Oak Ridge National Laboratory have left several contaminated seepage sites. In planning for remediation of such sites, ISV technology has been identified as a leading candidate because of the high risks associated with any retrieval option and because of the usual high quality of vitreous waste form. Major isotopes placed in the test trench were [sup 137]Cs and [sup 90]Sr, with lesser amounts of [sup 6O]Co, [sup 241]Am, and [sup 239,240]Pu. A total of 29 MWh of electrical power was delivered to the ground over a 5-day period producing a melt depth of 8.5 ft. During melting, 2.4% of the [sup 137]Cs volatilized from the melt into an off-gas containment hood and was captured quantitatively on a high efficiency particulate air filter. No volatilization of [sup 90]Sr, [sup 241]Am, or [sup 239,240]Pu was detected and > 99.993% retention of these isotopes in the melt was estimated. The use of added rare earth tracers (Ce, La, and Nd), as surrogates for transuranic isotopes, led to estimated melt retentions of >99.9995% during the test. The molten material, composed of the native soil and dolomitic limestone used for filling the test trench, reached a processing temperature of 1500[degrees]C. Standardized leaching procedures using Product Consistency Testing indicated that the ISV product has excellent characteristics relative to other vitreous nuclear waste forms