Search results for "RADIOCHEMISTRY"
showing 10 items of 273 documents
Tritium release from breeding blanket materials in high magnetic field
2007
Abstract Under the operating conditions of a fusion reactor, the blanket materials: ceramic and Be pebbles will be at a high temperature (up to 1123 K), under action of intense radiation (up to 10 19 n m −2 s −1 ) and magnetic field (MF) up to 7–10 T. In order to introduce action of radiation and MF in post-irradiation investigations of the tritium release from the blanket materials, a special rig for thermo-annealing of pre-irradiated samples at a high temperature up to 1120 K under irradiation with fast electrons of 5 MeV and dose rate 14 MGy/h in MF up to 1.7 T was used for this study. A delay of the tritium release in MF of 2.4 T at thermo-annealing of the lithium orthosilicate Li 4 S…
Application of the ESR spectrometry to evaluate the original dose in irradiated dried fruit
2008
The identification of irradiated dried fruit can be achieved by means of the electron spin resonance (ESR) spectrometry, as recommended by the European Community, since ionizing radiation induces free radicals in cellulose, a constituent of the shell. The aim of this work was to use the ESR spectrometry also as a quantitative procedure to evaluate the original dose in irradiated dried fruits, using the additive dose method. Little shell pieces, taken from nuts, chestnuts, peanuts and pistachios, were irradiated at original dose values in the range 1 to 8 kGy, and the ESR signal intensity was measured. Each specimen was then reirradiated with added doses of 1 kGy, and the ESR signal was me…
Response charactterization of ammonium tartrate solid state pellets for ESR dosimetry with radiotherapeutic photon and electron beams.
2001
Solid state pellets (1 mm thick) for electron spin resonance (ESR) dosimetry were made using ammonium tartrate as the radiation-sensitive substance. Their behaviour was experimentally investigated as a function of dose with 60Co gamma rays. The calibration function obtained permits measurements of absorbed dose in the 2-50 Gy range, with a combined uncertainty of +/-4%. The lowest detectable dose was about 0.5 Gy. These properties are comparable with or even better than those of ESR dosimeters made from other materials. The time stability of the ESR signal of ammonium tartrate dosimeters at different storage conditions after irradiation was studied. A rather complex behaviour was observed, …
Experiments on tritium generation and yield from lithium ceramics during neutron irradiation
2021
Abstract The vacuum extraction method with a mass spectrometry registration of tritium is presented in paper. It can provide a full-range analysis of gas phase composition in the chamber with samples under neutron irradiation. Lithium ceramics Li2TiO3 in the form of pebbles with lithium enrichment on 6Li isotope of 96% was examined. The paper shows the results of reactor experiments on study the extraction of tritium-containing molecules from lithium ceramics Li2TiO3 at various temperatures and reactor power levels at the WWR-K research reactor (Almaty, Kazakhstan). The time dependences of tritium yield from the ampoule with ceramics during reactor irradiation were obtained. Near-surface co…
Self radiolysis of tritiated water
2003
The mechanism of water radiolysis implies several reactions and depends on many parameters such as the radiation characteristics (type of radiation, energy…), the temperature and the chemical composition of irradiate water. Thus it is very difficult to foresee, without experimental data, the overall effect of these parameters. If radiolysis of pure water under γ rays or α particles has been widely studied, it is not the case for self radiolysis of tritiated water (low energy β− particles radiation). In order to fill this lack of experimental knowledge and to understand the radiolysis of stored tritiated water produced in tritium plants, we studied the evolution of hydrogen and oxygen concen…
Trace detection of radiotoxic isotopes by resonance ionization mass spectrometry
1995
Resonance ionization spectroscopy combined with mass spectrometry (RIMS) has become an important technique for ultratrace environmental analysis, and is particularly well suited for the detection of long-lived radio-toxic isotopes. A variety of experimental approaches have been developed to address the specific requirements posed by individual isotopes, which have widely differing physical, chemical, and environmental properties. In this paper we discuss the principles and recent progress in the development of three different methods that are being used for the analysis of radiotoxic species. These include measurement of actinides using triple-resonance ionization and time-of-flight mass sp…
Thermoluminescence study of irradiated lithium orthosilicate
1998
Abstract The thermoluminescental investigations of neutron and gamma irradiated lithium orthosilicate pellets were carried out. It has been shown that the addition of Cr 3+ and Fe 3+ ions with the total concentration up to 2.0 wt.% during preparation of lithium orthosilicate pellets, significantly reduces the formation of radiation defects in irradiated matrix. This phenomena can be explained by the reducing of the formation of primary radiation defects during irradiation due to stimulating the recombination processes by the ions of impurities. Several ion concentration combinations were studied. The thermoluminescental investigations of fast neutron irradiated lithium orthosilicate pellets…
Study of tritium and helium generation and release from lead-lithium eutectics Li15.7Pb under neutron irradiation
2019
Abstract This paper describes the experiments on study of tritium and helium generation and release processes from lead-lithium eutectics Li15.7Pb. The irradiation was performed at the IVG.1M research reactor at 6 MW of thermal power. The irradiation temperature increased step by step from 225 to 550 °C. A qualitative assessment of the experimental results showed that as the temperature rises above 390 °C, the tritium flux from the sample consisting of T2 and HT molecules decreases. It was concluded that the observed effect is similar to the previously observed one for lead-lithium eutectics with Li17Pb83 composition.
Effects of external energetic factors on tritium release from the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles
2009
Abstract Tritium release from samples of 9–13 mg of the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles under the separate and simultaneous action of temperature 490–770 K, 5 MeV fast-electron radiation 14 MGy h−1 for 3 h and magnetic field (MF) of 1.7 T was investigated. The pebbles were found to be very dissimilar with respect to their total tritium content—2.5–9 MBq g−1. The batch contained also some coarse agglomerates of the pebbles containing 10–19 MBq g−1 of tritium having also a high tritium release. For the pebbles having the total tritium 2.5–5.3 MBq g−1, the electron radiation for 3 h caused the fractional tritium release 17–26% (B = 0) and 21–29% (B = 1.7 T), the temperature …
Simple Solution for Single Final Vial Filling of Ga-68 Radiopharmaceuticals in One Hot Cell Isolator at Small-Scale Radiopharmacy Laboratories under …
2020
A simple solution for fulfilling biosafety and national drug agency demands of radiation and biosafety during Ga-68 radionuclide containing radiopharmaceutical production (RP) by small scale laboratories has been demonstrated based on a novel sterile seal concept of multi-layer bag system prototype. These mid-and inner enclosures of the prototype with vial inside were sterilized by 50 kGy of gamma radiation. The microbial safety validation based on two-week testing confirmed successful sterilization of the sealing bags with vails. The analysis of physicochemical properties, namely mechanical properties, gel fraction studies revealed that sterilization did not cause any undesired changes in …