Preliminary estimates by the U.S. Environmental Protection Agency (EPA) have indicated the potential for significant radiation doses to individuals near elemental phosphorus plants. During plant operations radionuclides associated with particulates and volatile metallic element radionuclides are released to the atmosphere. Of special interest are polonium-210 and lead-210. The purpose of this work assignment is to apprise EPA of the status of emission of radionuclides to the atmosphere. This work assignment involves collection of information on emission control technology related to the development of standards under the Clean Air Act. Each work task is designed as a chapter to be incorporated into a Background Information Document for the elemental phosphorus industry. Topics covered include general description of the industry and identification of plant-specific processes and emissions; plant-specific emission control techniques and costs; anticipated industry changes due to modernization, expansion, or process alterations; and definition of a model elemental phosphorus plant representative of those currently in operation. Three levels of control, ranging from minimum to maximum application of emission control techniques, are defined for the model plant along with estimated emissions and equipment costs.

A limited risk assessment and some cost/benefit considerations of greater confinement disposal (GCD) compared to shallow land burial (SLB) are presented. This study is limited to an analysis of the postclosure phase of hypothetical GCD and SLB facilities. Selected release scenarios are used which bound the range of risks to a maximally exposed individual and a hypothetical population. Based on the scenario assessments, GCD had a significant risk advantage over SLB for normal exposure pathways at both humid and arid sites, particularly for the human intrusion scenario. Since GCD costs are somewhat higher than SLB, it is necessary to weigh the higher costs of GCD against the higher risks of SLB. In this regard, GCD should be pursued as an alternative to SLB for certain types of low-level waste, and as an alternative to processing for wastes requiring improved stabilization or higher integrity packaging to be compatible with SLB. There are two reasons for this conclusion. First, GCD might diminish public apprehension regarding the disposal of wastes perceived to be too hazardous for SLB. Second, GCD may be a relatively cost-effective alternative to various stabilization and packaging schemes required to meet 10 CFR 61 near-surface requirements as well as beingmore » a cost-effective alternative to deep geologic disposal. Radionuclide transport through the biosphere and resultant dose consequences were determined using the RADTRAN radionuclide transport code. 19 references, 4 figures, 5 tables.« less

A backfill barrier, emplaced between the containerized waste and the host rock, can both protect the other engineered barriers and act as a primary barrier to the release of radionuclides from the waste package. Attributes that a backfill should provide in order to carry out its required function have been identified. Primary attributes are those that have a direct effect upon the release and transport of radionuclides from the waste package. Supportive attributes do not directly affect radionuclide release but are necessary to support the primary attributes. The primary attributes, in order of importance, are: minimize (retard or exclude) the migration of ground water between the host rock and the waste canister system; retard the migration of selected chemical species (corrosive species and radionuclides) in the ground water; control the Eh and pH of the ground water within the waste-package environment. The supportive attributes are: self-seal any cracks or discontinuities in the backfill or interfacing host geology; retain performance properties at all repository temperatures; retain peformance properties during and after receiving repository levels of gamma radiation; conduct heat from the canister system to the host geology; retain mechanical properties and provide resistance to applied mechanical forces; retain morphological stability and compatibility with structural barriers and with the host geology for required period of time. Screening and selection of candidate backfill materials has resulted in a preliminary list of materials for testing. Primary emphasis has been placed on sodium and calcium bentonites and zeolites used in conjunction with quartz sand or crushed host rock. Preliminary laboratory studies have concentrated on permeability, sorption, swelling pressure, and compaction properties of candidate backfill materials.