Simultaneous determination of60Co,131I and137Cs in model radioactive waste water by reverse radiometric flow injection analysis with the aid of a multichannel analyzer

Reverse radiometric flow injection analysis was used for the simultaneous determination of⁶⁰Co,¹³¹I and¹³⁷Cs in model radioactive waste water. A NaI (Tl) scintillation detector coupled to a Canberra MCA was used for measuring the activity of¹³⁷Cs at 662 keV,⁶⁰Co at 1173 keV and 1332 keV, and¹³¹I at 364 keV.     

Determination of Co and Cs by stopped-flow RFIA with the aid of multi-channel analyzer

Radiometric flow-injection analysis (RFIA) was used for the transport of carrier and sample solution. Radioactive nuclides⁶⁰Co and¹³⁷Cs were used as indicators and a NaI (Tl) scintillation detector coupled to a Canberra MCA for measuring the activity of¹³⁷Cs at 662 keV and⁶⁰Co at 1173 keV and 1332 keV. Experimental parameters related to RFIA were studied, too.     

Assessment of intake of a complex radionuclide bearing dust formed at a nuclear power plant

The aim of this work was to provide an experimental basis for assessing intakes of an industrial actinide-bearing dust from measurements of⁶⁰Co and¹³⁷Cs in the body or urine. Whilst these radionuclides comprised 72% and 19% of the radioactivity present, greater than 90% of the committed effective dose will result from the low concentrations of the actinides present, 0.4%. To assess the dose coefficient for the dust and predict the biokinetics of⁶⁰Co and¹³⁷Cs in workers, absorption parameters for transfer from lungs to blood obtained from an animal study were combined with information on particle deposition and clearance from the ICRP human respiratory tract model and with tissue distribution and excretion data from the most recent systemic models. All other radionuclides were assumed to have Type M absorption characteristics. The dose coefficient for the dust, 1.29·10^–7 Sv·Bq^–1 was estimated to contain 113 kBq⁶⁰Co, 29 kBq¹³⁷Cs and 0.64 kBq of the actinides. The predicted retention and excretion characteristics of⁶⁰Co and¹³⁷Cs in workers after acute or chronic exposure to the dust suggested that measurements of these radionuclides in the body or urine could detect intakes equivalent to a few percent of an annual dose limit of 20 mSv·y^–1.     

Non-isotopic indicators in radioanalytical chemistry

Three radioanalytical methods have been developed which allow to determine one element the using of radioisotopes of other elements with similar chemical properties. The methods have been applied to the determination of nickel with⁶⁰Co, of rubidium with¹³⁷Cs, and of potassium with⁸⁶Rb and¹³⁷Cs.     

Influence of plant roots upon the mobility of radionuclides in soil, with respect to location of contamination below the surface

The movement of⁸⁵Sr,¹³⁷Cs,⁵⁴Mn and⁶⁰Co in the 50 cm soil profile was studied with and without the presence of plant roots (triticum aestivum) in order to investigate the influence of roots and depth contamination upon the migration of radionuclides. The water table was maintained manually at 3 cm from the bottom. The physiochemical characteristics (E_h Fe^–2, NH ₄ ⁺ , pH and moisture content) as well as the total and extractable radioactivity were investigated. In the discrete contamination, where the location of contamination varied within the soil profile (0–5, 25–30 or 45–50 cm from the top), the influence of location upon the movement of these radionuclides was also studied. It was found that the changes in the soil physicochemical characteristics influenced the mobility of the four radionuclides. The extractability of⁵⁴Mn and⁶⁰Co was significantly increased in the reducing region of the soil, whereas that of⁸⁵Sr,¹³⁷Cs was not. Plant roots excerted significant effects upon the soil characteristics, via, reducing the E_h pH and moisture content of the soil; increasing the extractability of both⁵⁴Mn and⁶⁰Co from the depth of 35 cm downwards. Radionuclide migration occurred via physicochemical and biological transport. The biological transport via plant roots was of particular importance for¹³⁷Cs. Location of contamination had a significant influence upon the mobility of radionuclides. The migration of radionuclides was in the sequence of contamination in middle>bottom>top. The degree of the influence varied with radionuclides concemed. In the top layer contamination, the rank of the migration from the contamination layers, on the other hand⁵⁴Mn,⁶⁰Co and¹³⁷Cs were more mobile and the movement was:⁸⁵Sr⁵⁴Mn⁶⁰Co>¹³⁷Cs. In the middle and bottom contamination layers, on the other hand,⁵⁴Mn and⁶⁰Co and¹³⁷Cs were more mobile and the movement was⁸⁵Sr⁵⁴Mn⁶⁰Co>¹³⁷Cs. The results provide evidence conceming the soil-root interaction influencing the transfer efficiency of radionuclides from below the soil surface into the human food chain.     

Studies on some experimental parameters of radiometric flow injection analysis (RFIA) using137Cs and60Co

A simple radiometric flow injection analyzer with NaI(Tl) detector was used for the study of some experimental parameters of¹³⁷Cs and⁶⁰Co determination. A sample transfer system was developed employing both merging zone and sample injection principle.     

A method for assessing and correcting coincidence summing effects for germanium detector efficiency calibrations

The addition of⁵⁴Mn and⁶⁵Zn to a nine-radionuclide standard (containing²⁴¹Am.,¹⁰⁹Cd.⁵⁷Co,¹³⁹Ce,²⁰³Hg.¹¹³Sn,¹³⁷Cs,⁸⁸Y, and⁶⁰Co) provides the capability to determine the extent of coincidence summing for gamma rays from⁸⁸Y and⁶⁰Co. A method for correcting the efficiency points at 1332 keV (⁶⁰Co) and 1836 keV (⁸⁸Y) for coincidence summing is presented.     

Preliminary results on labelling antibody Mab B72.3 with90Y

Rapid, safe and cost effective techniques for study of radiochemical wastes have been investigated by many workers. This work deals with a further study on this aspect by reverse radiometric flow injection analysis (rRFIA) technique.¹³⁷Cs and⁶⁰Co were determined in model radioactive wastewaters.     

Sorption properties of chemically treated clinoptilolites with respect to Cs and Co

The sorption ability of clinoptilolite treated by NaOH solution has been studied. The distribution coefficients of¹³⁷Cs and⁶⁰Co were studied by the radiochemical method. The variation of distribution coefficients with pH was studied. Also the influence of competitive ions on distribution coefficients were investigated. The total cation exchange capacity and XRD analysis were also measured.     

Deposition of cesium and cobalt sorbed on zeolite in matrices of blast furnace slag

¹³⁷Cs and⁶⁰Co were sorbed from model solutions and waste water on chemically treated granular zeolite. The zeolite was incorporated into cement slurries based on blast furnace slag (BFS). The compressive and bending strength were measured after different times of hydration. The leaching tests were performed in water, base and acid solutions. The leachability was more pronounced only for samples in acidic solutions.     

Development of a method for the estimation of low amount of plutonium in 200 L waste drums in presence of high amount of β γ activity due to 137Cs and 60Co

The waste drum monitoring system based on HPGe detector was used to study its performance for the estimation of low amounts of plutonium in presence of high activity of ¹³⁷Cs and ⁶⁰Co. The counting was carried out by keeping amount of plutonium constant at 100 mg level and varying the count rate for the γ rays of ¹³⁷Cs and ⁶⁰Co. Present study has shown that the estimation of low amount of ²³⁹Pu in a waste drum can be carried out using 129 keV γ ray in the presence of ¹³⁷Cs up to an activity level of 16 mCi and in the presence of ⁶⁰Co up to an activity level of 8 mCi.     

Mathematical modeling of physico-chemical characteristics of cement-waste composites in radioactive waste management

An optimization of mortar (as matrix), improved with bentonite clay, used for immobilization of radionuclides⁶⁰Co,¹³⁷Cs,⁸⁵Sr and⁵⁴Mn, is presented. A relatively simple mathematical model is given, which permits minimization of leach rate and permeability and maximization of compressive strength. An optimal solution, based on experimental data, is given. These results will be used for a future Yugoslav radioactive waste storing center.     

Fixation of radioactive isotopes on bentonite as radioactive waste treatment step

Fixation of¹³⁷Cs,¹⁴⁴Ce,⁶⁰Co,⁹⁰Sr,²⁴⁰Th and²³³U from aqueous and phosphate media on bentonite clay was studied. The fixation of the radioactive ions on bentonite surfaces was dependent on the pH behavior of the metal ions. A method was proposed to use bentonite as an absorbent of ions from simulated radioactive waste as a treatment step.     

Diffusion of Sr, Cs, Co and I in argillaceous rock as studied by radiotracers</p> </p>

Summary Diffusions of⁸⁵Sr,¹³⁷Cs,⁶⁰Co and¹²⁵I radionuclides have been studied in borecore samples from Boda siltstone/claystone formation (BCF) under ambient and in situ conditions. In-diffusion (⁸⁵Sr,¹³⁷Cs,⁶⁰Co and¹²⁵I) and through-diffusion measurements (¹²⁵I) were performed at ambient conditions, and for iodine, in-diffusion measurements were also carried out at in situ conditions (100 bar, 50 °C). In the case of cationic species carrier-containing solutions were also applied.⁶⁰Co was detected only in the first slice of borecore at each sample, while¹³⁷Cs was detected also in the first-, second- and third slices according to the concentration-increase of inactive carrier. Among the investigated cations,⁸⁵Sr exhibited the fastest diffusion rate with 2.7-6.0 ^. 10^-12m²/s apparent diffusivity values. In the course of in-diffusion measurements 4.7 ^. 10^-11 m ² /s, during through-diffusion investigations 1.4-1.6 ^. 10^-12m²/s and at in situ conditions 5.0-8.0 ^. 10^-12 m²/s apparent diffusivities were obtained for¹²⁵I.Modest sorption of¹²⁵I can also be deduced from the results.</p> </p>     

Development of a method for nuclide leaching from glass fiber in HEPA filter

For the disposal of the high efficiency particulate air (HEPA) glass filter to environment, the glass fiber should be leached to lower its radioactive concentration. To derive the optimum method for removal of Co and Cs from HEPA glass fiber, four methods were applied in this study. Results of electrochemical leaching of glass fiber by 4.0 M HNO₃–0.1 M Ce(IV) solution showed that the removal efficiency of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs from glass fiber after 5 h was 96.4, 93.6, and 93.8%, respectively. Results by 5 wt% NaOH solution showed that the removal efficiency of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 30 h was 81.7, 82.1, and 10.0%, respectively. Results by repeat 2.0 M HNO₃ solution showed that the removal efficiencies of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 2 h of three repetitions were 96.2, 99.4, and 99.1%, respectively. Finally, results by repeat 4.0 M HNO₃ solution showed that the removal efficiencies of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Cs after 4 h of three repetitions were 100, 99.9, and 99.9%, respectively, and their radioactivities were below 0.1 Bq/g. Therefore, the chemical leaching method by 4.0 M HNO₃ solution was considered as an optimum one for removal of cesium and cobalt from HEPA glass fiber for self disposal. Also the removal efficiencies of ⁶⁰Co, ¹³⁴Cs, and ¹³⁷Cs from the waste-solution after its precipitation-filtration treatment for reuse of 4.0 M HNO₃ waste-solution were 88.0, 95.0, and 99.8%.     

Determination of137Cs,90Sr and fallout Pu in the volcanic soil of Korea

The cumulative depositions of¹³⁷Cs,⁹⁰Sr and fallout Pu in the volcanic ash soil of Korea were determined. The average accumulated depositions of¹³⁷Cs,⁹⁰Sr and fallout Pu in the volcanic soil were much higher than those in other forest sites of Korea. From depth profiles, it was found that¹³⁷Cs,⁹⁰Sr and^239,240Pu in the volcanic soil are more mobile than those in other forest sites of Korea, and that the downward movement of⁹⁰Sr is faster than¹³⁷Cs and^239,240Pu. A significant correlation was found between the concentration of¹³⁷Cs and those of⁹⁰Sr and^239,240Pu. The activity ratios of²³⁸Pu/^239,240Pu and²⁴¹Pu/^239,240Pu in soils are close to those observed in the cumulative deposit from the global fallout of nuclear weapon testings.     

The distribution and behaviour of artificial radionuclides in sediments of the north Wales coast,U.K.

The distribution of¹³⁴Cs,¹³⁷Cs and²¹⁴Am in surface and core sediments from areas in north Wales has been investigated. Coastal sites show a predominance of Sellafield-derived material for all three radionuclides whereas estuarine sites show an increased proportion of Chemobyl-derived caesium present. By the use of the¹³⁴Cs/¹³⁷Cs ratio, a mean proportion of Chemobyl-derived¹³⁷Cs in surface sediments collected in 1991 fell from 34% at an estuarine site to 11% at a coastal site. In deeper sections of cores representing sedimentation dates near the Chemobyl accident, up to 90% of¹³⁷Cs at the estuarine site and 26% at the coastal site can be attributed to Chemobyl. By using the position of the Chemobyl¹³⁴Cs and¹³⁷Cs peak in the cores, sedimentation rates of 0.7 mm·a^–1 were calculated.     

Natural and artificial radionuclides in soils from Paraná State,Brazil

Soil samples from Paraná State, Brazil, were collected in 1991 and compared with others collected at the same location in March 1977 and at the end of 1983. Pedological analyses were practiced on these samples and¹³⁷Cs and²³²Th,²²⁶Ra and⁴⁰K activities were determined by gammaray spectrometry. A latitude dependence of¹³⁷Cs was found as well. It was impossible to determine the¹³⁷Cs contribution from Chernobyl nuclear accident because of low fallout and intense leaching, erosion and re-suspension in soils of regions with high annual precipitation. Natural radionuclides did not show such effects.     

Comparative interpretation of leach rate of137Cs and60Co from cement matrix

A technique for leaching¹³⁷Cs and⁶⁰Co from a cement matrix, using three methods based on theoretical equations, has been developed. These were: Method I, diffusion equation derived for a plane source model, Method II, rate equation for diffusion coupled with a first-order reaction. The leaching data were also analyzed by an empirical method employing a polynomial equation, Method III. Results presented in this paper are examples of data obtained in a cement testing project which will influence the design of the future radioactive waste storage center.     

Radionuclide concentration in sewage sludge at several location in Austria after the Chernobyl accident

The concentration of the radionuclides¹⁰³Ru,¹³⁴Cs and¹³⁷Cs in sewage sludge samples which were collected between July and September 1986, were measured by -ray spectrometry. High concentration of¹⁰³Ru,¹³⁴Cs and¹³⁷Cs were found in sewage sludge samples from Lower-Austria /Scheibbs, Zwettl/ and Styria /Eisenerz, Leoben/. the radioactivity concentration of¹³⁷Cs was two times higher than that of¹³⁴Cs. Following concentration values were found:¹⁰³Ru 0.1–63.0 nCi kg^–1,¹³⁴Cs 0.3–41.6 nCi kg^–1, and¹³⁷Cs 0.3–83.3 nCi kg^–1. The activity of these nuclides decreased from July 1986 to September 1986.