[en] Moessbauer Effect (ME) of compounds like (C_nH₂N₊₁NH₃)₂ -Fe(Π)CL₄ and (CH₂)₆(NH₃)₂Fe(Π)CL₄ have been measured. The results indicate a conted spin antiferromagnet, with transition temperatures and magnetic field strengths according to value of n. Dielectric constant measurements of the above compounds as afunction of temperatures at different selected frequencies also have been carried out. The results confirm existence of structural phase transition shown by Me. (Author's) 10 refs., 6 figs., 1 tab

[en] In this report three different methods of neutron activation analysis applied to the determination of up to 20 trace elements in Egyptian rock samples and the results obtained are discussed. In Part I a physical approach is described for instrumental multielement activation analysis with whole neutron spectrum (without Cd-cover) using the monostandard (single comparator) method. 15 Samples representing different Egyptian granite rocks were analyzed. As many as 21 trace elements beside Fe, K and Na were determined. The accuracy of the method for nondestructive multielement analysis agrees within 3% with the relative method using multielement standards. In Part II a method is described for epithermal neutron activation analysis of 20 elements in granite rock samples using only one standard. Gold has been used as a single comparator due to its relatively high resonance integral value (I_o = 400) and in addition, it is preferable on Co in order to obtain a large epithermal activation in a short irradiation. The method of calculation is simple and rapid and can be done using small calculator. In Part III experiments are described in which a neutron capture gamma-ray spectroscopy facility assembled at the Institute of Radiochemistry, KfK (for analytical purposes) using Cf²⁵² neutron source of strength ∝ 6x10⁷ n/sec, has been used to check its applicability and sensitivity for quantitative analyses of ores. The analysis of Sm, Gd and Mn in phosphate and monazite rock samples has been carried out. The results from this study show a variation of about 25% from the values determined by RNAA method. The reasons for this discrepancy are discussed and suggestions are made to optimize the conditions of measurement and irradiation. (orig./RB)

[en] It is very important to calculate the radioactivity concentration for low-grade monazite ore (50%) and different other materials produced as results of chemical processing stages to avoid the risk to workers. Chemical processing of low-grade monazite pass through different stages, washing by hydrochloric acid and digested with sulfuric acid and influence of pH on the precipitation of rare earth elements has been studied. The radioactivity concentrations of ²³⁸U(²²⁶Ra) and ²³²Th as well as ⁴⁰K were calculated in crude low-grade ore and found to be 54,435 ± 3138, 442,105 ± 29,200 and 5841 ± 345 Bq/kg, respectively. These values are greatly higher than the exempt levels 25 Bq/kg. After chemical digestion of the ore, the results demonstrated that un-reacted material contains significant radioactivity reached to approximately 8, 13 and 23% for ²³⁸U, ²³²Th and ⁴⁰K, respectively. The results show that 60% of ²³²Th are located in the digested white slurry with small portions of ²³⁸U and ⁴⁰K. Most of ²³⁸U radioactivity is extracted in the green phosphoric acid which produced from conversion of P₂O₅ by H₂SO₄ into phosphoric acid. The average values of the Ra_eq for monazite ore, un-reacted black precipitate, white precipitate, brown precipitate and crystalline material samples were calculated and found to be 687,095 ± 44,921, 85,068 ± 5339, 388,381 ± 22,088, 313,046 ± 17,923 and 4531 ± 338 Bq/kg, respectively. The calculated values of Ra_eq are higher than the average world value (it must be less than 370 Bq/kg). Finally the external hazardous, internal hazardous and I_γr must be less than unity. This means that specific radiation protection program must be applied and implemented during monazite processing. - Highlights: • Egyptian monazite material has been contained a high concentrations of ²³⁸U, ²³²Th and their daughters during decay series. • Radiation hazards indices and environmental impact of low grade monazite processing stages have been evaluated. • Chemical processing of low-grade monazite ore have been generated radiation exposure levels was explored. • Regular monitoring during routine operation of monazite processing is highly recommended to protect the workers.

[en] Prompt gamma-rays from thermal induced nuclear reactions have been used to estimate the boron, chlorine and phosphorus contents in industrial and reference materials. A neutron capture gamma-ray spectroscopy facility for analytical purposes using 252-Cf sources has been designed and calibrated. The facility is principally designed for the measurement of the prompt gamma-ray spectra obtained due to thermal neutron capture by means of the internal target geometry. The capture spectra were recorded using a high resolution Ge(Li) system. The designed facility and the system used in this work are described in detail. A weight of 50 to 100 gm of each sample in a power or liquid form encapsulated in a polyethene container was used. Sensitivity curves using different standard concentration values of B, Cl and P, were constructed. The concentration range was from 0.005 to 30%. (orig.)

[en] Removal of radionuclides from wastewater before discharging to environment is necessary for the safety of living beings. Activated carbon prepared from doum stone (DS), an agricultural waste by-product, has been used for the sorption of ⁶⁰Co and ^152+154Eu radionuclides from aqueous solutions. DS has been characterized by different analytical tools. The efficiency of the adsorbent was investigated using batch sorption technique under different experimental conditions. The equilibrium sorption data were analyzed using Freundlich and Langmuir isotherm models. The kinetic experimental data were analyzed using four kinetic models including pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion model to examine the mechanism of sorption and potential rate-controlling step. The maximum capacity of DS was found to be 121 mg/g and 166 mg/g for cobalt and europium, respectively. Sorption efficiency of DS to remove ⁶⁰Co, ^152+154Eu and ¹³⁴Cs from real radioactive wastewater and environmental (river water and sea water) samples was also investigated. The results revealed that the prepared DS as low cost could be used as a promising material for the simultaneous removal of different radionuclides such as ⁶⁰Co, ^152+154Eu and ¹³⁴Cs, or trivalent actinides such as ^{241, 242m,243}Am from real radioactive waste and environmental water samples. - Highlights: • Activated carbon was produced from doum stone (DS) by chemical activation. • H₃PO₄ activated carbon is characterized by different analytical tools. • The prepared adsorbent was successfully applied to simultaneous remove the long-lived ⁶⁰Co, ^152+154Eu and ¹³⁴Cs radionuclides from real radioactive liquid waste and environmental samples from river and sea water.

[en] The uncontrolled spread out of radioiodine (especially "1"3"1I) produced from nuclear activities or accidents, due to its high volatility, to the biosphere represents an environmental impact because of its concentration in the thyroid gland and accumulation on soil surface. This work represents a simple method for isolation of radioiodine from aqueous solution in the form of insoluble solid compound and further recovery of it in aqueous phase for any further controlled use. Crystalline silver chloride was prepared and characterized. Batch sorption of "1"3"1I onto the prepared AgCl was studied from different aqueous media (H_2O and NaOH of different concentrations) and at different I"−:Ag molar ratios (from alkaline media) for different times at 25 °C. It was found that the sorption yield of "1"3"1I from 2.5 M NaOH solution (at I"−:Ag and S_2O_3"2"−:I"− molar ratios of 0.025 and 2, respectively) reached 97.7% after 6 h and only slightly increased to 98.6% after 16 h of contact time. The presence of H_2O_2 adversely affected the batch sorption process. The included REDOX and precipitation reactions were discussed. Batch desorption of the sorbed "1"3"1I from AgCl into aqueous phase was studied with NaOCl solutions of different concentrations and different contact times at 25 °C. Desorption yield of "1"3"1I was found to be 94.5% with 10 mL of 0.5 M NaOCl solution after contact time of 16 h. Kinetic analysis has been performed for both batch sorption and desorption processes. - Highlights: • Crystalline AgCl was prepared via a simple method and characterized. • Batch sorption and desorption of "1"3"1I onto and from AgCl particles was studied. • Kinetic analysis was conducted for both sorption and desorption processes.

[en] Ga, In, Pb doped and undoped samples of CdTe have been prepared using the THM technique. The dielectric measurements showed that K^', tan δ, R_xp and σ_ac are thermally activated properties. It is found that the regular band type conduction is contributing to the conduction mechanism. The role of dopant was found to lower the value of the activation energy for loss mechanism, which is the dominant mechanism to the observed complex permittivity and also for ac conduction. (author)

[en] The feasibility of using surfactants as extracting agent for the removal of radium species from TENORM sludge produced from petroleum industry is evaluated. In this investigation cationic and nonionic surfactants were used as extracting agents for the removal of radium radionuclides from the sludge waste. Two surfactants namely cetyltrimethylammonium bromide (CTAB) and Triton X-100 (TX100) were investigated as the extracting agents. Different parameters affecting the removal of both "2"2"6Ra and "2"2"8Ra by the two surfactants as well as their admixture were studied by the batch technique. These parameters include effect of shaking time, surfactants concentration and temperature as well as the effect of surfactants admixture. It was found that, higher solution temperature improves the removal efficiency of radium species. Combined extraction of nonionic and cationic surfactants produces synergistic effect in removal both "2"2"6Ra and "2"2"8Ra, where the removals reached 84% and 80% for "2"2"6Ra and "2"2"8Ra, respectively, were obtained using surfactants admixture. - Highlights: • Novel approach of chemical treatment of TENORM was studied. • Significant level of "2"2"6Ra and "2"2"8Ra is found in sludge waste. • Preliminary study of removal "2"2"6Ra and "2"2"8Ra from TENORM was studied

[en] Nuclear medicine facilities are considered one of the most important practices associated with potential radiological risks to personnel and the environment due to the significant amounts of solid and liquid radioactive waste generated from these facilities. Whenever possible and applicable, the licensee shall apply the most up-to-date technological advances to ensure that such radioactive waste is safely discharged to the public sewage. To date, there is no specific technical safety requirement endorsed by regulatory body in Egypt regarding drainage system design for nuclear medicine facilities. This paper discusses the design, commissioning and operation of a programmable drainage system in a Positron Emission Tomography/Computed Tomography (PET-CT) unit for collecting and draining sewage contaminated with the radioactive isotope ¹⁸F. The system operates automatically without the need for human intervention. The system has been tested using clean water and found to be working efficiently in accordance with the design parameters. The proposed system concept can be applied in other nuclear medicine facilities after scaling it up/down according to all radionuclides in use and the expected volume of associated radioactive waste. Based on the system's demonstrated performance, regulatory bodies are highly recommended to embrace such approach as a safety requirement to assist the licensees in complying with the safety standards during the planning and construction of PET-CT facilities. (authors)

[en] A physical approach is described for instrumental multielement activation analysis with whole neutron spectrum (without Cd-cover) using the monostandard (single comparator) method. To test the capabilities of this method, 15 samples representing different Egyiptian granite rocks were analyzed. As many as 21 trace elements beside Fe, K and Na were determined. Calculation of the experimental data was carried out using the 'Gamma-Monostandard Analysis' program. The accuracy of the method for nondestructive multielement analysis agrees within 3% with the relative method using multielement standards. (author)