Purpose: The presented materials are devoted to the development of a methodology for rationing the impact of plutonium intake by the amount of annual excess risk, which should not exceed 1 ×10-3. It is shown that the existing approach to the rationing of plutonium by the expected effective dose does not reflect the actual levels of personnel exposure and, therefore, does not provide the necessary level of radiation safety at plutonium processing plants. Results: Using data from epidemiological surveillance of a cohort of employees of the Mayak software, an assessment of the excessive relative risk per unit dose of radiation exposure for each of the plutonium-239 deposition organs was performed in order to describe the dependence of mortality from lung, liver and skeletal cancer on the dose of alpha radiation of plutonium-239. Equivalent doses to plutonium deposit organs and the annual excess risk generated by these doses for various plutonium intake scenarios are calculated based on the results of monitoring the activity of plutonium in urine. When calculating the annual effective dose based on the results of monitoring the annual equivalent dose, it is necessary to take into account the dependence of the weighing coefficients for the plutonium deposit bodies on the age of the employee at which the exposure occurred, and when assessing the magnitude of the radiation risk, the dependence of the risk coefficient on age. Conclusion: The use of the annual excess risk value as a controlled and normalized indicator for the individual dosimetry control of internal radiation from the plutonium intake is the most correct. The proposed approach to rationing can be used for acute and chronic inhalation intake of plutonium, as well as for the intake of plutonium through damaged skin.

Purpose: Investigation of paramagnetic properties of radiation-induced centers that occur when hair samples are irradiated with ionizing radiation, depending on the color of the sample. Material and methods: A Bruker Elexsys E580 electron paramagnetic resonance spectrometer was used. To improve the signal-to-noise ratio, the spectrum was recorded with three accumulations with a constant scan time equal to one minute. Measurements were made using a highly sensitive rectangular Bruker SuperHighQ resonator. For irradiation of samples, the linear electron accelerator UELR-10-10С2 of the innovation and implementation center for radiation sterilization of the Urals Federal University (Institute of Physics and technology) was used. Results: Research of the EPR signal parameters of the melanin in hair samples of different colors (black, brown, red and gray with different degrees of pigmentation) showed that the intensity of the EPR signal varies depending on the hair color. The higher the radiation sensitivity of the hair, the lighter the color of the hair. The melanin signal, which is the background for the radiation-induced signal, increases with increasing intensity of hair color.

This article assesses the radiological environment at the nuclear site of the Mayak PA, Russian Federation, during and after the accident in 1957, the so-called 'Kyshtym Accident', and the radiation doses to those who participated in the eradication of its consequences. Based on numerous archival documents, this paper presents the radiation data for 1957-1960, including individual dosimetry monitoring data and estimated doses to the Mayak workers, as well as the to personnel in supporting organisations and the military involved in the remediation operations. From 1957-1959 some 38 500 individuals took part in the clean-up actions and remediation of contaminated areas of the Mayak PA industrial site after the accident, including individuals exposed at the time of the accident: Mayak PA employees, militarypersonnel, and civil construction workers. External equivalent doses to 10 500 individuals were estimated in the range of 220 to 265 mSv, while there were cases of doses up to 950 mSv and higher. The collective dose received during the accident and its aftermath was in the region of 7300 person-Sv. By October-December 1957, the collective dose was about 4500 person-Sv. Collective doses recorded in 1958 and 1959 amounted to 2250 person-Sv and 480 person-Sv, respectively.

Purpose: to assess the radiation situation on the industrial site of the PA “Mayak” during the accident in 1957 and the radiation doses of the participants in the liquidation of consequences of this accident. Materials and methods: on the basis of the archival documents analysis, radiation situation data for 1957 – 1960, IDC data and calculated doses of the Mayak workers, as well as supporting organizations personnel and military units involved in the liquidation of the accident consequences and covered by individual monitoring are presented. Results: in 1957 – 1959 about 38,5 thousand people took part in the works on the territory of the PA “Mayak” industrial site for liquidation of consequences of the accident, including persons exposed at the time of the accident: employees of “Mayak”, military and civil builders. Radiation doses from 25 to 30 R received about 10,5 thousand people, while there were single cases of exposure in doses up to 100 R. Conclusion: the collective dose received during the accident and liquidation of its consequences in 1957 was about 820 000 person-R. Collective doses recorded in 1958 and 1959 amounted to 250 000 person-R and 54 000 person-R, respectively.

Риск-ориентированный подход при контроле внутреннего облучения от поступления плутонияВасиленко Е.К., Аладова Е

Individual doses from external γ-rays were estimated using biological dosimetry based on limited samplings (n₁= 15 and n₂ 12 individuals) which comprised the Mayak workers group with acute radiation sickness (ARS). The following primary data were used for calculation as initial parameters: estimated dose from ex- ternal γ-rays based on physical dosimetry methods - D (Gy); time before first vomiting - T (h); number of lymphocytes in peripheral blood on a second day after acute radiation exposure - L (10⁹/1); number of neutrophils in blood during first hours after accidental radiation exposure - N(10⁹/). A number of mathe- matical models used for dose estimation were verified: power-law dependence of the absorbed dose from ex- ternal γ-rays (D) on time before first vomiting (7), exponential dependence of D on the number of lympho- cytes in peripheral blood (L), dependence of D on the number of neutrophils in peripheral blood (N) and complex models forD association with Tand L parameters as well as-with Tand Nparameters. The biological dosimetry technique based on a complex approach was shown to provide the best agreement with physical dosimetry methods for individual assessment of doses from external γ-rays.

Недостатки нормирования облучения при поступлении плутонияВасиленко Е.К

Aim of the study: Assessment of reliability of radiation safety standards after inhalation intake of Pu-239. Material and methods: Using results of epidemiological study of lung cancer mortality in Mayak workers cohort and statistical data on all causes and lung cancer mortality in Russia the excess lifetime risk of lung cancer death was calculated. Results: Current radiation safety standards restrict annual intake of Pu-239 class “S” at 1300 Bq/year level. The annual limit of intake is calculated in a way that the level of committed effective dose in 50 years after intake should not exceed 20 mSv. At the same time radiation safety standards restrict the level of the excess lifetime risk of cancer death at the level of 0.05 (for category A personnel) and/or annual increment of excess lifetime risk at the level 0.001. The equivalent dose of alpha-particles to the lung after 50 years of inhalation intake of Pu class “S” when calculated according to DOSE-2008 model will be 7 Sv. Given the pattern of dose accumulation over time after this scenario of Pu class “S” inhalation intake we calculated excess relative risk of lung cancer death, lifetime excess risk of lung cancer death and annual increment of excess lifetime risk. In 50 years of exposure to inhalation intake of Pu-239 class “S” the excess lifetime risk of lung cancer death will be 0.08, i.e. will exceed the 0.05 limit provided in radiation safety standards. The annual increment of the lifetime risk will exceed limit of 0.001, provided by the radiation safety standards, at age 45 and older. These results demonstrate that the protection of personnel working with Pu-239 class “S” is insufficient in current radiation safety standards. One of the potential reasons is that lung contribution to total detriment for organism provided by ionizing radiation is averaged for all ages whereas for people of working age who contact to Pu at work this detriment doubles.

In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960.

Workers at the Mayak nuclear facility in the Russian Federation offer a unique opportunity to evaluate health risks from exposure to inhaled plutonium. Risks of mortality from lung cancer, the most serious carcinogenic effect of plutonium, were evaluated in 14,621 Mayak workers who were hired in the period from 1948–1982, followed for at least 5 years, and either monitored for plutonium or never worked with plutonium. Over the follow-up period from 1953–2008, there were 486 deaths from lung cancer, 446 of them in men. In analyses that were adjusted for external radiation dose and smoking, the plutonium excess relative risk (ERR) per Gy declined with attained age and was higher for females than for males. The ERR per Gy for males at age 60 was 7.4 (95% CI: 5.0–11) while that for females was 24 (95% CI: 11–56). When analyses were restricted to plutonium doses <0.2 Gy, the ERR per Gy for males at age 60 was similar: 7.0 (95% CI: 2.5–13). Of the 486 lung cancer deaths, 105 (22%) were attributed to plutonium exposure and 29 (6%) to external exposure. Analyses of the 12,708 workers with information on smoking indicated that the relationship of plutonium exposure and smoking was likely sub-multiplicative (P = 0.011) and strongly indicated that it was super-additive (P < 0.001). Although extensive efforts have been made to improve plutonium dose estimates in this cohort, they are nevertheless subject to large uncertainties. Large bioassay measurement errors alone are likely to have resulted in serious underestimation of risks, whereas other sources of uncertainty may have biased results in ways that are difficult to predict.

The nuclear workers of the Mayak Production Association had regular check-ups including medical diagnostic X-ray examinations since start of the production lines in 1948. Doses from diagnostic examinations need to be considered in reconstruction of occupational doses of the workers with electron paramagnetic resonance (EPR) of tooth enamel. The numbers and types of examinations of an individual worker can be assessed from the Mayak PA archives but no information was available on doses delivered to teeth by a single specific examination. Of the twenty one applied examination procedures only three affected the teeth, these being X-ray examinations of teeth, skull and cervical spine. For these three kinds of examinations operational procedures and operating modes of X-ray units were compiled from the archive and photon spectra were obtained from a catalog of spectral data for diagnostic X-rays. Entrance doses in air kerma were calculated using the fluence of photon spectra and absorbed dose in tooth enamel for various tooth positions and exposure geometry was then calculated using dose conversion coefficients obtained from Monte Carlo simulations. Doses were calculated for examinations in 1948-2000. Except for examination of the skull, absorbed doses in enamel of incisors were found to be about twice as large as in enamel of molars. In the period before 1970 the largest mean absorbed doses in tooth enamel were due to X-ray examination of teeth, with 64 mGy and 34 mGy calculated for incisors and molars, respectively. In the same period the lowest mean doses were due to X-ray examination of the skull, with 11 mGy and 12 mGy calculated for incisors and molars, respectively. In the period from 1970 to 2000, largest mean doses in enamel were due to X-ray examination of cervical spine, with 23 mGy and 12 mGy calculated for incisors and molars, respectively. (C) 2011 Elsevier Ltd. All rights reserved.

Photon energy distributions were measured in different workplaces of the Mayak Production Association (MPA), which was the first plutonium production plant in the former Soviet Union. In situ gamma spectrometry measurements were performed with a portable germanium detector. The spectral stripping method is used for the conversion of the in situ gamma-ray spectra to photon fluence rate energy distribution. This method requires the simulation of the portable germanium detector, which has been performed based on the MCNP code of Los Alamos. Measured photon fluence rate energy distributions were compared with calculated photon energy distributions (with the MCNP code) in two different workplaces: in the first workplace the geometry exposure was known. On the contrary, in the second workplace, as in most workplaces of MPA, the exposure geometry was unknown. The results obtained from the comparison between the experimental and calculated photon fluence rate energy distributions are presented and discussed.

Workers at the Mayak nuclear facility in the Russian Federation offer the only adequate human data for evaluating cancer risks from exposure to plutonium. Risks of mortality from cancers of the lung, liver and bone, the organs receiving the largest doses from plutonium, were evaluated in a cohort of 17,740 workers initially hired 1948‐1972 using, for the first time, recently improved individual organ dose estimates. Excess relative risk (ERR) models were used to evaluate risks as functions of internal (plutonium) dose, external (primarily gamma) dose, gender, attained age and smoking. By December 31, 2003, 681 lung cancer deaths, 75 liver cancer deaths and 30 bone cancer deaths had occurred. Of these 786 deaths, 239 (30%) were attributed to plutonium exposure. Significant plutonium dose‐response relationships ( p < 0.001) were observed for all 3 endpoints, with lung and liver cancer risks reasonably described by linear functions. At attained age 60, the ERRs per Gy for lung cancer were 7.1 for males and 15 for females; the averaged‐attained age ERRs for liver cancer were 2.6 and 29 for males and females, respectively; those for bone cancer were 0.76 and 3.4. This study is the first to present and compare dose‐response analyses for cancers of all 3 organs. The unique Mayak cohort with its high exposures and well characterized doses has allowed quantification of the plutonium dose‐response for lung, liver and bone cancer risks based on direct human data. These results will play an important role in plutonium risk assessment. Published 2008 Wiley‐Liss, Inc.