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PubMed2001

Determining the solubility of aqueous radioactive waste from a pharmaceutical research and development lab.

The management of radioactive waste disposal at pharmaceutical research facilities is often the responsibility of the Radiation Safety Office. Aqueous waste containing a variety of radionuclides may be generated by numerous research procedures. Disposal of this waste at commercial facilities is costly and each dollar spent in disposal costs is money not spent on research. An alternative to commercial disposal is release of radioactive aqueous waste into the sanitary sewer as provided by the Code of Federal Regulations (10CFR20.2003). This method of disposal must meet certain criteria regarding the amount and concentration of radioactivity released to the sewer. In addition, the material must be "readily soluble (or readily dispersible biological material) in water." This paper describes the process used at our R&D facility to determine the solubility of aqueous waste.

Drug Industry↗
PubMed1987

Radionuclide export by deer mice at a solid radioactive waste disposal area in southeastern Idaho.

Concentrations of 90Sr, 137Cs, 238Pu, 239+240Pu, and 241Am in deer mice tissues collected from a radioactive waste disposal area in southeastern Idaho were significantly (p less than 0.05) higher than those from a control area. The highest concentrations of Pu and Am occurred in pelts of deer mice inhabiting an area which had elevated surface and subsurface soil concentrations of these nuclides as compared to other Subsurface Disposal Area locations. Therefore, transuranic contamination in tissues likely originated from both soil depths. However, 137Cs and 90Sr in tissues likely originated from subsurface areas, since surface soils were below background concentrations for these nuclides. Based on a minimum of 6160 deer mice inhabiting the 36-ha waste disposal area over a 1-yr period, a total minimum inventory of 22.8 mu Ci radioactivity was contained in deer mice tissues. Of this estimate, 22.7 mu Ci activity was due to the radionuclides 90Sr and 137Cs. An estimated total of 8.4 mu Ci was transported from the disposal area in mice dispersing from the area. A calculated annual radionuclide inventory of 28.8 mu Ci in deer mice feces was deposited in and around the radioactive waste disposal area. Deer mice inhabiting the SDA are a mode of radionuclide uptake and transport; however, the environmental consequences of this transport mechanism are likely minimal. The results for deer mice, which make up 69% of the small mammal biomass, are discussed in relation to other small mammals within the disposal area. Other modes of transport associated with the deer mice, such as radionuclides in excavated soils associated with burrowing activities and predation, are also discussed.

Animals↗
PubMed1997

Collective doses to man from dumping of radioactive waste in the Arctic Seas.

A box model for the dispersion of radionuclides in the marine environment covering the Arctic Ocean and the North Atlantic Ocean has been constructed. Collective doses from ingestion pathways have been calculated from unit releases of the radionuclides 3H, 60Co, 63Ni, 90Sr, 129I, 137Cs, 239Pu and 241Am into a fjord on the east coast of NovayaZemlya. The results show that doses for the shorter-lived radionuclides (e.g. 137Cs) are derived mainly from seafood production in the Barents Sea. Doses from the longer-lived radionuclides (e.g. 239Pu) are delivered through marine produce further away from the Arctic Ocean. Collective doses were calculated for two release scenarios, both of which are based on information of the dumping of radioactive waste in the Barents and Kara Seas by the former Soviet Union and on preliminary information from the International Arctic Sea Assessment Programme. A worst-case scenario was assumed according to which all radionuclides in liquid and solid radioactive waste were available for dispersion in the marine environment at the time of dumping. Release of radionuclides from spent nuclear fuel was assumed to take place by direct corrosion of the fuel ignoring the barriers that prevent direct contact between the fuel and the seawater. The second scenario selected assumed that releases of radionuclides from spent nuclear fuel do not occur until after failure of the protective barriers. All other liquid and solid radioactive waste was assumed to be available for dispersion at the time of discharge in both scenarios. The estimated collective dose for the worst-case scenario was about 9 manSv and that for the second scenario was about 3 manSv. In both cases, 137Cs is the radionuclide predicted to dominate the collective doses as well as the peak collective dose rates.

Arctic Regions↗
PubMed1975

The management of radioactive wastes resulting from emergency situations on land and sea.

The term 'emergency' applies to unplanned events that have generated, or had the potential to generate, radioactive wastes that could not be handled locally. Reports of past emergencies form the basis for discussion of future trends in emergency situations, the factors that influence waste management, the technology of waste management and personnel requirements. The number of past emergencies has been small and these have not increased the volume of radioactive wastes significantly. The majority of future emergencies are likely to be associated with reactors as they have been in the past. Little change in the nature of the waste is expected, although the greater use of separated plutonium may create some new problems. The factors that influence emergency waste management fall into two categories, those that are concerned with the location of the emergency event, and those concerned with the characteristics of the wastes. As in the past, it can be expected that in most emergencies proven waste management techniques will be adapted to suit the local circumstances but there is a need for simpler and more economic methods. Trained personnel and comprehensive planning are cited as key factors in successful waste management operations.

Accidents↗
PubMed2003

Potential of pottery materials in manufacturing radioactive waste containers.

Various pottery materials were evaluated for possible use in manufacturing containers for radioactive waste. Their potential was examined from the viewpoints of the effectiveness of disposal and the changes induced in them by gamma rays. Samples of these materials were irradiated with high-energy neutrons and gamma rays in a reactor near its core. the physical and mechanical properties of the materials before and after gamma irradiation (in a 60Co gamma cell) were compared. The study showed that pottery materials are resistant to radiation. Therefore, they were proposed for manufacturing drums for disposal of radioactive waste of high gamma activity.

Journal Article↗
PubMed2005

[Parameters of physical and mental development of children and adolescents residing near enterprise for radioactive waste processing and stationary storage].

Operation of enterprise for radioactive waste processing and disposal does not influence negatively physical and mental development of children and adolescents residing in the area under observation. In some parameters, physical and mental development of children and adolescents residing in the area under observation surpasses that in reference area--that could be due to social and economic peculiarities.

Adolescent↗
PubMed2006

Improving the regulation and management of low-activity radioactive wastes.

This paper summarizes the first phase of a study in progress by a committee of the National Research Council's Board on Radioactive Waste Management. The Board initiated the study after observing that statutes and regulations administered by the federal and state agencies that control low-activity radioactive wastes have developed as a patchwork over almost 60 y. These controls usually reflect the enterprise or process that produced the waste rather than the waste's radiological hazard. Inconsistencies in the regulatory patchwork or its application may have led to overly restrictive controls for some low-activity wastes while others were neglected in comparison. In the first phase of this study, the committee reviewed current low-activity waste inventories, regulations, and management practices. This led the committee to develop five categories that encompass the spectrum of low-activity wastes and serve to illustrate gaps and inconsistencies in current regulations and management practices. The committee completed its first phase with four findings that will lead into the final phase of the study. This paper is excerpted from the committee's interim report that was issued in October 2003.

Decision Making↗
PubMed1988

Performance assessment of radioactive waste repositories.

The current plans for permanent disposal of radioactive waste call for its emplacement in deep underground repositories mined from geologically stable rock formations. The U.S. Nuclear Regulatory Commission and U.S. Environmental Protection Agency have established regulations setting repository performance standards for periods of up to 10,000 years after disposal. Compliance with these regulations will be based on a performance assessment that includes (i) identification and evaluation of the likelihood of all significant processes and events that could affect a repository, (ii) examination of the effects of these processes and events on the performance of a repository, and (iii) estimation of the releases of radionuclides, including the associated uncertainties, caused by these processes and events. These estimates are incorporated into a probability distribution function showing the likelihood of exceeding radionuclide release limits specified by regulations.

Evaluation Studies as Topic↗
PubMed2002

A model for evaluating radiological impacts on organisms other than man for use in post-closure assessments of geological repositories for radioactive wastes.

Bioaccumulation and dosimetric models have been developed that allow the computation of dose rates to a wide variety of plants and animals in the context of the deep geological disposal of solid radioactive wastes. These dose rates can be compared with the threshold dose rates at which significant deleterious effects have been observed in field and laboratory observations. This provides a general indication of whether effects on ecosystems could be observable, but does not quantify the level of those effects. To address this latter issue, two indicator organisms were identified and exposure-response relationships were developed for endpoints of potential interest (mortality in conifers and the induction of skeletal malformations in rodents irradiated in utero). The bioaccumulation, dosimetry and exposure-response models were implemented and used to evaluate the potential significance of radionuclide releases from a proposed deep geological repository for radioactive wastes in France. This evaluation was undertaken in the context of a programme of assessment studies being performed by the Agence nationale pour la gestion des déchets radioactifs (ANDRA).

Animals↗
PubMed1983

Biological elimination rates of radioisotopes by mallards contaminated at a liquid radioactive waste disposal area.

The biological elimination of nine gamma-emitting radioisotopes was studied in mallards (Anas platyrhynchos) which were released onto liquid radioactive waste pounds in southeastern Idaho. After 68, 75 or 145 days, the ducks were removed from the contaminated environment and placed in metabolic cages. Whole-body and feces-urine counts were made for 51 days and then the ducks were sacrificed and dissected for tissue analyses. The biological elimination of radioisotopes were fit to two compartment models using non-linear least squares estimation. Fecal-urine data substantiated two-compartment elimination of all radionuclides. Biological half-lives in mallards were 10 days (131I), 22 days (140Ba), 86 days (51Cr), 32 days (58Co), 26 days (75Se), 67 days (65Zn), 10 days (134Cs), 67 days (60Co) and 11 days (137Cs). Body burdens in ducks were at 90% of equilibrium with the radioactive waste pond water at the time of removal from the waste ponds. Tissue distribution of radionuclides on the day of removal from the ponds showed gut to have the highest concentrations followed by feather, liver and muscle. After 51 days in metabolic cages, feather had the greatest radionuclide concentrations followed by liver, muscle and gut. Liver contained the greatest variety of radionuclides and muscle the smallest. Biological elimination rates for the major dose-contributing nuclides (134Cs and 137Cs) to humans consuming contaminated waterfowl tissue indicate that the dose to man could be reduced substantially due to the rapid elimination of these radionuclides by mallards. Contaminated waterfowl would receive most of the internal dose in the first month after leaving the contaminated environment indicating that long-term doses would be inconsequential.

Animals↗
PubMed2006

[Experimental study on the treatment of low level radioactive waste water by inorganic nanofiltration membrane].

Soluble sodium poly(acrylic) acid (NaPAA) with molecular weight of 2000-5000 was selected as an assistant reagent of inorganic nanofiltration membrane which was used to treat low level radioactive waste water mainly containing radionuclides 90Sr, 137Cs and 60Co. The effect of non-active simulated wastewater pH and NaPAA concentration on the retention efficiency of non-active nuclides strontium, cesium and cobalt ions and membrane permeation flux were explored, and the effect mechanism was also preliminarily discussed. The optimum process parameters were decided: pH 7-8, NaPAA volume concentration no lower than 0.1%. Real radioactive waste water was treated under optimum experiment condition. The results show that the decontamination efficiency of total beta and gamma emitters of low-level radioactive wastewater were both up to about 95% by inorganic nanofiltration assisted by NaPAA, and the permeation flux was also satisfying.

Membranes, Artificial↗
PubMed1985

Biotic transport of radionuclides from a low-level radioactive waste site.

In the United States, concern for human exposures to radioactivity associated with the disposal of low-level radioactive waste has resulted in a series of regulatory guides, environmental assessments, management practices, and modeling tools. A large number of radionuclide transport processes and mechanisms that may contribute to human exposure have been modeled, using computer programs to make the required calculations. The objective of our work was to evaluate the relevance of potential biological transport processes in the assessment of potential impacts at low-level waste (LLW) disposal sites. As part of this effort, we developed an order-of-magnitude estimate for potential dose to man resulting from biological transport by burrowing animals and by plant translocation at a reference low-level waste site in the arid west. We also made comparative dose-to-man estimates for a more commonly considered human intrusion exposure scenario. Parameter values for defining a reference arid LLW disposal site and biotic transport processes are based on data reported in current literature. Estimates of waste volumes for the western United States are based on information described by the U.S. Nuclear Regulatory Commission in the Draft Environmental Impact Statement in support of 10 CFR Part 61. Our estimates of the dose-to-man resulting from biotic transport are of the same order of magnitude as those resulting from a more commonly evaluated human intrusion scenario. The previously assumed lack of potential importance of biotic transport at LLW sites in earlier assessment studies is not confirmed by our findings. Our results indicate that long-term biological transport processes have the potential to influence LLW site performance, and should be carefully evaluated as part of the impact assessment process.

Animal Population Groups↗
PubMed1999

A biosphere modeling methodology for dose assessments of the potential Yucca Mountain deep geological high level radioactive waste repository.

Recent developments in performance standards for proposed high level radioactive waste disposal at Yucca Mountain suggest that health risk or dose rate limits will likely be part of future standards. Approaches to the development of biosphere modeling and dose assessments for Yucca Mountain have been relatively lacking in previous performance assessments due to the absence of such a requirement. This paper describes a practical methodology used to develop a biosphere model appropriate for calculating doses from use of well water by hypothetical individuals due to discharges of contaminated groundwater into a deep well. The biosphere model methodology, developed in parallel with the BIOMOVS II international study, allows a transparent recording of the decisions at each step, from the specification of the biosphere assessment context through to model development and analysis of results. A list of features, events, and processes relevant to Yucca Mountain was recorded and an interaction matrix developed to help identify relationships between them. Special consideration was given to critical/potential exposure group issues and approaches. The conceptual model of the biosphere system was then developed, based on the interaction matrix, to show how radionuclides migrate and accumulate in the biosphere media and result in potential exposure pathways. A mathematical dose assessment model was specified using the flexible AMBER software application, which allows users to construct their own compartment models. The starting point for the biosphere calculations was a unit flux of each radionuclide from the groundwater in the geosphere into the drinking water in the well. For each of the 26 radionuclides considered, the most significant exposure pathways for hypothetical individuals were identified. For 14 of the radionuclides, the primary exposure pathways were identified as consumption of various crops and animal products following assumed agricultural use of the contaminated water derived from the deep well. Inhalation of dust (11 radionuclides) and external irradiation (1 radionuclide) were also identified as significant exposure modes. Contribution to the total flux to dose conversion factor from the drinking water pathway for each radionuclide was also assessed and for most radionuclides was found to be less than 10% of the total flux to dose conversion factor summed across all pathways. Some of the uncertainties related to the results were considered. The biosphere modeling results have been applied within an EPRI Total Systems Performance Assessment of Yucca Mountain. Conclusions and recommendations for future performance assessments are provided.

Computer Simulation↗
PubMed1956

The safe disposal of radioactive wastes.

A comprehensive review is given of the principles and problems involved in the safe disposal of radioactive wastes. The first part is devoted to a study of the basic facts of radioactivity and of nuclear fission, the characteristics of radioisotopes, the effects of ionizing radiations, and the maximum permissible levels of radioactivity for workers and for the general public. In the second part, the author describes the different types of radioactive waste-reactor wastes and wastes arising from the use of radioisotopes in hospitals and in industry-and discusses the application of the maximum permissible levels of radioactivity to their disposal and treatment, illustrating his discussion with an account of the methods practised at the principal atomic energy establishments.

Humans↗