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PubMed2006

An alternative to Portland Cement for waste encapsulation--the calcium sulfoaluminate cement system.

Currently, Portland Cement (PC) is used extensively in the solidification/stabilisation of a wide variety of wastes. In the nuclear industry, low and intermediate level radioactive wastes are encapsulated or immobilised within composite PC cement systems based on high replacement with blast furnace slag or fly ash. However, the high alkalinity of these PC-based systems will corrode reactive metals found in some wastes releasing hydrogen and forming expansive corrosion products. Alternative cement systems could provide a different hydration chemistry, which would allow wastes containing these metals to be encapsulated with lower reactivity. Calcium sulfoaluminate (CS A) cement is one such cement. It combines economy of cost and low emission of CO(2) with rapid strength gain and compatibility with other construction materials. Hydration provides an internal pore solution where the pH is considerably lower than that of PC. The main hydration product, ettringite, can incorporate a number of ions into its crystal structure, making it an ideal candidate for waste immobilisation. This paper details some results from a commercial CS A system that examines aspects of mixing, hydration of different formulations and aluminium corrosion behaviour. The fluidity of mixes can be adjusted by changing the formulations. All designed mixes were set within 24 h with little bleeding and the pH values were in the range of 10-11.5. In addition, a significant reduction in Al corrosion was observed compared to a composite OPC system. Although these results provide encouragement for the idea that CS A cement can provide a possible alternative to PC in the immobilisation of difficult and reactive wastes, further investigation is needed.

Aluminum↗
PubMed2005

Whether ionizing radiation is a risk factor for schizophrenia spectrum disorders?

The neural diathesis-stressor hypothesis of schizophrenia, where neurobiological genetic predisposition to schizophrenia can be provoked by environmental stressors is considered as a model of the effects of exposure to ionizing radiation. Analysis of information from electronic databases (MEDLINE, PsycINFO, EMBASE, Current Contents, Elsevier BIOBASE) and hand-made search was carried out. There are comparable reports on increases in schizophrenia spectrum disorders following exposure to ionizing radiation as a result of atomic bombing, nuclear weapons testing, the Chernobyl accident, environmental contamination by radioactive waste, radiotherapy, and also in areas with high natural radioactive background. The results of experimental radioneurobiological studies support the hypothesis of schizophrenia as a neurodegenerative disease. Exposure to ionizing radiation causes brain damage with limbic (cortical-limbic) system dysfunction and impairment of informative processes at the molecular level that can trigger schizophrenia in predisposed individuals or cause schizophrenia-like disorders. It is supposed that ionizing radiation can be proposed as a risk factor for schizophrenia spectrum disorders. The hypothesis that ionizing radiation is a risk factor for schizophrenia spectrum disorders can be tested using data from the Chernobyl accident aftermath. Implementation of a study on schizophrenia spectrum disorders in Chernobyl accident victims is of significance for both clinical medicine and neuroscience.

Brain↗
PubMed2004

Radiation safety standards and their application: international policies and current issues.

This paper briefly describes the current policies of the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection and how these policies are converted into international radiation safety standards by the International Atomic Energy Agency, which is the only global organization-within the United Nations family of international agencies-with a statutory mandate not only to establish such standards but also to provide for their application. It also summarizes the current status of the established corpus of such international standards, and of it foreseeable evolution, as well as of legally binding undertakings by countries around the world that are linked to these standards. Moreover, this paper also reviews some major current global issues related to the application of international standards, including the following: strengthening of national infrastructures for radiation safety, including technical cooperation programs for assisting developing countries; occupational radiation safety challenges, including the protection of pregnant workers and their unborn children, dealing with working environments with high natural radiation levels, and occupational attributability of health effects (probability of occupational causation); restricting discharges of radioactive substances into the environment: reviewing current international policies vis-a-vis the growing concern on the radiation protection of the "environment;" radiological protection of patients undergoing radiodiagnostic and radiotherapeutic procedures: the current International Action Plan; safety and security of radiation sources: post-11 September developments; preparedness and response to radiation emergencies: enhancing the international network; safe transport of radioactive materials: new apprehensions; safety of radioactive waste management: concerns and connections with radiation protection; and radioactive residues remaining after the termination of activities: radiation protection response to the forthcoming wave of decommissioning of installations with radioactive materials. The ultimate aim of this paper is to encourage information exchange, cooperation, and collaboration within the radiation protection professional community. In particular, the paper tries to facilitate consolidation of the growing international regime on radiation safety, including the expansion of legally binding undertakings by countries, the strengthening of the current corpus of international radiation safety standards, and the development of international provisions for ensuring the proper worldwide application of these standards, such as a system of international appraisals by peer review.

Government Agencies↗
PubMed1984

Behavior of radionuclides in sanitary landfills.

his study was undertaken to evaluate the possibility of disposing low-level radioactive waste in sanitary landfills with leachate containment to prevent environmental releases. To meet this objective, two simulated landfills, each 200 l. in volume and containing 55 kg of municipal refuse, were operated in the laboratory with simulated rainfall additions for a 9-month period to observe the extent to which radio-cobalt, -cesium, -strontium and tritium were leached into the liquid phase. One of the units was operated with leachate recycle, the other as a single pass control. Liquid samples were analyzed weekly for 3H, 58Co, 85Sr and 134Cs tracers. Weekly analyses were also performed for approximately 30 parameters to define the degree of stabilization of the waste. Major parameters included BOD, COD, pH and concentrations of specific organics, metals and gases. Concentrations of stable cobalt, strontium and cesium were also measured periodically. Soluble radioactivity levels in both systems were reduced by factors of 50 for 58Co, 5 for 85Sr and 7 for 134Cs, taking radioactive decay and dilution into account. Some radionuclide removal from the liquid phase was associated with major chemical changes in the landfills that occurred within 80 days for the control system and within 130 days for the recycle unit. Observed acid, sulfide, and CO2 concentrations suggested mechanisms for removing some of the radionuclides from leachate. Detection of 3H in the off-gas indicated that less than 1% of tritiated waste became airborne. The waste in the leachate recycle unit was more completely stabilized than in the control unit.

Environmental Pollution↗
PubMed2003

Worker and Environmental Protection Issues in the Remediation Of an Abandoned Source Manufacturing Facility.

The Gulf Nuclear Superfund Site located in Odessa, Texas, was an abandoned radioactive source production facility slated for cleanup as a Removal Action under the U.S. Environmental Protection Agency Region VI Superfund program. Prior to cessation of operations and abandonment of the facility in 1992, it was used for the production of radioactive sources used in the oil and gas industry and nuclear medicine applications. Pangea Group was contracted by the U.S. Army Corps of Engineers (USACE) Kansas City District to perform remediation of the site and other contaminated debris, cleaning of interior building surfaces, building demolition, and excavation/removal of contaminated soils and septic system. The project scope also included loading, containerization and transportation of low-level radioactive wastes for offsite disposal. Primary radionuclides present at the facility were Cs, Co, and Am. The project also included packaging and removal of radioactive sources and mixed waste consisting of radiologically contaminated lead shot and lead source containers. Included in the paper is a discussion of primary worker protection and environmental protection measures employed on the project. Worker protection issues included the control of industrial and construction safety hazards as well as control of external and internal radiation dose. Control of air emissions and contaminated wastewater were also very important, especially due to the location of the site. The site was located in an area containing both residential and commercial properties. Several residences and businesses were located immediately adjacent to the site. The project involved the participation of the USACE Kansas City District, EPA Region 6, and the Texas Bureau of Radiological Health. Field work on the project started in April 2001 and was completed approximately five months later.

Journal Article↗
PubMed2005

Protecting people against radiation exposure in the event of a radiological attack. A report of The International Commission on Radiological Protection.

This report responds to a widely perceived need for professional advice on radiological protection measures to be undertaken in the event of a radiological attack. The report, which is mainly concerned with possible attacks involving 'radioactive dispersion devices', re-affirms the applicability of existing ICRP recommendations to such situations, should they ever occur. Many aspects of the emergency scenarios expected to arise in the event of a radiological attack may be similar to those that experience has shown can arise from radiological accidents, but there may also be important differences. For instance, a radiological attack would probably be targeted at a public area, possibly in an urban environment, where the presence of radiation is not anticipated and the dispersion conditions commonly assumed for a nuclear or radiological emergency, such as at a nuclear installation, may not be applicable. First responders to a radiological attack and other rescuers need to be adequately trained and to have the proper equipment for identifying radiation and radioactive contamination, and specialists in radiological protection must be available to provide advice. It may be prudent to assume that radiological, chemical, and/or biological agents are involved in an attack until it is proven otherwise. This calls for an 'all-hazard' approach to the response. In the aftermath of an attack, the main aim of radiological protection must be to prevent the occurrence of acute health effects attributable to radiation exposure (termed 'deterministic' effects) and to restrict the likelihood of late health effects (termed 'stochastic' effects) such as cancers and some hereditable diseases. A supplementary aim is to minimise environmental contamination from radioactive residues and the subsequent general disruption of daily life. The report notes that action taken to avert exposures is a much more effective protective measure than protective measure the provision of medical treatment after exposure has occurred. Responders involved in recovery, remediation and eventual restoration should be subject to the usual international standards for occupational radiological protection, which are based on ICRP recommendations, including the relevant requirements for occupational dose limitation established in such standards. These restrictions may be relaxed for informed volunteers undertaking urgent rescue operations, and they are not applicable for voluntary life-saving actions. However, specific protection measures are recommended for female workers who may be pregnant or nursing an infant. The immediate countermeasures to protect the public in the rescue phase are primarily caring for people with traumatic injuries and controlling access. Subsequent actions include respiratory protection, personal decontamination, sheltering, iodine prophylaxis (if radio-iodines are involved), and temporary evacuation. In the recovery phase, the relocation and resettlement of people may be needed in extreme cases. This phase may require remedial action, including cleanup, management of the resulting radioactive waste, management of any human remains containing significant amounts of radioactive substances, and dealing with remaining radioactive residues. The guidance given in relation to public protection is based solely on radiological protection considerations and should be seen as a decision-aiding tool to prepare for the aftermath of a radiological attack. It is expected to serve as input to a final decision-making process that may include other societal concerns, consideration of lessons learned in the past (especially these involving the public perception of the risks posed by radioactive contamination) and the participation of interested parties. A radiological attack could also be the cause of radioactive contamination of water, food, and other widely consumed commodities. This possible outcome is considered unlikely to lead to significant internal contamination of a large number of people owing to the large amounts of radioactive material that would be required to cause high levels of contamination of water, food, and other commodities. Nonetheless, the report recommends radiological criteria for restricting the use of commodities under such circumstances. The report concludes by re-iterating that the response to radiological attacks should be planned beforehand following the customary processes for optimisation of radiological protection recommended by ICRP, and that optimised measures should be prepared in advance. Such plans should result in a systematic approach that can be modified if necessary to take into account the prevailing conditions and to invoke actions as warranted by the circumstances. Many potential scenarios clearly cannot induce immediate severe radiation injuries. Therefore, in order to prevent over-reaction, response measures prepared in advance should reflect the real expected gravity of the various possible scenarios.

Environmental Exposure↗