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The author describes the treatment systems which should be applied, particularly when dealing with groups III and IV as explained in the previous article, in order to counteract their noxious effects on persons and the environment. Some treatment systems are compared and the author explains how to treat radioactive wastes, residues and sterilization, microwaves and the incineration of sanitary residues.
The comprehensive monitoring and analysis of NORM is extremely difficult and involves a wide range of equipment and techniques. The instruments to be used can depend on both the national legislation of the country in which the measurements are being undertaken and the operational conditions under which they are carried out. These can dictate whether dose rate, alpha/beta contamination or gamma contamination measurements are taken. In some circumstances the total activity of the samples can be estimated using the gamma activities of the radionuclides present, while in others only full gamma and alpha spectral analysis will suffice.
Two separate experiments have examined the effect of exposing rainbow trout to chronic gamma-radiation, commencing immediately after fertilization. In experiment 1 the period of exposure extended for 20 days with groups receiving mean dose rates of 1.87, 3.73 and 9.03 mGy h-1, and mean total accumulated doses of 0.83, 1.66 and 4.01 Gy respectively. At 5 months of age fish were tested for specific antibody response to dinitrophenol coupled to keyhole limpet haemocyanin (DNP-KLH) and there was no significant difference in titre between irradiated groups and unirradiated controls. In experiment 2 the exposure period was extended to 246 days from fertilization. Mean dose-rates to the three groups used were the same as in the first experiment until hatching at 21 days and then lower with rates of 0.99, 1.9, and 4.66 mGy h-1 to the free-swimming fish. The mean total accumulated doses over the whole irradiation period were 5.43, 10.53 and 25.43 Gy respectively. The antibody response to DNP-KLH was significantly lower in trout receiving the highest dose-rate when compared with those of unirradiated controls or the lowest dose-rate group. The significance of these results is discussed in relation to radiation levels in areas of radioactive waste disposal, and results from a similar study published previously.
Gaseous 125I was present at 48 +/- 33 and 122 +/- 15 kBq in Na125I vials (74 MBq) purchased from Amersham and New England Nuclear, respectively. Gaseous 125I leaked to the amount of 37 +/- 22 and 130 +/- 67 kBq during radioiodination by the chloramine-T and the enzymatic methods using 18.5 MBq Na125I, respectively. Radioactive wastes from radioiodination using 18.5 MBq Na125I evolved about 5.5 kBq of gaseous 125I in first day of storage.
There is frequent debate in the media and the scientific published reports about the use of radiation for diagnosis and treatment, the benefits and risks of the nuclear industry, uranium mining and the storage of radioactive wastes. Driving this debate is increasing concern about reliance on fossil fuels for power generation for which alternatives are required. Unfortunately, there is generally a poor understanding of the relevant basic sciences compounded by widespread irrational fear of irradiation (radiation phobia). Radioactivity, with special reference to uranium and plutonium is simply described. How radiation affect tissues and the potential hazards to individuals and populations are explained. The origins of radiation phobia and its harmful consequences are examined. Whether we like it or not, Australia is heavily involved in the uranium industry by virtue of having one-third of the world's known reserves, exports of which are worth approximately $470m annually. As this paper has been written as simply as possible, it may also be of interest to readers who may have had little scientific training. It may be downloaded from the web using references provided in this article. It is concluded that ignorance and fear are major impediments to rational debate on radiation issues.
Waste management programs at the Radioactive Liquid Waste Treatment Facility (RLWTF) at the Los Alamos National Laboratory (LANL) are concerned with the levels of perchlorates due to the effects it can have on the environment and resultant regulations. The RLWTF treats industrial and radioactive wastes generated at multiple research and production facilities across the LANL. Perchloric acid is the major source of the perchlorate ion in the RLWTF used in the analytical chemistry laboratories and for metal dissolution. Perchlorate is present in the influent to the RLWTF at concentrations up to several thousands microg/l level. Ion chromatography is the method of choice to analyze the concentrations of perchlorate in the wastewater generated at the RLWTF. Perchlorate was separated by elution through a CS16/CG16 with an EG40 eluent generator. To minimize background conductivity and enhance analyte conductance, an anion self-regenerating suppressor was used. The method achieved a perchlorate method detection limit of 1 microg/l. The method is successfully being used to monitor the perchlorate levels at the RLWTF and provide data for the pilot tests to remove perchlorate from the RLWTF effluent.
The present investigation was undertaken to identify the long-lived radionuclide and its chemical forms existing in [15O]water which was synthesized from 15O produced by the nuclear reaction 14N(d,n)15O, and to develop a method for its removal to facilitate radioactive waste disposal. The long-lived nuclide was identified as tritium based on a comparison of its physical half-life and the energy spectrum of beta-rays with those of tritium. The major chemical form of tritium in the target gas was estimated to be molecular hydrogen. The tritium radioactivity was completely removed without a serious loss occurring to the yield of [15O]water by passing the irradiated target gas over a heated palladium catalyst followed by a calcium chloride column before the final synthesis of the [15O]water. This provided a practical way of removing tritium from the [15O]water.
The soil solid-liquid distribution coefficient (Kd) value is of great significance in understanding and modelling the environmental behaviour of soil contaminants. For many years, the batch sorption technique has been used for the determination of such values. Here, we propose an alternative 'mini-column' approach in which somewhat more realistic soil conditions are maintained. In particular, this approach allows for determination of radionuclide Kd values under realistic soil moisture contents and in a system in which time-dependent processes such as changes in redox potential can take place. Data obtained for radioactive iodine (a key radionuclide in the consideration of radioactive waste disposal) are presented and indicate that soil moisture content, particularly in conjunction with soil redox potential (through water-logging of the soil), has a marked effect on measured Kd values. The results indicate the advantages and potential usefulness of the mini-column approach in assessing the environmental behaviour of radioactive, and other, soil contaminants.
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Before their disposal, genotoxic substances are destroyed by strong oxidizing agents. If there are molecules labelled with radionuclides in the medium which is oxidized, then this treatment may bring about the release of gaseous radioactive compounds. We have looked for evidence of such a release following the action of K permanganate and sodium hypochlorite on molecules labelled with 3H, 14C, 32P, and 125I. Among the compounds examined, only those labelled with 14C showed significant quantities of radioactive gas released, with values up to 60% of the total radioactivity. For the other products, less than 0.6% of the radioactivity appeared in a volatile form.
A 6-month soil column experiment was conducted to compare the upward migration and plant uptake of radiochlorine and radioiodine from shallow, near-surface contaminated water tables. Both fixed and fluctuating water tables were studied. After 6 months, (36)Cl activity concentrations were relatively uniform throughout the soil profile apart from an accumulation at the soil surface, which was especially marked under a fluctuating water table scenario. In contrast, (125)I (a surrogate for (129)I) tended to accumulate at the boundary between the anoxic conditions at the base of the column and the oxic conditions above, due to its redox-dependent sorption behaviour. The uptake of (36)Cl by perennial ryegrass was much greater than that of (125)I due to its greater migration into the rooting zone and its ready availability in soil solution. In the context of radioactive waste disposal, where these radionuclides may potentially be released into groundwater, (36)Cl would be expected to present a greater potential for contamination of the biosphere than (129)I.
Radiocesium may be deposited in the environment as a result of accidents in nuclear installations, for example, as in Chernobyl. Significant internal contamination with radiocesium poses a serious risk to human health, and, therefore, expedient removal is essential to reduce the radiation body burden. In vitro hemodialysis was tested as a potential method to remove radiocesium from a pasteurized plasma solution of bovine or human blood. Clearance values were calculated by a flow independent method. Hemodialysis appears to be a good method to remove radiocesium from blood: within 4 h more than 90% of the administered radiocesium is removed from blood or plasma. Radiocesium in dialysis fluid can be concentrated on Prussian Blue coated columns that were tested previously for hemoperfusion. Radioactive waste disposal problems can be solved by concentration of radiocesium on these columns. In vivo experiments are necessary to confirm these in vitro results.
The release of uranium and other transuranics into the environment, and their subsequent mobility, are subjects of intense public concern. Uranium dominates the inventory of most medium- and low-level radioactive waste sites and under oxic conditions is highly mobile as U(VI), the soluble uranyl dioxocation (UO2)2+. Specialist anaerobic bacteria are, however, able to reduce U(VI)to insoluble U(IV), offering a strategy for the bioremediation of uranium-contaminated groundwater and a potential mechanism for the biodeposition of uranium ores. Despite the environmental importance of U(VI) bioreduction, there is little information on the mechanism of this transformation. In the course of this study we used X-ray absorption spectroscopy (XAS) to show that the subsurface metal-reducing bacterium Geobacter sulfurreducens reduces U(VI) by a one-electron reduction, forming an unstable (UO2)+ species. The final, insoluble U(IV) product could be formed either through further reduction of U(V) or through its disproportionation. When G. sulfurreducens was challenged with the chemically analogous (NpO2)+, which is stable with respect to disproportionation, it was not reduced, suggesting that it is disproportionation of U(V) which leads to the U(IV) product. This surprising discrimination between U and Np illustrates the need for mechanistic understanding and care in devising in situ bioremediation strategies for complex wastes containing other redox-active actinides, including plutonium.
Measurement of regional myocardial blood flow (RMBF) is crucial in experimental studies of myocardial ischemia and reperfusion in dogs. The standard measurement technique uses radioactive microspheres; however, not all institutions are able to dispose of radioactive waste and therefore cannot make use of this method. We tested a new, nonradioactive microsphere, labeled with colors instead of nuclides. Simultaneous blood flow measurements with two nuclide-labeled and two colored microspheres were performed after coronary occlusion in dogs. Both techniques show a within-method correlation of r greater than 0.98. Duplicate variability for paired RMBF values in 80 samples was 8.7 +/- 0.1% when computed with radioactive microspheres and 13.2 +/- 1.8% when computed with colored microspheres. There was a good correlation in the measurement of RMBF between the radioactive- and colored-microsphere methods (r = 0.98). The best-fitting linear regression line was expressed by the formula: Colored-microsphere RMBF = 1.11 (radioactive-microsphere RMBF)-0.02. When measured by colored microspheres, RMBF was approximately 8% higher than when computed with radioactive microspheres for blood flow values of 0-2 ml/min/g. When blood flow was increased pharmacologically to levels of 2-7.5 ml/min/g, colored microspheres yielded blood flow values 39% higher than the values computed by radioactive microspheres. We conclude that the nonradioactive, colored-microsphere method correlates with the radioactive technique, but at high flows, it yields values greater than those obtained with radioactive microspheres.
The article focuses on the radiation problems for the Navy personnel dealing with the nuclear and radioactive waste, since the existing standards become obsolete due to some new technologies in the development of the materials, endangering the environment and people's health.
On April 26, 1986, a serious reactor accident occurred at the Chernobyl nuclear power plant. A total radioactivity of 2 x 10(18) becquerel, i.e. 3.5% of the reactor inventory were released spreading throughout Europe. Radioactive tracers were iodine 131 (with a half-life of 8 days) and caesium 137 (with a half-life of 30 years). Measurements made in Magdeburg by the Institute of Hygiene on May 5th after a heavy thunderstorm indicated a considerable radioactive contamination. Measurements revealed 75,000 bq/kg in grasses, 44,000 bq/litre in storm water and 40,000 bq/kg in garden soil, however, these high values decreased to normal by the end of 1986. The paper describes a stay in Chernobyl in 1989 and the environmental and working conditions prevailing at site. An increase of the cancer rate in the contaminated areas was not observed until 1990; however, thyroid tumours increased in children in Belorussia after that time. The current caesium load of the soils in the area is 10(6) becquerel/cubic metre. As much as 480,000 bq/kg were measured in dried mushrooms picked in the autumn of 1997. Assuming a mean natural exposure to radiation of the population in Germany of 2.4 millisievert/year (mSv/a), the additional load caused by the Chernobyl accident was 5% in 1986, falling to below 0.1% in 1996. Today, 19 nuclear power plants are operating in Germany for power generation. Radioactive substances are used in medicine, research and industry. An opinion on the safety of transports and final dumping of radioactive waste is given, based on a visit to the Morsleben final dump site. The use of nuclear energy and a percentage replacement by renewable energies are discussed from a regional and global perspective (climate protection).
The purpose of this study was to evaluate and provide insights related to the influence of the intake of stable isotopes of carbon and iodine on the committed doses due to the ingestion of (14)C and (129)I. This was accomplished through the application of two different computational approaches. The first was based on the assumption that ground (drinking) water was the only source of intake of (14)C and (129)I, as well as stable carbon and stable iodine. In the second, the intake of (14)C and (129)I was still assumed to be restricted to that in the ground (drinking) water, but the intake of stable carbon and stable iodine was expanded to include that in other components of the diet. The doses were estimated using either a conversion formula or the applicable dose coefficients in Federal Guidance Reports No. 11 and No. 13. Serving as input for the analyses was the estimated maximum concentrations of (14)C or (129)I that would be present in the ground water due to potential releases from the proposed Yucca Mountain high-level radioactive waste repository during the first 10,000 y after closure. The estimated contributions of stable carbon and iodine through the consumption of ground water were based on analyses of samples collected in the Amargosa Valley, NV. The contributions through dietary intake were based on surveys conducted in the United States. Based on the accompanying analyses, it was noted that stable isotope intake has a significant effect on the estimated doses due to the intake of radioactive isotopes of the same element. While this is a well-known fact, this observation has international implications in terms of dose estimates for key radionuclides, such as (14)C and (129)I, a primary reason being the wide variations in the intakes of stable carbon and iodine in various countries. For this reason, analysts planning to apply the dose coefficients developed by the International Commission on Radiological Protection (ICRP) should either confirm that the average total intake in their country of stable isotope(s) of the radioactive isotope being evaluated is in reasonable agreement with the value assumed by the ICRP or suitably modify the ICRP dose coefficients to account for any differences. If such a procedure is to be implemented, there is a need for periodic updates of the dietary intakes of various stable elements in countries throughout the world. The importance of this is documented by recent surveys in Asia that revealed that their average total daily intake of stable iodine was less than half of the ICRP value for Reference Man. In this case, application of the ICRP dose coefficients, without modification, would underestimate the dose due to ingested (129)I by a factor of more than two. A related situation exists in the United States where the latest surveys indicate that the daily intake of stable iodine is 75% of the ICRP value.
The authors considered medical consequences of radiation accidents (burial of radioactive waste into Techa river and accident in 1957) in "Majak" Industrial Association. Results of long-term observations helped to evaluate health state of people who underwent chronic exposure to radiation and of their descendants.