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PubMed2005

"Reference Biospheres" for solid radioactive waste disposal: the BIOMASS methodology.

The BIOMASS Theme 1 project has developed a methodology for the logical and defensible construction of 'assessment biospheres': mathematical representations of biospheres used in the total system performance assessment of radioactive waste disposal. The BIOMASS Methodology provides a systematic approach to decision making, including decisions on how to address biosphere change. The BIOMASS Methodology was developed through consultation and collaboration with many relevant organisations, including regulators, operators and a variety of independent experts. It has been developed to be practical and to be consistent with recommendations from ICRP and IAEA on radiation protection in the context of the disposal of long-lived solid radioactive wastes. The five main steps in the methodology are described in this paper. The importance of a clear assessment context, to clarify intentions and to support a coherent biosphere assessment process within an overall repository performance assessment, is strongly emphasised. A well described assessment context is an important tool for ensuring consistency across the performance assessment as a whole. The use of interaction matrices has been found to be helpful in clarifying the interactions between different habitats within the biosphere system and the significant radionuclide transfer pathways within the biosphere system. Matrices also provide a useful means of checking for consistency.

Program Development↗
PubMed1986

Determination of 241Pu in low-level radioactive wastes from reactors.

Plutonium-241 is unique in low-level radioactive wastes (LLW) from nuclear power plants because it is the only significant beta-emitting transuranic nuclide in LLW, has a relatively short half-life of 14.4 y, and has a fairly high allowable concentration for shallow land burial. Radiochemical separation of Pu followed by liquid scintillation analysis was used to quantitate 241Pu in a wide range of solid, semi-solid, and liquid LLW samples from two nuclear plants in Michigan. The 241Pu concentrations varied considerably by sample type and reactor operational period as did their correlation with 137Cs, 144Ce, 239Pu and 240Pu concentrations in the same sample. These patterns were also found in reported data for 241Pu in LLW from other reactors, raising the difficulty of accurately determining the inventory (or source term) in a LLW shallow land burial site and its implications for predicting and controlling the future environmental and public health impacts of such disposal.

Cerium Radioisotopes↗
PubMed2006

An industry perspective on commercial radioactive waste disposal conditions and trends.

The United States is presently served by Class-A, -B and -C low-level radioactive waste and naturally-occurring and accelerator-produced radioactive material disposal sites in Washington and South Carolina; a Class-A and mixed waste disposal site in Utah that also accepts naturally-occurring radioactive material; and hazardous and solid waste facilities and uranium mill tailings sites that accept certain radioactive materials on a site-specific basis. The Washington site only accepts low-level radioactive waste from 11 western states due to interstate Compact restrictions on waste importation. The South Carolina site will be subject to geographic service area restrictions beginning 1 July 2008, after which only three states will have continued access. The Utah site dominates the commercial Class-A and mixed waste disposal market due to generally lower state fees than apply in South Carolina. To expand existing commercial services, an existing hazardous waste site in western Texas is seeking a Class-A, -B and -C and mixed waste disposal license. With that exception, no new Compact facilities are proposed. This fluid, uncertain situation has inspired national level rulemaking initiatives and policy studies, as well as alternative disposal practices for certain low-activity materials.

Decision Making↗
PubMed1990

[Treatment of radioactive waste phenol with Fenton's oxidation].

A new procedure was developed for the waste treatment of radioactive phenol on a laboratory scale. Waste phenol was dissolved in water (2% as phenol), and ferrous ion (10 mg/l as Fe2+) was added. Hydrogen peroxide (6% as H2O2) was added separately in three steps, 20, 30, and 50% of the volume, in order to avoid rapid reaction. The solution was heated at 80-90 degrees C for several hours in a beaker covered with a watch glass till the color of the solution changes from red purple to pale yellow. Then, the solution was neutralized with sodium hydroxide and heated for 1 h to decompose excess hydrogen peroxide. When the procedure is carried out with four 2 l beakers on a hot plate, 100 ml of phenol (1,200 ml of the aqueous solution saturated with phenol) can be oxidized simultaneously.

Laboratories↗
PubMed2005

Modelling of the shielding capabilities of the existing solid radioactive waste storages at Ignalina NPP.

There is only one nuclear power plant in Lithuania--Ignalina NPP (INPP). The INPP operates two similar units with design electrical power of 1500 MW. The units were commissioned in 1983 and 1987 respectively. From the beginning of the INPP operation all generated solid radioactive waste was collected and stored at the Soviet type solid radwaste facility located at INPP site. The INPP solid radwaste storage facility consists of four buildings, namely building No. 155, No. 155/1, No. 157 and No. 157/1. The buildings of the INPP solid radwaste storage facility are reinforced concrete structures above ground. State Nuclear Safety Inspectorate (VATESI) has specified that particular safety analysis must be performed for existing radioactive waste storage facilities of the INPP. As part of the safety analysis, shielding capabilities of the walls and roofs of these buildings were analysed. This paper presents radiation shielding analysis of the buildings No. 157 and No. 157/1 that are still in operation. The buildings No. 155 and No. 155/1 are already filled up with the waste and no additional waste loading is expected.

Computer Simulation↗
PubMed2003

Probabilistic risk analysis for a high-level radioactive waste repository.

A probabilistic risk analysis (PRA) for a high-level radioactive waste repository is very important since it gives an estimate of its health impacts, allowing comparisons to be made with the health impacts of competing technologies. However, it is extremely difficult to develop a credible PRA for a specific repository site because of large uncertainties in future climate, hydrology, geological processes, etc. At best, such a PRA would not be understandable to the public. An alternative proposed here is to develop a PRA for an average U.S. site, taking all properties of the site to be the U.S. average. The results are equivalent to the average results for numerous randomly selected sites. Such a PRA is presented here; it is easy to understand, and it is not susceptible to substantial uncertainty. Applying the results to a specific repository site then requires only a simple, intuitively acceptable "leap of faith" in assuming that with large expenditures of effort and money, experts can select a site that would be at least as secure as a randomly selected site.

Humans↗
PubMed1986

Carbon-14 in low-level radioactive waste from two nuclear power plants.

The amount of 14C in low-level radioactive wastes is important for determining the future impacts of their disposal. New regulations in the Code of Federal Regulations, Title 10, Part 61 (10 CFR 61) require quantitation of 14C and other radionuclides in such wastes not amenable to measurement by gamma spectroscopy. Sampling was done of major waste streams at the Palisades pressurized water reactor (PWR) and the Big Rock Point boiling water reactor (BWR) to determine quantities of 14C in the waste streams for comparison with other reported studies. Analyses were performed by releasing all 14C constituents in the waste samples in the form of 14CO2 by chemical processing or by heating the samples in a tube furnace containing CuO2 catalyst and trapping the evolved gas in a liquid scintillator for counting. The largest amounts of 14C were found in the resins and filters used for reactor water cleanup, a result which is similar to those of the available studies. From these data, the annual amounts of 14C in wastes from nominal PWRs and BWRs were estimated to be 4.7 and 0.5 Ci/GW(e)-yr, respectively.

Carbon Radioisotopes↗
PubMed1983

[Sea dumping of radioactive wastes].

This paper is an introduction to the problems of dumping at sea of radioactive wastes. A short survey is given on the dumping actions previously performed, the legal justification by international treaties, and the most important radioecological questions.

Animals↗
PubMed2006

[Stabiltiy and barries function provided by sanitary protective zone of radioactive waste neutralization site, according to data obtained through geoinformative technologies].

The authors defined a radioactive waste neutralization and disposal site as a complex of industrial chambers with used territory of ground with burial places, buffer sanitary protection zone and observation zone. This area is a complicated geotechnical zone where natural communities develop under chronic exposure to natural and artificial radionuclides coming from both global and technogenic sources. Using geoinformative technologies of radioecologic safety, the authors evaluated protective functions of buffer zone, its biopotential and stability to specific type of nature management. The studies helped to identify sorption and migration capacity of the territory.

Ecology↗
PubMed1994

Perceived risks of radioactive waste transport through Oregon: results of a statewide survey.

Transportation of hazardous materials, and particularly radioactive wastes, on public highways has become an important risk management issue. The unfavorability of public attitudes regarding hazardous and nuclear wastes signals the potential for strong public opposition to programs for transporting these materials. This paper presents the results of a survey conducted to assess public reactions to a long-term nuclear waste transport program planned to follow a route through a portion of rural Oregon. The survey assessed a number of key risk perception issues, including perceived health and safety risks of nuclear waste transport, relative risks of transport vs. storage at an existing site, trust in state officials, and satisfaction with life in communities along the transport route. The survey identified a number of attitudes and concerns that need to be understood and considered by those in charge of designing and implementing the waste-transportation program.

Data Collection↗
PubMed2005

Treatment of uncertainty and developing conceptual models for environmental risk assessments and radioactive waste disposal safety cases.

The common approach to performing quantitative risk assessments in the contaminated land industry in the UK lacks a formal methodology for the treatment of the full range of uncertainties and for documenting decisions regarding the development of conceptual models and the selection of computer codes. The approach presented here represents an alternative, more detailed, and systematic approach for developing conceptual models and addressing uncertainties when undertaking contaminated land risk assessments. It is intended that the advantages of this approach are recognised by practitioners in the contaminated land industry and adopted, where appropriate, to help improve the quality of contaminated land risk assessments. The identification of features, events, and processes (FEPs) has been applied to safety assessments of deep geological and near-surface disposal of radioactive wastes. One of the primary benefits of using this approach is in the development of conceptual models. The approach identifies the FEPs that need to be addressed during the development of conceptual models and in the selection of suitable computer codes that can be used to represent the conceptual models. This approach has been applied by BNFL at the low-level radioactive waste disposal site at Drigg in Cumbria and is currently being adopted for a contaminated land study at the Sellafield site, also in Cumbria. This paper presents the advantages of using FEPs in the development of conceptual models and the treatment of uncertainties. The paper also discusses the application of this approach to contaminated land studies and provides an example to demonstrate the application of the approach. BNFL's approach at the Drigg site involves the identification of components (features) and phenomena (events and processes) that govern interactions and dependencies between the components by arranging them in a matrix format.

Environmental Exposure↗
PubMed2003

Reconstruction of the radionuclide spectrum of liquid radioactive waste released into the Techa river in 1949-1951.

The major part of the liquid radioactive waste released by the Mayak Production Association (PA) radiochemical plant into the Techa river occurred in 1949-1951, but there is information on only one single radiochemical analysis of a water sample taken on 24 and 25 September 1951. These data are here used to assess the spectrum of radionuclides that were released between 1949 and 1951. For this purpose, details of the radiochemical methods of radionuclide extraction and radiometric measurements of beta-activity used at Mayak PA in the 1950s have been taken into account. It is concluded that the data from the radiochemical measurements agree with the theoretical composition of fission products in uranium after exposure times in the reactor (120 days) and subsequent hold times (35 days) that were typical for the procedures at that time. The results of the analysis are at variance with assumptions that underlie the current Techa river dosimetry system. They confirm the conclusion that the external doses to the Techa river residents in the critical period up to 1952 were predominantly due to short-lived fission products.

Beta Particles↗
PubMed1980

Microbial activity of trench leachates from shallow-land, low-level radioactive waste disposal sites.

Trench leachate samples collected anoxically from shallow-land, low-level radioactive waste disposal sites were analyzed for total aerobic and anaerobic populations, sulfate reducers, denitrifiers, and methanogens. Among the several aerobic and anaerobic bacteria isolated, only Bacillus sp., Pseudomonas sp., Citrobacter sp., and Clostridium sp. were identified. Mixed bacterial cultures isolated from the trench leachates were able to grow anaerobically in trench leachates, which indicates that the radionuclides and organic chemicals present were not toxic to these bacteria. Changes in concentrations of several of the organic constituents of the waste leachate samples were observed due to anaerobic microbial activity. Growth of a mixed culture of trench-water bacteria in media containing a mixture of radionuclides, 60Co, 85Sr, and 134,137Cs, was not affected at total activity concentrations of 2.6 X 10(2) and 2.7 X 10(3) pCi/ml.

Anaerobiosis↗
PubMed2005

A comparative radiological assessment of five European biosphere systems in the context of potential contamination of well water from the hypothetical disposal of radioactive waste.

In the framework of the BioMoSA project for the development of biosphere assessment models for radioactive waste disposal the Reference Biosphere Methodology developed in the IAEA programme BIOMASS was applied to five locations, situated in different European countries. Specific biosphere models were applied to assess the hypothetical contamination of a range of agricultural and environmental pathways and the dose to individuals, following contamination of well water. The results of these site-specific models developed by the different BioMoSA partners, and the individual normalised dose to the exposure groups were compared against each other. Ingestion of drinking water, fruit and vegetables were found to be among the most important pathways for almost all radionuclides. Stochastic calculations revealed that consumption habits, transfer factors, irrigation rates and distribution coefficients (Kd(s)) were the most important parameters that influence the end results. Variations in the confidence intervals were found to be higher for sorbing elements (e.g. (36)Cl, (237)Np, (99)Tc, (238)U, (129)I) than for mobile elements (e.g. (226)Ra, (79)Se, (135)Cs, (231)Pa, (239)Pu). The influence of daughter products, for which the distribution into the biosphere was calculated individually, was also shown to be important. This paper gives a brief overview of the deterministic and stochastic modelling results and the parameter sensitivity. A screening methodology was introduced to identify the most important pathways, simplify a generic biosphere tool and refine the existing models.

Adult↗
PubMed2005

Understanding the toxicity of buried radioactive waste and its impacts.

The oral ingestion toxicities of buried high level radioactive waste from nuclear power plants and of the natural radioactivity in the ground are calculated and expressed as cancer doses, the number of fatal cancers predicted by the linear no-threshold theory if all of the material were fed to people. Unless the size of the U.S. nuclear power industry is greatly expanded, there will probably never be more than 2 trillion cancer doses (CD) in U.S. repositories, as compared with 31 trillion CD in the ground above them. Measurements of the uranium, thorium, and radium in human bodies indicate that the latter cause 500 deaths per year in U.S. The great majority of this material is derived from the top few meters of soil that are penetrated by plant roots. It is concluded that the annual number of U.S. deaths from buried nuclear wastes will be about 1.0 (or less), orders of magnitude less than the number from coal burning electricity generation, the principal competitor of nuclear power.

Algorithms↗