2013, volume 9

The aim: justification of criteria for making decision on possibility of the regenerated fuel use in operating productions. Hygienic criteria have been formulated to be guided in order to make a decision on possibility and suitability to carry out planned change of technology at the enterprises of the nuclear fuel circle, its reconstruction, change the line of business, as well as usage of raw materials with worse characteristics.

This article contains the current situation in respect to the environmental concentrations of anthropogenic and natural tritium. There are presented and analyzed domestic standards for НТО of all Radiation Safety Standards (NRB), as well as the regulations analyzed for tritium in drinking water taken in other countries today. This article deals with the experience of limitation of tritium and focuses on the main problem of rationing of tritium — rationing of organically bound tritium.

Nuclear heritage are the objects of defense industry complex which aren't meeting modern requirements of nuclear and radiation safety, and also the territories polluted owing to previous nuclear activity and production of uranium. The main existing problem consists in the absence in the current legislation of complex standard and legal bases of activity on questions of the address with the nuclear heritage, the principles providing realization directed on prevention of harmful effects of objects of such heritage on the person and environment, decrease of burden on the subsequent generations.

Assessment of committed effective dose and the uncertainty of its calculation for different variants of 3H intake: 1) homogeneous and chronic, 2) single, is considered by the example of internal tritium doses that workers had got. It has been shown that in case of conditional measurement of 3H concentration in urine sample the estimate of tritium dose may vary within two orders of magnitude in the 95% confidence interval. The most effective way to reduce the range of uncertainty of dose estimation is to replace a quarterly monitoring with a monthly one. It leads to reduction of the range of uncertainty by one order of magnitude.

To perform biomedical full-scale investigation there had been developed a set of microscopic analysis of histologi-cal preparations. This complex includes cryotome for histological sections, a set of chemical reagents and laboratory glassware for staining, binocular loupes for registration microstructural changes, a microscope with a camera and lighting system on swivel stand, modernized otoscope, a laptop with graphics programs. The complex provides quantitative indicators needed to diagnose the severity and probability estimates of the effect estimation of impacts of extreme factors of different nature.

It is known that after the Chernobyl accident on the territories with deposition density of 137Cs less than 3.7x10" Bq/kg insufficient number of direct thyroid measurements for the public and a limited number of the spectrometrical measurements of 131l in soil were conducted. At the same time, in the case of availability of representative number of the estimates of the 131l ground deposition density for the territory under consideration, reliable estimates of the average dose to the thyroid for the public in a given settlement can be derived, for example for an adult population with further assessment of the doses for the residents of the other age-groups. In this regard, reconstruction of the ground deposition density of 131l (during the significant period of thyroid dose formation) on the basis of the determination of the ground deposition density of 129l is very helpful for reconstruction of the estimates of the thyroid dose for the residents of the settlements, for which the estimates of the 137Cs deposition density are available. However, to find a solution was necessary to resolve a specific but important task that distinguished from 129l (half-life is equal to 1.6x107 years) the level of 131l (half-life is equal to 8.04 days) was substantially decreasing during the period of thyroid dose formation. The
given article aimed a justification of approaches to account of radioactive decay of 131l in the course of determination of its ground deposition density on the basis of determination of the ground deposition density of 129l at the late stage after the accident.

In an overview and analytical study of the epidemiological data on the frequency of RET/РТС gene rearrangements in sporadic and radiogenic (patients after radiotherapy, residents of contaminated after the Chernobyl disaster areas, victims after the atomic bombings, etc.) carcinomas of the thyroid gland were examined. In general, the observed epidemiological laws were confirmed in radiobiology experiments by irradiation of different cultures of thyroid cells and ex vivo with the exception of Chernobyl cohorts. Induction of RET/РТС gene rearrangements by 131l exposure in children carcinomas of Chernobyl residents in mice did not observe too. It is concluded that the situation with the frequency of RET/РТС rearrangements in thyroid carcinoma in Chernobyl cohorts once again confirms the multifactorial nature of the induction and development of these tumors with a contribution of radiation and non-radiation factors (iodine deficiency and different stresses).

Aim: to compare the amount of DNA single-strand breaks (SSB) and alkali-labile sites (ALS) induced by DNA 365 nm ultraviolet (UV) versus X-rays radiation in human peripheral blood lymphocytes at in vitro conditions. Material and methods. Blood lymphocytes were isolated in a Ficoll-verografin density gradient. Irradiation of cells was performed using BLX-365 UV-unit (wavelength 365 ± 10nm)and RUSTM1 biological X-ray unit. Analysis of DNA SSB and ALS was carried out using comet assay at alkaline conditions. Results. For the first time it was demonstrated that the amount of SSB and ALS induced by 365 nm UV radiation at a dose of 10 kJ/m2 in human lymphocytes corresponds to the effect of X-rays at a dose of- 1 Gy. Conclusion. Exposure of human peripheral blood lymphocytes to 365 nm UV radiation at a dose of 1 kJ/m2 induces - 100 DNA SSB per cell.

Aim: to study the patterns of changes in the number of DNA double-strand breaks (DSB) in mammalian cells continuously exposed to low dose-rate y- radiation. Material and methods. Chinese hamster lung fibroblasts (V79) were used in this study. The y- irradiation of cells at a dose rate of 0.1 mGy/min was performed using the «Gamma-Panorama» unit (Cs-137). The fluorescence immunoassay of the phosphorylated H2AX-histone (y-H2AX) foci was used to investigate the DNA DSBs formation. Frequency of apoptotic cells was evaluated using «DNA halo» assay. 5 (6) — chloromethyl-2,7-dichlorodihydrofluorescein diacetate was used to estimate the reactive oxygen species (ROS) production. Results, it was showed that continuous low dose-rate irradiation of Chinese hamster V79 cells induces an increase of the y-H2AX foci number and ROS production rate at the early stages of exposure time (6-24 h, doses 3.6-14.4 cGy), while increasing exposition time and, therefore, the radiation dose (48-72 h, 28.8-43.2 cGy) caused a decrease in these endpoints to almost the control level. There was observed no significant changes in the frequency of apoptotic cells. Conclusion. It is assumed that the processes causing the DSB amount changes in mammalian cells continuously exposed to low dose-rate y-radiation are associated with the development of oxidative stress and subsequent activation of cellular antioxidant defense systems.

This article presents an analysis of the data published in connection with the problem of forecast of the development risk of diseases by chromosome aberration frequencies in cultures of human peripheral blood lymphocytes. In the last twenty years evidence of the possibility of such forecast for malignant disease was appeared when in the whole cytogenetic indices did not exceed control values. At the same time there are significant uncertainties due to interindi-vidual and intraindividual variability. In addition there are significant difficulties of distinction of chromosome aberrations induced by environmental influences and caused by internal processes in the body.